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+Project Gutenberg's Electricity for the farm, by Frederick Irving Anderson
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Electricity for the farm
+       Light, heat and power by inexpensive methods from the water
+       wheel or farm engine
+
+Author: Frederick Irving Anderson
+
+Release Date: November 14, 2008 [EBook #27257]
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THIS PROJECT GUTENBERG EBOOK ELECTRICITY FOR THE FARM ***
+
+
+
+
+Produced by Stacy Brown, Marcia Brooks, Steven Giacomelli
+and the Online Distributed Proofreading Team at
+https://www.pgdp.net (This file was produced from images
+produced by Core Historical Literature in Agriculture
+(CHLA), Cornell University)
+
+
+
+
+
+
+
+
+
+ELECTRICITY FOR THE FARM
+
+
+THE MACMILLAN COMPANY
+
+NEW YORK · BOSTON · CHICAGO · DALLAS
+ATLANTA · SAN FRANCISCO
+
+MACMILLAN & CO., Limited
+LONDON · BOMBAY · CALCUTTA · MELBOURNE
+
+THE MACMILLAN CO. OF CANADA, Ltd.
+TORONTO
+
+
+
+
+[Illustration: Even the tiny trout brook becomes a thing of utility
+as well as of joy
+
+(_Courtesy of the Fitz Water Wheel Company, Hanover, Pa._)]
+
+
+
+
+ELECTRICITY FOR
+THE FARM
+
+
+LIGHT, HEAT AND POWER BY INEXPENSIVE
+METHODS FROM THE WATER
+WHEEL OR FARM ENGINE
+
+
+BY
+FREDERICK IRVING ANDERSON
+
+AUTHOR OF "THE FARMER OF TO-MORROW," ETC., ETC.
+
+
+  New York
+  THE MACMILLAN COMPANY
+  1915
+
+_All rights reserved_
+
+
+
+
+  Copyright, 1915
+  By THE CURTIS PUBLISHING COMPANY
+  The Country Gentleman
+
+
+  Copyright, 1915
+  By THE MACMILLAN COMPANY
+  Set up and electrotyped. Published April, 1915.
+
+
+
+
+PREFACE
+
+
+This book is designed primarily to give the farmer a practical working
+knowledge of electricity for use as light, heat, and power on the
+farm. The electric generator, the dynamo, is explained in detail; and
+there are chapters on electric transmission and house-wiring, by which
+the farm mechanic is enabled to install his own plant without the aid
+and expense of an expert.
+
+With modern appliances, within the means of the average farmer, the
+generation of electricity, with its unique conveniences, becomes
+automatic, provided some dependable source of power is to be had--such
+as a water wheel, gasoline (or other form of internal combustion)
+engine, or the ordinary windmill. The water wheel is the ideal prime
+mover for the dynamo in isolated plants. Since water-power is running
+to waste on tens of thousands of our farms throughout the country,
+several chapters are devoted to this phase of the subject: these
+include descriptions and working diagrams of weirs and other simple
+devices for measuring the flow of streams; there are tables and
+formulas by which any one, with a knowledge of simple arithmetic, may
+determine the power to be had from falling water under given
+conditions; and in addition, there are diagrams showing in general the
+method of construction of dams, bulkheads, races, flumes, etc., from
+materials usually to be found on a farm. The tiny unconsidered brook
+that waters the farm pasture frequently possesses power enough to
+supply the farmstead with clean, cool, safe light in place of the
+dangerous, inconvenient oil lamp; a small stream capable of developing
+from twenty-five to fifty horsepower will supply a farmer (at
+practically no expense beyond the original cost of installation) not
+only with light, but with power for even the heavier farm operations,
+as threshing; and in addition will do the washing, ironing, and
+cooking, and at the same time keep the house warm in the coldest
+weather. Less than one horsepower of energy will light the farmstead;
+less than five horsepower of energy will provide light and small
+power, and take the drudgery out of the kitchen.
+
+For those not fortunate enough to possess water-power which can be
+developed, there are chapters on the use of the farm gasoline engine
+and windmill, in connection with the modern storage battery, as
+sources of electric current.
+
+It is desired to make acknowledgment for illustrations and assistance
+in gathering material for the book, to the editors of _The Country
+Gentleman_, Philadelphia, Pa.; The Crocker-Wheeler Company, Ampere, N.
+J.; The General Electric Company, Schenectady, N. Y.; the Weston
+Electrical Instrument Company, of Newark, N. J.; The Chase Turbine
+Manufacturing Company, Orange, Mass.; the C. P. Bradway Machine Works,
+West Stafford, Conn.; The Pelton Water Wheel Company, San Francisco
+and New York; the Ward Leonard Manufacturing Company, Bronxville, N.
+Y.; The Fairbanks, Morse Company, Chicago; and the Fitz Water Wheel
+Company, Hanover, Pa.
+
+
+
+
+TABLE OF CONTENTS
+
+
+                                                             PAGE
+
+  INTRODUCTION                                               xvii
+
+
+  PART I
+
+  WATER-POWER
+
+
+  CHAPTER I
+
+  A WORKING PLANT
+
+  The "agriculturist"--An old chair factory--A neighbor's
+  home-coming--The idle wheel in commission again--Light,
+  heat and power for nothing--Advantages
+  of electricity                                                3
+
+
+  CHAPTER II
+
+  A LITTLE PROSPECTING
+
+  Small amount of water required for an electric
+  plant--Exploring, on a dull day--A rough and ready
+  weir--What a little water will do--The water wheel
+  and the dynamo--Electricity consumed the instant
+  it is produced--The price of the average small
+  plant, not counting labor                                    22
+
+
+  CHAPTER III
+
+  HOW TO MEASURE WATER-POWER
+
+  What is a horsepower?--How the Carthaginians
+  manufactured horsepower--All that goes up must come
+  down--How the sun lifts water up for us to
+  use--Water the ideal power for generating
+  electricity--The weir--Table for estimating
+  flow of streams with a weir--Another method of
+  measuring--Figuring water horsepower--The size
+  of the wheel--What head is required--Quantity of
+  water necessary                                              32
+
+
+  CHAPTER IV
+
+  THE WATER WHEEL AND HOW TO INSTALL IT
+
+  Different types of water wheels--The impulse and the
+  reaction wheels--The impulse wheel adapted to
+  high heads and small amount of water--Pipe lines--Table
+  of resistance in pipes--Advantages and disadvantages
+  of the impulse wheel--Other forms
+  of impulse wheels--The reaction turbine, suited to
+  low heads and large quantity of water--Its advantages
+  and limitations--Developing a water-power
+  project: the dam; the race; the flume; the penstock;
+  and the tailrace--Water rights for the farmer                56
+
+
+  PART II
+
+  ELECTRICITY
+
+
+  CHAPTER V
+
+  THE DYNAMO; WHAT IT DOES, AND HOW
+
+  Electricity compared to the heat and light of the
+  Sun--The simple dynamo--The amount of electric energy
+  a dynamo will generate--The modern dynamo--Measuring
+  power in terms of electricity--The volt--The
+  ampere--The ohm--The watt and the kilowatt--Ohm's
+  Law of the electric circuit, and some
+  examples of its application--Direct current, and
+  alternating current--Three types of direct-current
+  dynamos: series, shunt, and compound                         89
+
+
+  CHAPTER VI
+
+  WHAT SIZE PLANT TO INSTALL
+
+  The farmer's wife his partner--Little and big
+  plants--Limiting factors--Fluctuations in water
+  supply--The average plant--The actual plant--Amount
+  of current required for various operations--Standard
+  voltage--A specimen allowance for electric
+  light--Heating and cooking by electricity--Electric
+  power: the electric motor                                   121
+
+
+  CHAPTER VII
+
+  TRANSMISSION LINES
+
+  Copper wire--Setting of poles--Loss of power in
+  transmission--Ohm's Law and examples of how it is
+  used in figuring size of wire--Copper-wire
+  tables--Examples of transmission lines--When to
+  use high voltages--Over-compounding a dynamo to
+  overcome transmission loss                                  153
+
+
+  CHAPTER VIII
+
+  WIRING THE HOUSE
+
+  The insurance code--Different kinds of wiring
+  described--Wooden moulding cheap and effective--The
+  distributing panel--Branch circuits--Protecting the
+  circuits--The use of porcelain tubes and other
+  insulating devices--Putting up chandeliers and
+  wall-brackets--"Multiple" connections--How to connect
+  a wall switch--Special wiring required for heat and
+  power circuits--Knob and cleat wiring, its advantages
+  and disadvantages                                           172
+
+
+  CHAPTER IX
+
+  THE ELECTRIC PLANT AT WORK
+
+  Direct-connected generating sets--Belt drive--The
+  switchboard--Governors and voltage regulators--Methods
+  of achieving constant pressure at all loads:
+  Over-compounding the dynamo; A system of resistances
+  (a home-made electric radiator); Regulating
+  voltage by means of the rheostat--Automatic
+  devices--Putting the plant in operation                     192
+
+
+  PART III
+
+  GASOLINE ENGINES, WINDMILLS, ETC.
+  THE STORAGE BATTERIES
+
+
+  CHAPTER X
+
+  GASOLINE ENGINE PLANTS
+
+  The standard voltage set--Two-cycle and four-cycle
+  gasoline engines--Horsepower, and fuel
+  consumption--Efficiency of small engines and
+  generators--Cost of operating a one-kilowatt plant          217
+
+
+  CHAPTER XI
+
+  THE STORAGE BATTERY
+
+  What a storage battery does--The lead battery and the
+  Edison battery--Economy of tungsten lamps for
+  storage batteries--The low-voltage battery for
+  electric light--How to figure the capacity of a
+  battery--Table of light requirements for a farm
+  house--Watt-hours and lamp-hours--The cost of storage
+  battery current--How to charge a storage
+  battery--Care of storage batteries                          229
+
+
+  CHAPTER XII
+
+  BATTERY CHARGING DEVICES
+
+  The automatic plant most desirable--How an automobile
+  lighting and starting system works--How the same
+  results can be achieved in house lighting, by means
+  of automatic devices--Plants without automatic
+  regulation--Care necessary--The use of heating devices
+  on storage battery current--Portable batteries--An
+  electricity "route"--Automobile power for
+  lighting a few lamps                                        250
+
+
+
+
+ILLUSTRATIONS
+
+
+  Even the tiny trout brook becomes a thing of utility as
+  well as of joy                                   _Frontispiece_
+
+  Farm labor and materials built this crib and stone dam       17
+
+  Measuring a small stream with a weir                         23
+
+  Efficient modern adaptations of the archaic undershot
+  and overshot water wheels                                    59
+
+  A direct-current dynamo or motor, showing details of
+  construction                                                 92
+
+  Details of voltmeter or ammeter                             128
+
+  Instantaneous photograph of high-pressure water jet being
+  quenched by buckets of a tangential wheel                   194
+
+  A tangential wheel, and a dynamo keyed to the same
+  shaft--the ideal method for generating electricity          194
+
+  A rough-and-ready farm electric plant, supplying two
+  farms with light, heat and power; and a Ward
+  Leonard-type circuit breaker for charging storage
+  batteries                                                   244
+
+
+
+
+INTRODUCTION
+
+
+The sight of a dozen or so fat young horses and mares feeding and
+frolicking on the wild range of the Southwest would probably inspire
+the average farmer as an awful example of horsepower running to waste.
+If, by some miracle, he came on such a sight in his own pastures, he
+would probably consume much time practising the impossible art of
+"creasing" the wild creatures with a rifle bullet--after the style of
+Kit Carson and other free rovers of the old prairies when they were in
+need of a new mount. He would probably spend uncounted hours behind
+the barn learning to throw a lariat; and one fine day he would sally
+forth to capture a horsepower or two--and, once captured, he would use
+strength and strategy breaking the wild beast to harness. A single
+horsepower--animal--will do the work of lifting 23,000 pounds one foot
+in one minute, providing the animal is young, and sound, and is fed
+12 quarts of oats and 10 or 15 pounds of hay a day, and is given a
+chance to rest 16 hours out of 24--providing also it has a dentist to
+take care of its teeth occasionally, and a blacksmith chiropodist to
+keep it in shoes. On the hoof, this horsepower is worth about
+$200--unless the farmer is looking for something fancy in the way of
+drafters, when he will have to go as high as $400 for a big fellow.
+And after 10 or 15 years, the farmer would look around for another
+horse, because an animal grows old.
+
+This animal horsepower isn't a very efficient horsepower. In fact, it
+is less than three-fourths of an actual horsepower, as engineers use
+the term. A real horsepower will do the work of lifting 33,000 pounds
+one foot in one minute--or 550 pounds one foot in one second. Burn a
+pint of gasoline, with 14 pounds of air, in a gasoline engine, and the
+engine will supply one 33,000-pound horsepower for an hour. The
+gasoline will cost about 2 cents, and the air is supplied free. If it
+was the air that cost two cents a pound, instead of the gasoline, the
+automobile industry would undoubtedly stop where it began some fifteen
+years ago. It is human nature, however, to grumble over this two
+cents.
+
+Yet the average farmer who would get excited if sound young chunks and
+drafters were running wild across his pastures, is not inspired by any
+similar desire of possession and mastery by the sight of a brook, or a
+rivulet that waters his meadows. This brook or river is flowing down
+hill to the sea. Every 4,000 gallons that falls one foot in one
+minute; every 400 gallons that falls 10 feet in one minute; or every
+40 gallons that falls 100 feet in one minute, means the power of one
+horse going to waste--not the $200 flesh-and-blood kind that can lift
+only 23,000 pounds a foot a minute--but the 33,000 foot-pound kind.
+Thousands of farms have small streams in their very dooryard, capable
+of developing five, ten, twenty, fifty horsepower twenty-four hours a
+day, for the greater part of the year. Within a quarter of a mile of
+the great majority of farms (outside of the dry lands themselves)
+there are such streams. Only a small fraction of one per cent of them
+have been put to work, made to pay their passage from the hills to the
+sea.
+
+The United States government geological survey engineers recently made
+an estimate of the waterfalls capable of developing 1,000 horsepower
+and over, that are running to waste, unused, in this country. They
+estimated that there is available, every second of the day and night,
+some 30,000,000 horsepower, in dry weather--and twice this during the
+eight wet months of the year. The waterfall capable of giving up 1,000
+horsepower in energy is not the subject of these chapters. It is the
+small streams--the brooks, the creeks, the rivulets--which feed the
+1,000 horsepower torrents, make them possible, that are of interest to
+the farmer. These small streams thread every township, every county,
+seeking the easiest way to the main valleys where they come together
+in great rivers.
+
+What profitable crop on your farm removes the least plant food? A
+bee-farmer enters his honey for the prize in this contest. Another
+farmer maintains that his ice-crop is the winner. But electricity
+generated from falling water of a brook meandering across one's acres,
+comes nearer to the correct answer of how to make something out of
+nothing. It merely utilizes the wasted energy of water rolling down
+hill--the weight of water, the pulling power of gravity. Water is
+still water, after it has run through a turbine wheel to turn an
+electric generator. It is still wet; it is there for watering the
+stock; and a few rods further down stream, where it drops five or ten
+feet again, it can be made to do the same work over again--and over
+and over again as long as it continues to fall, on its journey to the
+sea. The city of Los Angeles has a municipal water plant, generating
+200,000 horsepower of electricity, in which the water is used three
+times in its fall of 6,000 feet; and in the end, where it runs out of
+the race in the valley, it is sold for irrigation.
+
+One water-horsepower will furnish light for the average farm; five
+water-horsepower will furnish light and power, and do the ironing and
+baking. The cost of installing a plant of five water-horsepower should
+not exceed the cost of one sound young horse, the $200 kind--under
+conditions which are to be found on thousands of farms and farm
+communities in the East, the Central West, and the Pacific States.
+This electrical horsepower will work 24 hours a day, winter and
+summer, and the farmer would not have to grow oats and hay for it on
+land that might better be used in growing food for human beings. It
+would not become "aged" at the end of ten or fifteen years, and the
+expense of maintenance would be practically nothing after the first
+cost of installation. It would require only water as food--waste
+water. Two hundred and fifty cubic feet of water a minute, falling ten
+feet, will supply the average farm with all the conveniences of
+electricity. This is a very modest creek--the kind of brook or creek
+that is ignored by the man who would think time well spent in putting
+in a week capturing a wild horse, if a miracle should send such a
+beast within reach. And the task of harnessing and breaking this
+water-horsepower is much more simple and less dangerous than the task
+of breaking a colt to harness.
+
+
+
+
+PART I
+
+WATER-POWER
+
+
+
+
+ELECTRICITY FOR THE FARM
+
+CHAPTER I
+
+A WORKING PLANT
+
+     The "agriculturist"--An old chair factory--A neighbor's
+     home-coming--The idle wheel in commission again--Light, heat and
+     power for nothing--Advantages of electricity.
+
+
+Let us take an actual instance of one man who did go ahead and find
+out by experience just how intricate and just how simple a thing
+electricity from farm water-power is. This man's name was Perkins, or,
+we will call him that, in relating this story.
+
+Perkins was what some people call, not a farmer, but an
+"agriculturist,"--that is, he was a back-to-the-land man. He had been
+born and raised on a farm. He knew that you must harness a horse on
+the left side, milk a cow on the right, that wagon nuts tighten the
+way the wheel rims, and that a fresh egg will not float.
+
+He had a farm that would grow enough clover to fill the average dairy
+if he fed it lime; he had a boy coming to school age; and both he and
+his wife wanted to get back to the country. They had their little
+savings, and they wanted, first of all, to take a vacation, getting
+acquainted with their farm. They hadn't taken a vacation in fifteen
+years.
+
+He moved in, late in the summer, and started out to get acquainted
+with his neighbors, as well as his land. This was in the New England
+hills. Water courses cut through everywhere. In regard to its
+bountiful water supply, the neighborhood had much in common with all
+the states east of the Mississippi, along the Atlantic seaboard, in
+the lake region of the central west, and in the Pacific States. With
+this difference; the water courses in his neighborhood had once been
+of economic importance.
+
+A mountain river flowed down his valley. Up and down the valley one
+met ramshackle mills, fallen into decay. Many years ago before
+railroads came, before it was easy to haul coal from place to place
+to make steam, these little mills were centers of thriving industries,
+which depended on the power of falling water to make turned articles,
+spin cotton, and so forth. Then the railroads came, and it was easy to
+haul coal to make steam. And the same railroads that hauled the coal
+to make steam, were there to haul away the articles manufactured by
+steam power. So in time the little manufacturing plants on the river
+back in the hills quit business and moved to railroad stations. Then
+New England, from being a manufacturing community made up of many
+small isolated water plants, came to be a community made up of huge
+arteries and laterals of smoke stacks that fringed the railroads.
+Where the railroad happened to follow a river course--as the
+Connecticut River--the water-power plants remained; but the little
+plants back in the hills were wiped off the map--because steam power
+with railroads at the front door proved cheaper than water-power with
+railroads ten miles away.
+
+One night Perkins came in late from a long drive with his next-door
+neighbor. He had learned the first rule of courtesy in the country,
+which is to unhitch his own side of the horse and help back the buggy
+into the shed. They stumbled around in the barn putting up the horse,
+and getting down hay and grain for it, by the light of an oil lantern,
+which was set on the floor in a place convenient to be kicked over. He
+went inside and took supper by the light of a smoky smelly oil lamp,
+that filled the room full of dark corners; and when supper was over,
+the farmwife groped about in the cellar putting things away by the
+light of a candle.
+
+The next day his neighbor was grinding cider at his ramshackle water
+mill--one of the operations for which a week must be set aside every
+fall. Perkins sat on a log and listened to the crunch-crunch of the
+apples in the chute, and the drip of the frothy yellow liquid that
+fell into waiting buckets.
+
+"How much power have you got here?" he asked.
+
+"Thirty or forty horsepower, I guess."
+
+"What do you do with it, besides grinding cider to pickle your
+neighbors' digestion with?"
+
+"Nothing much. I've got a planer and a moulding machine in there, to
+work up jags of lumber occasionally. That's all. This mill was a
+chair-factory in my grandfather's day, back in 1830."
+
+"Do you use it thirty days in a year?"
+
+"No; not half that."
+
+"What are you going to do with it this winter?"
+
+"Nothing; I keep the gate open and the wheel turning, so it won't
+freeze, but nothing else. I am going to take the family to Texas to
+visit my wife's folks for three months. We've worked hard enough to
+take a vacation."
+
+"Will you rent me the mill while you are gone?"
+
+"Go ahead; you can have it for nothing, if you will watch the ice."
+
+"All right; let me know when you come back and I'll drive to town and
+bring you home."
+
+       *       *       *       *       *
+
+Three months went by, and one day in February the city man, in
+response to a letter, hitched up and drove to town to bring his
+neighbor back home. It was four o'clock in the afternoon when they
+started out, and it was six--dark--when they turned the bend in the
+road to the farm house. They helped the wife and children out, with
+their baggage, and as Perkins opened the door of the house, he reached
+up on the wall and turned something that clicked sharply.
+
+Instantly light sprang from everywhere. In the barn-yard a street lamp
+with an 18-inch reflector illuminated all under it for a space of 100
+feet with bright white rays of light. Another street lamp hung over
+the watering trough. The barn doors and windows burst forth in light.
+There was not a dark corner to be found anywhere. In the house it was
+the same. Perkins led the amazed procession from room to room of the
+house they had shut up for the winter. On the wall in the hall
+outside of every room was a button which he pushed, and the room
+became as light as day before they entered. The cellar door, in
+opening, automatically lighted a lamp illuminating that cavern as it
+had never been lighted before since the day a house was built over it.
+
+Needless to say, the farmer and his family were reduced to a state of
+speechlessness.
+
+"How the deuce did you do it?" finally articulated the farmer.
+
+"I put your idle water wheel to work," said Perkins; and then,
+satisfied with this exhibition, he put them back in the sleigh and
+drove to his home, where his wife had supper waiting.
+
+While the men were putting up the team in the electric lighted barn,
+the farmwife went into the kitchen. Her hostess was cooking supper on
+an electric stove. It looked like a city gas range and it cooked all
+their meals, and did the baking besides. A hot-water tank stood
+against the wall, not connected to anything hot, apparently. But it
+was scalding hot, by virtue of a little electric water heater the size
+of a quart tin can, connected at the bottom. Twenty-four hours a day
+the water wheel pumped electricity into that "can," so that hot water
+was to be had at any hour simply by turning a faucet. In the laundry
+there was an electric pump that kept the tank in the attic filled
+automatically. When the level of water in this tank fell to a certain
+point, a float operated a switch that started the pump; and when the
+water level reached a certain height, the same float stopped the pump.
+A small motor, the size of a medium Hubbard squash operated a washing
+machine and wringer on wash days. This same motor was a
+man-of-all-work for this house, for, when called on, it turned the
+separator, ground and polished knives and silverware, spun the sewing
+machine, and worked the vacuum cleaner.
+
+Over the dining room table hung the same hanging shade of old days,
+but the oil lamp itself was gone. In its place was a 100-watt
+tungsten lamp whose rays made the white table cloth fairly glisten.
+The wires carrying electricity to this lamp were threaded through the
+chains reaching to the ceiling, and one had to look twice to see where
+the current came from. In the sitting room, a cluster of electric
+bulbs glowed from a fancy wicker work basket that hung from the
+ceiling. The housewife had made use of what she had throughout the
+house. Old-fashioned candle-shades sat like cocked hats astride
+electric bulbs. There is little heat to an electric bulb for the
+reason that the white-hot wire that gives the light is made to burn in
+high vacuum, which transmits heat very slowly. The housewife had taken
+advantage of this fact and from every corner gleamed lights dressed in
+fancy designs of tissue paper and silk.
+
+"Now we will talk business," said Perkins when supper was over and
+they had lighted their pipes.
+
+The returned native looked dubious. His New England training had
+warned him long ago that one cannot expect to get something for
+nothing, and he felt sure there was a joker in this affair.
+
+"How much do I owe you?" he asked.
+
+"Nothing," said Perkins. "You furnish the water-power with your idle
+wheel, and I furnish the electric installation. This is only a small
+plant I have put in, but it gives us enough electricity to go around,
+with a margin for emergencies. I have taken the liberty of wiring your
+house and your horse-barn and cow-barn and your barn-yard. Altogether,
+I suppose you have 30 lights about the place, and during these long
+winter days you will keep most of them going from 3 to 5 hours a night
+and 2 or 3 hours in the early morning. If you were in town, those
+lights would cost you about 12 cents an hour, at the commercial rate
+of electricity. Say 60 cents a day--eighteen dollars a month. That
+isn't a very big electric light bill for some people I know in
+town--and they consider themselves lucky to have the privilege of
+buying electricity at that rate. Your wheel is running all winter to
+prevent ice from forming and smashing it. It might just as well be
+spinning the dynamo.
+
+"If you think it worth while," continued Perkins,--"this $18 worth of
+light you have on tap night and morning, or any hour of the day,--we
+will say the account is settled. That is, of course, if you will give
+me the use of half the electricity that your idle wheel is grinding
+out with my second-hand dynamo. We have about eight electrical
+horsepower on our wires, without overloading the machine. Next spring
+I am going to stock up this place; and I think about the first thing I
+do, when my dairy is running, will be to put in a milking machine and
+let electricity do the milking for me. It will also fill my silo,
+grind my mowing-machine knives, saw my wood, and keep water running in
+my barn. You will probably want to do the same.
+
+"But what it does for us men in the barn and barn-yard, isn't to be
+compared to what it does for the women in the house. When my wife
+wants a hot oven she presses a button. When she wants to put the
+'fire' out, she presses another. That's all there is to it. No heat,
+no smoke, no ashes. The same with ironing--and washing. No oil lamps
+to fill, no wicks to trim, no chimneys to wash, no kerosene to kick
+over and start a fire."
+
+"You say the current you have put in my house would cost me about $18
+a month, in town."
+
+"Yes, about that. Making electricity from coal costs money."
+
+"What does it cost here?"
+
+"Practically nothing. Your river, that has been running to waste ever
+since your grandfather gave up making chairs, does the work. There is
+nothing about a dynamo to wear out, except the bearings, and these can
+be replaced once every five or ten years for a trifle. The machine
+needs to be oiled and cared for--fill the oil cups about once in three
+days. Your water wheel needs the same attention. That's all there is
+to it. You can figure the cost of your current yourself--just about
+the cost of the lubricating oil you use--and the cost of the time you
+give it--about the same time you give to any piece of good machinery,
+from a sulky plow to a cream separator."
+
+This is a true story. This electric plant, where Perkins furnishes the
+electric end, and his neighbor the water-power, has been running now
+for two years, grinding out electricity for the two places twenty-four
+hours a day. Perkins was not an electrical engineer. He was just a
+plain intelligent American citizen who found sufficient knowledge in
+books to enable him to install and operate this plant. Frequently he
+is away for long periods, but his neighbor (who has lost his original
+terror of electricity) takes care of the plant. In fact, this farmer
+has given a lot of study to the thing, through curiosity, until he
+knows fully as much about it now as his city neighbor.
+
+He had the usual idea, at the start, that a current strong enough to
+light a 100 candlepower lamp would kick like a mule if a man happened
+to get behind it. He watched the city man handle bare wires and
+finally he plucked up courage to do it himself.
+
+It was a 110-volt current, the pressure used in our cities for
+domestic lighting. The funny part about it was, the farmer could not
+feel it at all at first. His fingers were calloused and no current
+could pass through them. Finally he sandpapered his fingers and tried
+it again. Then he was able to get the "tickle" of 110 volts. It wasn't
+so deadly after all--about the strength of a weak medical battery,
+with which every one is familiar. A current of 110 volts cannot do any
+harm to the human body unless contact is made over a very large
+surface, which is impossible unless a man goes to a lot of trouble to
+make such a contact. A current of 220 volts pressure--the pressure
+used in cities for motors--has a little more "kick" to it, but still
+is not uncomfortable. When the pressure rises to 500 volts (the
+pressure used in trolley wires for street cars), it begins to be
+dangerous. But there is no reason why a farm plant should be over 110
+volts, under usual conditions; engineers have decided on this pressure
+as the best adapted to domestic use, and manufacturers who turn out
+the numerous electrical devices, such as irons, toasters, massage
+machines, etc., fit their standard instruments to this voltage.
+
+[Illustration: Farm labor and materials built this crib and stone
+dam]
+
+As to the cost of this co-operative plant--it was in the neighborhood
+of $200. As we have said, it provided eight electrical horsepower on
+tap at any hour of the day or night--enough for the two farms, and a
+surplus for neighbors, if they wished to string lines and make use of
+it.
+
+The dynamo, a direct-current machine, 110 volts pressure, and what is
+known in the trade as "compound,"--that is, a machine that maintains a
+constant pressure automatically and does not require an attendant--was
+picked up second-hand, through a newspaper "ad" and cost $90. The
+switchboard, a make-shift affair, not very handsome, but just as
+serviceable as if it were made of marble, cost less than $25 all told.
+The transmission wire cost $19 a hundred pounds; it is of copper, and
+covered with weatherproofed tape. Perkins bought a 50-cent book on
+house-wiring, and did the wiring himself, the way the book told him
+to, a simple operation. For fixtures, as we have said, his wife
+devised fancy shades out of Mexican baskets, tissue paper, and silk,
+in which are hidden electric globes that glow like fire-flies at the
+pressing of a button. The lamps themselves are mostly old-style carbon
+lamps, which can be bought at 16 cents each retail. In his living room
+and dining room he used the new-style tungsten lamps instead of
+old-style carbon. These cost 30 cents each. Incandescent lamps are
+rated for 1,000 hours useful life. The advantage of tungsten lights is
+that they give three times as much light for the same expenditure of
+current as carbon lights. This is a big advantage in the city, where
+current is costly; but it is not so much of an advantage in the
+country where a farmer has plenty of water-power--because his current
+costs him practically nothing, and he can afford to be wasteful of it
+to save money in lamps. Another advantage he has over his city cousin:
+In town, an incandescent lamp is thrown away after it has been used
+1,000 hours because after that it gives only 80% of the light it did
+when new--quite an item when one is paying for current. The experience
+of Perkins and his neighbor in their coöperative plant has been that
+they have excess light anyway, and if a few bulbs fall off a fifth in
+efficiency, it is not noticeable. As a matter of fact most of their
+bulbs have been in use without replacing for the two years the plant
+has been in operation. The lamps are on the wall or the ceiling, out
+of the way, not liable to be broken; so the actual expense in
+replacing lamps is less than for lamp chimneys in the old days.
+
+Insurance companies recognize that a large percentage of farm fires
+comes from the use of kerosene; for this reason, they are willing to
+make special rates for farm homes lighted by electricity. They
+prescribe certain rules for wiring a house, and they insist that their
+agent inspect and pass such wiring before current is turned on. Once
+the wiring is passed, the advantage is all in favor of the farmer
+with electricity over the farmer with kerosene. The National Board of
+Fire Underwriters is sufficiently logical in its demands, and powerful
+enough, so that manufacturers who turn out the necessary fittings find
+no sale for devices that do not conform to insurance standards.
+Therefore it is difficult to go wrong in wiring a house.
+
+Finally, as to the added value a water-power electric plant adds to
+the selling price of a farm. Let the farmer answer this question for
+himself. If he can advertise his farm for sale, with a paragraph
+running: "Hydroelectric plant on the premises, furnishing electricity
+for light, heat, and power"--what do you suppose a wide-awake
+purchaser would be willing to pay for that? Perkins and his neighbor
+believe that $1,000 is a very modest estimate added by their electric
+plant to both places. And they talk of doing still more. They use only
+a quarter of the power of the water that is running to waste through
+the wheel. They are figuring on installing a larger dynamo, of say 30
+electrical horse-power, which will provide clean, dry, safe heat for
+their houses even on the coldest days in winter. When they have done
+this, they will consider that they are really putting their small
+river to work.
+
+
+
+
+CHAPTER II
+
+A LITTLE PROSPECTING
+
+     Small amount of water required for an electric plant--Exploring, on
+     a dull day--A rough and ready weir--What a little water will
+     do--The water wheel and the dynamo--Electricity consumed the
+     instant it is produced--The price of the average small plant, not
+     counting labor.
+
+
+The average farmer makes the mistake of considering that one must have
+a river of some size to develop power of any practical use. On your
+next free day do a little prospecting. We have already said that 250
+cubic feet of water falling 10 feet a minute will provide light, heat
+and small motor power for the average farm. A single water horsepower
+will generate enough electricity to provide light for the house and
+barn. But let us take five horsepower as a desirable minimum in this
+instance.
+
+[Illustration: Measuring a small stream with a weir]
+
+In your neighborhood there is a creek three or four feet wide,
+toiling along day by day, at its task of watering your fields. Find a
+wide board a little longer than the width of this creek you have
+scorned. Set it upright across the stream between the banks, so that
+no water flows around the ends or under it. It should be high enough
+to set the water back to a dead level for a few feet upstream, before
+it overflows. Cut a gate in this board, say three feet wide and ten
+inches deep, or according to the size of a stream. Cut this gate from
+the top, so that all the water of the stream will flow through the
+opening, and still maintain a level for several feet back of the
+board.
+
+This is what engineers call a weir, a handy contrivance for measuring
+the flow of small streams. Experts have figured out an elaborate
+system of tables as to weirs. All we need to do now, in this rough
+survey, is to figure out the number of square inches of water flowing
+through this opening and falling on the other side. With a rule,
+measure the depth of the overflowing water, from the bottom of the
+opening to the top of the dead level of the water behind the board.
+Multiply this depth by the width of the opening, which will give the
+square inches of water escaping. For every square inch of this water
+escaping, engineers tell us that stream is capable of delivering,
+roughly, one cubic foot of water a minute.
+
+Thus, if the water is 8 inches deep in an opening 32 inches wide, then
+the number of cubic feet this stream is delivering each minute is 8
+times 32, or 256 cubic feet a minute. So, a stream 32 inches wide,
+with a uniform depth of 8 inches running through our weir is capable
+of supplying the demands of the average farm in terms of electricity.
+Providing, of course, that the lay of the land is such that this water
+can be made to fall 10 feet into a water wheel.
+
+Go upstream and make a rough survey of the fall. In the majority of
+instances (unless this is some sluggish stream in a flat prairie) it
+will be found feasible to divert the stream from its main channel by
+means of a race--an artificial channel--and to convey it to a not
+far-distant spot where the necessary fall can be had at an angle of
+about 30 degrees from horizontal.
+
+If you find there is _twice_ as much water as you need for the amount
+of power you require, a five-foot fall will give the same result. Or,
+if there is only _one-half_ as much water as the 250 cubic feet
+specified, you can still obtain your theoretical five horsepower if
+the means are at hand for providing a fall of twenty feet instead of
+ten. Do not make the very common mistake of figuring that a stream is
+delivering a cubic foot a minute to each square inch of weir opening,
+simply because it _fills_ a certain opening. It is the excess water,
+falling _over_ the opening, after the stream has set back to a
+permanent dead level, that is to be measured.
+
+This farmer who spends an idle day measuring the flow of his brook
+with a notched board, may say here: "This is all very well. This is
+the spring of the year, when my brook is flowing at high-water mark.
+What am I going to do in the dry months of summer, when there are not
+250 cubic feet of water escaping every minute?"
+
+There are several answers to this question, which will be taken up in
+detail in subsequent chapters. Here, let us say, even if this brook
+does flow in sufficient volume only 8 months in a year--the dark
+months, by the way,--is not electricity and the many benefits it
+provides worth having eight months in the year? My garden provides
+fresh vegetables four months a year. Because it withers and dies and
+lies covered with snow during the winter, is that any reason why I
+should not plow and manure and plant my garden when spring comes
+again?
+
+A water wheel, the modern turbine, is a circular fan with curved iron
+blades, revolving in an iron case. Water, forced through the blades of
+this fan by its own weight, causes the wheel to revolve on its axis;
+and the fan, in turn causes a shaft fitted with pulleys to revolve.
+
+The water, by giving the iron-bladed fan a turning movement as it
+rushes through, imparts to it mechanical power. The shaft set in
+motion by means of this mechanical power is, in turn, belted to the
+pulley of a dynamo. This dynamo consists, first, of a shaft on which
+is placed a spool, wound in a curious way, with many turns of
+insulated copper wire. This spool revolves freely in an air space
+surrounded by electric magnets. The spool does not touch these
+magnets. It is so nicely balanced that the weight of a finger will
+turn it. Yet, when it is revolved by water-power at a predetermined
+speed--say 1,500 revolutions a minute--it generates electricity,
+transforms the mechanical power of the water wheel into another form
+of energy--a form of energy which can be carried for long distances on
+copper wires, which can, by touching a button, be itself converted
+into light, or heat, or back into mechanical energy again.
+
+If two wires be led from opposite sides of this revolving spool, and
+an electric lamp be connected from one to the other wire, the lamp
+will be lighted--will grow white hot,--hence _incandescent light_.
+The instant this lamp is turned on, the revolving spool feels a
+stress, the magnets by which it is surrounded begin to pull back on
+it. The power of the water wheel, however, overcomes this pull. If one
+hundred lights be turned on, the backward pull of the magnets
+surrounding the spool will be one hundred times as strong as for one
+light. For every ounce of electrical energy used in light or heat or
+power, the dynamo will require a like ounce of mechanical power from
+the water wheel which drives it.
+
+The story is told of a canny Scotch engineer, who, in the first days
+of dynamos, not so very long ago, scoffed at the suggestion that such
+a spool, spinning in free air, in well lubricated bearings, could
+bring his big Corliss steam engine to a stop. Yet he saw it done
+simply by belting this "spool," a dynamo, to his engine and asking the
+dynamo for more power in terms of light than his steam could deliver
+in terms of mechanical power to overcome the pull of the magnets.
+
+Electricity must be consumed the instant it is generated (except in
+rare instances where small amounts are accumulated in storage
+batteries by a chemical process). The pressure of a button, or the
+throw of a switch causes the dynamo instantly to respond with just
+enough energy to do the work asked of it, always in proportion to the
+amount required. Having this in mind, it is rather curious to think of
+electricity as being an article of export, an item in international
+trade. Yet in 1913 hydro-electric companies in Canada "exported" by
+means of wires, to this country over 772,000,000 kilowatt-hours (over
+one billion horsepower hours) of electricity for use in factories near
+the boundary line.
+
+This 250 cubic feet of water per minute then, which the farmer has
+measured by means of his notched board, will transform by means of its
+falling weight mechanical power into a like amount of electrical
+power--less friction losses, which may amount to as much as 60% in
+very small machines, and 15% in larger plants. That is, the brook
+which has been draining your pastures for uncounted ages contains the
+potential power of 3 and 4 young horses--with this difference: that it
+works 24 hours a day, runs on forever, and requires no oats or hay.
+And the cost of such an electric plant, which is ample for the needs
+of the average farm, _is in most cases less than the price of a good
+farm horse_--the $200 kind--not counting labor of installation.
+
+It is the purpose of these chapters to awaken the farmer to the
+possibilities of such small water-power as he or his community may
+possess; to show that the generating of electricity is a very simple
+operation, and that the maintenance and care of such a plant is within
+the mechanical ability of any American farmer or farm boy; and to show
+that electricity itself is far from being the dangerous death-dealing
+"fluid" of popular imagination. Electricity must be studied; and then
+it becomes an obedient, tireless servant. During the past decade or
+two, mathematical wizards have studied electricity, explored its
+atoms, reduced it to simple arithmetic--and although they cannot yet
+tell us _why_ it is generated, they tell us _how_. It is with this
+simple arithmetic, and the necessary manual operations that we have to
+do here.
+
+
+
+
+CHAPTER III
+
+HOW TO MEASURE WATER-POWER
+
+     What is a horsepower?--How the Carthaginians manufactured
+     horsepower--All that goes up must come down--How the sun lifts
+     water up for us to use--Water the ideal power for generating
+     electricity--The weir--Table for estimating flow of streams, with a
+     weir--Another method of measuring--Figuring water horsepower--The
+     size of the wheel--What head is required--Quantity of water
+     necessary.
+
+
+If a man were off in the woods and needed a horsepower of energy to
+work for him, he could generate it by lifting 550 pounds of stone or
+wood, or whatnot, one foot off the ground, and letting it fall back in
+the space of one second. As a man possesses capacity for work equal to
+one-fifth horsepower, it would take him five seconds to do the work of
+lifting the weight up that the weight itself accomplished in falling
+down. All that goes up must come down; and by a nice balance of
+physical laws, a falling body hits the ground with precisely the same
+force as is required to lift it to the height from which it falls.
+
+The Carthaginians, and other ancients (who were deep in the woods as
+regards mechanical knowledge) had their slaves carry huge stones to
+the top of the city wall; and the stones were placed in convenient
+positions to be tipped over on the heads of any besieging army that
+happened along. Thus by concentrating the energy of many slaves in one
+batch of stones, the warriors of that day were enabled to deliver
+"horsepower" in one mass where it would do the most good. The farmer
+who makes use of the energy of falling water to generate electricity
+for light, heat, and power does the same thing--he makes use of the
+capacity for work stored in water in being lifted to a certain height.
+As in the case of the gasoline engine, which burns 14 pounds of air
+for every pound of gasoline, the engineer of the water-power plant
+does not have to concern himself with the question of how this
+natural source of energy happened to be in a handy place for him to
+make use of it.
+
+The sun, shining on the ocean, and turning water into vapor by its
+heat has already lifted it up for him. This vapor floating in the air
+and blown about by winds, becomes chilled from one cause or another,
+gives up its heat, turns back into water, and falls as rain. This
+rain, falling on land five, ten, a hundred, a thousand, or ten
+thousand feet above the sea level, begins to run back to the sea,
+picking out the easiest road and cutting a channel that we call a
+brook, a stream, or a river. Our farm lands are covered to an average
+depth of about three feet a year with water, every gallon of which has
+stored in it the energy expended by the heat of the sun in lifting it
+to the height where it is found.
+
+The farmer, prospecting on his land for water-power, locates a spot on
+a stream which he calls Supply; and another spot a few feet down hill
+near the same stream, which he calls Power. Every gallon of water that
+falls between these two points, and is made to escape through the
+revolving blades of a water wheel is capable of work in terms of
+foot-pounds--an amount of work that is directly proportional to the
+_quantity_ of water, and to the _distance_ in feet which it falls to
+reach the wheel--_pounds_ and _feet_.
+
+
+_The Efficient Water Wheel_
+
+And it is a very efficient form of work, too. In fact it is one of the
+most efficient forms of mechanical energy known--and one of the
+easiest controlled. A modern water wheel uses 85 per cent of the total
+capacity for work imparted to falling water by gravity, and delivers
+it as rotary motion. Compare this water wheel efficiency with other
+forms of mechanical power in common use: Whereas a water wheel uses 85
+per cent of the energy of its water supply, and wastes only 15 per
+cent, a gasoline engine reverses the table, and delivers only 15 per
+cent of the energy in gasoline and wastes 85 per cent--and it is
+rather a high-class gasoline engine that can deliver even 15 per cent;
+a steam engine, on the other hand, uses about 17 per cent of the
+energy in the coal under its boilers and passes the rest up the
+chimney as waste heat and smoke.
+
+There is still another advantage possessed by water-power over its two
+rivals, steam and gas: It gives the most even flow of power. A gas
+engine "kicks" a wheel round in a circle, by means of successive
+explosions in its cylinders. A reciprocating steam engine "kicks" a
+wheel round in a circle by means of steam expanding first in one
+direction, then in another. A water wheel, on the other hand, is made
+to revolve by means of the pressure of water--by the constant force of
+gravity, itself--weight. Weight is something that does not vary from
+minute to minute, or from one fraction of a second to another. It is
+always the same. A square inch of water pressing on the blades of a
+water wheel weights ten, twenty, a hundred pounds, according to the
+height of the pipe conveying that water from the source of supply, to
+the wheel. So long as this column of water is maintained at a fixed
+height, the power it delivers to the wheel does not vary by so much as
+the weight of a feather.
+
+This property of falling water makes it the ideal power for generating
+electricity. Electricity generated from mechanical power depends on
+constant speed for steady pressure--since the electric current, when
+analyzed, is merely a succession of pulsations through a wire, like
+waves beating against a sea wall. Water-power delivers these waves at
+a constant speed, so that electric lights made from water-power do not
+flicker and jump like the flame of a lantern in a gusty wind. On the
+other hand, to accomplish the same thing with steam or gasoline
+requires an especially constructed engine.
+
+
+_The Simple Weir_
+
+Since a steady flow of water, and a constant head, bring about this
+ideal condition in the water wheel, the first problem that faces the
+farmer prospector is to determine the amount of water which his stream
+is capable of delivering. This is always measured, for convenience,
+in _cubic feet per minute_. (A cubic foot of water weighs 62.5 pounds,
+and contains 7-1/2 gallons.) This measurement is obtained in several
+ways, among which probably the use of a weir is the simplest and most
+accurate, for small streams.
+
+A weir is, in effect, merely a temporary dam set across the stream in
+such a manner as to form a small pond; and to enable one to measure
+the water escaping from this pond.
+
+It may be likened to the overflow pipe of a horse trough which is
+being fed from a spring. To measure the flow of water from such a
+spring, all that is necessary is to measure the water escaping through
+the overflow when the water in the trough has attained a permanent
+level.
+
+[Illustration: Detail of home-made weir]
+
+[Illustration: Cross-section of weir]
+
+The diagrams show the cross-section and detail of a typical weir,
+which can be put together in a few minutes with the aid of a saw and
+hammer. The cross-section shows that the lower edge of the slot
+through which the water of the temporary pond is made to escape, is
+cut on a bevel, with its sharp edge upstream. The wing on each side of
+the opening is for the purpose of preventing the stream from narrowing
+as it flows through the opening, and thus upsetting the calculations.
+This weir should be set directly across the flow of the stream,
+perfectly level, and upright. It should be so imbedded in the banks,
+and in the bottom of the stream, that no water can escape, except
+through the opening cut for that purpose. It will require a little
+experimenting with a rough model to determine just how wide and how
+deep this opening should be. It should be large enough to prevent
+water flowing over the top of the board; and it should be small
+enough to cause a still-water pond to form for several feet behind the
+weir. Keep in mind the idea of the overflowing water trough when
+building your weir. The stream, running down from a higher level
+behind, should be emptying into a still-water pond, which in turn
+should be emptying itself through the aperture in the board at the
+same rate as the stream is keeping the pond full.
+
+Your weir should be fashioned with the idea of some permanency so that
+a number of measurements may be taken, extending over a period of
+time--thus enabling the prospector to make a reliable estimate not
+only of the amount of water flowing at any one time, but of its
+fluctuations.
+
+Under expert supervision, this simple weir is an exact
+contrivance--exact enough, in fact, for the finest calculations
+required in engineering work. To find out how many cubic feet of water
+the stream is delivering at any moment, all that is necessary is to
+measure its depth where it flows through the opening. There are
+instruments, like the hook-gauge, which are designed to measure this
+depth with accuracy up to one-thousandth of an inch. An ordinary foot
+rule, or a folding rule, will give results sufficiently accurate for
+the water prospector in this instance. The depth should be measured
+not at the opening itself, but a short distance back of the opening,
+where the water is setting at a dead level and is moving very slowly.
+
+With this weir, every square inch of water flowing through the opening
+indicates roughly one cubic foot of water a minute. Thus if the
+opening is 10 inches wide and the water flowing through it is 5 inches
+deep, the number of cubic feet a minute the stream is delivering is 10
+× 5 = 50 square inches = 50 cubic feet a minute. This is a very small
+stream; yet, if it could be made to fall through a water wheel 10 feet
+below a pond or reservoir, it would exert a continuous pressure of
+30,000 pounds per minute on the blades of the wheel--nearly one
+theoretical horsepower.
+
+This estimate of one cubic foot to each square inch is a very rough
+approximation. Engineers have developed many complicated formulas for
+determining the flow of water through weirs, taking into account fine
+variations that the farm prospector need not heed. The so-called
+Francis formula, developed by a long series of actual experiments at
+Lowell, Mass., in 1852 by Mr. James B. Francis, with weirs 10 feet
+long and 5 feet 2 inches high, is standard for these calculations and
+is expressed (for those who desire to use it for special purposes) as
+follows:
+
+  Q = 3.33 L H^(3/2) or, Q = 3.33 L H sqrt(H),
+
+in which Q means _quantity_ of water in cubic feet per second, L is
+length of opening, in feet; and H is height of opening in feet.
+
+The following table is figured according to the Francis formula, and
+gives the discharge in cubic feet per minute, for openings one inch
+wide:
+
+TABLE OF WEIRS
+
+    Inches        0         1/4        1/2        3/4
+       1        0.403      0.563      0.740      0.966
+       2        1.141      1.360      1.593      1.838
+       3        2.094      2.361      2.639      2.927
+       4        3.225      3.531      3.848      4.173
+       5        4.506      4.849      5.200      5.558
+       6        5.925      6.298      6.681      7.071
+       7        7.465      7.869      8.280      8.697
+       8        9.121      9.552      9.990     10.427
+       9       10.884     11.340     11.804     12.272
+      10       12.747     13.228     13.716     14.208
+      11       14.707     15.211     15.721     16.236
+      12       16.757     17.283     17.816     18.352
+      13       18.895     19.445     19.996     20.558
+      14       21.116     21.684     22.258     22.835
+      15       23.418     24.007     24.600     25.195
+      16       25.800     26.406     27.019     27.634
+      17       28.256     28.881     29.512     30.145
+      18       30.785     31.429     32.075     32.733
+
+Thus, let us say, our weir has an opening 30 inches wide, and the
+water overflows through the opening at a uniform depth of 6-1/4
+inches, when measured a few inches behind the board at a point before
+the overflow curve begins. Run down the first column on the left to
+"6", and cross over to the second column to the right, headed "1/4".
+This gives the number of cubic feet per minute for this depth one inch
+wide, as 6.298. Since the weir is 30 inches wide, multiply 6.298 × 30
+= 188.94--or, say, 189 cubic feet per minute.
+
+Once the weir is set, it is the work of but a moment to find out the
+quantity of water a stream is delivering, simply by referring to the
+above table.
+
+
+_Another Method of Measuring a Stream_
+
+Weirs are for use in small streams. For larger streams, where the
+construction of a weir would be difficult, the U. S. Geological Survey
+engineers recommend the following simple method:
+
+Choose a place where the channel is straight for 100 or 200 feet, and
+has a nearly constant depth and width; lay off on the bank a line 50
+or 100 feet in length. Throw small chips into the stream, and measure
+the time in seconds they take to travel the distance laid off on the
+bank. This gives the surface velocity of the water. Multiply the
+average of several such tests by 0.80, which will give very nearly the
+mean velocity. Then it is necessary to find the cross-section of the
+flowing water (its average depth multiplied by width), and this
+number, in square feet, multiplied by the velocity in feet per second,
+will give the number of cubic feet the stream is delivering each
+second. Multiplied by 60 gives cubic feet a minute.
+
+
+_Figuring a Stream's Horsepower_
+
+By one of the above simple methods, the problem of _Quantity_ can
+easily be determined. The next problem is to determine what _Head_ can
+be obtained. _Head_ is the distance in feet the water may be made to
+fall, from the Source of Supply, to the water wheel itself. The power
+of water is directly proportional to _head_, just as it is directly
+proportional to _quantity_. Thus the typical weir measured above was
+30 inches wide and 6-1/4 deep, giving 189 cubic feet of water a
+minute--_Quantity._ Since such a stream is of common occurrence on
+thousands of farms, let us analyze briefly its possibilities for
+power: One hundred and eighty-nine cubic feet of water weighs 189 ×
+62.5 pounds = 11,812.5 pounds. Drop this weight one foot, and we have
+11,812.5 foot-pounds. Drop it 3 feet and we have 11,812 × 3 =
+35,437.5 foot-pounds. Since 33,000 foot-pounds exerted in one minute
+is one horsepower, we have here a little more than one horsepower. For
+simplicity let us call it a horsepower.
+
+[Illustration: Detail of a water-power plant, showing setting of
+wheel, and dynamo connection]
+
+Now, since the work to be had from this water varies directly with
+_quantity_ and _head_, it is obvious that a stream _one-half_ as big
+falling _twice_ as far, would still give one horsepower at the wheel;
+or, a stream of 189 cubic feet a minute falling _ten times_ as far, 30
+feet, would give _ten times_ the power, or _ten_ horsepower; a stream
+falling _one hundred times_ as far would give _one hundred_
+horsepower. Thus small quantities of water falling great distances, or
+large quantities of water falling small distances may accomplish the
+same results. From this it will be seen, that the simple formula for
+determining the theoretical horsepower of any stream, in which
+Quantity and Head are known, is as follows:
+
+                               Cu. Ft.
+                               per       Feet
+                               minute  × head × 62.5
+  (A) Theoretical Horsepower = ----------------------
+                                       33,000
+
+_As an example, let us say that we have a stream whose weir
+measurement shows it capable of delivering 376 cubic feet a minute,
+with a head (determined by survey) of 13 feet 6 inches. What is the
+horsepower of this stream?_
+
+  Answer:
+
+         Cu. ft. p. m.   head   pounds
+            376        × 13.5 ×  62.5
+  H.P. = ----------------------------- = 9.614 horsepower
+                     33,000
+
+This is _theoretical horsepower_. To determine the _actual_ horsepower
+that can be counted on, in practice, it is customary, with small water
+wheels, to figure 25 per cent loss through friction, etc. In this
+instance, the actual horsepower would then be 7.2.
+
+
+_The Size of the Wheel_
+
+Water wheels are not rated by horsepower by manufacturers, because the
+same wheel might develop one horsepower or one hundred horsepower, or
+even a thousand horsepower, according to the conditions under which
+it is used. With a given supply of water, the head, in feet,
+determines the size of wheel necessary. The farther a stream of water
+falls, the smaller the pipe necessary to carry a given number of
+gallons past a given point in a given time.
+
+A small wheel, under 10 × 13.5 ft. head, would give the same power
+with the above 376 cubic feet of water a minute, as a large wheel
+would with 10 × 376 cubic feet, under a 13.5 foot head.
+
+This is due to the _acceleration of gravity_ on falling bodies. A
+rifle bullet shot into the air with a muzzle velocity of 3,000 feet a
+second begins to diminish its speed instantly on leaving the muzzle,
+and continues to diminish in speed at the fixed rate of 32.16 feet a
+second, until it finally comes to a stop, and starts to descend. Then,
+again, its speed accelerates at the rate of 32.16 feet a second, until
+on striking the earth it has attained the velocity at which it left
+the muzzle of the rifle, less loss due to friction.
+
+The acceleration of gravity affects falling water in the same manner
+as it affects a falling bullet. At any one second, during its course
+of fall, it is traveling at a rate 32.16 feet a second in excess of
+its speed the previous second.
+
+In figuring the size wheel necessary under given conditions or to
+determine the power of water with a given nozzle opening, it is
+necessary to take this into account. The table on page 51 gives
+velocity per second of falling water, ignoring the friction of the
+pipe, in heads from 5 to 1000 feet.
+
+The scientific formula from which the table is computed is expressed
+as follows, for those of a mathematical turn of mind:
+
+Velocity (ft. per sec.) = sqrt(2gh); or, velocity is equal to the
+square root of the product (g = 32.16,--times head in feet, multiplied
+by 2).
+
+
+    SPOUTING VELOCITY OF WATER, IN FEET PER SECOND, IN HEADS
+    OF FROM 5 TO 1,000 FEET
+
+      Head   Velocity
+
+       5       17.9
+       6       19.7
+       7       21.2
+       8       22.7
+       9       24.1
+      10       25.4
+      11       26.6
+      11.5     27.2
+      12       27.8
+      12.5     28.4
+      13       28.9
+      13.5     29.5
+      14       30.0
+      14.5     30.5
+      15       31.3
+      15.5     31.6
+      16       32.1
+      16.5     32.6
+      17       33.1
+      17.5     33.6
+      18       34.0
+      18.5     34.5
+      19       35.0
+      19.5     35.4
+      20       35.9
+      20.5     36.3
+      21       36.8
+      21.5     37.2
+      22       37.6
+      22.5     38.1
+      23       38.5
+      23.5     38.9
+      24       39.3
+      24.5     39.7
+      25       40.1
+      26       40.9
+      27       41.7
+      28       42.5
+      29       43.2
+      30       43.9
+      31       44.7
+      32       45.4
+      33       46.1
+      34       46.7
+      35       47.4
+      36       48.1
+      37       48.8
+      38       49.5
+      39       50.1
+      40       50.7
+      41       51.3
+      42       52.0
+      43       52.6
+      44       53.2
+      45       53.8
+      46       54.4
+      47       55.0
+      48       55.6
+      49       56.2
+      50       56.7
+      55       59.5
+      60       62.1
+      65       64.7
+      70       67.1
+      75       69.5
+      80       71.8
+      85       74.0
+      90       76.1
+      95       78.2
+     100       80.3
+     200      114.0
+     300      139.0
+     400      160.0
+     500      179.0
+    1000      254.0
+
+
+_In the above example, we found that 376 cubic feet of water a minute,
+under 13.5 feet head, would deliver 7.2 actual horsepower. Question:
+What size wheel would it be necessary to install under such
+conditions?_
+
+By referring to the table of velocity above, (or by using the
+formula), we find that water under a head of 13.5 feet, has a spouting
+velocity of 29.5 feet a second. This means that a solid stream of
+water 29.5 feet long would pass through the wheel in one second. _What
+should be the diameter of such a stream, to make its cubical contents
+376 cubic feet a minute or 376/60 = 6.27 cubic feet a second?_ The
+following formula should be used to determine this:
+
+                             144 × cu. ft. per second
+  (B) Sq. Inches of wheel = --------------------------
+                             Velocity in ft. per sec.
+
+Substituting values, in the above instance, we have:
+
+  Answer: Sq. Inches of wheel =
+
+       144 × 6.27 (Cu. Ft. Sec.)
+      --------------------------- = 30.6 sq. in.
+          29.5 (Vel. in feet.)
+
+That is, a wheel capable of using 30.6 square inches of water would
+meet these conditions.
+
+
+_What Head is Required_
+
+Let us attack the problem of water-power in another way. _A farmer
+wishes to install a water wheel that will deliver 10 horsepower on the
+shaft, and he finds his stream delivers 400 cubic feet of water a
+minute. How many feet fall is required?_ Formula:
+
+                      33,000 × horsepower required
+  (C) Head in feet = ------------------------------
+                       Cu. Ft. per minute × 62.5
+
+Since a theoretical horsepower is only 75 per cent efficient, he would
+require 10 × 4/3 = 13.33 theoretical horsepower of water, in this
+instance. Substituting the values of the problem in the formula, we
+have:
+
+                  33,000 × 13.33
+  Answer: Head = ---------------- = 17.6 feet fall required.
+                    400 × 62.5
+
+_What capacity of wheel would this prospect (400 cubic feet of water a
+minute falling 17.6 feet, and developing 13.33 horsepower) require?_
+
+By referring to the table of velocities, we find that the velocity for
+17.5 feet head (nearly) is 33.6 feet a second. Four hundred feet of
+water a minute is 400/60 = 6.67 cu. ft. a second. Substituting these
+values, in formula (B) then, we have:
+
+  Answer: Capacity of wheel =
+
+      144 × 6.67
+      ---------- = 28.6 square inches of water.
+         33.6
+
+
+_Quantity of Water_
+
+Let us take still another problem which the prospector may be called
+on to solve: _A man finds that he can conveniently get a fall of 27
+feet. He desires 20 actual horsepower. What quantity of water will be
+necessary, and what capacity wheel?_
+
+Twenty actual horsepower will be 20 × 4/3 = 26.67 theoretical
+horsepower. Formula:
+
+                              33,000 × Hp. required
+  (D) Cubic feet per minute = ---------------------
+                              (Head in feet × 62.5)
+
+Substituting values, then, we have:
+
+  Cu. ft. per minute =
+
+  33,000 × 26.67
+  -------------- = 521.5 cubic feet a minute.
+    27 × 62.5
+
+A head of 27 feet would give this stream a velocity of 41.7 feet a
+second, and, from formula (B) we find that the capacity of the wheel
+should be 30 square inches.
+
+It is well to remember that the square inches of wheel capacity does
+not refer to the size of pipe conveying water from the head to the
+wheel, but merely to the actual nozzle capacity provided by the wheel
+itself. In small installations of low head, such as above a penstock
+at least six times the nozzle capacity should be used, to avoid losing
+effective head from friction. Thus, with a nozzle of 30 square inches,
+the penstock or pipe should be 180 square inches, or nearly 14 inches
+square inside measurement. A larger penstock would be still better.
+
+
+
+
+CHAPTER IV
+
+THE WATER WHEEL AND HOW TO INSTALL IT
+
+     Different types of water wheels--The impulse and reaction
+     wheels--The impulse wheel adapted to high heads and small amount of
+     water--Pipe lines--Table of resistance in pipes--Advantages and
+     disadvantages of the impulse wheel--Other forms of impulse
+     wheels--The reaction turbine, suited to low heads and large
+     quantity of water--Its advantages and limitations--Developing a
+     water-power project: the dam; the race; the flume; the penstock;
+     and the tailrace--Water rights for the farmer.
+
+
+In general, there are two types of water wheels, the _impulse_ wheel
+and the _reaction_ wheel. Both are called turbines, although the name
+belongs, more properly, to the reaction wheel alone.
+
+Impulse wheels derive their power from the _momentum_ of falling
+water. Reaction wheels derive their power from the _momentum and
+pressure_ of falling water. The old-fashioned _undershot_, _overshot_,
+and _breast_ wheels are familiar to all as examples of impulse
+wheels. Water wheels of this class revolve in the air, with the energy
+of the water exerted on one face of their buckets. On the other hand,
+reaction wheels are enclosed in water-tight cases, either of metal or
+of wood, and the buckets are entirely surrounded by water.
+
+The old-fashioned undershot, overshot, and breast wheels were not very
+efficient; they wasted about 75 per cent of the power applied to them.
+A modern impulse wheel, on the other hand, operates at an efficiency
+of 80 per cent and over. The loss is mainly through friction and
+leakage, and cannot be eliminated altogether. The modern reaction
+wheel, called the _turbine_, attains an equal efficiency. Individual
+conditions govern the type of wheel to be selected.
+
+
+_The Impulse, or Tangential Water Wheel_
+
+The modern impulse, or tangential wheel (so called because the driving
+stream of water strikes the wheel at a tangent) is best adapted to
+situations where the amount of water is limited, and the head is
+large. Thus, a mountain brook supplying only seven cubic feet of water
+a minute--a stream less than two-and-a-half inches deep flowing over a
+weir with an opening three inches wide--would develop two actual
+horsepower, under a head of 200 feet--not an unusual head to be found
+in the hill country. Under a head of one thousand feet, a stream
+furnishing 352.6 cubic feet of water a minute would develop 534.01
+horsepower at the nozzle.
+
+Ordinarily these wheels are not used under heads of less than 20 feet.
+A wheel of this type, six feet in diameter, would develop six
+horsepower, with 188 cubic feet of water a minute and 20-foot head.
+The great majority of impulse wheels are used under heads of 100 feet
+and over. In this country the greatest head in use is slightly over
+2,100 feet, although in Switzerland there is one plant utilizing a
+head of over 5,000 feet.
+
+[Illustration: Runner of Pelton wheel, showing peculiar shape of the
+buckets]
+
+[Illustration: The Fitz overshoot wheel
+
+Efficient Modern Adaptations of the Archaic Undershot and Overshot
+Water Wheels]
+
+The old-fashioned impulse wheels were inefficient because of the fact
+that their buckets were not constructed scientifically, and much of
+the force of the water was lost at the moment of impact. The impulse
+wheel of to-day, however, has buckets which so completely absorb the
+momentum of water issuing from a nozzle, that the water falls into the
+tailrace with practically no velocity. When it is remembered that the
+nozzle pressure under a 2,250-foot head is nearly 1,000 pounds to the
+square inch, and that water issues from this nozzle with a velocity of
+23,000 feet a minute, the scientific precision of this type of bucket
+can be appreciated.
+
+A typical bucket for such a wheel is shaped like an open clam shell,
+the central line which cuts the stream of water into halves being
+ground to a sharp edge. The curves which absorb the momentum of the
+water are figured mathematically and in practice become polished like
+mirrors. So great is the eroding action of water, under great
+heads--especially when it contains sand or silt--that it is
+occasionally necessary to replace these buckets. For this reason the
+larger wheels consist merely of a spider of iron or steel, with each
+bucket bolted separately to its circumference, so that it can be
+removed and replaced easily. Usually only one nozzle is provided; but
+in order to use this wheel under low heads--down to 10 feet--a number
+of nozzles are used, sometimes five, where the water supply is
+plentiful.
+
+The wheel is keyed to a horizontal shaft running in babbited bearings,
+and this same shaft is used for driving the generator, either by
+direct connection, or by means of pulleys and a belt. The wheel may be
+mounted on a home-made timber base, or on an iron frame. It takes up
+very little room, especially when it is so set that the nozzle can be
+mounted under the flooring. The wheel itself is enclosed, above the
+floor, in a wooden box, or a casing made of cast or sheet iron, which
+should be water-tight.
+
+Since these wheels are usually operated under great heads, the problem
+of regulating their water supply requires special consideration. A
+gate is always provided at the upper, or intake end, where the water
+pipe leaves the flume. Since the pressure reaches 1,000 pounds the
+square inch and more, there would be danger of bursting the pipe if
+the water were suddenly shut off at the nozzle itself. For this reason
+it is necessary to use a needle valve, similar to that in an ordinary
+garden hose nozzle; and by such a valve the amount of water may be
+regulated to a nicety. Where the head is so great that even such a
+valve could not be used safely, provision is made to deflect the
+nozzle. These wheels have a speed variation amounting to as much as 25
+per cent from no-load to full load, in generating electricity, and
+since the speed of the prime mover--the water wheel--is reflected
+directly in the voltage or pressure of electricity delivered, the
+wheel must be provided with some form of automatic governor. This
+consists usually of two centrifugal balls, similar to those used in
+governing steam engines; these are connected by means of gears to the
+needle valve or the deflector.
+
+As the demand for farm water-powers in our hill sections becomes more
+general, the tangential type of water wheel will come into common use
+for small plants. At present it is most familiar in the great
+commercial installations of the Far West, working under enormous
+heads. These wheels are to be had in the market ranging in size from
+six inches to six feet and over. Wheels ranging in size from six
+inches to twenty-four inches are called water motors, and are to be
+had in the market, new, for $30 for the smallest size, and $275 for
+the largest. Above three feet in diameter, the list prices will run
+from $200 for a 3-foot wheel to $800 for a 6-foot wheel. Where one has
+a surplus of water, it is possible to install a multiple nozzle wheel,
+under heads of from 10 to 100 feet, the cost for 18-inch wheels of
+this pattern running from $150 to $180 list, and for 24-inch wheels
+from $200 to $250. A 24-inch wheel, with a 10-foot head would give
+1.19 horsepower, enough for lighting the home, and using an electric
+iron. Under a 100-foot head this same wheel would provide 25.9
+horsepower, to meet the requirements of a bigger-than-average farm
+plant.
+
+
+_The Pipe Line_
+
+The principal items of cost in installing an impulse wheel are in
+connection with the pipe line, and the governor. In small heads, that
+is, under 100 feet, the expense of pipe line is low. Frequently,
+however, the governor will cost more than the water motor itself,
+although cheaper, yet efficient, makes are now being put on the market
+to meet this objection. In a later chapter, we will take up in detail
+the question of governing the water wheel, and voltage regulation, and
+will attempt to show how this expense may be practically eliminated by
+the farmer.
+
+To secure large heads, it is usually necessary to run a pipe line many
+hundreds (and in many cases, many thousands) of feet from the flume to
+the water wheel. Water flowing through pipes is subject to loss of
+head, by friction, and for this reason the larger the pipe the less
+the friction loss. Under no circumstances is it recommended to use a
+pipe of less than two inches in diameter, even for the smallest water
+motors; and with a two-inch pipe, the run should not exceed 200 feet.
+Where heavy-pressure mains, such as those of municipal or commercial
+water systems, are available, the problem of both water supply and
+head becomes very simple. Merely ascertain the pressure of the water
+in the mains _when flowing_, determine the amount of power required
+(as illustrated in a succeeding chapter of this book), and install the
+proper water motor with a suitably sized pipe.
+
+Where one has his own water supply, however, and it is necessary to
+lay pipe to secure the requisite fall, the problem is more difficult.
+Friction in pipes acts in the same way as cutting down the head a
+proportional amount; and by cutting down the head, your water motor
+loses power in direct proportion to the number of feet head lost. This
+head, obtained by subtracting friction and other losses from the
+surveyed head, is called the _effective head_, and determines the
+amount of power delivered at the nozzle.
+
+The tables on pages 66-67 show the friction loss in pipes up to 12
+inches in diameter, according to the amount of water, and the length
+of pipe.
+
+In this example it is seen that a 240-foot static head is reduced by
+friction to 230.1 feet effective head. By referring to the table we
+find the wheel fitting these conditions has a nozzle so small that it
+cuts down the rate of flow of water in the big pipe to 4.4 feet a
+second, and permits the flow of only 207 cubic feet of water a minute.
+The actual horsepower of this tube and nozzle, then, can be figured by
+applying formula (A), Chapter III, allowing 80 per cent for the
+efficiency of the wheel. Thus:
+
+  Actual horsepower =
+
+      207 × 230.1 × 62.5
+      ------------------ = 90.21 × .80 = 72.168 Hp.
+            33,000
+
+To calculate what the horsepower of this tube 12 inches in diameter
+and 900 feet long, would be without a nozzle, under a head of 240
+feet, introduces a new element of friction losses, which is too
+complicated to figure here. Such a condition would not be met with in
+actual practice, in any event. The largest nozzles used, even in the
+jumbo plants of the Far West, rarely exceed 10 inches in diameter; and
+the pipe conveying water to such a nozzle is upwards of eight feet in
+diameter.
+
+
+    PIPE FRICTION TABLES
+
+    INDICATING THE CALCULATED LOSS OF HEAD DUE TO FRICTION IN RIVETED
+    STEEL PIPE WITH VARIOUS WATER QUANTITIES AND VELOCITIES
+
+    [Courtesy of the Pelton Water Wheel Company]
+
+    Heavy-faced figures = Loss of head in feet for each one thousand
+    feet of pipe. Light-faced figures = Water quantity in cubic feet per
+    minute.
+
+--------+-------------------------------------------------------------------------------------------+
+Pipe    |                      Velocity in Feet per Second                                          |
+Diameter+------+------+------+------+------+------+------+------+------+------+------+------+-------+
+        |  2.0 |  2.2 |  2.4 |  2.6 |  2.8 |  3.0 |  3.2 |  3.4 |  3.6 |  3.8 |  4.0 |  4.2 |  4.4  |
+--------+------+------+------+------+------+------+------+------+------+------+------+------+-------+
+        |=17.1=|=20.0=|=25.6=|=28.3=|=32.0=|=37.3=|=40.9=|=45.8=|=50.4=|=56.0=|=62.3=|=68.1=|=74.9= |
+    3"  |  5.9 |  6.5 |  7.1 |  7.7 |  8.3 |  8.9 |  9.4 | 10.0 | 10.6 | 11.2 | 11.8 | 12.4 | 13.0  |
+        |=11.0=|=13.0=|=15.0=|=17.3=|=20.2=|=23.2=|=26.2=|=29.6=|=33.0=|=36.5=|=41.0=|=45.4=|=49.2= |
+    4"  | 10.5 | 11.5 | 12.6 | 13.6 | 14.7 | 15.7 | 16.8 | 17.8 | 18.8 | 19.9 | 21.0 | 22.0 | 23.0  |
+        | =7.7=| =9.4=|=11.0=|=12.9=|=14.9=|=16.9=|=19.5=|=21.6=|=24.0=|=27.0=|=29.8=|=32.9=|=36.0= |
+    5"  | 16.4 | 18.0 | 19.6 | 21.2 | 22.9 | 24.5 | 26.1 | 27.8 | 29.5 | 31.0 | 32.7 | 34.3 | 36.0  |
+        | =6.0=| =7.2=| =8.6=| =9.9=|=11.7=|=13.0=|=14.6=|=16.6=|=19.0=|=21.5=|=23.4=|=25.5=|=27.8= |
+    6"  | 23.5 | 25.9 | 28.2 | 30.6 | 32.9 | 35.3 | 37.7 | 40.0 | 42.4 | 44.7 | 47.1 | 49.5 | 51.8  |
+        | =4.9 | =6.9=| =7.0=| =8.1=| =9.3=|=10.6=|=12.0=|=13.6=|=15.2=|=17.0=|=19.0=|=21.0=|=23.0= |
+    7"  | 32.0 | 35.3 | 38.5 | 41.7 | 44.9 | 48.1 | 51.3 | 54.5 | 57.7 | 60.9 | 64.1 | 67.3 | 70.5  |
+        | =4.0=| =4.9=| =6.0=| =6.9=| =7.8=| =9.1=|=10.0=|=10.2=|=13.0=|=14.4=|=15.9=|=17.2=|=19.2= |
+    8"  | 41.9 | 46.1 | 50.2 | 54.4 | 58.6 | 62.8 | 67.0 | 71.2 | 75.4 | 79.6 | 83.7 | 87.9 | 92.1  |
+        | =3.4=| =4.2=| =5.1=| =5.9=| =6.7=| =7.7=| =8.9=| =9.8=|=11.0=|=12.2=|=13.8=|=15.0=|=16.0= |
+    9"  | 53.0 | 58.3 | 63.6 | 68.9 | 74.2 | 79.5 | 84.8 | 90.1 | 95.4 |101   |106   |111   |116    |
+        | =2.9=| =3.7=| =4.4=| =5.1=| =5.9=| =6.7=| =7.5=| =8.6=| =9.5=|=10.6=|=12.1=|=13.1=|=14.1= |
+   10"  | 65.4 | 72.0 | 78.5 | 85.1 | 91.6 | 98.2 |105   |111   |118   |124   |131   |137   |144    |
+        | =2.6=| =3.2=| =3.8=| =4.4=| =5.1=| =5.9=| =6.6=| =7.5=| =8.4=| =9.5=|=10.3=|=10.1=|=12.5= |
+   11"  | 79   | 87   | 95   |103   |111   |119   |127   |134   |142   |150   |158   |166   |174    |
+        |=2.36=| =2.9=| =3.4=| =3.9=| =4.5=| =5.2=| =5.9=| =6.7=| =7.5=| =8.5=| =9.4=|=10.0=|=11.0= |
+   12"  |94    |103   |113   |122   |132   |141   |151   |160   |169   |179   |188   |198   |207    |
+--------+------+------+------+------+------+------+------+------+------+------+------+------+-------+
+
+
+--------+------+------+------+------+-------+-------+-------+-------+-------+-------+-------+-------+
+        | 4.6  |  4.8 |  5.0 | 5.2  |   5.4 |   5.6 |   5.8 |   6.0 |   7.0 |   8.0 |  9.0  |  10.0 |
+--------+------+------+------+------+-------+-------+-------+-------+-------+-------+-------+-------+
+        |=78.1=|=82.0=|=89.5=|=98.9=|=105.0=|=113.2=|=120.8=|=130.0=|=162.8=|=216.0=|=270.= |=323.= |
+    3"  | 13.6 | 14.2 | 14.8 | 15.3 |  15.9 |  16.5 |  17.1 |  17.7 |  20.6 |  23.5 |  26.5 |  29.5 |
+        |=52.3=|=57.0=|=61.5=|=68.0=| =72.5=| =78.2=| =83.1=| =89.5=|=121.= |=155.= |=198.= |=242.= |
+    4"  | 24.1 | 25.1 | 26.2 | 27.2 |  28.3 |  29.3 |  30.4 |  31.5 |  36.6 |  41.9 |  47.2 |  52.4 |
+        |=39.2=|=42.3=|=46.0=|=49.8=| =53.5=| =58.0=| =62.0=| =67.0=| =89.= |=118.= |=148.= |=182.= |
+    5"  | 37.6 | 39.2 | 40.9 | 42.5 |  44.1 |  45.8 |  47.5 |  49.1 |  57.1 |  65.4 |  73.7 |  82.0 |
+        |=30.6=|=33.1=|=35.6=|=39.0=| =41.6=| =44.6=| =48.0=| =51.6=| =69.0=| =89.0=|=114.= |=140.= |
+    6"  | 54.1 | 56.5 | 58.9 | 61.2 |  63.6 |  65.9 |  68.3 |  70.7 |  82.4 |  94.3 | 106   | 118   |
+        |=25.1=|=27.3=|=29.5=|=32.0=| =34.5=| =37.1=| =40.0=| =43.0=| =58.0=| =75.0=| =95.0=|=116.= |
+    7"  | 73.7 | 76.9 | 80.2 | 83.3 |  86.6 |  89.8 |  93.0 |  96.2 | 112   | 128   | 145   | 161   |
+        |=20.0=|=22.5=|=24.9=|=27.0=| =28.8=| =30.6=| =32.8=| =35.5=| =47.5=| =61.2=| =78.6=| =95.1=|
+    8"  | 96.3 |101   |105   |109   | 113   | 117   | 121   | 125   | 146   | 168   | 189   | 210   |
+        |=17.1=|=19.2=|=21.0=|=22.9=| =24.6=| =26.2=| =28.0=| =30.1=| =40.1=| =52.1=| =66.6=| =82.0=|
+    9"  |122   |127   |132   |138   | 143   | 148   | 154   | 159   | 185   | 212   | 238   | 265   |
+        |=14.8=|=16.7=|=17.9=|=19.9=| =21.0=| =22.7=| =24.3=| =25.9=| =34.8=| =45.9=| =58.0=| =70.1=|
+   10"  |150   |157   |163   |170   | 177   | 183   | 190   | 196   | 229   | 261   | 295   | 327   |
+        |=13.0=|=14.7=|=15.9=|=17.1=| =18.2=| =20.1=| =21.3=| =22.6=| =30.7=| =40.0=| =50.8=| =62.0=|
+   11"  |182   |190   |198   |206   | 214   | 222   | 229   | 237   | 277   | 316   | 356   | 396   |
+        |=11.6=|=13.0=|=14.0=|=15.1=| =16.1=| =17.8=| =19.1=| =20.2=| =27.1=| =35.9=| =45.4=| =55.9=|
+   12"  |217   |226   |235   |245   | 254   | 264   | 273   | 283   | 330   | 377   | 425   | 472   |
+--------+---------+----------+------+-------+-------+-------+-------+-------+-------+-------+-------+
+
+    EXAMPLE
+
+    Assume the surveyed head as 240 feet, the water quantity as 207
+    cubic feet per minute and a pipe line 12 inches in diameter 900 feet
+    long. To ascertain the friction loss, refer to column of pipe
+    diameter and follow across the column for 12 inches diameter to the
+    quantity, 207 cubic feet per minute. The heavy-faced figures above
+    207 indicate that the loss per 1000 feet of pipe length is 11 feet.
+    Therefore, since the pipe in the example is 900 feet long, the loss
+    will be
+
+    11.' × 900/1000 or 9.9 feet, and the effective head will be
+    240' - 9.9' = 230.1'
+
+
+Steel tubing for supply pipes, from 3 to 12 inches in diameter is
+listed at from 20 cents to $1.50 a foot, according to the diameter and
+thickness of the material. Discounts on these prices will vary from 25
+to 50 per cent. The farmer can cut down the cost of this pipe by
+conveying his supply water from its natural source to a pond, by means
+of an open race, or a wooden flume. An ingenious mechanic can even
+construct his own pipe out of wood, though figuring labor and
+materials, it is doubtful if anything would be saved over a riveted
+steel pipe, purchased at the regular price. This pipe, leading from
+the pond, or forebay, to the water wheel, should be kept as short as
+possible; at the same time, the fall should not be too sharp. An angle
+of 30° will be found very satisfactory, although pipe is frequently
+laid at angles up to 50°.
+
+
+_Other Types of Impulse Wheels_
+
+In recent years more efficient forms of the old-fashioned overshoot,
+pitch-back breast, and undershoot wheels have been developed, by
+substituting steel or other metal for wood, and altering the shape of
+the buckets to make better use of the power of falling water.
+
+In some forms of overshoot wheels, an efficiency of over 90 per cent
+is claimed by manufacturers; and this type offers the additional
+advantage of utilizing small quantities of water, as well as being
+efficient under varying quantities of water. They utilize the falling
+weight of water, although by giving the water momentum at the point of
+delivery, by means of the proper fall, impulse too is utilized in some
+measure. The modern steel overshoot wheel receives water in its
+buckets from a spout set a few degrees back of dead center; and its
+buckets are so shaped that the water is retained a full
+half-revolution of the wheel. The old-style overshoot wheel was
+inefficient principally because the buckets began emptying themselves
+at the end of a quarter-revolution. Another advantage claimed for
+these wheels over the old style is that, being made of thin metal,
+their buckets attain the temperature of the water itself, thus
+reducing the danger of freezing to a minimum. They are manufactured in
+sizes from 6 feet in diameter to upwards of fifty feet; and with
+buckets of from 6 inches to 10 feet in width. In practice it is usual
+to deliver water to the buckets by means of a trough or pipe, through
+a suitable spout and gate, at a point two feet above the crown of the
+wheel. For this reason, the diameter of the wheel corresponds very
+closely to the head in feet.
+
+
+_The Reaction Turbine_
+
+The reaction turbine is best adapted to low heads, with a large supply
+of water. It is not advisable, under ordinary circumstances, to use it
+under heads exceeding 100 feet, as its speed is then excessive. It
+may be used under falls as low as two feet. Five thousand cubic feet
+of water a minute would give approximately 14 actual horsepower under
+such a head. A sluggish creek that flows in large volume could thus be
+utilized for power with the reaction turbine, whereas it would be
+useless with an impulse wheel. Falls of from five to fifteen feet are
+to be found on thousands of farm streams, and the reaction turbine is
+admirably adapted to them.
+
+Reaction turbines consist of an iron "runner" which is in effect a
+rotary fan, the pressure and momentum of the column of water pressing
+on the slanted blades giving it motion and power. These wheels are
+manufactured in a great variety of forms and sizes; and are to be
+purchased either as the runner (set in bearings) alone, or as a runner
+enclosed in an iron case. In case the runner alone is purchased, the
+owner must enclose it, either with iron or wood. They vary in price
+according to size, and the means by which the flow of water is
+controlled. A simple 12-inch reaction turbine wheel, such as would be
+suitable for many power plants can be had for $75. A twelve-inch
+wheel, using 18 or 20 square inches of water, would generate about
+7-1/2 horsepower under a 20-foot head, with 268 cubic feet of water a
+minute. Under a 30-foot head, and with 330 cubic feet of water such a
+wheel will give 14 horsepower. A 36-inch wheel, under a 5-foot head,
+would use 2,000 cubic feet of water, and give 14 horsepower. Under a
+30-foot head, this same wheel, using 4,900 cubic feet of water a
+minute, would develop over 200 horsepower. If the farmer is confronted
+by the situation of a great deal of water and small head, a large
+wheel would be necessary. Thus he could secure 35 horsepower with only
+a 3-foot head, providing his water supply is equal to the draft of
+8,300 cubic feet a minute.
+
+From these sample figures, it will be seen that the reaction turbine
+will meet the requirements of widely varying conditions up to, say a
+head of 100 feet. The farmer prospector should measure first the
+quantity of water to be depended on, and then the number of feet fall
+to be had. The higher the fall, with certain limits, the smaller the
+expense of installation, and the less water required. When he has
+determined _quantity_ and _head_, the catalogue of a reputable
+manufacturer will supply him with what information is necessary to
+decide on the style and size wheel he should install. In the older
+settled communities, especially in New England, a farmer should be
+able to pick up a second-hand turbine, at half the price asked for a
+new one; and since these wheels do not depreciate rapidly, it would
+serve his purpose as well, in most cases, as a new one.
+
+[Illustration: A typical vertical turbine]
+
+Reaction turbines may be either horizontal or vertical. If they are
+vertical, it is necessary to connect them to the main shaft by means
+of a set of bevel gears. These gears should be substantially large,
+and if the teeth are of hard wood (set in such a manner that they can
+be replaced when worn) they will be found more satisfactory than if of
+cast or cut metal.
+
+[Illustration: Two wheels on a horizontal shaft
+
+(Courtesy of the C. P. Bradway Company, West Stafford, Conn.)]
+
+The horizontal turbine is keyed to its shaft, like the impulse wheel,
+so that the wheel shaft itself is used for driving, without gears or a
+quarter-turn belt. (The latter is to be avoided, wherever possible.)
+There are many forms of horizontal turbines; they are to be had of the
+duplex type, that is, two wheels on one shaft. These are arranged so
+that either wheel may be run separately, or both together, thus
+permitting one to take advantage of the seasonal fluctuation in water
+supply. A convenient form of these wheels includes draft tubes, by
+which the wheel may be set several feet above the tailrace, and the
+advantage of this additional fall still be preserved. In this case the
+draft tube must be airtight so as to form suction, when filled with
+escaping water, and should be proportioned to the size of the wheel.
+Theoretically these draft tubes might be 34 feet long, but in practice
+it has been found that they should not exceed 10 or 12 feet under
+ordinary circumstances. They permit the wheel to be installed on the
+main floor of the power station, with the escape below, instead of
+being set just above the tailrace level itself, as is the case when
+draft tubes are not used.
+
+Reaction turbines when working under a variable load require water
+governors (like impulse wheels) although where the supply of water is
+large, and the proportion of power between water wheel and dynamo is
+liberal--say two to one, or more--this necessity is greatly reduced.
+Reaction wheels as a rule govern themselves better than impulse
+wheels, due both to the fact that they use more water, and that they
+operate in a small airtight case. The centrifugal ball governor is the
+type usually used with reaction wheels as well as with impulse wheels.
+This subject will be discussed more fully later.
+
+
+_Installing a Power Plant_
+
+In developing a power prospect, the dam itself is usually not the site
+of the power plant. In fact, because of danger from flood water and
+ice, it is better to locate it in a more protected spot, leading the
+water to the wheel by means of a race and flume.
+
+[Illustration: Bird's-eye view of a developed water-power plant]
+
+A typical crib dam, filled with stone, is shown in section in the
+diagram, and the half-tone illustration shows such a dam in course of
+construction. The first bed of timbers should be laid on hard-pan or
+solid rock in the bed of the stream parallel to its flow. The second
+course, across the stream, is then begun, being spiked home by means
+of rods cut to length and sharpened by the local blacksmith, from
+3/4-inch Norway iron. Hemlock logs are suitable for building the crib;
+and as the timbers are finally laid, it should be filled in and made
+solid with boulders. This filling in should proceed section by
+section, as the planking goes forward, otherwise there will be no
+escape for the water of the stream, until it rises and spills over
+the top timbers. The planking should be of two-inch chestnut, spiked
+home with 60 penny wire spikes. When the last section of the crib is
+filled with boulders and the water rises, the remaining planks may be
+spiked home with the aid of an iron pipe in which to drive the spike
+by means of a plunger of iron long enough to reach above the level of
+the water. When the planking is completed, the dam should be well
+gravelled, to within a foot or two of its crest. Such dams are
+substantial, easily made with the aid of unskilled labor, and the
+materials are to be had on the average farm with the exception of the
+hardware.
+
+[Illustration: Cross-section of a rock and timber dam]
+
+This dam forms a pond from which the race draws its supply of water
+for the wheel. It also serves as a spillway over which the surplus
+water escapes. The race should enter the pond at some convenient
+point, and should be protected at or near its point of entrance by a
+bulkhead containing a gate, so that the supply of water may be cut off
+from the race and wheel readily. The lay of the land will determine
+the length and course of the race. The object of the race is to secure
+the required head by carrying a portion of the available water to a
+point where it can escape, by a fall of say 30° to the tailrace. It
+may be feasible to carry the race in a line almost at right angles to
+the stream itself, or, again, it may be necessary to parallel the
+stream. If the lay of the land is favorable, the race may be dug to a
+distance of a rod or so inshore, and then be permitted to cut its own
+course along the bank, preventing the water escaping back to the river
+or brook before the site of the power plant is reached, by building
+suitable retaining embankments. The race should be of ample size for
+conveying the water required without too much friction. It should end
+in a flume constructed stoutly of timbers. It is from this flume that
+the penstock draws water for the wheel. When the wheel gate is closed
+the water in the mill pond behind the dam, and in the flume itself
+should maintain an approximate level. Any surplus flow is permitted to
+escape over flushboards in the flume; these same flushboards maintain
+a constant head when the wheel is in operation by carrying off what
+little surplus water the race delivers from the pond.
+
+[Illustration: Detail of bulkhead gate]
+
+At some point in the race or flume, the flow should be protected from
+leaves and other trash by means of a rack. This rack is best made of
+1/4 or 1/2-inch battens from 1-1/2 to 3 inches in width, bolted
+together on their flat faces and separated a distance equal to the
+thickness of the battens by means of iron washers. This rack will
+accumulate leaves and trash, varying with the time of year and should
+be kept clean, so as not to cut down the supply of water needed by the
+wheel.
+
+The penstock, or pipe conveying water from the flume to the wheel,
+should be constructed of liberal size, and substantially, of two-inch
+chestnut planking, with joints caulked with oakum, and the whole well
+bound together to resist the pressure of the water. Means should be
+provided near the bottom for an opening through which to remove any
+obstructions that may by accident pass by the rack. Many wheels have
+plates provided in their cases for this purpose.
+
+The tailrace should be provided with enough fall to carry the escaping
+water back to the main stream, without backing up on the wheel itself
+and thus cutting down the head.
+
+It is impossible to make any estimates of the cost of such a
+water-power plant. The labor required will in most instances be
+supplied by the farmer himself, his sons, and his help, during times
+when farm operations are slack.
+
+
+_Water Rights of the Farmer_
+
+The farmer owns the bed of every stream not navigable, lying within
+the boundary lines of the farm; and his right to divert and make use
+of the water of such streams is determined in most states by common
+law. In the dry-land states where water is scarce and is valuable for
+irrigation, a special set of statutes has sprung up with the
+development of irrigation in this country.
+
+A stream on the farm is either public or private; its being navigable
+or "floatable" (suitable for floating logs) determining which. Water
+rights are termed in law "riparian" rights, and land is riparian only
+when water flows over it or along its borders.
+
+Green (Law for the American Farmer) says:
+
+"Water is the common and equal property of every one through whose
+land it flows, and the right of each land-owner to use and consume it
+without destroying, or unreasonably impairing the rights of others, is
+the same. An owner of land bordering on a running stream has the right
+to have its waters flow naturally, and none can lawfully divert them
+without his consent. Each riparian proprietor has an equal right with
+all the others to have the stream flow in its natural way without
+substantial reduction in volume, or deterioration in quality, subject
+to a proper and reasonable use of its waters for domestic,
+agricultural and manufacturing purposes, and he is entitled to use it
+himself for such purposes, but in doing so must not substantially
+injure others. In addition to the right of drawing water for the
+purposes just mentioned, a riparian proprietor, if he duly regards the
+rights of others, and does not unreasonably deplete the supply, has
+also the right to take the water for some other proper uses."
+
+Thus, the farmer who seeks to develop water-power from a stream
+flowing across his own land, has the right to divert such a stream
+from its natural channel--providing it is not a navigable or floatable
+stream--but in so doing, he must return it to its own channel for
+lower riparian owners. The generation of water-power does not pollute
+the water, nor does it diminish the water in quantity, therefore the
+farmer is infringing on no other owner's rights in using the water for
+such a purpose.
+
+When a stream is a dividing line between two farms, as is frequently
+the case, each proprietor owns to the middle of the stream and
+controls its banks. Therefore to erect a dam across such a private
+stream and divert all or a part of the water for power purposes,
+requires the consent of the neighboring owner. The owner of the dam is
+responsible for damage due to flooding, to upstream riparian owners.
+
+
+
+
+PART II
+
+ELECTRICITY
+
+
+
+
+CHAPTER V
+
+THE DYNAMO; WHAT IT DOES, AND HOW
+
+     Electricity compared to the heat and light of the Sun--The simple
+     dynamo--The amount of electric energy a dynamo will generate--The
+     modern dynamo--Measuring power in terms of electricity--The
+     volt--The ampere--The ohm--The watt and the kilowatt--Ohm's Law of
+     the electric circuit, and some examples of its application--Direct
+     current, and alternating current--Three types of direct-current
+     dynamos: series, shunt, and compound.
+
+
+What a farmer really does in generating electricity from water that
+would otherwise run to waste in his brook, is to install a private Sun
+of his own--which is on duty not merely in daylight, but twenty-four
+hours a day; a private Sun which is under such simple control that it
+shines or provides heat and power, when and where wanted, simply by
+touching a button.
+
+This is not a mere fanciful statement. When you come to look into it
+you find that electricity actually is the life-giving power of the
+Sun's rays, so transformed that it can be handily conveyed from place
+to place by means of wires, and controlled by mechanical devices as
+simple as the spigot that drains a cask.
+
+Nature has the habit of traveling in circles. Sometimes these circles
+are so big that the part of them we see looks like a straight line,
+but it is not. Even parallel lines, according to the mathematicians,
+"meet in infinity." Take the instance of the water wheel which the
+farmer has installed under the fall of his brook. The power which
+turns the wheel has the strength of many horses. It is there in a
+handy place for use, because the Sun brought it there. The Sun, by its
+heat, lifted the water from sea-level, to the pond where we find
+it--and we cannot get any more power out of this water by means of a
+turbine using its pressure and momentum in falling, than the Sun
+itself expended in raising the water against the force of gravity.
+
+Once we have installed the wheel to change the energy of falling water
+into mechanical power, the task of the dynamo is to turn this
+mechanical power into another mode of motion--electricity. And the
+task of electricity is to change this mode of motion back into the
+original heat and light of the Sun--which started the circle in the
+beginning.
+
+Astronomers refer to the Sun as "he" and "him" and they spell his name
+with a capital letter, to show that he occupies the center of our
+small neighborhood of the universe at all times.
+
+
+_Magnets and Magnetism_
+
+The dynamo is a mechanical engine, like the steam engine, the water
+turbine or the gas engine; and it converts the mechanical motion of
+the driven wheel into electrical motion, with the aid of a magnet.
+Many scientists say that the full circle of energy that keeps the
+world spinning, grows crops, and paints the sky with the Aurora
+Borealis, begins and ends with magnetism--that the sun's rays are
+magnetic rays. Magnetism is the force that keeps the compass needle
+pointing north and south. Take a steel rod and hold it along the
+north and south line, slightly inclined towards the earth, and strike
+it a sharp blow with a hammer, and it becomes a magnet--feeble, it is
+true, but still a magnet.
+
+Take a wire connected with a common dry battery and hold a compass
+needle under it and the needle will immediately turn around and point
+directly across the wire, showing that the wire possesses magnetism
+encircling it in invisible lines, stronger than the magnetism of the
+earth.
+
+[Illustration: (_Courtesy of the Crocker-Wheeler Company_)
+
+A direct-current dynamo or motor, showing details of construction]
+
+Insulate this wire by covering it with cotton thread, and wind it
+closely on a spool. Connect the two loose ends to a dry battery, and
+you will find that you have multiplied the magnetic strength of a
+single loop of wire by the number of turns on the spool--concentrated
+all the magnetism of the length of that wire into a small space. Put
+an iron core in the middle of this spool and the magnet seems still
+more powerful. Lines of force which otherwise would escape in great
+circles into space, are now concentrated in the iron. The iron core
+is a magnet. Shut off the current from the battery and the iron is
+still a magnet--weak, true, but it will always retain a small portion
+of its magnetism. Soft iron retains very little of its magnetism. Hard
+steel retains a great deal, and for this reason steel is used for
+permanent magnets, of the horseshoe type so familiar.
+
+
+_A Simple Dynamo_
+
+A dynamo consists, first, of a number of such magnets, wound with
+insulated wire. Their iron cores point towards the center of a circle
+like the spokes of a wheel; and their curved inner faces form a circle
+in which a spool, wound with wire in another way, may be spun by the
+water wheel.
+
+Now take a piece of copper wire and make a loop of it. Pass one side
+of this loop in front of an electric magnet.
+
+As the wire you hold in your hands passes the iron face of the magnet,
+a wave of energy that is called electricity flows around this loop at
+the rate of 186,000 miles a second--the same speed as light comes to
+us from the sun. As you move the wire away from the magnet, a second
+wave starts through the wire, flowing in the opposite direction. You
+can prove this by holding a compass needle under the wire and see it
+wag first in one direction, then in another.
+
+[Illustration: A wire "cutting" the lines of force of an
+electro-magnet]
+
+This is a simple dynamo. A wire "cutting" the invisible lines of
+force, that a magnet is spraying out into the air, becomes
+"electrified." Why this is true, no one has ever been able to explain.
+
+The amount of electricity--its capacity for work--which you have
+generated with the magnet and wire, does not depend alone on the
+pulling power of that simple magnet. Let us say the magnet is very
+weak--has not enough power to lift one ounce of iron. Nevertheless,
+if you possessed the strength of Hercules, and could pass that wire
+through the field of force of the magnet many thousands of times a
+second, you would generate enough electricity in the wire to cause the
+wire to melt in your hands from heat.
+
+[Illustration: Cross-section of an armature revolving in its field]
+
+[Illustration: Forms of annealed steel discs used in armature
+construction]
+
+This experiment gives the theory of the dynamo. Instead of passing
+only one wire through the field of force of a magnet, we have hundreds
+bound lengthwise on a revolving drum called an armature. Instead of
+one magnetic pole in a dynamo we have two, or four, or twenty
+according to the work the machine is designed for--always in pairs, a
+North pole next to a South pole, so that the lines of force may flow
+out of one and into another, instead of escaping in the surrounding
+air. If you could see these lines of force, they would appear in
+countless numbers issuing from each pole face of the field magnets,
+pressing against the revolving drum like hair brush bristles--trying
+to hold it back. This drum, in practice, is built up of discs of
+annealed steel, and the wires extending lengthwise on its face are
+held in place by slots to prevent them from flying off when the drum
+is whirled at high speed. The drum does not touch the face of the
+magnets, but revolves in an air space. If we give the electric
+impulses generated in these wires a chance to flow in a circuit--flow
+out of one end of the wires, and in at the other, the drum will
+require more and more power to turn it, in proportion to the amount of
+electricity we permit to flow. Thus, if one electric light is turned
+on, the drum will press back with a certain strength on the water
+wheel; if one hundred lights are turned on it will press back one
+hundred times as much. Providing there is enough power in the water
+wheel to continue turning the drum at its predetermined speed, the
+dynamo will keep on giving more and more electricity if asked to,
+until it finally destroys itself by fire. You cannot take more power,
+in terms of electricity, out of a dynamo that you put into it, in
+terms of mechanical motion. In fact, to insure flexibility and
+constant speed at all loads, it is customary to provide twice as much
+water wheel, or engine, power as the electrical rating of the dynamo.
+
+[Illustration: An armature partly wound, showing slots and commutator]
+
+We have seen that a water wheel is 85 per cent efficient under ideal
+conditions. A dynamo's efficiency in translating mechanical motion
+into electricity, varies with the type of machine and its size. The
+largest machines attain as high as 90 per cent efficiency; the
+smallest ones run as low as 40 per cent.
+
+
+_Measuring Electric Power_
+
+The amount of electricity any given dynamo can generate depends,
+generally speaking, on two factors, i. e., (1) the power of the water
+wheel, or other mechanical engine that turns the armature; and (2) the
+size (carrying capacity) of the wires on this drum.
+
+Strength, of electricity, is measured in _amperes_. An ampere of
+electricity is the unit of the rate of flow and may be likened to a
+gallon of water per minute.
+
+In surveying for water-power, in Chapter III, we found that the
+number of gallons or cubic feet of water alone did not determine the
+amount of power. We found that the number of gallons or cubic feet
+multiplied by the distance in feet it falls in a given time, was the
+determining factor--pounds (quantity) multiplied by feet per
+second--(velocity).
+
+[Illustration: Showing the analogy of water to volts and amperes of
+electricity]
+
+The same is true in figuring the power of electricity. We multiply the
+_amperes_ by the number of electric impulses that are created in the
+wire in the course of one second. The unit of velocity, or pressure of
+the electric current is called a _volt_. Voltage is the pressure which
+causes electricity to flow. A volt may be likened to the velocity in
+feet per second of water in falling past a certain point. If you
+think a moment you will see that this has nothing to do with quantity.
+A pin-hole stream of water under 40 pounds pressure has the same
+velocity as water coming from a nozzle as big as a barrel, under the
+same pressure. So with electricity under the pressure of one volt or
+one hundred volts.
+
+One volt is said to consist of a succession of impulses caused by _one
+wire cutting 100,000,000 lines of magnetic force in one second_. Thus,
+if the strength of a magnet consisted of one line of force, to create
+the pressure of one volt we would have to "cut" that line of force
+100,000,000 times a second, with one wire; or 100,000 times a second
+with one thousand wires. Or, if a magnet could be made with
+100,000,000 lines of force, a single wire cutting those lines once in
+a second would create one volt pressure. In actual practice, field
+magnets of dynamos are worked at densities up to and over 100,000
+lines of force to the square inch, and armatures contain several
+hundred conductors to "cut" these magnetic lines. The voltage then
+depends on the speed at which the armature is driven. In machines for
+isolated plants, it will be found that the speed varies from 400
+revolutions per minute, to 1,800, according to the design of dynamo
+used.
+
+[Illustration: Pressure determines volume of flow in a given time]
+
+Multiplying amperes (strength) by volts (pressure), gives us _watts_
+(power). Seven hundred and forty-six watts of electrical energy is
+equal to one horsepower of mechanical energy--will do the same work.
+Thus an electric current under a pressure of 100 volts, and a density
+of 7.46 amperes, is one horsepower; as is 74.6 amperes, at 10 volts
+pressure; or 746 amperes at one volt pressure. For convenience (as a
+watt is a small quantity) electricity is measured in _kilowatts_, or
+1,000 watts. Since 746 watts is one horsepower, 1,000 watts or one
+kilowatt is 1.34 horsepower. The work of such a current for one hour
+is called a _kilowatt-hour_, and in our cities, where electricity is
+generated from steam, the retail price of a kilowatt-hour varies from
+10 to 15 cents.
+
+Now as to how electricity may be controlled, so that a dynamo will not
+burn itself up when it begins to generate.
+
+Again we come back to the analogy of water. The amount of water that
+passes through a pipe in any given time, depends on the size of the
+pipe, if the pressure is maintained uniform. In other words the
+_resistance_ of the pipe to the flow of water determines the amount.
+If the pipe be the size of a pin-hole, a very small amount of water
+will escape. If the pipe is as big around as a barrel, a large amount
+will force its way through. So with electricity. Resistance,
+introduced in the electric circuit, controls the amount of current
+that flows. A wire as fine as a hair will permit only a small quantity
+to pass, under a given pressure. A wire as big as one's thumb will
+permit a correspondingly greater quantity to pass, the pressure
+remaining the same. The unit of electrical resistance is called the
+_ohm_--named after a man, as are all electrical units.
+
+
+_Ohm's Law_
+
+The _ohm_ is that amount of _resistance_ that will permit the passage
+of _one ampere_, under the pressure of _one volt_. It would take two
+volts to force two amperes through one ohm; or 100 volts to force 100
+amperes through the resistance of one ohm. From this we have Ohm's
+Law, a simple formula which is the beginning and end of all electric
+computations the farmer will have to make in installing his
+water-power electric plant. Ohm's Law tells us that the density of
+current (amperes) that can pass through a given resistance in ohms (a
+wire, a lamp, or an electric stove) equals _volts_ divided by
+_ohms_--or _pressure_ divided by _resistance_. This formula may be
+written in three ways, thus:
+
+C = E/R, or R = E/C or, E = C × R. Or to express the same thing in
+words, _current_ equals _volts_ divided by _ohms_; _ohms_ equals
+_volts_ divided by _current_; or _volts_ equals _current_ multiplied
+by _ohms_. So, with any two of these three determining factors known,
+we can find the third. As we have said, this simple law is the
+beginning and end of ordinary calculations as to electric current, and
+it should be thoroughly understood by any farmer who essays to be his
+own electrical engineer. Once understood and applied, the problem of
+the control of the electric current becomes simple a b c.
+
+
+_Examples of Ohm's Law_
+
+Let us illustrate its application by an example. The water wheel is
+started and is spinning the dynamo at its rated speed, say 1,500
+r.p.m. Two heavy wires, leading from brushes which collect electricity
+from the revolving armature, are led, by suitable insulated supports
+to the switchboard, and fastened there. They do not touch each other.
+Dynamo mains must not be permitted to touch each other _under any
+conditions_. They are separated by say four inches of air. Dry air is
+a very poor conductor of electricity. Let us say, for the example,
+that dry air has a resistance to the flow of an electric current, of
+1,000,000 ohms to the inch--that would be 4,000,000 ohms. How much
+electricity is being permitted to escape from the armature of this
+110-volt dynamo, when the mains are separated by four inches of dry
+air? Apply Ohm's law, C equals E divided by R. E, in this case is 110;
+R is 4,000,000; therefore C (amperes) equals 110/4,000,000--an
+infinitesimal amount--about .0000277 ampere.
+
+Let us say that instead of separating these two mains by air we
+separated them by the human body--that a man took hold of the bare
+wires, one in each hand. The resistance of the human body varies from
+5,000 to 10,000 ohms. In that case C (amperes) equals 110/5,000, or
+110/10,000--about 1/50th, or 1/100th of an ampere. This illustrates
+why an electric current of 110 volts pressure is not fatal to human
+beings, under ordinary circumstances. The body offers too much
+resistance. But, if the volts were 1,100 instead of the usual 110 used
+in commercial and private plants for domestic use, the value of C, by
+this formula at 5,000 ohms, would be nearly 1/5th ampere. To drive
+1/5th ampere of electricity through the human body would be fatal in
+many instances. The higher the voltage, the more dangerous the
+current. In large water-power installations in the Far West, where the
+current must be transmitted over long distances to the spot where it
+is to be used, it is occasionally generated at a pressure of 150,000
+volts. Needless to say, contact with such wires means instant death.
+Before being used for commercial or domestic purposes, in such cases,
+the voltage is "stepped down" to safe pressures--to 110, or to 220, or
+to 550 volts--always depending on the use made of it.
+
+Now, if instead of interposing four inches of air, or the human body,
+between the mains of our 110-volt dynamo, we connected an incandescent
+lamp across the mains, how much electricity would flow from the
+generator? An incandescent lamp consists of a vacuum bulb of glass, in
+which is mounted a slender thread of carbonized fibre, or fine
+tungsten wire. To complete a circuit, the current must flow through
+this wire or filament. In flowing through it, the electric current
+turns the wire or filament white hot--incandescent--and thus turns
+electricity back into light, with a small loss in heat. In an ordinary
+16 candlepower carbon lamp, the resistance of this filament is 220
+ohms. Therefore the amount of current that a 110-volt generator can
+force through that filament is 110/220, or 1/2 ampere.
+
+[Illustration: Armature and field coils of a direct current dynamo]
+
+One hundred lamps would provide 100 paths of 220 ohms resistance each
+to carry current, and the amount required to light 100 such lamps
+would be 100 × 1/2 or 50 amperes. Every electrical device--a lamp, a
+stove, an iron, a motor, etc.,--must, by regulations of the Fire
+Underwriters' Board be plainly marked with the voltage of the current
+for which it is designed and the amount of current it will consume.
+This is usually done by indicating its capacity in watts, which as we
+have seen, means volts times amperes, and from this one can figure
+ohms, by the above formulas.
+
+
+_A Short Circuit_
+
+We said a few paragraphs back that under no conditions must two bare
+wires leading from electric mains be permitted to touch each other,
+without some form of resistance being interposed in the form of lamps,
+or other devices. Let us see what would happen if two such bare wires
+did touch each other. Our dynamo as we discover by reading its plate,
+is rated to deliver 50 amperes, let us say, at 110 volts pressure.
+Modern dynamos are rated liberally, and can stand 100% overload for
+short periods of time, without dangerous overheating. Let us say that
+the mains conveying current from the armature to the switchboard are
+five feet long, and of No. 2 B. & S. gauge copper wire, a size which
+will carry 50 amperes without heating appreciably. The resistance of
+this 10 feet of No. 2 copper wire, is, as we find by consulting a wire
+table, .001560 ohms. If we touch the ends of these two five-foot wires
+together, we instantly open a clear path for the flow of electric
+current, limited only by the carrying capacity of the wire and the
+back pressure of .001560 ohms resistance. Using Ohm's Law, C equals E
+divided by R, we find that C (amperes) equals 110/.001560 or _70,515
+amperes_!
+
+[Illustration: A direct current dynamo]
+
+Unless this dynamo were properly protected, the effect of such a
+catastrophe would be immediate and probably irreparable. In effect, it
+would be suddenly exerting a force of nearly 10,000 horsepower against
+the little 10 horsepower water wheel that is driving this dynamo. The
+mildest thing that could happen would be to melt the feed-wire or to
+snap the driving belt, in which latter case the dynamo would come to a
+stop. If by any chance the little water wheel was given a chance to
+maintain itself against the blow for an instant, the dynamo, rated at
+50 amperes, would do its best to deliver the 70,515 amperes you called
+for--and the result would be a puff of smoke, and a ruined dynamo.
+This is called a "short circuit"--one of the first "don'ts" in
+handling electricity.
+
+As a matter of fact every dynamo is protected against such a calamity
+by means of safety devices, which will be described in a later
+chapter--because no matter how careful a person may be, a partial
+short circuit is apt to occur. Happily, guarding against its
+disastrous effects is one of the simplest problems in connection with
+the electric plant.
+
+
+_Direct Current and Alternating Current_
+
+When one has mastered the simple Ohm's Law of the electric circuit,
+the next step is to determine what type of electrical generator is
+best suited to the requirements of a farm plant.
+
+In the first place, electric current is divided into two classes of
+interest here--_alternating_, and _direct_.
+
+We have seen that when a wire is moved through the field of a magnet,
+there is induced in it two pulsations--first in one direction, then in
+another. This is an _alternating_ current, so called because it
+changes its direction. If, with our armature containing hundreds of
+wires to "cut" the lines of force of a group of magnets, we connected
+the beginning of each wire with one copper ring, and the end of each
+wire with another copper ring, we would have what is called an
+_alternating-current_ dynamo. Simply by pressing a strap of flexible
+copper against each revolving copper ring, we would gather the sum of
+the current of these conductors. Its course would be represented by
+the curved line in the diagram, one loop on each side of the middle
+line (which represents time) would be a _cycle_. The number of
+_cycles_ to the second depends on the speed of the armature; in
+ordinary practice it is usually twenty-five or sixty. Alternating
+current has many advantages, which however, do not concern us here.
+Except under very rare conditions, a farmer installing his own plant
+should not use this type of machine.
+
+[Illustration: Diagram of alternating and direct current]
+
+If, however, instead of gathering all the current with brushes bearing
+on two copper rings, we collected all the current traveling in one
+direction, on one set of brushes--and all the current traveling in the
+other direction on another set of brushes,--we would straighten out
+this current, make it all travel in one direction. Then we would have
+a _direct current_. A direct current dynamo, the type generally used
+in private plants, does this. Instead of having two copper rings for
+collecting the current, it has a single ring, made up of segments of
+copper bound together, but insulated from each other, one segment for
+each set of conductors on the armature. This ring of many segments, is
+called a _commutator_, because it commutates, or changes, the
+direction of the electric impulses, and delivers them all in one
+direction. In effect, it is like the connecting rod of a steam engine
+that straightens out the back-and-forth motion of the piston in the
+steam cylinder and delivers the motion to a wheel running in one
+direction.
+
+Such a current, flowing through a coil of wire would make a magnet,
+one end of which would always be the north end, and the other end the
+south end. An alternating current, on the other hand, flowing through
+a coil of wire, would make a magnet that changed its poles with each
+half-cycle. It would no sooner begin to pull another magnet to it,
+than it would change about and push the other magnet away from it, and
+so on, as long as it continued to flow. This is one reason why a
+direct current dynamo is used for small plants. Alternating current
+will light the same lamps and heat the same irons as a direct current;
+but for electric power it requires a different type of motor.
+
+
+_Types of Direct Current Dynamos_
+
+Just as electrical generators are divided into two classes,
+alternating and direct, so direct current machines are divided into
+three classes, according to the manner in which their output, in
+amperes and volts, is regulated. They differ as to the manner in which
+their field magnets (in whose field of force the armature spins) are
+excited, or made magnetic. They are called _series_, _shunt_, and
+_compound_ machines.
+
+
+_The Series Dynamo_
+
+By referring to the diagram, it will be seen that the current of a
+_series_ dynamo issues from the armature mains, and passes through the
+coils of the field magnets before passing into the external circuit to
+do its work. The residual magnetism, or the magnetism left in the
+iron cores of the field magnets from its last charge, provides the
+initial excitation, when the machine is started. As the resistance of
+the external circuit is lowered, by turning on more and more lights,
+more and more current flows from the armature, through the field
+magnets. Each time the resistance is lowered, therefore, the current
+passing through the field magnets becomes more dense in amperes, and
+makes the field magnets correspondingly stronger.
+
+We have seen that the voltage depends on the number of lines of
+magnetic force cut by the armature conductors in a given time. If the
+speed remains constant then, and the magnets grow stronger and
+stronger, the voltage will rise in a straight line. When no current is
+drawn, it is 0; at full load, it may be 100 volts, or 500, or 1,000
+according to the machine. This type of machine is used only in street
+lighting, in cities, with the lights connected in "series," or one
+after another on the same wire, the last lamp finally returning the
+wire to the machine to complete the circuit. This type of dynamo has
+gained the name for itself of "mankiller," as its voltage becomes
+enormous at full load. It is unsuitable, in every respect, for the
+farm plant. Its field coils consist of a few turns of very heavy wire,
+enough to carry all the current of the external circuit, without
+heating.
+
+[Illustration: Connections of a series dynamo]
+
+
+_The Shunt Dynamo_
+
+The shunt dynamo, on the other hand, has field coils connected
+directly _across_ the circuit, from one wire to another, instead of in
+"series." These coils consist of a great many turns of very fine wire,
+thus introducing _resistance_ into the circuit, which limits the
+amount of current (amperes) that can be forced through them at any
+given voltage. As a shunt dynamo is brought up to its rated speed, its
+voltage gradually rises until a condition of balance occurs between
+the field coils and the armature. There it remains constant. When
+resistance on the external circuit is lowered, by means of turning on
+lamps or other devices, the current from the armature increases in
+working power, by increasing its amperes. Its voltage remains
+stationary; and, since the resistance of its field coils never
+changes, the magnets do not vary in strength.
+
+[Illustration: Connections of a shunt dynamo]
+
+The objection to this type of machine for a farm plant is that, in
+practice, the armature begins to exercise a de-magnetizing effect on
+the field magnets after a certain point is reached--weakens them;
+consequently the voltage begins to fall. The voltage of a shunt dynamo
+begins to fall after half-load is reached; and at full load, it has
+fallen possibly 20 per cent. A rheostat, or resistance box on the
+switchboard, makes it possible to cut out or switch in additional
+resistance in the field coils, thus varying the strength of the field
+coils, within a limit of say 15 per cent, to keep the voltage
+constant. This, however, requires a constant attendance on the
+machine. If the voltage were set right for 10 lights, the lights would
+grow dim when 50 lights were turned on; and if it were adjusted for 50
+lights, the voltage would be too high for only ten lights--would cause
+them to "burn out."
+
+Shunt dynamos are used for charging storage batteries, and are
+satisfactory for direct service only when an attendant is constantly
+at hand to regulate them.
+
+
+_The Compound Dynamo_
+
+The ideal between these two conditions would be a compromise, which
+included the characteristics of both _series_ and _shunt_ effects.
+That is exactly what the _compound_ dynamo effects.
+
+A compound dynamo is a shunt dynamo with just enough series turns on
+its field coils, to counteract the de-magnetizing effect of the
+armature at full load. A machine can be designed to make the voltage
+rise gradually, or swiftly, by combining the two systems. For country
+homes, the best combination is a machine that will keep the voltage
+constant from no load to full load. A so-called _flat-compounded_
+machine does this. In actual practice, this voltage rises slightly at
+the half-load line--only two or three volts, which will not damage the
+lamps in a 110-volt circuit.
+
+The compound dynamo is therefore self-regulating, and requires no
+attention, except as to lubrication, and the incidental care given to
+any piece of machinery. Any shunt dynamo can be made into a compound
+dynamo, by winding a few turns of heavy insulated wire around the
+shunt coils, and connecting them in "series" with the external
+circuit. How many turns are necessary depends on conditions. Three or
+four turns to each coil usually are sufficient for "flat compounding."
+If the generating plant is a long distance from the farm house where
+the light, heat, and power are to be used, the voltage drops at full
+load, due to resistance of the transmission wires. To overcome this,
+enough turns can be wound on top of the shunt coils to cause the
+voltage to rise at the switchboard, but remain stationary at the spot
+where the current is used. The usual so-called flat-compounded dynamo,
+turned out by manufacturers, provides for constant voltage at the
+switchboard. Such a dynamo is eminently fitted for the farm electric
+plant. Any other type of machine is bound to cause constant trouble
+and annoyance.
+
+[Illustration: Connections of a compound dynamo]
+
+
+
+
+CHAPTER VI
+
+WHAT SIZE PLANT TO INSTALL
+
+     The farmer's wife his partner--Little and big plants--Limiting
+     factors--Fluctuations in water supply--The average plant--The
+     actual plant--Amount of current required for various
+     operations--Standard voltage--A specimen allowance for electric
+     light--Heating and cooking by electricity--Electric power: the
+     electric motor.
+
+
+The farmer's wife becomes his partner when he has concluded the
+preliminary measurements and surveys for building his water-power
+electric plant. Now the question is, how big a plant is necessary, or
+how small a plant can he get along with. Electricity may be used for a
+multitude of purposes on the farm, in its sphere of furnishing
+portable light, heat and power; but when this multitude of uses has
+been enumerated, it will be found that the wife shares in the benefits
+no less than the farmer himself. The greatest dividend of all,
+whether dividends are counted in dollars or happiness, is that
+electricity takes the drudgery out of housework. Here, the work of the
+farmer himself ends when he has brought electricity to the house, just
+as his share in housework ends when he has brought in the kerosene,
+and filled the woodbox. Of the light and heat, she will use the lion's
+share; and for the power, she will discover heretofore undreamed-of
+uses. So she must be a full partner when it comes to deciding how much
+electricity they need.
+
+How much electricity, in terms of light, heat, and power, will the
+farmer and his wife have use for? How big a plant should be installed
+to meet the needs of keeping house and running the farm?
+
+The answer hangs mainly on how much water-power there is available,
+through all the seasons of the year, with which to generate
+electricity. Beyond that, it is merely a question of the farmer's
+pocketbook. How much money does he care to spend? Electricity is a
+cumulative "poison." The more one uses it, the more he wants to use
+it. After a plant has been in operation a year, the family have
+discovered uses for electricity which they did not think of in the
+beginning. For this reason, it is well to put in a plant larger than
+the needs of the moment seem to require. An electrical horsepower or
+two one way or another will not greatly change the first cost, and you
+will always find use for any excess.
+
+Once for all, to settle the question of water-power, the water wheel
+should be twice the normal capacity of the dynamo it drives, in terms
+of power. This allows for overload, which is bound to occur
+occasionally; and it also insures smooth running, easy governing, and
+the highest efficiency. Since the electric current, once the plant is
+installed, will cost practically nothing, the farmer can afford to
+ignore the power going to waste, and consider only how to get the best
+service.
+
+
+_The Two Extremes_
+
+The amount of water to be had to be turned into electricity, will vary
+with location, and with the season. It may be only enough, the
+greater part of the year, for a "toy" plant--a very practical toy, by
+the way--one that will keep half a dozen lights burning in the house
+and barn at one time; under some conditions water may be so scarce
+that it must be stored for three or four days to get enough power to
+charge a storage battery for these six or eight lights. A one-quarter,
+or a one-half kilowatt electrical generator, with a one horsepower (or
+smaller) wheel, will light a farmstead very satisfactorily--much
+better than kerosene lamps.
+
+On the other hand, the driving power of your wheel may be sufficient
+to furnish 50 or 100 lights for the house, barn, and out-buildings,
+and barn-yard and drives; to provide ample current for irons,
+toasters, vacuum cleaners, electric fans, etc.; to do all the cooking
+and baking and keep the kitchen boiler hot; and to heat the house in
+the coldest weather with a dry clean heat that does not vitiate the
+air, with no ashes, smoke or dust or woodchopping--nothing but an
+electric switch to turn on and off; and to provide power for motors
+ranging from tiny ones to run the sewing machine, to one of 15
+horsepower to do the threshing. A plant capable of developing from 30
+to 50 kilowatts of electricity, and requiring from 50 to 100
+horsepower at the water wheel, would do all this, depending on the
+size of the farmstead. One hundred horsepower is a very small water
+project, in a commercial way; and there are thousands of farms
+possessing streams of this capacity.
+
+
+_Fluctuations in Water Supply_
+
+It would be only during the winter months that such a plant would be
+driven to its full capacity; and since water is normally plentiful
+during these months, the problem of power would be greatly simplified.
+The heaviest draft on such a plant in summer would be during
+harvesting; otherwise it would be confined to light, small power for
+routine work, and cooking. Thus, a plant capable of meeting all the
+ordinary requirements of the four dry months of summer, when water is
+apt to be scarce, doubles or quadruples its capacity during the
+winter months, to meet the necessities of heat for the house.
+
+A dynamo requires only as much power to drive it, at any given time,
+as is being used in terms of electricity. There is some small loss
+through friction, of course, but aside from this the power required of
+the prime mover (the water wheel) is always in proportion to the
+amount of current flowing. When water is scarce, and the demands for
+current for heating are low, it is good practice to close a portion of
+the buckets of the turbine wheel with wooden blocks provided for this
+purpose. It is necessary to keep the speed of the dynamo uniform under
+all water conditions; and where there is a great fluctuation between
+high and low water periods, it is frequently necessary to have a
+separate set of pulleys for full gate and for half-gate. The head must
+remain the same, under all conditions. Changing the gate is in effect
+choking or opening the nozzle supplying the wheel, to cut down or
+increase its consumption of water.
+
+
+_The Average Plant_
+
+It will be the exceptional plant, however, among the hundreds of
+thousands to be had on our farms, which will banish not only the oil
+lamp and kitchen stove, but all coal or wood burning stoves as
+well--which will heat the house in below-zero weather, and provide
+power for the heavier operations of the farm. Also, on the other hand,
+it will be the exceptional plant whose capacity is limited to
+furnishing a half-dozen lights and no more.
+
+A happy medium between these two conditions is the plant large enough
+to supply between five and ten electrical horsepower, in all seasons.
+Such a plant will meet the needs of the average farm, outside of
+winter heating and large power operations, and will provide an excess
+on which to draw in emergencies, or to pass round to one's neighbors.
+It is such a plant that we refer to when we say that (not counting
+labor) its cost, under ordinary conditions should not greatly exceed
+the price of one sound young horse for farm work.
+
+Since the plant we described briefly in the first chapter, meets the
+requirements of this "average plant" let us inquire a little more
+fully into its installation, maintenance, and cost.
+
+
+_An Actual Plant_
+
+In this instance, the water-power was already installed, running to
+waste, in fact. The wheel consists of the so-called thirty-six inch
+vertical turbine, using 185 square inches of water, under a 14-foot
+head. Water is supplied to this wheel by a wooden penstock 33 inches
+square, inside measurements, and sloping at an angle of 30° from the
+flume to the wheel.
+
+[Illustration: Details of voltmeter or ammeter]
+
+This wheel, under a 14-foot head, takes 2,312 cubic feet of water a
+minute; and it develops 46.98 actual horsepower (as may be figured by
+using the formulas of Chapter III). The water supply is provided by a
+small mountain river. The dam is 10 feet high, and the race, which
+feeds the flume from the mill pond is 75 yards long. The race has two
+spillways, one near the dam, and the second at the flume itself, to
+maintain an even head of water at all times.
+
+
+_Half-Gate_
+
+Since the water supply varies with the seasons, it has been found
+practical to run the wheel at half-gate--that is, with the gate only
+half-open. A set of bevel gears work the main shaft, which runs at
+approximately 200 revolutions per minute; and the dynamo is worked up
+to its required speed of 1,500 revolutions per minute through a
+countershaft.
+
+The dynamo is a modern four-pole machine, compound-wound, with a rated
+output of 46 amperes, at 125 volts--in other words a dynamo of 5.75
+kilowatts capacity, or 7.7 electrical horsepower. At full load this
+dynamo would require a driving power of 10 horsepower, counting it as
+75 per cent efficient; and, to conform to our rule of two water
+horsepower to one electrical horsepower, the wheel should be capable
+of developing 20 horsepower. As a matter of fact, in this particular
+instance, shutting down the wheel to half-gate more than halves the
+rated power of the wheel, and little more than 15 horsepower is
+available. This allowance has proved ample, under all conditions met
+with, in this plant.
+
+The dynamo is mounted on a firm floor foundation; and it is belted
+from the countershaft by an endless belt running diagonally. A
+horizontal belt drive is the best. Vertical drive should be avoided
+wherever possible.
+
+
+_The Switchboard_
+
+The switchboard originally consisted of a wooden frame on which were
+screwed ordinary asbestos shingles, and the instruments were mounted
+on these. Later, a sheet of electric insulating fibre was substituted,
+for look's sake. The main requisite is something substantial--and
+fireproof. The switchboard instruments consist of a voltmeter, with a
+range of from 0 to 150 volts; an ammeter, with a range, 0 to 75
+amperes; a field regulating rheostat (which came with the dynamo); a
+main switch, with cartridge fuses protecting the machine against a
+draft of current over 60 amperes; and two line switches for the two
+owners, one fuse at 20 amperes, and the other at 40 amperes. Electric
+fuses are either cartridges or plugs, enclosing lead wire of a size
+corresponding to their rating. All the current of the line they
+protect passes through this lead wire. If the current drawn exceeds
+the capacity of the lead wire, it melts from the heat, and thus opens
+the circuit, and cuts off the current.
+
+[Illustration: A switchboard and its connections: _G._ Dynamo; _A._
+Shunt field coils; _B._ Series coils; _DD._ Fuses; _FF._ Main switch;
+_F._ Field switch; _C._ Ammeter; _V._ Voltmeter; _E._ Lamp; _R._
+Rheostat. Dotted lines show connections on back of board]
+
+
+_Items of Cost_
+
+This water wheel would cost $250 new. There is a duplicate in the
+neighborhood bought at second-hand, for $125. The dynamo cost $90,
+and was picked up second-hand in New York City. New it would cost
+$150. The voltmeter cost $7, and the ammeter $10; and the switches and
+fuses could be had for $5. A wheel one-half the size, using one-half
+the amount of water at full gate, would do the work required, and the
+cost would be correspondingly less.
+
+
+_Capacity_
+
+This plant supplies two farms with electric light. One farm (that of
+the owner of the wheel) has 30 lamps, of 16 candlepower each, and two
+barn-yard lamps of 92 candlepower each. His wife has an electric iron
+and an electric water heater. Needless to say, all these lamps, and
+the iron and water heater are not in use at one time.
+
+[Illustration: Carbon Lamps Gem Type (1/4 scale)]
+
+The partner who owns the electric part of the plant has 30 lamps in
+his house and barn, many of them being 25 watt tungsten, which give
+more light for less power, but cost more to buy. They are not all in
+use at one time, though (since the current costs nothing) the
+inclination is to turn them on at night and let them burn. In his
+kitchen he has an electric range, and a water heater for the 40 gallon
+boiler. In addition to this he has all sorts of appliances,--irons,
+toasters, grills, a vacuum cleaner, a vibrator, etc. Naturally all
+these appliances are not in use at one time, else the draft on the
+plant would be such as to "blow" the fuses. For instance, all the
+baking is done in daylight; and when the oven is used after dark, they
+are careful to turn off all lights not needed. An ideal plant, of
+course, would be a plant big enough to take care of the sum of lamps
+and handy devices used at one time.
+
+To make this plant ideal, (for, being an actual affair, it has
+developed some short-comings, with the extension of the use of
+electricity) it would require a dynamo whose capacity can be figured,
+from the following:
+
+                                                        Watts
+    15 carbon lamps, 16 candlepower, @60 watts each      900
+    10 tungsten lamps, 20 candlepower, @25 watts each    250
+    2 tungsten lamps, 92 candlepower, @100 watts each    200
+    Water heater, continuous service                     800
+    Toaster, occasional service                          600
+    Iron, occasional service                             400
+    Oven-baking, roasting, etc                         2,000
+    2 stove plates @1,000 watts each                   2,000
+    1 stove plate                                        400
+    Vacuum cleaner, occasional service                   200
+    Vibrator, occasional service                         100
+    Small water heater, quart capacity                   400
+    Small motor, 1/4 horsepower, occasional              250
+    Motor, 1/2 hp, pumping water, etc                    500
+    Electric fan, occasional service                     100
+                                                     -------
+             Total current, one house                  9,100
+
+
+    30 carbon lamps, 16 candlepower, @60               1,800
+    2 lamps, 100 watt tungsten                           200
+    Electric iron                                        400
+    Small water or milk heater                           600
+                                                     -------
+             Total current, 2nd house                  3,000
+                            1st house                  9,100
+                                                     -------
+                                                      12,100
+
+Thus, in this plant, if every electrical device were turned on at
+once, the demand on the dynamo would be for 12.1 kilowatts, or an
+overload of over 100 per cent. The main-switch fuse, being for 60
+amperes, would "blow" or melt, and cut off all current for the
+moment. To repair the damage would be merely the work of a second--and
+at a cost of a few cents--simply insert a new fuse, of which there
+must be a supply on hand at all times. Or, if either owner exceeded
+his capacity, the line fuses (one for 20 amperes, and the other for 40
+amperes) would instantly cut off all current from the greedy one.
+
+[Illustration: 25 and 40 watt Mazda tungsten lamps (1/4 scale)]
+
+
+_Lessons From This Plant_
+
+The story of this plant illustrates two things which the farmer and
+his wife must take into account when they are figuring how much
+electricity they require. First, it illustrates how one uses more and
+more current, as he finds it so serviceable and labor-saving, and at
+the same time free. The electric range and the water boiler, in the
+above instance, were later acquisitions not counted on in figuring the
+original installation. Second, it illustrates, that while the normal
+load of this generator is _5.75_ kilowatts, one does not have to limit
+the electrical conveniences in the home to this amount. True, he
+cannot use more electricity than his plant will produce _at any one
+time_,--but it is only by a stretch of the imagination that one may
+conceive the necessity of using them all at once. Ironing, baking, and
+the use of small power are usually limited to daylight hours when no
+lights are burning.
+
+As a matter of fact, this plant has proved satisfactory in every way;
+and only on one or two occasions have fuses been "blown", and then it
+was due to carelessness. A modern dynamo is rated liberally. It will
+stand an overload of as much as 100 per cent for a short time--half an
+hour or so. The danger from overloading is from heating. When the
+machine grows too hot for the hand, it is beginning to char its
+insulation, to continue which, of course would ruin it. The best plant
+is that which works under one-half or three-quarters load, under
+normal demands.
+
+
+_Standard Voltage_
+
+We are assuming the farmer's plant to be, in 99 cases out of 100, the
+standard 110-volt, direct current type. Such a plant allows for at
+least a 10 per cent regulation, in voltage, up or down the scale;
+supplies for this voltage are to be had without delay in even the more
+remote parts of the country, and (being sold in greater volume) they
+are cheaper than those for other voltages.
+
+There are two general exceptions to this rule as to 110-volt plants:
+(1) If the plant is located at a distance greater than a quarter of a
+mile from the house, it will be found cheaper (in cost of transmission
+line, as will be shown later) to adopt the 220-volt plant; (2), If the
+water supply is so meagre that it must be stored for many hours at a
+time, and then used for charging storage batteries, it will be found
+most economical to use a 30-volt plant. A storage battery is made up
+of cells of approximately 2 volts each; and, since more than 55 such
+cells would be required for a 110-volt installation, its cost would
+be prohibitive, with many farmers.
+
+So we will assume that this plant is a 110-volt plant, to be run
+without storage battery. It will be well to make a chart, dividing the
+farm requirements into three heads--light, heat, and power.
+
+
+_Light_
+
+[Illustration: 60 and 100 watt Mazda tungsten lamp. These lamps may be
+had in sizes from 10 to 500 watts (1/4 scale)]
+
+[Illustration: The lamp of the future. A 1000 watt Mazda nitrogen
+lamp, giving 2000 candlepower (1/4 scale)]
+
+Light is obtained by means of incandescent lamps. There are two styles
+in common use, the carbon and the tungsten lamp. It requires 3.5 to 4
+watts of electricity to produce one candlepower in a carbon lamp. It
+requires from 1 to 1.25 watt to produce one candlepower in the
+tungsten lamp. The new nitrogen lamp, not yet in general use, requires
+only 1/2 watt to the candlepower. Since tungsten lamps give three
+times the light of the carbon lamp, they are the most economical to
+use in the city or town where one is paying for commercial current.
+But, in the country where water-power furnishes current for nothing,
+it will be found most economical to use the carbon lamp, since its
+cost at retail is 16 cents, as compared with 30 cents for a
+corresponding size in tungsten. A 60 watt carbon lamp, of 16
+candlepower; or a 25 watt tungsten lamp, of 20 candlepower, are the
+sizes to use. In hanging lamps, as over the dining room table, a 100
+watt tungsten lamp, costing 70 cents, and giving 92 candlepower light
+is very desirable; and for lighting the barn-yard, these 100 watt
+tungsten lamps should be used. For reading lamps, the tungsten style,
+of 40 or 60 watt capacity, will be found best. Otherwise, in all
+locations use the cheaper carbon lamp. Both styles have a rated life
+of 1,000 hours, after which they begin to fall off in efficiency. Here
+again, the farmer need not worry over lack of highest efficiency, as a
+lamp giving only 80 per cent of its rated candlepower is still
+serviceable when he is not paying for the current. With care not to
+use them at voltages beyond their ratings, lamps will last for years.
+
+
+_A Specimen Light Allowance_
+
+Below is a typical table of lights for a large farm house, the barns
+and barn-yard. It is given merely as a guide, to be varied for each
+individual case:
+
+                                                        Watts
+    Kitchen, 2 lights @60 watts                          120
+    Dining room, 1 light, tungsten                       100
+    Living room, table lamp with 3 tungstens @40         120
+    Living room, 2 wall fixtures, 4 lamps @60 watts      240
+    Parlor, same as living room                          360
+    Pantry, 1 hanging lamp                                60
+    Cellar, one portable lamp                             60
+    Woodshed, 1 hanging lamp                              60
+    2 bedrooms, 2 lights each @ 60                       240
+    2 bed rooms, 1 light each @60                        120
+    Bathroom, 1 "turn-down" light, @60                    60
+    Hall, downstairs, 2 lights @60                       120
+    Hall, upstairs, 1 light                               60
+    Attic, 1 light                                        60
+    Porch, 1 light                                        60
+    Barn and barn-yard:
+    Barn-yard entrance, 1 tungsten                       100
+    Watering trough,    1    "                           100
+    Front gate,         1    "                           100
+    Horse barn, 4 lights @60                             240
+    Cow barn, 4 lights @60                               240
+    Pig house, 1 light                                    60
+    Hay barn, 2 lights, @60                              120
+                                                     -------
+    Total for farmstead                                2,800
+
+This provides for 44 lights, an extremely liberal allowance. How many
+of these lights will be burning at any one time? Probably not one-half
+of them; yet the ideal plant is that which permits all fixtures to be
+in service at one time on the rare occasions when necessary. Thus, for
+lighting only, 2,800 watts maximum service would require a 4 kilowatt
+generator, and 10 water horsepower, on the liberal rating of two to
+one. A 3 kilowatt generator would take care of these lights, with a 30
+per cent overload (which is not excessive) for maximum service. The
+above liberal allowance of lights may be cut in two, or four--or even
+eight--and still throw a kerosene lamp in shadow. It all depends on
+the number of lights one wants burning at one time; and the power of
+the water wheel.
+
+If the 36 carbon lights in the above table were replaced by 25 watt
+tungsten lights, the saving in power would be 35 watts each, or 1,260
+watts, nearly two electrical horsepower; while the added first cost
+would be 14 cents a light, or $5.04. A generator of 2 kilowatt
+capacity would take care of all these lights then, with 460 watts to
+spare.
+
+
+_Heating_
+
+Electric heating and cooking is in its infancy, due to the prohibitive
+cost of commercial current in our cities. Here the farmer has the
+advantage again, with his cheap current.
+
+For heating the house, it is calculated that 2 watts is required for
+each cubic foot of air space in a room, during ordinary winter
+weather. Thus, a room 10 × 12, and 8 feet high, would contain 960
+cubic feet, and would require 1,820 watts energy to heat it in cold
+weather. Five such rooms would require 9.1 kilowatts; and 10 such
+rooms, or their equivalent, would require 18.2 kilowatts.
+
+Electric heating devices are divided into two classes: (1) those which
+can be used on lamp circuits, _and do not draw more than 660 watts
+each_; and (2) those which draw more than 660, therefore _require
+special wiring_. The capacity of these devices is approximately as
+follows:
+
+    Lamp circuit devices:              Watts
+        Electric iron                400 to 660
+        Toaster                      350 to 660
+        Vacuum cleaner               200 to 400
+        Grill                        400 to 660
+        Small water heater           400 to 660
+        Hot plates                   400 to 660
+
+    Lamp circuit devices:
+        Coffee percolator            400 to 660
+        Chafing dish                 400 to 660
+        Electric fan                 100 to 250
+
+    Special circuit devices:
+        Hot water boiler heater      800 to 1,200
+        Small ovens                  660 to 1,200
+        Range ovens                1,200 to 3,000
+        Range, hot plates            400 to 1,300
+        Radiators (small)            750 to 1,500
+        Radiators (large)          1,500 to 6,000
+
+The only device in the above list which is connected continuously, is
+the hot water boiler, and this can be credited with at least one
+electrical horsepower 24 hours a day. It is a small contrivance, not
+much bigger than a quart can, attached to the back of the kitchen
+boiler, and it keeps the water hot throughout the house at all hours.
+Its cost will vary with the make, ranging from $8 to $15; and since it
+is one of the real blessings of the farm kitchen and bathroom, it
+should be included in all installations where power permits. Electric
+radiators will be used 24 hours a day in winter, and not at all in
+summer. They are portable, and can be moved from room to room, and
+only such rooms as are in actual use need be heated. The other devices
+are for intermittent service, many of them (like the iron) for only a
+few hours each week.
+
+The grill, chafing dish, coffee percolator, etc., which are used on
+the dining room table while the family is at meals, each draw an
+equivalent of from 6 to 10 carbon lights. By keeping this in view and
+turning off spare lights, one can have the use of them, with even a
+small plant. Thus, a one kilowatt plant permits the use of any one of
+these lamp circuit devices at a time, with a few lights in addition.
+
+
+_Power_
+
+Electric power is to be had through motors. A direct current dynamo
+and a direct current motor are identical in construction. That is, a
+motor becomes a generator if belted to power; and a generator becomes
+a motor, if connected to electric mains. This is best illustrated by
+citing the instance of a trans-continental railroad which crosses the
+Bitter Root Mountains by means of electric power. Running 200 miles up
+a 2 per cent grade, it is drawn by its motors. Coasting 200 miles
+down the 2 per cent grade on the other side of the mountains, its
+motors become generators. They act as brakes, and at the same time
+they pump the power of the coasting weight of this train back into the
+wires to help a train coming up the other side of the mountains.
+
+[Illustration: Connections of shunt motor and starting rheostat]
+
+Just as there are three types of direct current generators, so there
+are three types of direct current motors: _series_, _shunt_, and
+_compound_, with features already explained in the case of generators.
+Motors are rated by horsepower, and generators are rated by kilowatts.
+Thus a one kilowatt generator has a capacity of 1,000 watts; as a
+motor, it would be rated as 1000/746 horsepower, or 1.34 horsepower.
+Their efficiency varies with their size, ranging from 40 to 60 per
+cent in very small motors, and up to 95 per cent in very large ones.
+The following table may be taken as a guide in calculating the power
+required by motors, on 110-volt circuits:
+
+     1/4 Horsepower     2-1/2 amperes, or 275 watts
+     1/2 hp             4-1/2 amperes, or 500 watts
+      1  hp             9     amperes, or 990 watts
+      2  hp            17     amperes, or 1.97 kilowatts
+      3  hp            26     amperes, or 2.86 kilowatts
+      5  hp            40     amperes, or 4.40 kilowatts
+    7-1/2 hp           60     amperes, or 6.60 kilowatts
+     10  hp            76     amperes, or 8.36 kilowatts
+     15  hp           112     amperes, or 12.32 kilowatts
+
+An electric motor, in operation, actually generates electricity, which
+it pushes back into the line as a counter-electromotive-force. The
+strength of this counter force, in volts, depends on the motor's
+speed, the same as if it were running as a dynamo. For this reason,
+when a motor is started, and before it comes up to speed, there would
+be a rush of current from the line, with nothing to hold it back, and
+the motor would be burned out unless some means were provided to
+protect it for the moment. This is done by means of a starting
+rheostat, similar to the regulating rheostat on the dynamo
+switchboard. This resistance box is connected in "series" with the
+armature, in the case of shunt and compound motors; and with the
+entire motor circuit in the case of a series machine.
+
+A _series_ motor has a powerful starting torque, and adjusts its speed
+to the load. It is used almost altogether in street cars. It can be
+used in stump pulling, or derrick work, such as using a hay fork. It
+must always be operated under load, otherwise, it would increase in
+speed until it tore itself to pieces through mechanical strain. The
+ingenious farmer who puts together an electric plow, with the mains
+following behind on a reel, will use a series motor.
+
+A _shunt_ motor should be used in all situations where a fairly
+uniform speed under load is required, such as separating, in milking
+machines, running a lathe, an ensilage cutter, vacuum cleaners,
+grinders, etc.
+
+The _compound_ motor has the characteristics of the series and shunt
+motors, giving an increased starting torque, and a more nearly
+constant speed under varying loads than the shunt motor, since the
+latter drops off slightly in speed with increasing load.
+
+
+_Flexible Power_
+
+An electric motor is an extremely satisfactory form of power because
+it is so flexible. Thus, one may use a five horsepower motor for a one
+horsepower task, and the motor will use only one electrical horsepower
+in current--just enough to overcome the task imposed on it. For this
+reason, a large-sized motor may be used for any operation, from one
+requiring small power, up to its full capacity. It will take an
+overload, the same as a dynamo. In other words it is "eager" for any
+task imposed on it; therefore it must be protected by fuses, or it
+will consume itself, if too big an overload is imposed on it.
+
+A one horsepower shunt or compound motor is very serviceable for
+routine farm operations, such as operating the separator, the churn,
+the milking machine, grinder, pump, and other small power jobs. Motors
+of 1/4 horsepower are handy in the kitchen, for grinding knives,
+polishing silver, etc., and can be used also for vacuum cleaners, and
+running the sewing machine. For the larger operations, motors will
+vary from three horsepower for cutting ensilage, to fifteen horsepower
+for threshing. They can be mounted on trucks and conveyed from one
+point to another, being fed current from the mains by means of
+suitable wires wound on reels.
+
+Remember, in estimating the size of your plant for light, heat, and
+power, that it does not have to be big enough to use all the devices
+at one time. Also remember, that two water horsepower to one
+electrical horsepower is a very liberal allowance; and that a
+generator working under one-half or two-thirds capacity at normal
+loads will require less attention than a machine constantly being
+worked above its capacity. Therefore, let your generator be of liberal
+size, because the difference in cost between a 5 and 10 kilowatt
+machine is not in proportion to their capacity. In fact (especially
+among second-hand machines), the difference in cost is very small. The
+mere fact that the generator is of 110 electrical horsepower capacity
+does not require a turbine of 20 horsepower. The chances are that
+(unless you wish to heat your house and do large power jobs) you will
+not use more than 3 to 5 electrical horsepower normally; therefore an
+allowance of 10 water horsepower, in this case, would be ample. A
+plant used simply for lighting the house and barn, for irons, and
+toasters, and one horsepower motors, need not exceed 2 or 2-1/2
+kilowatts for the generator, and 5 or 6 horsepower for the turbine
+wheel. Normally it would not use one-half this capacity.
+
+
+
+
+CHAPTER VII
+
+TRANSMISSION LINES
+
+     Copper wire--Setting of poles--Loss of power in transmission--Ohm's
+     Law and examples of how it is used in figuring size of
+     wire--Copper-wire tables--Examples of transmission lines--When to
+     use high voltages--Over-compounding a dynamo to overcome
+     transmission loss.
+
+
+Having determined on the location of the farm water-power electric
+plant, and its capacity, in terms of electricity, there remains the
+wiring, for the transmission line, and the house and barn.
+
+For transmission lines, copper wire covered with waterproof braid--the
+so-called weatherproof wire of the trade--is used. Under no
+circumstances should a wire smaller than No. 8, B. & S. gauge be used
+for this purpose, as it would not be strong enough mechanically. The
+poles should be of chestnut or cedar, 25 feet long, and set four feet
+in the ground. Where it is necessary to follow highways, they should
+be set on the fence line; and in crossing public highways, the
+ordinance of your own town must guide you. Some towns prescribe a
+height of 19 feet above the road, others 27 feet, some 30. Direct
+current, such as is advised for farm installations, under ordinary
+circumstances, does not affect telephone wires, and therefore
+transmission lines may be strung on telephone poles. Poles are set at
+an average distance of 8 rods; they are set inclined outward on
+corners. Sometimes it is necessary to brace them with guy wires or
+wooden braces. Glass insulators are used to fasten the wires to the
+cross-arms of the poles, and the tie-wires used for this purpose must
+be the same size as the main wire and carry the same insulation.
+
+
+_Size of Wire for Transmission_
+
+To determine the size of the transmission wires will require knowledge
+of the strength of current (in amperes) to be carried, and the
+distance in feet. In transmission, the electric current is again
+analogous to water flowing in pipes. It is subject to resistance,
+which cuts down the amount of current (in watts) delivered.
+
+[Illustration: Bringing wires into the house or barn]
+
+The loss in transmission is primarily measured in volts; and since the
+capacity of an electric current for work equals the _volts_ multiplied
+by _amperes_, which gives _watts_, every volt lost reduces the working
+capacity of the current by so much. This loss is referred to by
+electrical engineers as the "C^2R loss," which is another way of
+saying that the loss is equal to the _square of the current in
+amperes_, multiplied by _ohms_ resistance. Thus, if the amperes
+carried is 10, and the ohms resistance of the line is 5, then the loss
+in watts to convey that current would be (10 × 10) × 5, or 500 watts,
+nearly a horsepower.
+
+The pressure of _one volt_ (as we have seen in another chapter) is
+sufficient to force _one ampere_, through a resistance of _one ohm_.
+Such a current would have no capacity for work, since its pressure
+would be consumed in the mere act of transmission.
+
+If, however, the pressure were _110 volts_, and the current _one
+ampere_, and the resistance _one ohm_, the effective pressure after
+transmission would be 110-1, or 109 volts.
+
+To force a 110-volt current of _50 amperes_ through the resistance of
+_one ohm_, would require the expenditure of _50 volts_ pressure. Its
+capacity for work, after transmission, would be 110-50, or _60 volts,
+× 50 amperes_, or 3,000 watts. As this current consisted of _110 ×
+50_, or 5,500 watts at the point of starting, the loss would be 2,500
+watts, or about 45 per cent. It is bad engineering to allow more than
+10 per cent loss in transmission.
+
+There are two ways of keeping this loss down. One is by increasing
+the size of the transmission wires, thus cutting down the resistance
+in ohms; the other way is by raising the voltage, thus cutting down
+the per cent loss. For instance, suppose the pressure was 1,100 volts,
+instead of 110 volts. Five amperes at 1,100 volts pressure, gives the
+same number of watts, power, as 50 amperes, at 110 volts pressure.
+Therefore it would be necessary to carry only 5 amperes, at this rate.
+The loss would be 5 volts, or less than 1/2 of 1 per cent, as compared
+with 45 per cent with 110 volts.
+
+[Illustration: Splicing transmission wire]
+
+In large generating stations, where individual dynamos frequently
+generate as much as 20,000 horsepower, and the current must be
+transmitted over several hundred miles of territory, the voltage is
+frequently as high as 150,000, with the amperes reduced in proportion.
+Then the voltage is lowered to a suitable rate, and the amperage
+raised in proportion, by special machinery, at the point of use.
+
+It is the principle of the C^2R loss, which the farmer must apply in
+determining the size of wire he is to use in transmitting his current
+from the generator switchboard to his house or barn. The wire table on
+page 159, together with the formula to be used in connection with it,
+reduce the calculations necessary to simple arithmetic. In this table
+the resistance of the various sizes of wire is computed from the fact
+that a wire of pure copper 1 foot long, and 1/1000 inch in diameter
+(equal to one circular mill) offers a resistance of 10.6 ohms to the
+foot. The principle of the C^2R loss is founded on Ohm's Law, which is
+explained in Chapter V.
+
+The formula by which the size of transmission wire is determined, for
+any given distance, and a given number of amperes, is as follows:
+
+  Distance ft. one way × 22 × No. of amperes   circular
+  ------------------------------------------ =  mills.
+             Number of volts lost
+
+In other words, multiply the _distance in feet_ from mill to house by
+22, and multiply this product by the _number of amperes_ to be
+carried. Then divide the product by the _number of volts_ to be lost;
+and the result will be the diameter of the wire required _in circular
+mills_. By referring to the table above, the B. & S. gauge of the wire
+necessary for transmission, can be found from the nearest
+corresponding number under the second column, entitled "circular mills
+area."
+
+
+     COPPER WIRE TABLE
+
+  --------+----------+-----------+-----------+-----------+------------
+          |          | _Area in  | _(R) Ohms |           |
+  _B.& S. | _Feet    | circular  | per 1,000 | _Feet     | _(R) Ohms
+  Gauge_  | per Lb._ | mills_    | feet_     | per Ohm_  | per pound_
+  --------+----------+-----------+-----------+-----------+------------
+   0000   |   1.561  | 211,600   |   .04904  | 20,392.90 |  .00007653
+   000    |   1.969  | 167,805   |   .06184  | 16,172.10 |  .00012169
+   00     |   2.482  | 133,079   |   .07797  | 12,825.40 |  .00019438
+   0      |   3.130  | 105,534   |   .09829  | 10,176.40 |  .00030734
+     1    |   3.947  |  83,694   |   .12398  |  8,066.00 |  .00048920
+     2    |   4.977  |  66,373   |   .15633  |  6,396.70 |  .00077784
+     3    |   6.276  |  52,634   |   .19714  |  5,072.50 |  .00123700
+     4    |   7.914  |  41,742   |   .24858  |  4,022.90 |  .00196660
+     5    |   9.980  |  33,102   |   .31346  |  3,190.20 |  .00312730
+     6    |  12.58   |  26,250   |   .39528  |  2,529.90 |  .00497280
+     7    |  15.87   |  20,816   |   .49845  |  2,006.20 |  .00790780
+     8    |  20.01   |  16,509   |   .62840  |  1,591.10 |  .01257190
+     9    |  25.23   |  13,094   |   .79242  |  1,262.00 |  .01998530
+    10    |  31.82   |  10,381   |   .99948  |  1,000.50 |  .03178460
+    11    |  40.12   |   8,234.0 |  1.26020  |    793.56 |  .05054130
+    12    |  50.59   |   6,529.9 |  1.58900  |    629.32 |  .08036410
+    13    |  63.79   |   5,178.4 |  2.00370  |    499.06 |  .12778800
+    14    |  80.44   |   4,106.8 |  2.52660  |    395.79 |  .20318000
+    15    | 101.4    |   3,256.7 |  3.18600  |    313.87 |  .32307900
+    16    | 127.9    |   2,582.9 |  4.01760  |    248.90 |  .51373700
+    17    | 161.3    |   2,048.2 |  5.06600  |    197.39 |  .81683900
+    18    | 203.4    |   1,624.3 |  6.38800  |    156.54 | 1.29876400
+  --------+----------+-----------+-----------+-----------+------------
+
+
+     CARRYING CAPACITY OF WIRES AND WEIGHT
+
+  -----------+-------------------+--------------------+--------------------
+             | _Weight 1,000 ft. | _Carrying capacity | _Carrying capacity
+  _B. & S.   |  Weatherproof     | Weatherproof       | rubber cov.
+  Gauge No._ |  (Pounds)_        | (Amperes)_         | (Amperes)_
+  -----------+-------------------+--------------------+--------------------
+    0000     |        800        |        312         |        175
+     000     |        666        |        262         |        145
+      00     |        500        |        220         |        120
+       0     |        363        |        185         |        100
+       1     |        313        |        156         |         95
+       2     |        250        |        131         |         70
+       3     |        200        |        110         |         60
+       4     |        144        |         92         |         50
+       5     |        125        |         77         |         45
+       6     |        105        |         65         |         35
+       7     |         87        |         55         |         30
+       8     |         69        |         46         |         25
+      10     |         50        |         32         |         20
+      12     |         31        |         23         |         15
+      14     |         22        |         16         |         10
+      16     |         14        |          8         |          5
+      18     |         11        |          5         |          3
+  -----------+-------------------+--------------------+--------------------
+
+Since two wires are required for electrical transmission, the above
+formula is made simple by counting the distance only one way, in feet,
+and doubling the resistance constant, 10.6, which, for convenience is
+taken as 22, instead of 21.2.
+
+
+_Examples of Transmission Lines_
+
+As an example, let us say that Farmer Jones has installed a
+water-power electric plant on his brook, _200 yards distant_ from his
+house. The generator is a 5 kilowatt machine, capable of producing _45
+amperes_ at _110 volts pressure_. He has a 3 horsepower motor, drawing
+26 amperes at full load; he has 20 lights of varying capacities,
+requiring 1,200 watts, or 10 amperes when all on; and his wife uses
+irons, toasters, etc., which amount to another 9 or 10 amperes--say 45
+altogether. The chances are that he will never use all of the
+apparatus at one time; but for flexibility, and his own satisfaction
+in not having to stop to think if he is overloading his wires, he
+would like to be able to draw the full _45 amperes_ if he wishes to.
+He is willing to allow _5 per cent loss_ in transmission. _What size
+wires will be necessary, and what will they cost?_ Substituting these
+values in the above formula, the result is:
+
+  Answer: 600 × 22 × 45
+          ------------- = 108,000 circular mills.
+               5.5
+
+[Illustration: Transmission wire on glass insulator]
+
+Referring to the table, No. 0 wire is 105,534 circular mills, and is
+near enough; so this wire would be used. It would require 1,200 feet,
+which would weigh, by the second table, 435.6 pounds. At 19 cents a
+pound, it would cost $82.76.
+
+Farmer Jones says this is more money than he cares to spend for
+transmission. As a matter of fact, he says, he never uses his motor
+except in the daytime, when his lights are not burning; so the maximum
+load on his line at any one time would be _26 amperes_, not 45. _What
+size wire would he use in this instance?_
+
+Substituting 26 for 45 in the equation, the result is 61,300 circular
+mills, which corresponds to No. 2 wire. It would cost $57.00.
+
+Now, if Farmer Jones, in an emergency, wished to use his motor at the
+same time he was using all his lights and his wife was ironing and
+making toast--in other words, if he wanted to use the _45 amperes_
+capacity of his dynamo, _how many volts would he lose?_ To get this
+answer, we change the formula about, until it reads as follows:
+
+   Distance in feet × 22 × amperes
+  --------------------------------- = Number of volts lost
+           circular mills
+
+Substituting values, we have, in this case, 600 × 22 × 45/66,373 (No.
+2) = 9 volts, nearly, less than 10 per cent. This is a very efficient
+line, under the circumstances. Now if he is willing to lose 10 per
+cent on _half-load_, instead of full load, he can save still more
+money in line wire. In that case (as you can find by applying the
+formula again), he could use No. 5 wire, at a cost of $28.50. He would
+lose 11 volts pressure drawing 26 amperes; and he would lose 18 volts
+pressure drawing 45 amperes, if by any chance he wished to use full
+load.
+
+In actual practice, this dynamo would be regulated, by means of the
+field resistance, to register 110 plus 11 volts, or 121 volts at the
+switchboard to make up for the loss at half-load. At full load, his
+voltage at the end of the line would be 121 minus 18, or 103 volts;
+his motor would run a shade slower, at this voltage, and his lights
+would be slightly dimmer. He would probably not notice the difference.
+If he did, he could walk over to his generating station, and raise
+the voltage a further 7 volts by turning the rheostat handle another
+notch.
+
+[Illustration: A barn-yard light]
+
+Thousands of plants can be located within 100 feet of the house. If
+Farmer Jones could do this, he could use No. 8 wire, costing $2.62.
+The drop in pressure would be 5.99 volts at full load--so small it
+could be ignored entirely. In this case the voltmeter should be made
+to read 116 volts at the switchboard, by means of the rheostat.
+
+If, on the other hand, this plant were 1,000 feet away from the house
+and the loss 10 volts the size wire would be
+
+  1,000 × 22 × 45
+  ---------------  = 99,000 circular mills;
+        10
+
+a No. 0 wire comes nearest to this figure, and its cost, for 2,000
+feet, at 19 cents a pound, would be $137.94. A No. 0000 wire, costing
+$294.00, would give a 5 per cent drop at full load. In this case, the
+cost of transmission can be reduced to a much lower figure, by
+allowing a bigger drop at half-load, with regulation at the
+switchboard. Thus, a No. 2 wire here, costing but $95, would be
+satisfactory in every way. The loss at half-load would be about 9
+volts, and the rheostat would be set permanently for 119 or 120 volts.
+A modern dynamo can be regulated in voltage by over 25 per cent in
+either direction, without harm, if care is taken not to overload it.
+
+
+_Benefit of Higher Voltages_
+
+If Farmer Jones' plant is a half of a mile away from the house, he
+faces a more serious proposition in the way of transmission. Say he
+wishes to transmit 26 amperes with a loss of 10 volts. What size wire
+will be necessary?
+
+        2640 × 22 × 26
+  Thus: -------------- = 151,000 circular mills.
+              10
+
+A No. 000 wire is nearest this size, and 5,280 feet of it would cost
+over $650.00. This cost would be prohibitive. If, however, he
+installed a 220-volt dynamo--at no increase in cost--then he would
+have to transmit only a half of 26 amperes, or 13 amperes, and he
+could allow 22 volts loss, counting 10 per cent. In this case, the
+problem would work out as follows:
+
+  2640 × 22 × 13
+  -------------- = 34,320 circular mills,
+        22
+
+or approximately a No. 5 wire which, at 19 cents a pound, would cost
+$120.65.
+
+Install a 550-volt generator, instead of a 220-volt machine and the
+amperes necessary would be cut to 5.2, and the volts lost would be
+raised to 55. In this case a No. 12 wire would carry the current; but
+since it would not be strong enough for stringing on poles, a No. 8
+wire would be used, costing about $63.
+
+It will be readily seen from these examples how voltage influences the
+efficiency of transmission. Current generated at a pressure in excess
+of 550 volts is not to be recommended for farm plants unless an expert
+is in charge. A safer rule is not to exceed 220 volts, for while 550
+volts is not necessarily deadly, it is dangerous. When one goes into
+higher voltages, it is necessary to change the type of dynamo to
+_alternating current_, so that the current can be transformed to safe
+voltages at the point where it is used. Since only the occasional farm
+plant requires a high-tension system, the details of such a plant will
+not be gone into here.
+
+In transmitting the electric current over miles of territory,
+engineers are accustomed to figure 1,000 volts for each mile. Since
+this is a deadly pressure, it should not be handled by any one not an
+expert, which, in this case, the farmer is not.
+
+
+_Over-Compounding the Generator_
+
+One can absorb the loss in transmission frequently, by
+over-compounding the machine. In describing the compound machine, in
+Chapter Five, it is shown that the usual compound dynamo on the market
+is the so-called flat-compounded type. In such a dynamo, the voltage
+remains constant at the switchboard, from no load to full load,
+allowing for a slight curve which need not be taken into account.
+
+Now, by adding a few more turns to the series wires on the field coils
+of such a dynamo, a machine is to be had which gradually raises its
+voltage as the load comes on in increasing volume. Thus, one could
+secure such a machine, which would begin generating at 110 volts, and
+would gradually rise to 150 at full load. Yet the voltage would remain
+constant at the point of use, the excess being absorbed in
+transmission. A machine of this type can be made to respond to any
+required rise in voltage.
+
+As an example of how to take advantage of this very valuable fact, let
+us take an instance:
+
+Say that Farmer Jones has a transmission line 1,000 feet long strung
+with No. 7 copper wire. This 2,000 feet of wire would introduce a
+resistance of one ohm in the circuit. That is, every ampere of current
+drawn at his house would cause the working voltage there to fall one
+volt. If he drew 26 amperes, the voltage would fall, at the house, 26
+volts. If his switchboard voltage was set at say 120, the voltage at
+his house, at 26 amperes of load, would fall to 94 volts, which would
+cause his lights to dim considerably. It would be a very
+unsatisfactory transmission line, with a flat-compounded dynamo.
+
+On the other hand, if his dynamo was over-compounded 25 per cent--that
+is, if it gained 28 volts from no load to full load, the system would
+be perfect. In this case, the dynamo would be operated at 110 volts
+pressure at the switchboard with no load. At full load the voltmeter
+would indicate 110 plus 26, or 136 volts. The one or two lights burned
+at the power plant would be subject to a severe strain; but the 50 or
+100 lights burned at the house and barn would burn at constant
+voltage, which is very economical for lamps.
+
+The task of over-compounding a dynamo can be done by any trained
+electrician. The farmer himself, if he progresses far enough in his
+study of electricity, can do it. It is necessary to remove the top or
+"series" winding from the field coils. Count the number of turns of
+this wire to each spool. Then procure some identical wire in town and
+begin experimenting. Say you found four turns of field wire to each
+spool. Now wind on five, or six, being careful to wind it in the same
+direction as the coils you removed and connect it in the same way. If
+this additional number of turns does not raise the voltage enough, in
+actual practice, when the dynamo is running from no load to full load,
+add another turn or two. With patience, the task can be done by any
+careful mechanic. The danger is in not winding the coils the same way
+as before, and getting the connections wrong. To prevent this mistake,
+make a chart of the "series" coils as you take them off.
+
+To make the task of over-compounding your own dynamo even more simple,
+write to the manufacturers, giving style and factory number of your
+machine. Tell them how much voltage rise you wish to secure, and ask
+them how many turns of "series" wire should be wound on each spool in
+place of the old "series" coil. They could tell you exactly, since
+they have mathematical diagrams of each machine they make.
+
+Avoid overloading an over-compounded machine. Since its voltage is
+raised automatically, its output in watts is increased a similar
+amount at the switchboard, and, for a given resistance, its output in
+amperes would be increased the same amount, as can be ascertained by
+applying Ohm's Law. Your ammeter is the best guide. Your machine is
+built to stand a certain number of amperes, and this should not be
+exceeded in general practice.
+
+
+
+
+CHAPTER VIII
+
+WIRING THE HOUSE
+
+     The insurance code--Different kinds of wiring described--Wooden
+     moulding cheap and effective--The distributing panel--Branch
+     circuits--Protecting the circuits--The use of porcelain tubes and
+     other insulating devices--Putting up chandeliers and wall
+     brackets--"Multiple" connections--How to connect a wall
+     switch--Special wiring required for heat and power circuits--Knob
+     and cleat wiring, its advantages and drawbacks.
+
+
+The task of wiring your house is a simple one, with well-defined rules
+prescribed by your insurance company. Electricity, properly installed,
+is much safer than oil lamps--so much so indeed that insurance
+companies are ready to quote especial rates. But they require that the
+wiring be done in accordance with rules laid down by their experts,
+who form a powerful organization known as the National Board of Fire
+Underwriters. Ask your insurance agent for a copy of the code rules.
+
+Danger of fire from an electric current comes from the "short
+circuit," partial or complete; and it is against this danger that the
+rules guard one. The amount of electricity flowing through a short
+circuit is limited only by the fuse protecting that line; and since
+there is no substance known that can withstand the heat of the
+electric arc, short circuits must be guarded against. Happily the
+current is so easily controlled that the fire hazard is eliminated
+entirely--something which cannot be done with oil lamps.
+
+In house-wiring for farm plants, the wire should be rubber-covered,
+and not smaller than No. 14 B. & S. gauge. This is the wire to use on
+all lamp circuits. It costs about $0.85 cents per 100 feet. There are
+four kinds of wiring permitted, under the insurance code:
+
+(1) _Flexible armoured cable_: This consists of two-wire cable,
+protected with a covering of flexible steel. It is installed out of
+sight between the walls, and provides suitable outlets for lamps,
+etc., by means of metal boxes set flush with the plaster. It is
+easily installed in a house being built, but requires much tearing
+down of plaster for an old house. Since its expense prohibits it in
+the average farm house, this system will not be described in detail
+here.
+
+(2) _Rigid and flexible conduit_: As the name implies this system
+consists of iron pipe, in connection with flexible conduit, run
+between the walls. It differs from the above system, in that the pipes
+with their fittings and outlet boxes are installed first, and the
+wires are then "fished" through them. Duplex wires--the two wires of
+the circuit woven in one braid--are used; and a liberal amount of
+soapstone, and occasionally kerosene, are used to make the wires slip
+easily into place. This is the most expensive system, and the best;
+but it is difficult to install it in an old house without tearing down
+a good deal of plaster. It has the advantage of being absolutely
+waterproof and fireproof.
+
+(3) _Wooden moulding_: This is simply moulding, providing two
+raceways for the insulated wires to run in, and covered with a
+capping. It is nailed or screwed firmly to the wall, on top of the
+plaster; and when the wires have been installed in their respective
+slots and the capping tacked on, the moulding is given a coat of paint
+to make it in harmony with the other moulding in the room. This system
+is cheap, safe, and easily installed, and will be described in detail
+here.
+
+[Illustration: Detail of wooden moulding]
+
+(4) _Open wiring_: In open wiring, the wires are stretched from one
+support to another (such as beams) and held by means of porcelain
+cleats, or knobs. It is the simplest to install; but it has the
+objection of leaving the wires unprotected, and is ugly. It is very
+satisfactory in barns or out-buildings however.
+
+
+_The Distributing Panel_
+
+The first point to consider in wiring a house with wooden moulding is
+the distribution board. It should be located centrally, on the wall
+near the ceiling, so as to be out of ordinary reach. It consists of a
+panel of wood--though fireproof material is better--firmly screwed to
+the wall, and containing in a row, the porcelain cut-outs, as shown in
+the cut, from which the various branch circuits are to be led. Each
+cut-out provides for two branch circuits; and each branch contains
+receptacles for two plug fuses. These fuses should be of 6 amperes
+each. The Insurance Code limits the amount of electricity that may be
+drawn on any branch lamp circuit to 660 watts; and these fuses protect
+the circuit from drafts beyond this amount.
+
+[Illustration: Porcelain cut-out and plug fuse]
+
+The mains, leading from the entrance switch, as shown in the diagram,
+to the panel board, should be of the same size as the transmission
+wire itself, and rubber-covered. These mains terminate at the
+distributing board. They are connected to the terminals of the
+cut-outs by means of heavy brass screws.
+
+
+_Wire Joints_
+
+[Illustration: Examples of cleat and knob wiring, 1, 2, 3; wire
+joints, 4; flexible armoured conductor, 5]
+
+The branch circuits are, as has been said, of No. 14 rubber-covered
+wire, running concealed in wooden moulding. All joints or splices in
+this wire are made, as shown in the illustration, by first scraping
+the wires bright, and fastening them stoutly together. This joint is
+then soldered, to make the connection electrically perfect. Soft
+solder is used, with ordinary soldering salts. There are several
+compounds on the market, consisting of soft solder in powder form,
+ready-mixed with flux. Coat the wire joint with this paste and apply
+the flame of an alcohol lamp. The soldered joint is then covered with
+rubber tape, and over this ordinary friction tape is wound on. A neat
+joint should not be larger than the diameter of the wire before
+insulation is removed.
+
+
+_Branch Circuits_
+
+First, make a diagram of your rooms and indicate where you wish lamps,
+or outlets for other purposes. Since wooden moulding can be run across
+ceilings, and up or down walls, lamps may be located in places where
+they are out of the way. In planning the circuit, remember that you
+will want many outlets in handy places on the walls, from which
+portable cords will convey current to table lamps, to electric irons
+and toasters and other handy devices which can be used on the lamp
+circuit. These outlets are made of porcelain, in two pieces. One
+piece is merely a continuation of the moulding itself; and the other
+is a cap to connect permanently to the end of the lamp or iron cord,
+which may be snapped into place in a second. Since there are a great
+many designs of separable current taps on the market, it is well to
+select one design and stick to it throughout the house, so that any
+device can be connected to any outlet.
+
+The code permits 660 watts on each circuit. This would allow 12 lamps
+of 55 watts each. It is well to limit any one circuit to 6 lamps; this
+will give leeway for the use of small stoves, irons, toasters, etc.
+without overloading the circuit and causing a fuse to blow.
+
+Having installed your distributing board, with its cut-outs, figure
+out the course of your first branch circuit. Let us say it will
+provide lights and outlets for the dining room and living room. It
+will be necessary to run the wires through the partitions or floors in
+several places. For this purpose porcelain tubes should be used,
+costing one to three cents each. Knock holes in the plaster at the
+determined point, insert the tubes so they project 3/4 inch on each
+side, and fill up the ragged edge of the hole neatly with plaster.
+
+[Illustration: The distributing panel]
+
+When all the tubes have been set in place, begin laying the moulding.
+Run it in a straight line, on the wall against the ceiling wherever
+possible, mitering the joints neatly. Whenever it is necessary to
+change the run from the ceiling to the wall and a miter cannot be
+made, the wires should be protected in passing from one slot to the
+other by being enclosed in non-metallic flexible conduit, called
+circular loom.
+
+In running wooden moulding, avoid brick walls liable to sweat or draw
+dampness; keep away from places where the heat of a stove might
+destroy the rubber insulation of the wires; do not pass nearer than
+six inches to water pipes when possible--and when it is necessary to
+pass nearer than this, the wooden moulding should pass above the pipe,
+not below it, with at least an inch of air space intervening, thus
+avoiding dampness from sweating of pipes.
+
+[Illustration: Snap switch connections]
+
+Places where chandeliers or wall bracket lamps are to be installed
+permanently are fitted with wooden terminal blocks, which fit over
+the moulding and flush with the plaster. These, after holes have been
+bored in them for the wires, and the wires drawn through, should be
+screwed firmly to the wall or ceiling, always choosing a joist or beam
+for support. Then a crow's-foot, or tripod of iron, tapped and
+threaded for iron pipe, is screwed to the terminal block. The iron
+pipe of the chandelier or wall bracket is then screwed home in this
+crow's-foot.
+
+Do not begin stringing wires until all the moulding of the circuit has
+been laid. Then thread the wires through the wall or floor tubes and
+lay them in their respective slots. If trouble be found making them
+stay in place before the capping is put on, small tacks may be driven
+into the moulding beside them to hold them. When a terminal block is
+reached, a loop is made of each wire, through the hole cut in the
+block, if the circuit is to continue in the same direction. If it is
+to end there, the two wires are drawn through taut, and cut off at a
+length of 5 or 6 inches. These end wires, or loops, are then scraped
+bare and spliced to the two wires coming out of the chandelier or
+wall bracket. This joint is then soldered and covered with tape, and
+the shell of the chandelier is screwed into place, covering the joint.
+
+[Illustration: Detail of wooden moulding]
+
+If the moulding is run along the walls flush with the ceiling, as is
+usual, a branch is made for a wall light, or wall tap, by means of a
+porcelain "T," or branch-block, which provides the means for running
+the circuit at right angles to itself without letting the wires come
+in contact with each other where they cross. Separable current taps
+should be installed in handy places on all circuits, so that small
+heating devices may be used without removing the lamps from their
+sockets. The two wires are bared for half an inch where they run
+through these current taps, and are fastened by means of brass screws.
+
+
+_"Multiple" Connections_
+
+All electric devices for this installation--lamps, irons, vacuum
+cleaners, motors--must be connected _across_ the circuit--that is,
+bridged, from one wire to the other. This is called _multiple_, or
+shunt connection. There is only one exception to it, in wiring the
+house. That one exception is installing a wall switch, the ordinary
+snap switch. Since this wall switch, is, in effect, merely an
+instrument, which opens or closes a circuit, it should be connected to
+only one wire, which is cut to provide two ends for the screw
+connections in the switch. When a moulding branch is run down from the
+ceiling to some convenient spot for a snap switch (with which to turn
+the lights of a room on or off), a porcelain "T" is not used. All that
+is necessary to do is to loop the bottom wire of the circuit down
+through the branch moulding, and connect it to the switch at a
+terminal block, or porcelain base.
+
+In wiring lamp fixtures, No. 14 rubber-covered wire will usually prove
+too large. For this purpose, No. 18 may be used, with one lamp to each
+loop. Hanging lamps may not be supported by electric lamp cord itself,
+if there is more than one lamp in the cluster, because the weight is
+apt to break the electrical connections. In such a case, the lamp
+should be supported by a chain, and the twisted cord conveying current
+to the electric bulbs, is woven in the links of the chain. For the
+pantry, kitchen, woodshed, barn, etc., a single hanging lamp may be
+suspended from a fielding rosette, as shown in the cut, provided a
+single knot is tied inside both the rosette and the lamp socket, to
+make it secure. This makes a very cheap fixture. The rosette of
+porcelain will cost 15 cents; the lamp socket 20 cents, and the lamp
+cord suspending the lamp and carrying the current will cost 1-1/2
+cents a foot; while a tin shade will cost another 15 cents.
+
+[Illustration: Detail of simple hanging lamp supported by rosette]
+
+
+_Official Inspection_
+
+In all communities, your insurance agent must inspect and pass your
+wiring before you are permitted to throw the main switch and turn on
+the electricity. Frequently they require that the moulding be left
+uncapped, until they have inspected it. If you have more than 660
+watts in lamps to a circuit; if your joints are not soldered and well
+taped; if the moulding is used in any concealed or damp place, the
+agent is liable to condemn your work and refuse permission to turn on
+the electricity. However the rules are so clearly defined that it is
+difficult to go wrong; and a farmer who does his own wiring and takes
+pride in its appearance is more apt to be right than a professional
+electrician who is careless at his task. After the work has been
+passed, tack on the moulding capping, with brads, and paint the
+moulding to match the woodwork.
+
+Wooden moulding wiring is perfectly satisfactory if properly
+installed. It is forbidden in many large cities, because of the
+liability of careless workmanship. It should never be installed in
+damp places, or out of sight. If the work is well done, the system
+leaves nothing to be desired; and it has the additional advantage of
+being cheap, and easily done by any farmer who can use carpenter
+tools. Farmers with moulding machinery can make their own moulding.
+The code prescribes it shall be of straight-grained wood; that the
+raceways for the wires shall be separated by a tongue of wood one-half
+inch wide; and that the backing shall be at least 3/8 inch thick. It
+must be covered, inside and out, with at least two coats of
+moisture-repellant paint. It can be had ready-made for about 2 cents a
+foot.
+
+
+_Special Heating Circuits_
+
+If one plans using electricity for heavy-duty stoves, such as ranges
+and radiators, it is necessary to install a separate heating circuit.
+This is the best procedure in any event, even when the devices are all
+small and suited to lamp circuits. The wire used can be determined by
+referring to the table for carrying capacity, under the column headed
+"rubber-covered." A stove or range drawing 40 amperes, would require a
+No. 4 wire, in moulding. A good plan is to run the heating circuit
+through the basement, attaching it to the rafters by means of
+porcelain knobs. Branches can then be run up through the floor to
+places where outlets are desired. Such a branch circuit should carry
+fuses suitable to the allowed carrying capacity of the wire.
+
+
+_Knob and Cleat Wiring_
+
+Knob and cleat wiring, such as is used extensively for barns and
+out-buildings, requires little explanation. The wires should not be
+closer than 2-1/2 inches in open places, and a wider space is better.
+The wires should be drawn taut, and supported by cleats or knobs at
+least every four feet. In case of branch circuits, one wire must be
+protected from the other it passes by means of a porcelain tube. It
+should never be used in damp places, and should be kept clear of dust
+and litter, and protected from abrasion.
+
+[Illustration: Knob and cleat wiring]
+
+Knob and tube wiring is frequently used in houses, being concealed
+between walls or flooring. In this case, the separate wires are
+stretched on adjoining beams or rafters, and porcelain tubes are used,
+in passing through cross beams. For a ceiling or wall outlet, a
+spliced branch is passed through the plaster by means of porcelain
+tubes or flexible loom.
+
+Wires from the house to the barn should be uniform with transmission
+wires. At the point of entry to buildings they must be at least six
+inches apart, and must take the form of the "drop loop" as shown in
+the illustration. A double-pole entrance switch must be provided,
+opening downward, with a double-pole fuse. In passing over buildings
+wires must not come closer than 7 feet to flat roofs, or one foot to a
+ridge roof. Feed-wires for electric motors should be determined from
+the table of safe carrying capacities, and should be of liberal size.
+
+
+
+
+CHAPTER IX
+
+THE ELECTRIC PLANT AT WORK
+
+     Direct-connected generating sets--Belt drive--The
+     switchboard--Governors and voltage regulators--Methods of achieving
+     constant pressure at all loads: Over-compounding the dynamo; A
+     system of resistances; (A home-made electric radiator); Regulating
+     voltage by means of the rheostat--Automatic devices--Putting the
+     plant in operation.
+
+
+Dynamos may be connected to water wheels either by means of a belt, or
+the armature may spin on the same shaft as the water wheel itself. The
+latter is by far the more desirable way, as it eliminates the loss of
+power through shafting and belting, and does away altogether
+with the belts themselves as a source of trouble. An installation
+with the water wheel and armature on the same shaft is called a
+"direct-connected set" and is of almost universal use in large power
+plants.
+
+To be able to use such a direct-connected set, the dynamo must be
+designed to develop its full voltage when run at a speed identical
+with that of the water wheel. That is, if the dynamo is wound to be
+run at a speed of 800 revolutions per minute, it must be driven by a
+water wheel which runs at this speed and can be governed within narrow
+limits. Small impulse wheels running under great heads attain high
+speed, and for such wheels it is possible to obtain a suitable dynamo
+at low cost. For instance, a 12-inch impulse wheel, running under a
+200-foot head will develop 6-3/4 horsepower when running at a speed of
+875 revolutions per minute. A dynamo for direct coupling to such a
+wheel should have a rated speed within 5 per cent of 875 r.p.m.; and,
+as generators of this speed are to be had from the stock of almost all
+manufacturers, there would be no extra charge.
+
+When it comes to the larger wheels, however, of the impulse type, or
+to turbines operating under their usual head the question becomes a
+little more difficult. In such cases, the speed of the water wheel
+will vary from 150 revolutions per minute, to 400, which is slow
+speed for a small dynamo. As a general rule, the higher the speed of a
+dynamo, the lower the cost; because, to lower the speed for a given
+voltage, it is necessary either to increase the number of conductors
+on the armature, or to increase the number of field coils, or both.
+That means a larger machine, and a corresponding increase in cost.
+
+In practice, in large plants, with alternating-current machines it has
+become usual to mount the field magnets on the shaft, and build the
+armature as a stationary ring in whose air space the field coils
+revolve. This simplifies the construction of slow-speed, large-output
+dynamos. Such a machine, however, is not to be had for the modest
+isolated plant of the farmer with his small water-power.
+
+[Illustration: Instantaneous photograph of high-pressure water jet
+being quenched by buckets of a tangential wheel]
+
+[Illustration: A tangential wheel, and a dynamo keyed to the same
+shaft--the ideal method for generating electricity. The centrifugal
+governor is included on the same base]
+
+Dynamos can be designed for almost any waterwheel speed, and, among
+small manufacturers especially, there is a disposition to furnish
+these special machines at little advance in price over their stock
+machines. Frequently it is merely a matter of changing the winding on
+a stock machine. The farmer himself, in many cases, can re-wind an old
+dynamo to fit the speed requirements of a direct-connected drive if
+the difference is not too great. All that would be necessary to
+effect this change would be to get the necessary winding data from the
+manufacturer himself, and proceed with the winding. This data would
+give the gauge of wire and the number of turns required for each spool
+of the field magnets; and the gauge of wire and number of turns
+required for each slot in the armature. The average boy who has
+studied electricity (and there is something about electricity that
+makes it closer to the boy's heart than his pet dog) could do this
+work. The advantages of direct drive are so many that it should be
+used wherever possible.
+
+When direct drive cannot be had, a belt must be used, either from a
+main shaft, or a countershaft. The belt must be of liberal size, and
+must be of the "endless" variety--with a scarfed joint. Leather belt
+lacing, or even the better grades of wire lacing, unless very
+carefully used, will prove unsatisfactory. The dynamo feels every
+variation in speed, and this is reflected in the lights. There is
+nothing quite so annoying as flickering lights. Usually this can be
+traced to the belt connections. Leather lacing forms a knot which
+causes the lights to flicker at each revolution of the belt. The
+endless belt does away with this trouble. Most dynamos are provided
+with sliding bases, by which the machine can be moved one way or
+another a few inches, to take up slack in the belt. To take advantage
+of this, the belt must be run in a horizontal line, or nearly so.
+Vertical belting is to be avoided.
+
+The dynamo is mounted on a wooden base, in a dry location where it is
+protected from the weather, or dampness from any source. It must be
+mounted firmly, to prevent vibration when running up to speed; and the
+switchboard should occupy a place within easy reach. Wires running
+from the dynamo to the switchboard should be protected from injury,
+and must be of ample size to carry the full current of the machine
+without heating. A neat way is to carry them down through the flooring
+through porcelain tubes, thence to a point where they can be brought
+up at the back of the switchboard. If there is any danger of injury to
+these mains they may be enclosed in iron pipe. Keep the wires out of
+sight as much as possible, and make all connections on the back of the
+switchboard.
+
+
+_The Switchboard_
+
+[Illustration: Connecting switchboard instruments]
+
+The switchboard is constructed of some fireproof material, preferably
+slate or marble. When the cost of this material is an item to
+consider, build a substantial wooden frame for your switchboard. You
+can then screw asbestos shingles to this to hold the various
+instruments and with a little care such a switchboard can be made to
+look business-like, and it is fully as serviceable as the more
+expensive kind. The switchboard instruments have already been
+described briefly. They consist of a voltmeter (to measure voltage);
+an ammeter (to measure the strength of the current drawn, in amperes),
+a rheostat (to regulate the voltage of the machine to suit the
+individual requirements); and the usual switches and fuses. The main
+switch should be so wired that when open it will throw all the current
+off the line, but still leave the field coils, the voltmeter, and the
+switchboard lamp in circuit. The main-switch fuses should have a
+capacity about 50 per cent in excess of the full load of the dynamo.
+If the machine is rated for 50 amperes, 75-ampere fuses should be
+installed. This permits throwing on an overload in an emergency; and
+at the same time guards against a short circuit. If the capacity of
+the machine is under 30 amperes, plug fuses, costing 3 cents each, can
+be used. If it is above this capacity, cartridge fuses, costing a
+little more, are required. A supply of these fuses should be kept
+handy at all times.
+
+
+_Governors and Voltage Regulators_
+
+[Illustration: A centrifugal governor (Courtesy of the C. P. Bradway
+Company, West Stafford, Conn.)]
+
+The necessity for water wheel governors will vary with conditions. As
+a general rule, it may be said that reaction turbines working under a
+low head with a large quantity of water do not require as much
+governing as the impulse wheel, working under high heads with small
+quantities of water. When governing is necessary at all, it is because
+the prime mover varies in speed from no load to full load. Planning
+one's plant with a liberal allowance of power--two water horsepower to
+one electrical horsepower is liberal--reduces the necessity of
+governors to a minimum. As an instance of this, the plant described
+in some detail in Chapters One and Six of this volume, runs without a
+governor.
+
+However, a surplus of water-power is not usual. Generally plants are
+designed within narrow limits; and then the need of a governor becomes
+immediately apparent. There are many designs of governors on the
+market, the cheapest being of the centrifugal type, in which a pair of
+whirling balls are connected to the water wheel gate by means of
+gears, and open or close the gate as the speed lowers or rises.
+
+Constant speed is necessary because voltage is directly dependent on
+speed. If the speed falls 25 per cent, the voltage falls likewise; and
+a plant with the voltage varying between such limits would be a
+constant source of annoyance, as well as expense for burned-out lamps.
+
+Since constant voltage is the result aimed at by the use of a
+governor, the same result can be attained in other ways, several of
+which will be explained here briefly.
+
+
+_Over-Compounding_
+
+(1) Over-compounding the dynamo. This is simple and cheap, if one buys
+the right dynamo in the first instance; or if he can do the
+over-compounding himself, by the method described in the concluding
+paragraphs of Chapter Seven. If it is found that the speed of the
+water wheel drops 25 per cent between no load and full load, a dynamo
+with field coils over-compounded to this extent would give a fairly
+constant regulation. If you are buying a special dynamo for direct
+drive, your manufacturer can supply you with a machine that will
+maintain constant voltage under the normal variations in speed of your
+wheel.
+
+
+_A System of Resistances_
+
+(2) Constant load systems. This system provides that the dynamo shall
+be delivering a fixed amount of current at all times, under which
+circumstances the water wheel would not require regulation, as the
+demands on it would not vary from minute to minute or hour to hour.
+
+This system is very simply arranged. It consists of having a set of
+"resistances" to throw into the circuit, in proportion to the amount
+of current used.
+
+Let us say, as an example, that a 50-ampere generator is used at a
+pressure of 110 volts; and that it is desirable to work this plant at
+80 per cent load, or 40 amperes current draft. When all the lights or
+appliances were in use, there would be no outside "resistance" in the
+circuit. When none of the lights or appliances were in use (as would
+be the case for many hours during the day) it would be necessary to
+consume this amount of current in some other way--to _waste it_. A
+resistance permitting 40 amperes of current to flow, would be
+necessary. Of what size should this resistance be?
+
+The answer is had by applying Ohm's Law, explained in Chapter Five.
+The Law in this case, would be read R = E/C. Therefore, in this case R
+= 110/40 = 2-3/4 ohms resistance, would be required, switched across
+the mains, to keep the dynamo delivering its normal load.
+
+The cheapest form of this resistance would be iron wire. In place of
+iron wire, German silver wire could be used. German silver wire is to
+be had cheaply, and is manufactured in two grades, 18% and 30%, with a
+resistance respectively 18 and 30 times that of copper for the same
+gauge. Nichrome wire has a resistance 60 times that of copper; and
+manganin wire has a resistance 65 times that of copper, of the same
+gauge.
+
+First figure the number of feet of copper wire suitable for the
+purpose. Allowing 500 circular mills for each ampere, the gauge of the
+wire should be 40 × 500 = 20,000 circular mills, or approximately No.
+7 B. & S. gauge. How many feet of No. 7 copper wire would give a
+resistance of 2-3/4 ohms? Referring to the copper wire table, we find
+that it requires 2006.2 of No. 7 wire to make one ohm. Then 2-3/4 ohms
+would require 5,517 feet.
+
+Since 30 per cent German silver wire is approximately 30 times the
+resistance of copper, a No. 7 German silver wire, for this purpose,
+would be 1/30 the length of the copper wire, or 186 feet. If nichrome
+wire were used, it would be 1/60th the length of copper for the same
+gauge, or 93 feet. This resistance wire can be wound in spirals and
+made to occupy a very small space. As long as it is connected in
+circuit, the energy of the dynamo otherwise consumed as light would be
+wasted as heat. This heat could be utilized in the hot water boiler or
+stove when the lights were turned off.
+
+In actual practice, however, the resistance necessary to keep the
+dynamo up to full load permanently, would not be furnished by one set
+of resistance coils. Each lamp circuit would have a set of resistance
+coils of its own. A double-throw switch would turn off the lamps and
+turn on the resistance coils, or _vice versa_.
+
+Let us say a lamp circuit consisted of 6 carbon lamps, of 16
+candlepower each. It would consume 6 × 1/2 ampere, or 3 amperes of
+current, and interpose a resistance of 36.6 ohms--say 37 ohms. Three
+amperes would require a wire of at least 1,500 circular mills in area
+for safety. This corresponds to a No. 18 wire. A No. 18 copper wire
+interposes a resistance of one ohm, for each 156.5 feet length. For 37
+ohms, 5,790 feet would be required, for copper wire, which of course
+would be impractical. Dividing by 30 gives 193 feet for 30% German
+silver wire; and dividing by 60 gives 96 feet of nichrome wire of the
+same gauge.
+
+It is simple to figure each circuit in this way and to construct
+resistance units for each switch. Since the resistance units develop
+considerable heat, they must be enclosed and protected.
+
+
+_A Home-made Stove or Radiator_
+
+While we are on the subject of resistance coils it might be well here
+to describe how to make stoves for cooking, and radiators for heating
+the house, at small expense. These stoves consist merely of
+resistances which turn hot--a dull red--when the current is turned on.
+Iron wire, German silver wire, or the various trade brands of
+resistance wire, of which nichrome, calido, and manganin are samples,
+can be used. In buying this wire, procure the table of resistance and
+carrying capacity from the manufacturers. From this table you can make
+your own radiators to keep the house warm in winter. Iron wire has the
+disadvantage of oxidizing when heated to redness, so that it goes to
+pieces after prolonged use. It is cheap, however, and much used for
+resistance in electrical work.
+
+Let us say we wish to heat a bathroom, a room 6 × 8, and 8 feet
+high--that is a room containing 384 cubic feet of air space. Allowing
+2 watts for each cubic foot, we would require 768 watts of current, or
+practically 7 amperes at 110 volts. What resistance would be required
+to limit the current to this amount? Apply Ohm's Law, as before, and
+we have R equals E divided by C, or R equals 110 divided by 7, which
+is 15.7 ohms. Forty-two feet of No. 20 German silver wire would emit
+this amount of heat and limit the current output to 7 amperes. In the
+Far West, it is quite common, in the outlying district, to find
+electric radiators made out of iron pipe covered with asbestos, on
+which the requisite amount of iron wire is wound and made secure. This
+pipe is mounted in a metal frame. Or the frame may consist of two
+pipes containing heating elements; and a switch, in this case, is so
+arranged that either one or two heating elements may be used at one
+time, according to the weather. An ingenious mechanic can construct
+such a radiator, experimenting with the aid of an ammeter to ascertain
+the length of wire required for any given stove.
+
+
+_Regulating Voltage at Switchboards_
+
+The voltage of any given machine may be regulated, within wide limits,
+by means of the field rheostat on the switchboard.
+
+A dynamo with a rated speed of 1,500 revolutions per minute, for 110
+volts, will actually attain this voltage at as low as 1,200 r.p.m. if
+all the regulating resistance be cut out. You can test this fact with
+your own machine by cutting out the resistance from the shunt field
+entirely, and starting the machine slowly, increasing its speed
+gradually, until the voltmeter needle registers 110 volts. Then
+measure the speed. It will be far below the rated speed of your
+machine.
+
+If, on the other hand, the speed of such a machine runs up to 2,500 or
+over--that is, an excess of 67%--the voltage would rise
+proportionally, unless extra resistance was cut in. By cutting in such
+resistance--by the simple expedient of turning the rheostat handle on
+the switchboard,--the field coils are so weakened that the voltage is
+kept at the desired point in spite of the excessive speed of the
+machine. Excessive speeds are to be avoided, as a rule, because of
+mechanical strain. But within a wide range, the switchboard rheostat
+can be used for voltage regulation.
+
+As it would be a source of continual annoyance to have to run to the
+switchboard every time the load of the machine was varied greatly this
+plan would not be practical for the isolated plant, unless the
+rheostat could be installed,--with a voltmeter--in one's kitchen.
+This could be done simply by running a small third wire from the
+switchboard to the house. Then, when the lights became dim from
+excessive load, a turn of the handle would bring them back to the
+proper voltage; and when they flared up and burned too bright, a turn
+of the handle in the opposite direction would remedy matters. By this
+simple arrangement, any member of the family could attend to voltage
+regulation with a minimum of bother.
+
+
+_Automatic Devices_
+
+There are several automatic devices for voltage regulation at the
+switchboard on the market. These consist usually of vibrator magnets
+or solenoids, in which the strength of the current, varying with
+different speeds, reacts in such a way as to regulate field
+resistance. Such voltage regulators can be had for $40 or less, and
+are thoroughly reliable.
+
+       *       *       *       *       *
+
+To sum up the discussion of governors and voltage regulators: If you
+can allow a liberal proportion of water-power, and avoid crowding
+your dynamo, the chances are you will not need a governor for the
+ordinary reaction turbine wheel. Start your plant, and let it run for
+a few days or a few weeks without a governor, or regulator. Then if
+you find the operation is unsatisfactory, decide for yourself which of
+the above systems is best adapted for your conditions. Economy as well
+as convenience will affect your decision. The plant which is most
+nearly automatic is the best; but by taking a little trouble and
+giving extra attention, a great many dollars may be saved in extras.
+
+
+_Starting the Dynamo_
+
+You are now ready to put your plant in operation. Your dynamo has been
+mounted on a wooden foundation, and belted to the countershaft, by
+means of an endless belt.
+
+See that the oil cups are filled. Then throw off the main switch and
+the field switch at the switchboard; open the water gate slowly, and
+occasionally test the speed of the dynamo. When it comes up to rated
+speed, say 1,500 per minute, let it run for a few minutes, to be sure
+everything is all right.
+
+Having assured yourself that the mechanical details are all right, now
+look at the voltmeter. It is probably indicating a few volts pressure,
+from 4 to 8 or 10 perhaps. This pressure is due to the residual
+magnetism in the field cores, as the field coils are not yet
+connected. If by any chance, the needle does not register, or is now
+back of 0, try changing about the connections or the voltmeter on the
+back of the switchboard.
+
+Now snap on the field switch. Instantly the needle will begin to move
+forward, though slowly; and it will stop. Turn the rheostat handle
+gradually; as you advance it, the voltmeter needle will advance.
+Finally you will come to a point where the needle will indicate 110
+volts.
+
+If you have designed your transmission line for a drop of 5 volts at
+half-load, advance the rheostat handle still further, until the
+needle points to 115 volts. Let the machine run this way for some
+time. When assured all is right, throw on the main switch, and turn on
+the light at the switchboard. Then go to the house and gradually turn
+on lights. Come back and inspect the dynamo as the load increases. It
+should not run hot, nor even very warm, up to full load. Its brushes
+should not spark, though a little sparking will do no harm.
+
+Your plant is now ready to deliver current up to the capacity of its
+fuses. See that it does not lack good lubricating oil, and do not let
+its commutator get dirty. The commutator should assume a glossy
+chocolate brown color. If it becomes dirty, or the brushes spark
+badly, hold a piece of fine sandpaper against it. Never use emery
+paper! If, after years of service, it becomes roughened by wear, have
+it turned down in a lathe. Occasionally, every few weeks, say, take
+the brushes out and clean them with a cloth. They will wear out in the
+course of time and can be replaced for a few cents each. The bearings
+may need replacing after several years' continuous use.
+
+Otherwise your electric plant will take care of itself. Keep it up to
+speed, and keep it clean and well oiled. Never shut it down unless you
+have to. In practice, dynamos run week after week, year after year,
+without stopping. This one, so long as you keep it running true to
+form, will deliver light, heat and power to you for nothing, which
+your city cousin pays for at the rate of 10 cents a kilowatt-hour.
+
+
+
+
+PART III
+
+GASOLINE ENGINES, WINDMILLS, ETC. THE STORAGE BATTERIES
+
+
+
+
+CHAPTER X
+
+GASOLINE ENGINE PLANTS
+
+     The standard voltage set--Two-cycle and four-cycle gasoline
+     engines--Horsepower, and fuel consumption--Efficiency of small
+     engines and generators--Cost of operating a one-kilowatt plant.
+
+
+Electricity is of so much value in farm operations, as well as in the
+farm house, that the farmer who is not fortunate enough to possess
+water-power of his own, or to live in a community where a coöperative
+hydro-electric plant may be established, should not deny himself its
+many conveniences. In place of the water wheel to turn the dynamo,
+there is the gasoline engine (or other forms of internal combustion
+engine using oil, gas, or alcohol as fuel); in many districts where
+steam engines are used for logging or other operations, electricity
+may be generated as a by-product; and almost any windmill capable of
+pumping water can be made to generate enough electricity for lighting
+the farm house at small expense.
+
+The great advantage of water-power is that the expense of
+maintenance--once the plant is installed--is practically nothing. This
+advantage is offset in some measure by the fact that other forms of
+power, gas, steam, or windmills, are already installed, in many
+instances and that their judicious use in generating electricity does
+not impair their usefulness for the other farm operations for which
+they were originally purchased. In recent years gasoline engines have
+come into general use on farms as a cheap dependable source of power
+for all operations; and windmills date from the earliest times. They
+may be installed and maintained cheaply, solely for generating
+electricity, if desired. Steam engines, however, require so much care
+and expert attention that their use for farm electric plants is not to
+be advised, except under conditions where a small portion of their
+power can be used to make electricity as a by-product.
+
+There are two types of gasoline engine electric plants suitable for
+the farm, in general use:
+
+First: The Standard Voltage Set, in which the engine and dynamo are
+mounted on one base, and the engine is kept running when current is
+required for any purpose. These sets are usually of the 110-volt type,
+and all standard appliances, such as irons, toasters, motors, etc.,
+may be used in connection with them. Since the electricity is drawn
+directly from the dynamo itself, without a storage battery, it is
+necessary that these engines be efficient and governed as to speed
+within a five per cent variation from no load to full load.
+
+Second: Storage Battery Sets, in which the dynamo is run only a few
+hours each week, and the electricity thus generated is "stored" by
+chemical means, in storage batteries, for use when required. Since, in
+this case, the current is drawn from the battery, instead of the
+dynamo, when used for lighting or other purposes, it is not necessary
+that a special type of engine be used to insure constant speed.
+
+
+_The Standard Voltage Set_
+
+In response to a general demand, the first type (the direct-connected
+standard voltage set) has been developed to a high state of efficiency
+recently, and is to be had in a great variety of sizes (ranging from
+one-quarter kilowatt to 25 kilowatts and over) from many
+manufacturers.
+
+The principle of the gasoline engine as motive power is so familiar to
+the average farmer that it needs but a brief description here.
+Gasoline or other fuel (oil, gas, or alcohol) is transformed into
+vapor, mixed with air in correct proportions, and drawn into the
+engine cylinder and there exploded by means of a properly-timed
+electric spark.
+
+Internal combustion engines are of two general types--four-cycle and
+two-cycle. The former is by far the more common. In a four-cycle
+engine the piston must travel twice up and down in each cylinder, to
+deliver one power stroke. This results in one power impulse in each
+cylinder every two revolutions of the crank shaft. On its first down
+stroke, the piston sucks in gas. On its first up stroke, it compresses
+the gas. At the height of this stroke, the gas is exploded by means of
+the electric spark and the piston is driven down, on its power stroke.
+The fourth stroke is called the scavening stroke, and expels the
+burned gas. This completes the cycle.
+
+A one-cylinder engine of the ordinary four-cycle type has one power
+stroke for every two revolutions of the fly wheel. A two-cylinder
+engine has one power stroke for one revolution of the fly wheel; and a
+four-cylinder engine has two power strokes to each revolution. The
+greater the number of cylinders, the more even the flow of power. In
+automobiles six cylinders are common, and in the last year or two,
+eight-cylinder engines began appearing on the market in large numbers.
+A twelve-cylinder engine is the prospect for the immediate future.
+
+Since the dynamo that is to supply electric current direct to lamps
+requires a steady flow of power, the single-cylinder gas or gasoline
+engine of the four-cycle type is not satisfactory as a rule. The
+lights will flicker with every other revolution of the fly wheel. This
+would be of no importance if the current was being used to charge a
+storage battery--and right here lies the reason why a cheaper engine
+may be used in connection with a storage battery than when the dynamo
+supplies the current direct for lighting.
+
+A two-cylinder engine is more even in its flow of power and a
+four-cylinder engine still better. For this reason, standard voltage
+generating sets without battery are usually of two or four cylinders
+when of the four-cycle type. When a single-cylinder engine is used, it
+should be of the two-cycle type. In the two-cycle engine, there is one
+power stroke to each up-and-down journey of the piston. This effect is
+produced by having inlet and exhaust ports in the crank case, so
+arranged that, when the piston arrives at the bottom of the power
+stroke, the waste gases are pushed out, and fresh gas drawn in before
+the up stroke begins.
+
+For direct lighting, the engine must be governed so as not to vary
+more than five per cent in speed between no load and full load. There
+are many makes on the market which advertise a speed variation of
+three per cent under normal loads. Governors are usually of the
+centrifugal ball type, integral with the fly wheel, regulating the
+amount of gas and air supplied to the cylinders in accordance with the
+speed. Thus, if such an engine began to slow down because of increase
+in load, the centrifugal balls would come closer together, and open
+the throttle, thus supplying more gas and air and increasing the
+speed. If the speed became excessive, due to sudden shutting off of
+lights, the centrifugal balls would fly farther apart, and the
+throttle would close until the speed was again adjusted to the load.
+
+These direct-connected standard voltage sets are as a rule fitted with
+the 110-volt, direct current, compound type of dynamo, the duplicate
+in every respect of the machine described in previous chapters for
+water-power plants. They are practically automatic in operation and
+will run for hours without attention, except as to oil and gasoline
+supply. They may be installed in the woodshed or cellar without
+annoyance due to noise or vibration. It is necessary to start them, of
+course, when light or power is desired, and to stop them when no
+current is being drawn. There have appeared several makes on the
+market in which starting and stopping are automatic. Storage batteries
+are used in connection with these latter plants for starting the
+engine. When a light is turned on, or current is drawn for any
+purpose, an automatic switch turns the dynamo into a motor, and it
+starts the engine by means of the current stored in the battery.
+Instantly the engine has come up to speed, the motor becomes a dynamo
+again and begins to deliver current. When the last light is turned
+off, the engine stops automatically.
+
+Since the installation of a direct-connected standard voltage plant of
+this type is similar in every respect, except as to motive power, to
+the hydro-electric plant, its cost, with this single exception, is the
+same. The same lamps, wire, and devices are used.
+
+With gasoline power, the cost of the engine offsets the cost of the
+water wheel. The engine is more expensive than the ordinary gasoline
+engine; but even this item of cost is offset by the cost of labor and
+materials used in installing a water wheel.
+
+The expense of maintenance is limited to gasoline and oil.
+Depreciation enters in both cases; and though it may be more rapid
+with a gasoline engine than a water wheel, that item will not be
+considered here. The cost of lubricating oil is inconsiderable. It
+will require, when operated at from one-half load to full load,
+approximately one pint of gasoline to each horsepower hour. When
+operated at less than half-load, its efficiency lowers. Thus, for a
+quarter-load, an average engine of this type may require three pints
+of gasoline for each horsepower hour. For this reason it is well, in
+installing such a plant, to have it of such size that it will be
+operating on at least three-fourths load under normal draft of
+current. Norman H. Schneider, in his book "Low Voltage Electric
+Lighting," gives the following table of proportions between the engine
+and dynamo:
+
+     Actual watts    Actual Horsepower    Nearest engine size
+       150                   .5                 1/2
+       225                   .7                 3/4
+       300                   .86              1
+       450                  1.12              1-1/4
+       600                  1.5               1-1/2
+       750                  1.7               1-3/4
+      1000                  2.3               2-1/2
+      2000                  4.5               5
+      4000                  9.0              10
+
+This table is figured for an efficiency of only 40 per cent for the
+smaller generators, and 60 per cent for the larger. In machines from 5
+to 25 kilowatts, the efficiency will run considerably higher.
+
+To determine the expense of operating a one-kilowatt gasoline
+generator set of this type, as to gasoline consumption, we can assume
+at full load that the gasoline engine is delivering 2-1/2 horsepower,
+and consuming, let us say, 1-1/4 pint of gasoline for each horsepower
+hour (to make allowance for lower efficiency in small engines). That
+would be 3.125 pints of gasoline per hour. Allowing a ten per cent
+loss of current in wiring, we have 900 watts of electricity to use,
+for this expenditure of gasoline. This would light 900 ÷ 25 = 36 lamps
+of 25 watts each, a liberal allowance for house and barn, and
+permitting the use of small cooking devices and other conveniences
+when part of the lights were not in use. With gasoline selling at 12
+cents a gallon, the use of this plant for an hour at full capacity
+would cost $0.047. Your city cousin pays 9 cents for the same current
+on a basis of 10 cents per kilowatt-hour; and in smaller towns where
+the rate is 15 cents, he would pay 13-1/2 cents.
+
+Running this plant at only half-load--that is, using only 18 lights,
+or their equivalent--would reduce the price to about 3 cents an
+hour--since the efficiency decreases with smaller load. It is
+customary to figure an average of 3-1/2 hours a day throughout the
+year, for all lights. On this basis the cost of gasoline for this
+one-kilowatt plant would be 16-1/2 cents a day for full load, and
+approximately 10-1/2 cents a day for half-load. This is extremely
+favorable, as compared with the cost of electric current in our cities
+and towns, at the commercial rate, especially when one considers that
+light and power are to be had at any place or at any time on the farm
+simply by starting the engine. A smaller plant, operating at less cost
+for fuel, would furnish ample light for most farms; but it is well to
+remember in this connection plants smaller than one kilowatt are
+practical for light only, since electric irons, toasters, etc., draw
+from 400 to 660 watts each. Obviously a plant of 300 watts capacity
+would not permit the use of these instruments, although it would
+furnish 10 or 12 lamps of 25 watts each.
+
+
+
+
+CHAPTER XI
+
+THE STORAGE BATTERY
+
+     What a storage battery does--The lead battery and the Edison
+     battery--Economy of tungsten lamps for storage batteries--The
+     low-voltage battery for electric light--How to figure the capacity
+     of a battery--Table of light requirements for a farm
+     house--Watt-hours and lamp-hours--The cost of storage battery
+     current--How to charge a storage battery--Care of storage
+     batteries.
+
+
+For the man who has a small supply of water to run a water wheel a few
+hours at a time, or who wishes to store electricity while he is doing
+routine jobs with a gasoline engine or other source of power, the
+storage battery solves the problem. The storage battery may be likened
+to a tank of water which is drawn on when water is needed, and which
+must be re-filled when empty. A storage battery, or accumulator is a
+device in which a chemical action is set up when an electric current
+is passed through it. This is called _charging_. When such a battery
+is charged, it has the property of giving off an electric current by
+means of a reversed chemical action when a circuit is provided,
+through a lamp or other connection. This reversed action is called
+_discharging_. Such a battery will discharge nearly as much current as
+is required originally to bring about the first chemical action.
+
+There are two common types of storage battery--the lead accumulator,
+made up of lead plates (alternately positive and negative); and the
+two-metal accumulator, of which the Edison battery is a
+representative, made up of alternate plates of iron and nickel. In the
+lead accumulator, the "positive" plate may be recognized by its brown
+color when charging, while the "negative" plate is usually light gray,
+or leaden in color. The action of the charging current is to form
+oxides of lead in the plates; the action of the discharging current is
+to reduce the oxides to metallic lead again. This process can be
+repeated over and over again during the life of the battery.
+
+Because of the cost of the batteries themselves, it is possible (from
+the viewpoint of the farmer and the size of his pocketbook) to store
+only a relatively small amount of electric current. For this reason,
+the storage battery was little used for private plants, where expense
+is a considerable item, up to a few years ago. Carbon lamps require
+from 3-1/2 to 4 watts for each candlepower of light they give out; and
+a lead battery capable of storing enough electricity to supply the
+average farm house with light by means of carbon lamps for three or
+four days at a time without recharging, proved too costly for private
+use.
+
+
+_The Tungsten Lamp_
+
+With the advent of the new tungsten lamp, however, reducing the
+current requirements for light by two-thirds, the storage battery
+immediately came into its own, and is now of general use.
+
+Since incandescent lamps were first invented scientists have been
+trying to find some metal of high fusion to use in place of the carbon
+filament of the ordinary lamp. The higher the fusing point of this
+filament of wire, the more economical would be the light. Edison
+sought, thirty years ago, for just the qualities now found in tungsten
+metal. Tungsten metal was first used for incandescent lamps in the
+form of a paste, squirted into the shape of a thread. This proved too
+fragile. Later investigators devised means of drawing tungsten into
+wire; and it is tungsten wire that is now used so generally in
+lighting. A tungsten lamp has an average efficiency of 1-1/4 watts per
+candlepower, compared with 3-1/2 to 4 watts of the old-style carbon
+lamp. In larger sizes the efficiency is as low as .9 watt per
+candlepower; and only recently it has been found that if inert
+nitrogen gas is used in the glass bulb, instead of using a high vacuum
+as is the general practice, the efficiency of the lamp becomes still
+higher, approaching .5 watt for each candlepower in large lamps. This
+new nitrogen lamp is not yet being manufactured in small domestic
+sizes, though it will undoubtedly be put on the market in those sizes
+in the near future.
+
+[Illustration: The Fairbanks Morse oil engine storage battery set]
+
+The tungsten lamp, requiring only one-third as much electric current
+as the carbon lamp, for the same amount of light, reduces the size
+(and the cost) of the storage battery in the same degree, thus
+bringing the storage battery within the means of the farmer. Some idea
+of the power that may be put into a small storage battery is to be had
+from the fact that a storage battery of only 6 volts pressure, such as
+is used in self-starters on automobiles, will turn a motor and crank a
+heavy six-cylinder engine; or it will run the automobile, without
+gasoline, for a mile or more with its own accumulated store of
+electric current.
+
+
+_The Low Voltage Battery_
+
+The 30-volt storage battery has become standard for small lighting
+plants, since the introduction of the tungsten lamp. Although the
+voltage of each separate cell of this battery registers 2.5 volts when
+fully charged, it falls to approximately 2 volts per cell immediately
+discharging begins. For this reason, it is customary to figure the
+working pressure of each cell at 2 volts. This means that a 30-volt
+battery should consist of at least 15 cells. Since, however, the
+voltage falls below 2 for each cell, as discharging proceeds, it is
+usual to include one additional cell for regulating purposes. Thus,
+the ordinary 30-volt storage battery consists of 16 cells, the last
+cell in the line remaining idle until the lamps begin to dim, when it
+is switched in by means of a simple arrangement of connections. This
+maintains a uniform pressure of 30 volts from the beginning to the end
+of the charge, at the lamp socket.
+
+We saw in earlier chapters that the 110-volt current is the most
+satisfactory, under all conditions, where the current is to be used
+for heating and small power, as well as light. But a storage battery
+of 110 volts would require at least 55 cells, which would make it too
+expensive for ordinary farm use. As a 30-volt current is just as
+satisfactory for electric light, this type has become established, in
+connection with the battery, and it is used for electric lighting
+only, as a general rule.
+
+Batteries are rated first, as to voltage; second, as to their capacity
+in ampere hours--that is, the number of amperes that may be drawn from
+them in a given number of hours. Thus, a battery rated at 60 ampere
+hours would give 60 amperes, at 30 volts pressure, for one hour; 30
+amperes for 2 hours; 15 amperes for 4 hours; 7-1/2 amperes for 8
+hours; 3-3/4 amperes for 16 hours; etc., etc. In practice, a battery
+should not be discharged faster than its 8-hour rate. Thus, a
+60-ampere hour battery should not be drawn on at a greater rate than
+7-1/2 amperes per hour.
+
+This 8-hour rate also determines the rate at which a battery should
+be re-charged, once it is exhausted. Thus, this battery should be
+charged at the rate of 7-1/2 amperes for 8 hours, with another hour
+added to make up for losses that are bound to occur. A battery of
+120-ampere hour capacity should be charged for 8 or 9 hours at the
+rate of 120 ÷ 8, or 15 amperes, etc.
+
+To determine the size of battery necessary for any particular
+instance, it is necessary first to decide on the number of lamps
+required, and their capacity. Thirty-volt lamps are to be had in the
+market in sizes of 10, 15 and 20 watts; they yield respectively 8, 12,
+and 16 candlepower each. Of these the 20-watt lamp is the most
+satisfactory for the living rooms; lamps of 10 or 15 watts may be used
+for the halls, the bathroom and the bedrooms. At 30 volts pressure
+these lamps would require a current of the following density in
+amperes:
+
+     Candle
+     Power     30-volt lamp    Amperes
+       8         10 watts        0.33
+      12         15 watts        0.50
+      16         20 watts        0.67
+
+Let us assume, as an example, that Farmer Brown will use 20-watt
+lamps in his kitchen, dining room, and sitting room; and 10-watt lamps
+in the halls, bathroom, and bedrooms. His requirements may be figured
+either in lamp hours or in watt-hours. Since he is using two sizes of
+lamps, it will be simpler to figure his requirements in watt-hours.
+Thus:
+
+                          Number     Size of   Hours    Watt-
+          Room          of lamps     lamps     burned   hours
+
+         Kitchen           1           20        4       80
+         Dining room       2           20        2       80
+         Sitting room      3           20        4      240
+    (3)  Bedrooms          1 (each)    10        1       30
+         Bathroom          1           10        2       20
+    (2)  Halls             1 (each)    10        4       80
+         Pantry            1           10        1       10
+         Cellar            1           10        1       10
+                                                       ----
+           Total                                        550
+
+Since amperes equal watts divided by volts, the number of ampere hours
+required in this case each night would be 550 ÷ 30 = 18.3 ampere
+hours; or approximately 4-1/2 amperes per hour for 4 hours.
+
+Say it is convenient to charge this battery every fourth day. This
+would require a battery of 4 × 18.3 ampere hours, or 73.2 ampere
+hours. The nearest size on the market is the 80-ampere hour battery,
+which would be the one to use for this installation.
+
+To charge this battery would require a dynamo capable of delivering 10
+amperes of current for 9 hours. The generator should be of 45 volts
+pressure (allowing 2-1/2 volts in the generator for each 2 volts of
+battery) and the capacity of the generator would therefore be 450
+watts. This would require a 1-1/4 horsepower gasoline engine. At 1-1/4
+pints of gasoline for each horsepower, nine hours work of this engine
+would consume 14 pints of gasoline--or say 16 pints, or two gallons.
+At 12 cents a gallon for gasoline, lighting your house with this
+battery would cost 24 cents for four days, or 6 cents a day. Your city
+cousin, using commercial current, would pay 5-1/2 cents a day for the
+same amount of current at 10 cents a kilowatt-hour; or 8-1/4 cents at
+a 15-cent rate. If the battery is charged by the farm gasoline engine
+at the same time it is doing its other work, the cost would be still
+less, as the extra gasoline required would be small.
+
+This figure does not take into account depreciation of battery and
+engine. The average farmer is too apt to overlook this factor in
+figuring the cost of machinery of all kinds, and for that reason is
+unprepared when the time comes to replace worn-out machinery. The
+dynamo and switchboard should last a lifetime with ordinary care, so
+there is no depreciation charge against them. The storage battery, a
+30-volt, 80-ampere hour installation, should not cost in excess of
+$100; and, if it is necessary to buy a gasoline engine, a 1-1/4
+horsepower engine can be had for $50 or less according to the type.
+Storage batteries of the lead type are sold under a two-years'
+guarantee--which does not mean that their life is limited to that
+length of time. With good care they may last as long as 10 years; with
+poor care it may be necessary to throw them away at the end of a year.
+The engine should be serviceable for at least 10 years, with ordinary
+replacements; and the storage battery may last from 6 to 10 years,
+with occasional renewal of parts. If it were necessary to duplicate
+both at the end of ten years, this would make a carrying charge of
+$1.25 a month for depreciation, which must be added to the cost of
+light.
+
+
+_Figuring by Lamp Hours_
+
+If all the lamps are to be of the same size--either ten, fifteen, or
+twenty watts, the light requirements of a farm house can be figured
+readily by lamp hours. In that event, the foregoing table would read
+as follows:
+
+                                             Lamp hours
+    Kitchen, 1 lamp, 4 hours                      4
+    Sitting room, 3 lamps, 4 hours each          12
+    Dining room, 2 lamps, 2 hours each            4
+    Bedrooms, 3 lamps, 1 hour each                3
+    Halls, 2 lamps, 4 hours each                  8
+    Bathroom, 1 lamp, 2 hours                     2
+    Pantry and cellar, 2 lamps, 1 hour each       2
+
+To determine the ampere hours from this table, multiply the total
+number of lamp hours by the current in amperes required for each lamp.
+As 10, 15, and 20-watt tungsten lamps require .33, .50 and .67
+amperes, respectively at 30 volts pressure, the above requirements in
+ampere hours would be 12, 17-1/2, or 24 ampere hours, according to the
+size of lamp chosen. This gives the average current consumption for
+one night. If it is desired to charge the battery twice a week on the
+average, multiply the number of lamp hours by 4, to get the size of
+battery required.
+
+The foregoing illustration is not intended to indicate average light
+requirements for farms, but is given merely to show how a farmer may
+figure his own requirements. In some instances, it will be necessary
+to install a battery of 120 or more ampere hours, whereas a battery of
+40 or 60 ampere hours would be quite serviceable in other instances.
+It all depends on how much light you wish to use and are willing to
+pay for, because with a storage battery the cost of electric light is
+directly in proportion to the number of lights used.
+
+As a general rule, a larger generator and engine are required for a
+larger battery--although it is possible to charge a large battery
+with a small generator and engine by taking more time for the
+operation.
+
+
+_How to Charge a Storage Battery_
+
+Direct current only can be used for charging storage batteries. In the
+rare instance of alternating current only being available, it must be
+converted into direct current by any one of the many mechanical,
+chemical, or electrical devices on the market--that is, the
+alternating current must be straightened out, to flow always in one
+direction.
+
+A shunt-wound dynamo must be used; else, when the voltage of the
+battery rises too high, it may "back up" and turn the dynamo as a
+motor, causing considerable damage. If a compound dynamo is already
+installed, or if it is desired to use such a machine for charging
+storage batteries, it can be done simply by disconnecting the series
+windings on the field coils, thus turning the machine into a shunt
+dynamo.
+
+The voltage of the dynamo should be approximately 50 per cent above
+the working pressure of the battery. For this reason 45-volt machines
+are usually used for 30 or 32-volt batteries. Higher voltages may be
+used, if convenient. Thus a 110-volt dynamo may be used to charge a
+single 2-volt cell if necessary, although it is not advisable.
+
+
+_Direction of Current_
+
+Electricity flows from the positive to the negative terminal. A
+charging current must be so connected that the negative wire of the
+dynamo is always connected to the negative terminal of the battery,
+and the positive wire to the positive terminal. As the polarity is
+always marked on the battery, there is little danger of making a
+mistake in this particular.
+
+When the storage battery is charged, and one begins to use its
+accumulation of energy, the current comes out in the opposite
+direction from which it entered in charging. In this respect, a
+storage battery is like a clock spring, which is wound up in one
+direction, and unwinds itself in the other. With all storage battery
+outfits, an ammeter (or current measure) is supplied with zero at the
+center. When the battery is being charged, the indicating needle
+points in one direction in proportion to the strength of the current
+flowing in; and when the battery is being discharged, the needle
+points in the opposite direction, in proportion to the strength of the
+current flowing out.
+
+Sometimes one is at loss, in setting about to connect a battery and
+generator, to know which is the positive and which the negative wire
+of the generator. A very simple test is as follows:
+
+Start the generator and bring it up to speed. Connect some form of
+resistance in "series" with the mains. A lamp in an ordinary lamp
+socket will do very well for this resistance. Dip the two ends of the
+wire (one coming from the generator, the other through the lamp) into
+a cup of water, in which a pinch of salt is dissolved. Bring them
+almost together and hold them there. Almost instantly, one wire will
+begin to turn bright, and give off bubbles. The wire which turns
+bright and gives off bubbles is the _negative_ wire. The other is the
+positive.
+
+[Illustration: A rough-and-ready farm electric plant, supplying two
+farms with light, heat and power; and a Ward Leonard-type
+circuit-breaker for charging storage batteries]
+
+
+_Care of Battery_
+
+Since specific directions are furnished with all storage batteries, it
+is not necessary to go into the details of their care here. Storage
+battery plants are usually shipped with all connections made, or
+plainly indicated. All that is necessary is to fill the batteries with
+the acid solution, according to directions, and start the engine. If
+the engine is fitted with a governor, and the switchboard is of the
+automatic type, all the care necessary in charging is to start the
+engine. In fact, many makes utilize the dynamo as a "self-starter" for
+the engine, so that all that is necessary to start charging is to
+throw a switch which starts the engine. When the battery is fully
+charged, the engine is stopped automatically.
+
+The "electrolyte" or solution in which the plates of the lead battery
+are immersed, is sulphuric acid, diluted with water in the proportion
+of one part of acid to five of water, by volume.
+
+The specific gravity of ordinary commercial sulphuric acid is 1.835.
+Since its strength is apt to vary, however, it is best to mix the
+electrolyte with the aid of the hydrometer furnished with the battery.
+The hydrometer is a sealed glass tube, with a graduated scale somewhat
+resembling a thermometer. The height at which it floats in any given
+solution depends on the density of the solution. It should indicate
+approximately 1.15 for a storage battery electrolyte before charging.
+It should not be over 1.15--or 1,150 if your hydrometer reads in
+thousandths.
+
+Only pure water should be used. Distilled water is the best, but fresh
+clean rain water is permissible. Never under any circumstances use
+hydrant water, as it contains impurities which will injure the
+battery, probably put it out of commission before its first charge.
+
+_Pour the acid into the water._ Never under any circumstances pour the
+water into the acid, else an explosion may occur from the heat
+developed. Mix the electrolyte in a stone crock, or glass container,
+stirring with a glass rod, and testing from time to time with a
+hydrometer. Let it stand until cool and then pour it into the battery
+jars, filling them to 1/2 inch above the top of the plates.
+
+Then begin charging. The first charge will probably take a longer time
+than subsequent charges. If the installation is of the automatic type,
+all that is necessary is to start the engine. If it is not of the
+automatic type, proceed as follows:
+
+First be sure all connections are right. Then start the engine and
+bring the dynamo up to its rated speed. Adjust the voltage to the
+pressure specified. Then throw the switch connecting generator to
+battery. Watch the ammeter. It should register in amperes, one-eighth
+of the ampere-hour capacity of the battery, as already explained. If
+it registers too high, reduce the voltage of the generator slightly,
+by means of the field rheostat connected to the generator. This will
+also reduce the amperes flowing. If too low, raise the voltage until
+the amperes register correctly. Continue the charging operation until
+the cells begin to give off gas freely; or until the specific gravity
+of the electrolyte, measured by the hydrometer, stands at 1.24. Your
+battery is now fully charged. Throw the switch over to the service
+line, and your accumulator is ready to furnish light if you turn on
+your lamps.
+
+Occasionally add distilled water to the cells, to make up for
+evaporation. It is seldom necessary to add acid, as this does not
+evaporate. If the battery is kept fully charged, it will not freeze
+even when the thermometer is well below zero.
+
+A storage battery should be installed as near the house as
+possible--in the house, if possible. Since its current capacity is
+small, transmission losses must be reduced to a minimum.
+
+In wiring the house for storage battery service, the same rules apply
+as with standard voltage. Not more than 6 amperes should be used on
+any single branch circuit. With low voltage batteries (from 12 volts
+to 32 volts) it is well to use No. 10 or No. 12 B. & S. gauge
+rubber-covered wire, instead of the usual No. 14 used with standard
+voltage. The extra expense will be only a few cents for each circuit,
+and precious volts will be saved in distribution of the current.
+
+
+
+
+CHAPTER XII
+
+BATTERY CHARGING DEVICES
+
+     The automatic plant most desirable--How an automobile lighting and
+     starting system works--How the same results can be achieved in
+     house lighting, by means of automatic devices--Plants without
+     automatic regulation--Care necessary--The use of heating devices on
+     storage battery current--Portable batteries--An electricity
+     "route"--Automobile power for lighting a few lamps.
+
+
+The water-power electric plants described in preceding chapters are
+practically automatic in operation. This is very desirable, as such
+plants require the minimum of care. It is possible to attain this same
+end with a storage battery plant.
+
+Automatic maintenance approaches a high degree of perfection in the
+electric starting and lighting device on a modern automobile. In this
+case, a small dynamo geared to the main shaft is running whenever the
+engine is running. It is always ready to "pump" electricity into the
+storage battery when needed. An electric magnet, wound in a peculiar
+manner, automatically cuts off the charging current from the dynamo,
+when the battery is "full;" and the same magnet, or "regulator,"
+permits the current to flow into the battery when needed. The
+principle is the same as in the familiar plumbing trap, which
+constantly maintains a given level of water in a tank, no matter how
+much water may be drawn from the tank. The result, in the case of the
+automobile battery, is that the battery is always kept fully charged;
+for no sooner does the "level" of electricity begin to drop (when used
+for starting or lighting) than the generator begins to charge. This is
+very desirable in more ways than one. In the first place, the energy
+of the battery is always the same; and in the second place, the mere
+fact that the battery is always kept fully charged gives it a long
+life.
+
+The same result can be achieved in storage battery plants for house
+lighting, where the source of power is a gasoline or other engine
+engaged normally in other work. Then your electric current becomes
+merely a by-product of some other operation.
+
+Take a typical instance where such a plant would be feasible: Farmer
+Brown has a five horsepower gasoline engine--an ordinary farm engine
+for which he paid probably $75 or $100. Electric light furnished
+direct from such an engine would be intolerable because of its
+constant flickering. This five horsepower engine is installed in the
+milk room of the dairy, and is belted to a countershaft. This
+countershaft is belted to the vacuum pump for the milking machine, and
+to the separator, and to a water pump, any one of which may be thrown
+into service by means of a tight-and-loose pulley. This countershaft
+is also belted to a small dynamo, which runs whenever the engine is
+running. The milking machine, the separator, and the water pump
+require that the gasoline engine be run on the average three hours
+each day.
+
+The dynamo is connected by wires to the house storage battery through
+a properly designed switchboard. The "brains" of this switchboard is
+a little automatic device (called a regulator or a circuit breaker),
+which opens and shuts according to the amount of current stored in the
+battery and the strength of the current from the generator. When the
+battery is "full," this regulator is "open" and permits no current to
+flow. Then the dynamo is running idle, and the amount of power it
+absorbs from the gasoline engine is negligible. When the "level" of
+electricity in the battery falls, due to drawing current for light,
+the regulator is "shut," that is, the dynamo and battery are
+connected, and current flows into the battery.
+
+These automatic instruments go still farther in their brainy work.
+They do not permit the dynamo to charge the battery when the voltage
+falls below a fixed point, due to the engine slowing down; neither do
+they permit the dynamo current to flow when the voltage gets too high
+due to sudden speeding up of the engine.
+
+Necessarily, an instrument which will take care of a battery in this
+way, is intricate in construction. That is not an argument against it
+however. A watch is intricate, but so long as we continue to wind it
+at stated intervals, it keeps time. So with this storage battery
+plant: so long as Farmer Brown starts his engine to do his farm chores
+every day, his by-product of electricity is stored automatically.
+
+Such installations are not expensive. A storage battery capable of
+lighting 8 tungsten lamps, of 16 candlepower each, continuously for 8
+hours (or fewer lamps for a longer time); a switchboard containing all
+the required regulating instruments; and a dynamo of suitable size,
+can be had for from $250 to $300. All that is necessary to put such a
+plant in operation, is to belt the dynamo to the gasoline engine so
+that it will run at proper speed; and to connect the wires from dynamo
+to switchboard, and thence to the house service. The dynamo required
+for the above plant delivers 10 amperes at 45 volts pressure, or 10 ×
+45 = 450 watts. A gasoline, gas, or oil engine, or a windmill of
+1-1/2 horsepower furnishes all the power needed. If the farmer uses
+his engine daily, or every other day, for other purposes, the cost of
+power will be practically negligible. With this system electric lights
+are available at any time day or night; and when the gasoline engine
+is in service daily for routine farm chores, the battery will never
+run low.
+
+This system is especially desirable where one uses a windmill for
+power. The speed of the windmill is constantly fluctuating, so much so
+in fact that it could not be used for electric light without a storage
+battery. But when equipped with a regulator on the switchboard which
+permits the current to flow only when the battery needs it, and then
+only when the speed of the windmill is correct, the problem of turning
+wind power into electric light is solved.
+
+       *       *       *       *       *
+
+If the farmer does not desire to go to the additional expense of
+automatic regulation, there are cheaper plants, requiring attention
+for charging. These plants are identical with those described above,
+except they have no regulators. With these plants, when the battery
+runs low (as is indicated by dimming of the lights) it is necessary to
+start the engine, bring it up to speed, adjust the dynamo voltage to
+the proper pressure, and throw a switch to charge the battery. For
+such plants it is customary to run the engine to charge the battery
+twice a week. It is necessary to run the engine from 8 to 10 hours to
+fully charge the discharged battery. When the battery approaches full
+charge, the fact is evidenced by so-called "gassing" or giving off of
+bubbles. Another way to determine if the battery is fully charged is
+by means of the voltmeter, as the volts slowly rise to the proper
+point during the process of charging. A third way, and probably the
+most reliable is by the use of the hydrometer. The voltage of each
+cell when fully charged should be 2.5; it should never be discharged
+below 1.75 volts. Many storage battery electric light plants on the
+market are provided with a simple and inexpensive circuit breaker,
+which automatically cuts off the current and stops the engine when the
+battery is charged. The current is then thrown from the dynamo to the
+house service by an automatic switch. If such a circuit breaker is not
+included, it is necessary to throw the switch by hand when charging is
+begun or ended.
+
+Since the principal item of first cost, as well as depreciation, in a
+storage battery electric light plant is the storage battery itself,
+the smallest battery commensurate with needs is selected. Since the
+amount of current stored by these batteries is relatively small,
+electric irons and heating devices such as may be used freely on a
+direct-connected plant without a battery, are rather expensive
+luxuries. For instance, an electric iron drawing 400 watts an hour
+while in use, requires as much energy as 20 tungsten lamps of 16
+candlepower each burning for the same length of time. Its rate of
+current consumption would be over 13 amperes, at 30 volts; which would
+require a larger battery than needed for light in the average farm
+home.
+
+The use to which electricity from a storage battery is put, however,
+is wholly a matter of expense involved; and if one is willing to pay
+for these rather expensive luxuries, there is no reason why he should
+not have them. Heating, in any form, by electricity, requires a large
+amount of current proportionally. As a matter of fact, there is less
+heat to be had in thermal units from a horsepower-hour of electricity
+than from three ounces of coal. When one is generating current from
+water-power, or even direct from gasoline or oil, this is not an
+argument against electric heating devices. But it becomes a very
+serious consideration when one is installing a storage battery as the
+source of current, because of the high initial cost, and depreciation
+of such a battery.
+
+Farmers who limit the use of their storage battery plants to lighting
+will get the best service.
+
+
+_Portable Batteries_
+
+Abroad it is becoming quite common for power companies to deliver
+storage batteries fully charged, and call for them when discharged.
+Without a stretch of the imagination, we can imagine an ingenious
+farmer possessing a water-power electric plant building up a thriving
+business among his less fortunate neighbors, with an "electricity"
+route. It could be made quite as paying as a milk route.
+
+[Illustration: Connections for charging storage batteries on 110-volt
+mains]
+
+Many communities have water or steam power at a distance too great to
+transmit 110-volt current by wire economically; and because of lack of
+expert supervision, they do not care to risk using current at a
+pressure of 500 volts or higher, because of its danger to human life.
+
+In such a case it would be quite feasible for families to wire their
+houses, and carry their batteries to the generating plant two or
+three times a week to be charged. There are a number of portable
+batteries on the market suitable for such service, at voltages ranging
+from 6 to 32 volts. The best results would be obtained by having two
+batteries, leaving one to be charged while the other was in use; and
+if the generating station was located at the creamery or feed mill,
+where the farmer calls regularly, the trouble would be reduced to a
+minimum.
+
+Such a battery would necessarily be small, and of the sealed type,
+similar to those used in automobiles. It could be used merely for
+reading lamps--or it could be used for general lighting, according to
+the expense the farmer is willing to incur for batteries.
+
+An ordinary storage battery used in automobile ignition and lighting
+systems is of the 6-volt, 60-ampere type, called in trade a "6-60."
+Lamps can be had for these batteries ranging in sizes from 2
+candlepower to 25 candlepower. A lamp of 15 candlepower, drawing 2-1/2
+amperes, is used for automobile headlights, and, as any one knows
+after an experience of meeting a headlight on a dark road, they give a
+great deal of light. A "6-60" battery keeps one of these lamps running
+for 24 hours, or two lamps running 12 hours. A minimum of wiring would
+be required to install such a battery for the reading lights in the
+sitting room, and for a hanging light in the dining room. The
+customary gates for charging these batteries in a large city is 10
+cents; but in a country plant it could be made less.
+
+To charge such a battery on a 110-volt direct current, it is necessary
+to install some means of limiting the amount of current, or in other
+words, the charging rate. This charging rate, for 8 hours should be,
+as we have seen, one-eighth of the ampere-hour capacity of the
+battery. Thus a "6-60" battery would require a 7-1/2 ampere current.
+
+Connecting two such batteries in "series" (that is, the negative pole
+of one battery to the positive pole of the second) would make a
+12-volt battery. Ten or twelve such batteries could be connected in
+"series," and a 110-volt direct current generator would charge them in
+8 hours at a 7-1/2 ampere rate.
+
+The diagram on page 259 shows the connections for charging on a
+110-volt circuit.
+
+An ordinary 16-candlepower carbon lamp is of 220 ohms resistance, and
+(by Ohm's Law, C equals E divided by R) permits 1/2 ampere of current
+to flow. By connecting 15 such lamps across the mains, in parallel,
+the required 7-1/2 amperes of current would be flowing from the
+generator through the lamps, and back again. Connect the battery in
+"series" at any point on either of the two mains, between the lamps
+and the generator, being careful to connect the positive end to the
+positive pole of the battery, and _vice versa_.
+
+Lamps are the cheapest form of resistance; but in case they are not
+available, any other form of resistance can be used. Iron wire wound
+in spirals can be used, or any of the many makes of special resistance
+wire on the market. First it is necessary to determine the amount of
+resistance required.
+
+We have just seen that the charging rate of a 60-ampere hour battery
+is 7-1/2 amperes. Applying Ohm's Law here, we find that ohms
+resistance equals volts divided by amperes, or R = 110/7.5 = 14.67
+ohms. With a 220-volt current, the ohms resistance required in series
+with the storage battery of this size would be 29.33 ohms.
+
+
+_Automobile Power for Lighting_
+
+There are many ingenious ways by which an automobile may be utilized
+to furnish electric light for the home. The simplest is to run wires
+direct from the storage battery of the self-starting system, to the
+house or barn, in such a way that the current may be used for reading
+lamps in the sitting room. By a judicious use of the current in this
+way, the normal operation of the automobile in the daytime will keep
+the battery charged for use of the night lamps, and if care is used,
+such a plan should not affect the life of the battery. Care should be
+used also, in this regard, not to discharge the battery too low to
+prevent its utilizing its function of starting the car when it was
+desired to use the car. However, if the battery were discharged below
+its starting capacity, by any peradventure, the car could be started
+by the old-fashioned cranking method.
+
+Using an automobile lighting system for house lighting implies that
+the car be stored in a garage near the house or barn; as this battery
+is too low in voltage to permit transmitting the current any distance.
+One hundred feet, with liberal sized transmission wires is probably
+the limit.
+
+That such a system is feasible is amply proved by an occurrence
+recently reported in the daily papers. A doctor summoned to a remote
+farm house found that an immediate operation was necessary to save the
+patient's life. There was no light available, except a small kerosene
+lamp which was worse than nothing. The surgeon took a headlight off
+his car, strung a pair of wires through a window, and instantly had at
+his command a light of the necessary intensity.
+
+Another manner in which an automobile engine may be used for house
+lighting is to let it serve as the charging power of a separate
+storage battery. The engine can be belted to the generator, in such a
+case, by means of the fly wheel. Or a form of friction drive can be
+devised, by means of which the rear wheels (jacked up off the floor)
+may supply the necessary motive power. In such a case it would be
+necessary to make allowance for the differential in the rear axle, so
+that the power developed by the engine would be delivered to the
+friction drive.
+
+
+
+
+The following pages contain advertisements of Macmillan books by the
+same author or on related subjects.
+
+
+WATER POWER ENGINEERS
+
+DESIGNERS AND MANUFACTURERS
+
+HUNT SUPERIOR QUALITY
+
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+Wheels, Flumes, Governors, Supply Pipes, Gates, Hoists, Valves,
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+
+Three types of water power developing wheels, ranged to meet every
+condition.
+
+[Illustration]
+
+     Div. No. 1--Turbine Water Wheels for large powers and large
+     quantities of water.
+
+     Div. No. 2--Rim Leverage Wheels for small powers and very limited
+     quantities of water.
+
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+     high heads.
+
+Send for special catalogues and Water Power Blanks to fill in for
+estimates on suitable type of Water Wheel for developing your water
+power to best advantage.
+
+  RODNEY HUNT MACHINE COMPANY
+  60 MILL STREET
+  ORANGE, MASSACHUSETTS, U.S.A.
+
+
+THE FARMER OF TOMORROW
+
+_Cloth, 12mo, $1.50_
+
+     "A crisp, entertaining, and instructive discussion of the
+     conditions which have brought about the present agricultural
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+
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+     discussions."--_Annals of the American Academy of Political and
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+
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+
+     "The growing, popular question of farming analyzed from all angles,
+     with many helpful suggestions."--_Leslie's Weekly._
+
+     "Any person of intelligence, alive to the present and future
+     welfare of his country will find 'The Farmer of Tomorrow,' a book
+     of absorbing character."--_Times-Star._
+
+
+  THE MACMILLAN COMPANY
+  Publishers
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+
+
+Coöperation in Agriculture
+
+By G. HAROLD POWELL
+
+_Cloth, 12mo, $1.50_
+
+     "The author has a broad outlook and never fails to suggest that the
+     economic advantages of coöperation may frequently be quite
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+     speaks."--_Political Science Quarterly._
+
+     "A volume which explains in a lucid way the features of the
+     existing system and the measures taken by farmers to protect their
+     interests."--_Journal of the Royal Statistical Society._
+
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+     agricultural coöperation, but has confined himself to its more
+     important phases. His work shows a grasp of the issues involved and
+     a ripeness of conclusion that comes only from actual contact with
+     the practical side of coöperation."--_American Economic Review._
+
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+
+  THE MACMILLAN COMPANY
+  Publishers
+  64-66 Fifth Avenue
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+
+
+RURAL SCIENCE SERIES
+
+Edited by L. H. BAILEY
+
+_Each volume illustrated. Cloth, 12mo._
+
+A series of practical books for farmers and gardeners, sold as a set
+or separately. Each one is the work of a competent specialist, and is
+suitable for consultation alike by the amateur or professional tiller
+of the soil, the scientist or the student. Illustrations of marked
+beauty are freely used, and the books are clearly printed and well
+bound.
+
+ON SELECTION OF LAND, ETC.
+
+  Isaac P. Roberts' The Farmstead                             $1 50
+  T. F. Hunt's How to Choose a Farm                            1 75
+  E. S. Cheyney and J. P. Wentling's The Farm Woodlot          1 50
+  Glenn W. Herrick's Insects Injurious to the Household        1 75
+
+ON TILLAGE, ETC.
+
+  F. H. King's The Soil                                        1 50
+  Isaac P. Roberts' The Fertility of the Land                  1 50
+  F. H. King's Irrigation and Drainage                         1 50
+  Edward B. Voorhees' Fertilizers                              1 25
+  Edward B. Voorhees' Forage Crops                             1 50
+  J. A. Widtsoe's Dry Farming                                  1 50
+  L. H. Bailey's Principles of Agriculture                     1 25
+  S. M. Tracy's Forage Crops for the South                     1 50
+
+ON PLANT DISEASES, ETC.
+
+  E. C. Lodeman's The Spraying of Plants                       1 25
+
+ON GARDEN-MAKING
+
+  L. H. Bailey's Garden-Making                                 1 50
+  L. H. Bailey's Vegetable-Gardening                           1 50
+  L. H. Bailey's Forcing Book                                  1 25
+  L. H. Bailey's Plant Breeding                                2 00
+
+ON FRUIT-GROWING, ETC.
+
+  L. H. Bailey's Nursery Book                                  1 50
+  L. H. Bailey's Fruit-Growing (New Edition)                   1 75
+  L. H. Bailey's The Pruning Book                              1 50
+  F. W. Card's Bush Fruits                                     1 50
+  W. Paddock & O. B. Whipple's Fruit-Growing in Arid Regions   1 50
+  J. E. Coit's Citrus Fruits                                  _Prepar_
+
+ON THE CARE OF LIVE-STOCK
+
+  Nelson S. Mayo's The Diseases of Animals                     1 50
+  W. H. Jordan's The Feeding of Animals                        1 50
+  I. P. Roberts' The Horse                                     1 25
+  M. W. Harper's Breaking and Training of Horses               1 75
+  George C. Watson's Farm Poultry. New edition                 1 50
+  John A. Craig's Sheep Farming                                1 50
+
+ON DAIRY WORK, FARM CHEMISTRY, ETC.
+
+  Henry H. Wing's Milk and Its Products. New edition           1 50
+  J. G. Lipman's Bacteria and Country Life                     1 50
+
+ON ECONOMICS AND ORGANIZATION
+
+  William A. McKeever's Farm Boys and Girls                    1 50
+  I. P. Roberts' The Farmer's Business Handbook                1 25
+  George T. Fairchild's Rural Wealth and Welfare               1 25
+  H. N. Ogden's Rural Hygiene                                  1 50
+  J. Green's Law for the American Farmer                       1 50
+  G. H. Powell's Coöperation in Agriculture                    1 50
+
+  THE MACMILLAN COMPANY
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+
+
+RURAL TEXT-BOOK SERIES
+
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+
+_Each volume illustrated. Cloth, 12mo._
+
+While the RURAL SCIENCE SERIES is designed primarily for popular
+reading and for general use, this related new series is designed for
+classroom work and for special use in consultation and reference. The
+RURAL TEXT-BOOK SERIES is planned to cover eventually the entire range
+of public school and college texts.
+
+  Duggar, B. M.
+    Physiology of Plant Production                     $1 60
+
+  Duggar, John Frederick
+    Southern Field Crops                                1 75
+
+  Gay, C. Warren
+    Principles and Practice of Judging Live-Stock       1 50
+
+  Harper, M. W.
+    Animal Husbandry for Schools                        1 40
+
+  Hitchcock, A. S.
+    Grasses                                             1 50
+
+  Livingston, George
+    Field Crop Production                               1 40
+
+  Lyon, T. L. and Fippin, E. O.
+    Principles of Soil Management                       1 75
+
+  Mann, A. R.
+    Beginnings in Agriculture                             75
+
+  Montgomery, G. F.
+    Corn Crops                                          1 60
+
+  Piper, Charles V.
+    Forage Plants and Their Culture                     1 75
+
+  Warren, G. F.
+    Elements of Agriculture                             1 10
+
+  Warren, G. F.
+    Farm Management                                     1 75
+
+  Wheeler, H. J.
+    Manures and Fertilizers                             1 60
+
+  Widtsoe, John A.
+    Principles of Irrigation Practice                   1 75
+
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+The Rural Outlook Set
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+
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+$5.00 per set; carriage extra. Each volume also sold separately._
+
+In this set are included three of Professor Bailey's most popular
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+Movement." The long and persistent demand for a uniform edition of
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+
+THE COUNTRY LIFE MOVEMENT
+
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+
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+
+THE OUTLOOK TO NATURE (New and Revised Edition)
+
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+
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+
+THE STATE AND THE FARMER (New Edition)
+
+_Cloth, 12mo, $1.25 postage extra_
+
+It is the relation of the farmer to the government that Professor
+Bailey here discusses in its varying aspects. He deals specifically
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+geographical centers of farming in the United States, and in the
+growth of agricultural institutions.
+
+THE NATURE STUDY IDEA (New Edition)
+
+_Cloth, 12mo, $1.25 postage extra_
+
+"It would be well," the critic of _The Tribune Farmer_ once wrote, "if
+'The Nature Study Idea' were in the hands of every person who favors
+nature study in the public schools, of every one who is opposed to it,
+and most important, of every one who teaches it or thinks he does." It
+has been Professor Bailey's purpose to interpret the new school
+movement to put the young into relation and sympathy with nature,--a
+purpose which he has admirably accomplished.
+
+  THE MACMILLAN COMPANY
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+<html xmlns="http://www.w3.org/1999/xhtml">
+  <head>
+    <meta http-equiv="Content-Type" content="text/html;charset=iso-8859-1" />
+    <title>
+      The Project Gutenberg eBook of Electricity For The Farm, by Frederick Irving Anderson.
+    </title>
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+<pre>
+
+Project Gutenberg's Electricity for the farm, by Frederick Irving Anderson
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Electricity for the farm
+       Light, heat and power by inexpensive methods from the water
+              wheel or farm engine
+
+Author: Frederick Irving Anderson
+
+Release Date: November 14, 2008 [EBook #27257]
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THIS PROJECT GUTENBERG EBOOK ELECTRICITY FOR THE FARM ***
+
+
+
+
+Produced by Stacy Brown, Marcia Brooks, Steven Giacomelli
+and the Online Distributed Proofreading Team at
+https://www.pgdp.net (This file was produced from images
+produced by Core Historical Literature in Agriculture
+(CHLA), Cornell University)
+
+
+
+
+
+
+</pre>
+
+
+
+
+
+<p><span class='pagenum'><a name="Page_i" id="Page_i">[Pg i]</a></span></p>
+
+
+
+
+
+<h1>ELECTRICITY FOR THE FARM</h1>
+
+
+
+<p><span class='pagenum'><a name="Page_ii" id="Page_ii">[Pg ii]</a></span></p>
+
+<div class="figcenter" style="width: 250px;">
+<img src="images/pub.jpg" width="250" height="77" alt="" title="" />
+</div>
+
+<p class="center">
+<span class="mac1">THE MACMILLAN COMPANY</span><br />
+<span class="mac2">NEW YORK &middot; BOSTON &middot; CHICAGO &middot; DALLAS<br />
+ATLANTA &middot; SAN FRANCISCO</span><br />
+<br />
+<span class="mac1">MACMILLAN &amp; CO., <span class="smcap">Limited</span></span><br />
+<span class="mac2">LONDON &middot; BOMBAY &middot; CALCUTTA<br />
+MELBOURNE</span><br />
+<br />
+<span class="mac1">THE MACMILLAN CO. OF CANADA, <span class="smcap">Ltd.</span></span><br />
+<span class="mac2">TORONTO</span><br />
+</p>
+
+
+
+<hr style="width: 65%;" />
+
+<div class="figcenter" style="width: 500px;"><a name="frontis" id="frontis"></a>
+<img src="images/frontis.jpg" width="500" height="414" alt="" title="" />
+Even the tiny trout brook becomes a thing of utility as well as of
+joy<br />
+
+(<i>Courtesy of the Fitz Water Wheel Company, Hanover,
+Pa.</i>)
+</div>
+
+<hr style="width: 65%;" />
+
+<p><span class='pagenum'><a name="Page_iii" id="Page_iii">[Pg iii]</a></span></p>
+
+<h1>
+ELECTRICITY FOR THE FARM</h1>
+
+
+<p class="subhead3">LIGHT, HEAT AND POWER BY INEXPENSIVE<br />
+METHODS FROM THE WATER<br />
+WHEEL OR FARM ENGINE</p>
+
+<h3>BY</h3>
+
+<h2>FREDERICK IRVING ANDERSON</h2>
+
+<p class="subhead3">AUTHOR OF "THE FARMER OF TO-MORROW," ETC., ETC.</p>
+
+<p class="padtop subhead3">New York<br />
+THE MACMILLAN COMPANY<br />
+1915<br />
+<br />
+<i>All rights reserved</i></p>
+
+
+
+
+<p><span class='pagenum'><a name="Page_iv" id="Page_iv">[Pg iv]</a></span></p>
+
+<p class="subhead3 padtop">
+<span class="smcap">Copyright, 1915</span><br />
+<span class="smcap">By</span> THE CURTIS PUBLISHING COMPANY<br />
+The Country Gentleman<br />
+<br />
+<br />
+<span class="smcap">Copyright</span>, 1915<br />
+<span class="smcap">By</span> THE MACMILLAN COMPANY<br />
+Set up and electrotyped. Published April, 1915.<br />
+</p>
+
+
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_v" id="Page_v">[Pg v]</a></span></p>
+<h2><a name="PREFACE" id="PREFACE"></a>PREFACE</h2>
+
+
+<p>This book is designed primarily to give the farmer a practical working
+knowledge of electricity for use as light, heat, and power on the
+farm. The electric generator, the dynamo, is explained in detail; and
+there are chapters on electric transmission and house-wiring, by which
+the farm mechanic is enabled to install his own plant without the aid
+and expense of an expert.</p>
+
+<p>With modern appliances, within the means of the average farmer, the
+generation of electricity, with its unique conveniences, becomes
+automatic, provided some dependable source of power is to be had&mdash;such
+as a water wheel, gasoline (or other form of internal combustion)
+engine, or the ordinary windmill. The water wheel is the ideal prime
+mover for the dynamo in isolated plants. Since water-power is running
+to waste on tens of thousands of our<span class='pagenum'><a name="Page_vi" id="Page_vi">[Pg vi]</a></span> farms throughout the country,
+several chapters are devoted to this phase of the subject: these
+include descriptions and working diagrams of weirs and other simple
+devices for measuring the flow of streams; there are tables and
+formulas by which any one, with a knowledge of simple arithmetic, may
+determine the power to be had from falling water under given
+conditions; and in addition, there are diagrams showing in general the
+method of construction of dams, bulkheads, races, flumes, etc., from
+materials usually to be found on a farm. The tiny unconsidered brook
+that waters the farm pasture frequently possesses power enough to
+supply the farmstead with clean, cool, safe light in place of the
+dangerous, inconvenient oil lamp; a small stream capable of developing
+from twenty-five to fifty horsepower will supply a farmer (at
+practically no expense beyond the original cost of installation) not
+only with light, but with power for even the heavier farm operations,
+as threshing; and in addition will do the washing, ironing, and
+cooking, and at the<span class='pagenum'><a name="Page_vii" id="Page_vii">[Pg vii]</a></span> same time keep the house warm in the coldest
+weather. Less than one horsepower of energy will light the farmstead;
+less than five horsepower of energy will provide light and small
+power, and take the drudgery out of the kitchen.</p>
+
+<p>For those not fortunate enough to possess water-power which can be
+developed, there are chapters on the use of the farm gasoline engine
+and windmill, in connection with the modern storage battery, as
+sources of electric current.</p>
+
+<p>It is desired to make acknowledgment for illustrations and assistance
+in gathering material for the book, to the editors of <i>The Country
+Gentleman</i>, Philadelphia, Pa.; The Crocker-Wheeler Company, Ampere, N.
+J.; The General Electric Company, Schenectady, N. Y.; the Weston
+Electrical Instrument Company, of Newark, N. J.; The Chase Turbine
+Manufacturing Company, Orange, Mass.; the C. P. Bradway Machine Works,
+West Stafford, Conn.; The Pelton Water Wheel Company, San Francisco
+and New<span class='pagenum'><a name="Page_viii" id="Page_viii">[Pg viii]</a></span> York; the Ward Leonard Manufacturing Company, Bronxville, N.
+Y.; The Fairbanks, Morse Company, Chicago; and the Fitz Water Wheel
+Company, Hanover, Pa.</p>
+
+
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_ix" id="Page_ix">[Pg ix]</a></span></p>
+
+
+<h2><a name="TABLE_OF_CONTENTS" id="TABLE_OF_CONTENTS"></a>TABLE OF CONTENTS</h2>
+
+
+<table summary="contents" style="width: 60%;"><tbody>
+<tr>
+<td class="tl" style="width: 80%;">INTRODUCTION</td>                                           <td class="tr"><a href="#Page_xvii">xvii</a></td>
+</tr><tr>
+
+<td class="thead1" colspan="2">PART I</td>
+</tr><tr>
+<td class="thead1" colspan="2">WATER-POWER</td>
+</tr><tr>
+<td class="thead1" colspan="2">CHAPTER I</td>
+</tr><tr>
+<td class="thead2" colspan="2">A WORKING PLANT</td>
+</tr><tr>
+<td class="tl">The "agriculturist"&mdash;An old chair factory&mdash;A neighbor's
+home-coming&mdash;The idle wheel in commission again&mdash;Light,
+heat and power for nothing&mdash;Advantages
+of electricity</td>   <td class="tr"><a href="#Page_3">3</a></td>
+</tr><tr>
+
+<td class="thead1" colspan="2">CHAPTER II</td>
+</tr><tr>
+<td class="thead2" colspan="2">A LITTLE PROSPECTING</td>
+</tr><tr>
+<td class="tl">Small amount of water required for an electric plant&mdash;Exploring,
+on a dull day&mdash;A rough and ready weir&mdash;What
+a little water will do&mdash;The water wheel
+and the dynamo&mdash;Electricity consumed the instant
+it is produced&mdash;The price of the average small
+plant, not counting labor</td>   <td class="tr"><a href="#Page_22">22</a></td>
+</tr><tr>
+
+<td class="thead1" colspan="2">CHAPTER III</td>
+</tr><tr>
+<td class="thead2" colspan="2">HOW TO MEASURE WATER-POWER</td>
+</tr><tr>
+<td class="tl">What is a horsepower?&mdash;How the Carthaginians manufactured
+horsepower&mdash;All that goes up must come
+down&mdash;How the sun lifts water up for us to use&mdash;Water
+the ideal power for generating electricity&mdash;The
+weir&mdash;Table for estimating flow of streams
+with a weir&mdash;Another method of measuring&mdash;Figuring
+water horsepower&mdash;The size of the wheel&mdash;What
+head is required&mdash;Quantity of water necessary</td>   <td class="tr"><a href="#Page_32">32</a></td>
+</tr>
+<tr>
+<td class="thead1" colspan="2">CHAPTER IV</td>
+</tr><tr>
+<td class="thead2" colspan="2">THE WATER WHEEL AND HOW TO INSTALL IT</td>
+</tr><tr>
+<td class="tl" >Different types of water wheels&mdash;The impulse and the
+reaction wheels&mdash;The impulse wheel adapted to
+high heads and small amount of water&mdash;Pipe lines&mdash;Table
+of resistance in pipes&mdash;Advantages and disadvantages
+of the impulse wheel&mdash;Other forms
+of impulse wheels&mdash;The reaction turbine, suited to
+low heads and large quantity of water&mdash;Its advantages
+and limitations&mdash;Developing a water-power
+project: the dam; the race; the flume; the penstock;
+and the tailrace&mdash;Water rights for the farmer</td>   <td class="tr"><a href="#Page_56">56</a></td>
+</tr><tr>
+
+<td class="thead1" colspan="2">PART II</td>
+</tr><tr>
+<td class="thead1" colspan="2">ELECTRICITY</td>
+</tr><tr>
+<td class="thead1" colspan="2">CHAPTER V</td>
+</tr><tr>
+<td class="thead2" colspan="2">THE DYNAMO; WHAT IT DOES, AND HOW</td>
+</tr><tr>
+<td class="tl">Electricity compared to the heat and light of the Sun&mdash;The
+simple dynamo&mdash;The amount of electric energy
+a dynamo will generate&mdash;The modern dynamo&mdash;Measuring
+power in terms of electricity&mdash;The volt&mdash;The
+ampere&mdash;The ohm&mdash;The watt and the kilowatt&mdash;Ohm's
+Law of the electric circuit, and some
+examples of its application&mdash;Direct current, and
+alternating current&mdash;Three types of direct-current
+dynamos: series, shunt, and compound</td>   <td class="tr"><a href="#Page_89">89</a></td>
+</tr>
+<tr>
+<td class="thead1" colspan="2">CHAPTER VI</td>
+</tr><tr>
+<td class="thead2" colspan="2">WHAT SIZE PLANT TO INSTALL</td>
+</tr><tr>
+<td class="tl" >The farmer's wife his partner&mdash;Little and big plants&mdash;Limiting
+factors&mdash;Fluctuations in water supply&mdash;The
+average plant&mdash;The actual plant&mdash;Amount
+of current required for various operations&mdash;Standard
+voltage&mdash;A specimen allowance for electric light&mdash;Heating
+and cooking by electricity&mdash;Electric power:
+the electric motor</td>   <td class="tr"><a href="#Page_121">121</a></td>
+</tr><tr>
+
+<td class="thead1" colspan="2">CHAPTER VII</td>
+</tr><tr>
+<td class="thead2" colspan="2">TRANSMISSION LINES</td>
+</tr><tr>
+<td class="tl">Copper wire&mdash;Setting of poles&mdash;Loss of power in transmission&mdash;Ohm's
+Law and examples of how it is
+used in figuring size of wire&mdash;Copper-wire tables&mdash;Examples
+of transmission lines&mdash;When to use high
+voltages&mdash;Over-compounding a dynamo to overcome
+transmission loss</td>   <td class="tr"><a href="#Page_153">153</a></td>
+</tr><tr>
+
+<td class="thead1" colspan="2">CHAPTER VIII</td>
+</tr><tr>
+<td class="thead2" colspan="2">WIRING THE HOUSE</td>
+</tr><tr>
+<td class="tl">The insurance code&mdash;Different kinds of wiring described&mdash;Wooden
+moulding cheap and effective&mdash;The distributing
+panel&mdash;Branch circuits&mdash;Protecting the
+circuits&mdash;The use of porcelain tubes and other insulating
+devices&mdash;Putting up chandeliers and wall-brackets&mdash;"Multiple"
+connections&mdash;How to connect
+a wall switch&mdash;Special wiring required for heat and
+power circuits&mdash;Knob and cleat wiring, its advantages
+and disadvantages</td>   <td class="tr"><a href="#Page_172">172</a></td>
+</tr>
+<tr>
+<td class="thead1" colspan="2">CHAPTER IX</td>
+</tr><tr>
+<td class="thead2" colspan="2">THE ELECTRIC PLANT AT WORK</td>
+</tr><tr>
+<td class="tl" >Direct-connected generating sets&mdash;Belt drive&mdash;The
+switchboard&mdash;Governors and voltage regulators&mdash;Methods
+of achieving constant pressure at all loads:
+Over-compounding the dynamo; A system of resistances
+(a home-made electric radiator); Regulating
+voltage by means of the rheostat&mdash;Automatic
+devices&mdash;Putting the plant in operation</td>   <td class="tr"><a href="#Page_192">192</a></td>
+</tr><tr>
+
+<td class="thead1" colspan="2">PART III</td>
+</tr><tr>
+<td class="thead1" colspan="2">GASOLINE ENGINES, WINDMILLS, ETC.<br />THE STORAGE BATTERIES</td>
+</tr><tr>
+<td class="thead1" colspan="2">CHAPTER X</td>
+</tr><tr>
+<td class="thead2" colspan="2">GASOLINE ENGINE PLANTS</td>
+</tr><tr>
+<td class="tl">The standard voltage set&mdash;Two-cycle and four-cycle
+gasoline engines&mdash;Horsepower, and fuel consumption&mdash;Efficiency
+of small engines and generators&mdash;Cost
+of operating a one-kilowatt plant</td>   <td class="tr"><a href="#Page_217">217</a></td>
+
+</tr><tr>
+<td class="thead1" colspan="2">CHAPTER XI</td>
+</tr><tr>
+<td class="thead2" colspan="2">THE STORAGE BATTERY</td>
+</tr><tr>
+<td class="tl">What a storage battery does&mdash;The lead battery and the
+Edison battery&mdash;Economy of tungsten lamps for
+storage batteries&mdash;The low-voltage battery for
+electric light&mdash;How to figure the capacity of a battery&mdash;Table
+of light requirements for a farm house&mdash;Watt-hours
+and lamp-hours&mdash;The cost of storage
+battery current&mdash;How to charge a storage battery&mdash;Care
+of storage batteries</td>   <td class="tr"><a href="#Page_229">229</a></td>
+</tr>
+<tr>
+<td class="thead1" colspan="2">CHAPTER XII</td>
+</tr><tr>
+<td class="thead2" colspan="2">BATTERY CHARGING DEVICES</td>
+</tr><tr>
+<td class="tl" >The automatic plant most desirable&mdash;How an automobile
+lighting and starting system works&mdash;How the same
+results can be achieved in house lighting, by means
+of automatic devices&mdash;Plants without automatic
+regulation&mdash;Care necessary&mdash;The use of heating devices
+on storage battery current&mdash;Portable batteries&mdash;An
+electricity "route"&mdash;Automobile power for
+lighting a few lamps</td>   <td class="tr"><a href="#Page_250">250</a></td>
+</tr></tbody></table>
+
+
+<p><span class='pagenum'><a name="Page_xiv" id="Page_xiv">[Pg xiv]</a></span>&nbsp;</p>
+
+<hr style="width: 65%;" />
+
+
+<p><span class='pagenum'><a name="Page_xv" id="Page_xv">[Pg xv]</a></span></p>
+<h2><a name="ILLUSTRATIONS" id="ILLUSTRATIONS"></a>ILLUSTRATIONS</h2>
+
+<p style="margin-left: 20%; margin-right: 20%;">
+<a href="#frontis">Even the tiny trout brook becomes a thing of utility as well as of joy</a><br />
+<br />
+<a href="#i16">Farm labor and materials built this crib and stone dam</a><br />
+<br />
+<a href="#i22">Measuring a small stream with a weir</a><br />
+<br />
+<a href="#i58">Efficient modern adaptations of the archaic undershot
+and overshot water wheels</a><br />
+<br />
+<a href="#i92">A direct-current dynamo or motor, showing details of
+construction</a><br />
+<br />
+<a href="#i128">Details of voltmeter or ammeter</a><br />
+<br />
+<a href="#i194-1">Instantaneous photograph of high-pressure water jet being
+quenched by buckets of a tangential wheel</a><br />
+<br />
+<a href="#i194-2">A tangential wheel, and a dynamo keyed to the same
+shaft&mdash;the ideal method for generating electricity</a><br />
+<br />
+<a href="#i244">A rough-and-ready farm electric plant, supplying two
+farms with light, heat and power; and a Ward
+Leonard-type circuit breaker for charging storage
+batteries</a><br />
+</p>
+
+<p><span class='pagenum'><a name="Page_xvi" id="Page_xvi">[Pg xvi]</a></span>&nbsp;</p>
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_xvii" id="Page_xvii">[Pg xvii]</a></span></p>
+<h2><a name="INTRODUCTION" id="INTRODUCTION"></a>INTRODUCTION</h2>
+
+
+<p>The sight of a dozen or so fat young horses and mares feeding and
+frolicking on the wild range of the Southwest would probably inspire
+the average farmer as an awful example of horsepower running to waste.
+If, by some miracle, he came on such a sight in his own pastures, he
+would probably consume much time practising the impossible art of
+"creasing" the wild creatures with a rifle bullet&mdash;after the style of
+Kit Carson and other free rovers of the old prairies when they were in
+need of a new mount. He would probably spend uncounted hours behind
+the barn learning to throw a lariat; and one fine day he would sally
+forth to capture a horsepower or two&mdash;and, once captured, he would use
+strength and strategy breaking the wild beast to harness. A single
+horsepower&mdash;animal&mdash;will do the work of lifting 23,000 pounds one foot
+in one minute, providing the animal is<span class='pagenum'><a name="Page_xviii" id="Page_xviii">[Pg xviii]</a></span> young, and sound, and is fed
+12 quarts of oats and 10 or 15 pounds of hay a day, and is given a
+chance to rest 16 hours out of 24&mdash;providing also it has a dentist to
+take care of its teeth occasionally, and a blacksmith chiropodist to
+keep it in shoes. On the hoof, this horsepower is worth about
+$200&mdash;unless the farmer is looking for something fancy in the way of
+drafters, when he will have to go as high as $400 for a big fellow.
+And after 10 or 15 years, the farmer would look around for another
+horse, because an animal grows old.</p>
+
+<p>This animal horsepower isn't a very efficient horsepower. In fact, it
+is less than three-fourths of an actual horsepower, as engineers use
+the term. A real horsepower will do the work of lifting 33,000 pounds
+one foot in one minute&mdash;or 550 pounds one foot in one second. Burn a
+pint of gasoline, with 14 pounds of air, in a gasoline engine, and the
+engine will supply one 33,000-pound horsepower for an hour. The
+gasoline will cost about 2 cents, and the air is supplied free. If it
+was the air that cost two cents a pound, instead of the<span class='pagenum'><a name="Page_xix" id="Page_xix">[Pg xix]</a></span> gasoline, the
+automobile industry would undoubtedly stop where it began some fifteen
+years ago. It is human nature, however, to grumble over this two
+cents.</p>
+
+<p>Yet the average farmer who would get excited if sound young chunks and
+drafters were running wild across his pastures, is not inspired by any
+similar desire of possession and mastery by the sight of a brook, or a
+rivulet that waters his meadows. This brook or river is flowing down
+hill to the sea. Every 4,000 gallons that falls one foot in one
+minute; every 400 gallons that falls 10 feet in one minute; or every
+40 gallons that falls 100 feet in one minute, means the power of one
+horse going to waste&mdash;not the $200 flesh-and-blood kind that can lift
+only 23,000 pounds a foot a minute&mdash;but the 33,000 foot-pound kind.
+Thousands of farms have small streams in their very dooryard, capable
+of developing five, ten, twenty, fifty horsepower twenty-four hours a
+day, for the greater part of the year. Within a quarter of a mile of
+the great majority of farms (outside of the<span class='pagenum'><a name="Page_xx" id="Page_xx">[Pg xx]</a></span> dry lands themselves)
+there are such streams. Only a small fraction of one per cent of them
+have been put to work, made to pay their passage from the hills to the
+sea.</p>
+
+<p>The United States government geological survey engineers recently made
+an estimate of the waterfalls capable of developing 1,000 horsepower
+and over, that are running to waste, unused, in this country. They
+estimated that there is available, every second of the day and night,
+some 30,000,000 horsepower, in dry weather&mdash;and twice this during the
+eight wet months of the year. The waterfall capable of giving up 1,000
+horsepower in energy is not the subject of these chapters. It is the
+small streams&mdash;the brooks, the creeks, the rivulets&mdash;which feed the
+1,000 horsepower torrents, make them possible, that are of interest to
+the farmer. These small streams thread every township, every county,
+seeking the easiest way to the main valleys where they come together
+in great rivers.</p>
+
+<p>What profitable crop on your farm removes<span class='pagenum'><a name="Page_xxi" id="Page_xxi">[Pg xxi]</a></span> the least plant food? A
+bee-farmer enters his honey for the prize in this contest. Another
+farmer maintains that his ice-crop is the winner. But electricity
+generated from falling water of a brook meandering across one's acres,
+comes nearer to the correct answer of how to make something out of
+nothing. It merely utilizes the wasted energy of water rolling down
+hill&mdash;the weight of water, the pulling power of gravity. Water is
+still water, after it has run through a turbine wheel to turn an
+electric generator. It is still wet; it is there for watering the
+stock; and a few rods further down stream, where it drops five or ten
+feet again, it can be made to do the same work over again&mdash;and over
+and over again as long as it continues to fall, on its journey to the
+sea. The city of Los Angeles has a municipal water plant, generating
+200,000 horsepower of electricity, in which the water is used three
+times in its fall of 6,000 feet; and in the end, where it runs out of
+the race in the valley, it is sold for irrigation.</p>
+
+<p>One water-horsepower will furnish light<span class='pagenum'><a name="Page_xxii" id="Page_xxii">[Pg xxii]</a></span> for the average farm; five
+water-horsepower will furnish light and power, and do the ironing and
+baking. The cost of installing a plant of five water-horsepower should
+not exceed the cost of one sound young horse, the $200 kind&mdash;under
+conditions which are to be found on thousands of farms and farm
+communities in the East, the Central West, and the Pacific States.
+This electrical horsepower will work 24 hours a day, winter and
+summer, and the farmer would not have to grow oats and hay for it on
+land that might better be used in growing food for human beings. It
+would not become "aged" at the end of ten or fifteen years, and the
+expense of maintenance would be practically nothing after the first
+cost of installation. It would require only water as food&mdash;waste
+water. Two hundred and fifty cubic feet of water a minute, falling ten
+feet, will supply the average farm with all the conveniences of
+electricity. This is a very modest creek&mdash;the kind of brook or creek
+that is ignored by the man who would think time well spent in putting
+in a week<span class='pagenum'><a name="Page_xxiii" id="Page_xxiii">[Pg xxiii]</a></span> capturing a wild horse, if a miracle should send such a
+beast within reach. And the task of harnessing and breaking this
+water-horsepower is much more simple and less dangerous than the task
+of breaking a colt to harness.</p>
+
+
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_1" id="Page_1">[Pg 1]</a></span></p>
+<h2><a name="PART_I" id="PART_I"></a>PART I</h2>
+
+<p class="subhead1">WATER-POWER</p>
+
+
+<p><span class='pagenum'><a name="Page_2" id="Page_2">[Pg 2]</a></span></p>
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_3" id="Page_3">[Pg 3]</a></span></p>
+<h2>ELECTRICITY FOR THE FARM</h2>
+
+<h2>CHAPTER I</h2>
+
+<p class="subhead2">A WORKING PLANT</p>
+
+<div class="blockquot"><p>The "agriculturist"&mdash;An old chair factory&mdash;A neighbor's
+home-coming&mdash;The idle wheel in commission again&mdash;Light, heat and
+power for nothing&mdash;Advantages of electricity.</p></div>
+
+
+<p>Let us take an actual instance of one man who did go ahead and find
+out by experience just how intricate and just how simple a thing
+electricity from farm water-power is. This man's name was Perkins, or,
+we will call him that, in relating this story.</p>
+
+<p>Perkins was what some people call, not a farmer, but an
+"agriculturist,"&mdash;that is, he was a back-to-the-land man. He had been
+born and raised on a farm. He knew that you must harness a horse on
+the left side, milk a cow on the right, that wagon nuts tighten the
+way the wheel rims, and that a fresh egg will not float.</p>
+
+<p><span class='pagenum'><a name="Page_4" id="Page_4">[Pg 4]</a></span></p><p>He had a farm that would grow enough clover to fill the average dairy
+if he fed it lime; he had a boy coming to school age; and both he and
+his wife wanted to get back to the country. They had their little
+savings, and they wanted, first of all, to take a vacation, getting
+acquainted with their farm. They hadn't taken a vacation in fifteen
+years.</p>
+
+<p>He moved in, late in the summer, and started out to get acquainted
+with his neighbors, as well as his land. This was in the New England
+hills. Water courses cut through everywhere. In regard to its
+bountiful water supply, the neighborhood had much in common with all
+the states east of the Mississippi, along the Atlantic seaboard, in
+the lake region of the central west, and in the Pacific States. With
+this difference; the water courses in his neighborhood had once been
+of economic importance.</p>
+
+<p>A mountain river flowed down his valley. Up and down the valley one
+met ramshackle mills, fallen into decay. Many years ago before
+railroads came, before it was easy to<span class='pagenum'><a name="Page_5" id="Page_5">[Pg 5]</a></span> haul coal from place to place
+to make steam, these little mills were centers of thriving industries,
+which depended on the power of falling water to make turned articles,
+spin cotton, and so forth. Then the railroads came, and it was easy to
+haul coal to make steam. And the same railroads that hauled the coal
+to make steam, were there to haul away the articles manufactured by
+steam power. So in time the little manufacturing plants on the river
+back in the hills quit business and moved to railroad stations. Then
+New England, from being a manufacturing community made up of many
+small isolated water plants, came to be a community made up of huge
+arteries and laterals of smoke stacks that fringed the railroads.
+Where the railroad happened to follow a river course&mdash;as the
+Connecticut River&mdash;the water-power plants remained; but the little
+plants back in the hills were wiped off the map&mdash;because steam power
+with railroads at the front door proved cheaper than water-power with
+railroads ten miles away.</p>
+
+<p><span class='pagenum'><a name="Page_6" id="Page_6">[Pg 6]</a></span></p><p>One night Perkins came in late from a long drive with his next-door
+neighbor. He had learned the first rule of courtesy in the country,
+which is to unhitch his own side of the horse and help back the buggy
+into the shed. They stumbled around in the barn putting up the horse,
+and getting down hay and grain for it, by the light of an oil lantern,
+which was set on the floor in a place convenient to be kicked over. He
+went inside and took supper by the light of a smoky smelly oil lamp,
+that filled the room full of dark corners; and when supper was over,
+the farmwife groped about in the cellar putting things away by the
+light of a candle.</p>
+
+<p>The next day his neighbor was grinding cider at his ramshackle water
+mill&mdash;one of the operations for which a week must be set aside every
+fall. Perkins sat on a log and listened to the crunch-crunch of the
+apples in the chute, and the drip of the frothy yellow liquid that
+fell into waiting buckets.</p>
+
+<p>"How much power have you got here?" he asked.</p>
+
+<p><span class='pagenum'><a name="Page_7" id="Page_7">[Pg 7]</a></span></p><p>"Thirty or forty horsepower, I guess."</p>
+
+<p>"What do you do with it, besides grinding cider to pickle your
+neighbors' digestion with?"</p>
+
+<p>"Nothing much. I've got a planer and a moulding machine in there, to
+work up jags of lumber occasionally. That's all. This mill was a
+chair-factory in my grandfather's day, back in 1830."</p>
+
+<p>"Do you use it thirty days in a year?"</p>
+
+<p>"No; not half that."</p>
+
+<p>"What are you going to do with it this winter?"</p>
+
+<p>"Nothing; I keep the gate open and the wheel turning, so it won't
+freeze, but nothing else. I am going to take the family to Texas to
+visit my wife's folks for three months. We've worked hard enough to
+take a vacation."</p>
+
+<p>"Will you rent me the mill while you are gone?"</p>
+
+<p>"Go ahead; you can have it for nothing, if you will watch the ice."</p>
+
+<p>"All right; let me know when you come<span class='pagenum'><a name="Page_8" id="Page_8">[Pg 8]</a></span> back and I'll drive to town and
+bring you home."</p>
+
+<hr style='width: 45%;' />
+
+<p>Three months went by, and one day in February the city man, in
+response to a letter, hitched up and drove to town to bring his
+neighbor back home. It was four o'clock in the afternoon when they
+started out, and it was six&mdash;dark&mdash;when they turned the bend in the
+road to the farm house. They helped the wife and children out, with
+their baggage, and as Perkins opened the door of the house, he reached
+up on the wall and turned something that clicked sharply.</p>
+
+<p>Instantly light sprang from everywhere. In the barn-yard a street lamp
+with an 18-inch reflector illuminated all under it for a space of 100
+feet with bright white rays of light. Another street lamp hung over
+the watering trough. The barn doors and windows burst forth in light.
+There was not a dark corner to be found anywhere. In the house it was
+the same. Perkins led the amazed procession from room to room of the
+house they had<span class='pagenum'><a name="Page_9" id="Page_9">[Pg 9]</a></span> shut up for the winter. On the wall in the hall
+outside of every room was a button which he pushed, and the room
+became as light as day before they entered. The cellar door, in
+opening, automatically lighted a lamp illuminating that cavern as it
+had never been lighted before since the day a house was built over it.</p>
+
+<p>Needless to say, the farmer and his family were reduced to a state of
+speechlessness.</p>
+
+<p>"How the deuce did you do it?" finally articulated the farmer.</p>
+
+<p>"I put your idle water wheel to work," said Perkins; and then,
+satisfied with this exhibition, he put them back in the sleigh and
+drove to his home, where his wife had supper waiting.</p>
+
+<p>While the men were putting up the team in the electric lighted barn,
+the farmwife went into the kitchen. Her hostess was cooking supper on
+an electric stove. It looked like a city gas range and it cooked all
+their meals, and did the baking besides. A hot-water tank<span class='pagenum'><a name="Page_10" id="Page_10">[Pg 10]</a></span> stood
+against the wall, not connected to anything hot, apparently. But it
+was scalding hot, by virtue of a little electric water heater the size
+of a quart tin can, connected at the bottom. Twenty-four hours a day
+the water wheel pumped electricity into that "can," so that hot water
+was to be had at any hour simply by turning a faucet. In the laundry
+there was an electric pump that kept the tank in the attic filled
+automatically. When the level of water in this tank fell to a certain
+point, a float operated a switch that started the pump; and when the
+water level reached a certain height, the same float stopped the pump.
+A small motor, the size of a medium Hubbard squash operated a washing
+machine and wringer on wash days. This same motor was a
+man-of-all-work for this house, for, when called on, it turned the
+separator, ground and polished knives and silverware, spun the sewing
+machine, and worked the vacuum cleaner.</p>
+
+<p>Over the dining room table hung the same hanging shade of old days,
+but the oil lamp<span class='pagenum'><a name="Page_11" id="Page_11">[Pg 11]</a></span> itself was gone. In its place was a 100-watt
+tungsten lamp whose rays made the white table cloth fairly glisten.
+The wires carrying electricity to this lamp were threaded through the
+chains reaching to the ceiling, and one had to look twice to see where
+the current came from. In the sitting room, a cluster of electric
+bulbs glowed from a fancy wicker work basket that hung from the
+ceiling. The housewife had made use of what she had throughout the
+house. Old-fashioned candle-shades sat like cocked hats astride
+electric bulbs. There is little heat to an electric bulb for the
+reason that the white-hot wire that gives the light is made to burn in
+high vacuum, which transmits heat very slowly. The housewife had taken
+advantage of this fact and from every corner gleamed lights dressed in
+fancy designs of tissue paper and silk.</p>
+
+<p>"Now we will talk business," said Perkins when supper was over and
+they had lighted their pipes.</p>
+
+<p>The returned native looked dubious. His New England training had
+warned him long<span class='pagenum'><a name="Page_12" id="Page_12">[Pg 12]</a></span> ago that one cannot expect to get something for
+nothing, and he felt sure there was a joker in this affair.</p>
+
+<p>"How much do I owe you?" he asked.</p>
+
+<p>"Nothing," said Perkins. "You furnish the water-power with your idle
+wheel, and I furnish the electric installation. This is only a small
+plant I have put in, but it gives us enough electricity to go around,
+with a margin for emergencies. I have taken the liberty of wiring your
+house and your horse-barn and cow-barn and your barn-yard. Altogether,
+I suppose you have 30 lights about the place, and during these long
+winter days you will keep most of them going from 3 to 5 hours a night
+and 2 or 3 hours in the early morning. If you were in town, those
+lights would cost you about 12 cents an hour, at the commercial rate
+of electricity. Say 60 cents a day&mdash;eighteen dollars a month. That
+isn't a very big electric light bill for some people I know in
+town&mdash;and they consider themselves lucky to have the privilege of
+buying electricity at that rate. Your wheel is running all winter to<span class='pagenum'><a name="Page_13" id="Page_13">[Pg 13]</a></span>
+prevent ice from forming and smashing it. It might just as well be
+spinning the dynamo.</p>
+
+<p>"If you think it worth while," continued Perkins,&mdash;"this $18 worth of
+light you have on tap night and morning, or any hour of the day,&mdash;we
+will say the account is settled. That is, of course, if you will give
+me the use of half the electricity that your idle wheel is grinding
+out with my second-hand dynamo. We have about eight electrical
+horsepower on our wires, without overloading the machine. Next spring
+I am going to stock up this place; and I think about the first thing I
+do, when my dairy is running, will be to put in a milking machine and
+let electricity do the milking for me. It will also fill my silo,
+grind my mowing-machine knives, saw my wood, and keep water running in
+my barn. You will probably want to do the same.</p>
+
+<p>"But what it does for us men in the barn and barn-yard, isn't to be
+compared to what it does for the women in the house. When my wife
+wants a hot oven she presses a button. When she wants to put the
+'fire' out, she presses<span class='pagenum'><a name="Page_14" id="Page_14">[Pg 14]</a></span> another. That's all there is to it. No heat,
+no smoke, no ashes. The same with ironing&mdash;and washing. No oil lamps
+to fill, no wicks to trim, no chimneys to wash, no kerosene to kick
+over and start a fire."</p>
+
+<p>"You say the current you have put in my house would cost me about $18
+a month, in town."</p>
+
+<p>"Yes, about that. Making electricity from coal costs money."</p>
+
+<p>"What does it cost here?"</p>
+
+<p>"Practically nothing. Your river, that has been running to waste ever
+since your grandfather gave up making chairs, does the work. There is
+nothing about a dynamo to wear out, except the bearings, and these can
+be replaced once every five or ten years for a trifle. The machine
+needs to be oiled and cared for&mdash;fill the oil cups about once in three
+days. Your water wheel needs the same attention. That's all there is
+to it. You can figure the cost of your current yourself&mdash;just about
+the cost of the lubricating oil you use&mdash;and the cost of the time you
+give it&mdash;about the same time<span class='pagenum'><a name="Page_15" id="Page_15">[Pg 15]</a></span> you give to any piece of good machinery,
+from a sulky plow to a cream separator."</p>
+
+<p>This is a true story. This electric plant, where Perkins furnishes the
+electric end, and his neighbor the water-power, has been running now
+for two years, grinding out electricity for the two places twenty-four
+hours a day. Perkins was not an electrical engineer. He was just a
+plain intelligent American citizen who found sufficient knowledge in
+books to enable him to install and operate this plant. Frequently he
+is away for long periods, but his neighbor (who has lost his original
+terror of electricity) takes care of the plant. In fact, this farmer
+has given a lot of study to the thing, through curiosity, until he
+knows fully as much about it now as his city neighbor.</p>
+
+<p>He had the usual idea, at the start, that a current strong enough to
+light a 100 candlepower lamp would kick like a mule if a man happened
+to get behind it. He watched the city man handle bare wires and
+finally he plucked up courage to do it himself.</p>
+
+<p><span class='pagenum'><a name="Page_16" id="Page_16">[Pg 16]</a></span></p><p>It was a 110-volt current, the pressure used in our cities for
+domestic lighting. The funny part about it was, the farmer could not
+feel it at all at first. His fingers were calloused and no current
+could pass through them. Finally he sandpapered his fingers and tried
+it again. Then he was able to get the "tickle" of 110 volts. It wasn't
+so deadly after all&mdash;about the strength of a weak medical battery,
+with which every one is familiar. A current of 110 volts cannot do any
+harm to the human body unless contact is made over a very large
+surface, which is impossible unless a man goes to a lot of trouble to
+make such a contact. A current of 220 volts pressure&mdash;the pressure
+used in cities for motors&mdash;has a little more "kick" to it, but still
+is not uncomfortable. When the pressure rises to 500 volts (the
+pressure used in trolley wires for street cars), it begins to be
+dangerous. But there is no reason why a farm plant should be over 110
+volts, under usual conditions; engineers have decided on this pressure
+as the best adapted to domestic use, and manufacturers who turn out
+the numerous electrical devices, such as irons, toasters, massage
+machines, etc., fit their standard instruments to this voltage.</p>
+
+
+<div class="figcenter" style="width: 500px;"><a name="i16" id="i16"></a>
+<img src="images/i16.jpg" width="500" height="363" alt="" title="" />
+Farm labor and materials built this crib and stone
+dam
+</div>
+
+<p><span class='pagenum'><a name="Page_17" id="Page_17">[Pg 17]</a></span></p>
+
+<p>As to the cost of this co-operative plant&mdash;it was in the neighborhood
+of $200. As we have said, it provided eight electrical horsepower on
+tap at any hour of the day or night&mdash;enough for the two farms, and a
+surplus for neighbors, if they wished to string lines and make use of
+it.</p>
+
+<p>The dynamo, a direct-current machine, 110 volts pressure, and what is
+known in the trade as "compound,"&mdash;that is, a machine that maintains a
+constant pressure automatically and does not require an attendant&mdash;was
+picked up second-hand, through a newspaper "ad" and cost $90. The
+switchboard, a make-shift affair, not very handsome, but just as
+serviceable as if it were made of marble, cost less than $25 all told.
+The transmission wire cost $19 a hundred pounds; it is of copper, and
+covered with weatherproofed tape. Perkins bought a 50-cent book on<span class='pagenum'><a name="Page_18" id="Page_18">[Pg 18]</a></span>
+house-wiring, and did the wiring himself, the way the book told him
+to, a simple operation. For fixtures, as we have said, his wife
+devised fancy shades out of Mexican baskets, tissue paper, and silk,
+in which are hidden electric globes that glow like fire-flies at the
+pressing of a button. The lamps themselves are mostly old-style carbon
+lamps, which can be bought at 16 cents each retail. In his living room
+and dining room he used the new-style tungsten lamps instead of
+old-style carbon. These cost 30 cents each. Incandescent lamps are
+rated for 1,000 hours useful life. The advantage of tungsten lights is
+that they give three times as much light for the same expenditure of
+current as carbon lights. This is a big advantage in the city, where
+current is costly; but it is not so much of an advantage in the
+country where a farmer has plenty of water-power&mdash;because his current
+costs him practically nothing, and he can afford to be wasteful of it
+to save money in lamps. Another advantage he has over his city cousin:
+In town, an incandescent lamp is<span class='pagenum'><a name="Page_19" id="Page_19">[Pg 19]</a></span> thrown away after it has been used
+1,000 hours because after that it gives only 80% of the light it did
+when new&mdash;quite an item when one is paying for current. The experience
+of Perkins and his neighbor in their co&ouml;perative plant has been that
+they have excess light anyway, and if a few bulbs fall off a fifth in
+efficiency, it is not noticeable. As a matter of fact most of their
+bulbs have been in use without replacing for the two years the plant
+has been in operation. The lamps are on the wall or the ceiling, out
+of the way, not liable to be broken; so the actual expense in
+replacing lamps is less than for lamp chimneys in the old days.</p>
+
+<p>Insurance companies recognize that a large percentage of farm fires
+comes from the use of kerosene; for this reason, they are willing to
+make special rates for farm homes lighted by electricity. They
+prescribe certain rules for wiring a house, and they insist that their
+agent inspect and pass such wiring before current is turned on. Once
+the wiring is passed, the advantage is all in favor of the<span class='pagenum'><a name="Page_20" id="Page_20">[Pg 20]</a></span> farmer
+with electricity over the farmer with kerosene. The National Board of
+Fire Underwriters is sufficiently logical in its demands, and powerful
+enough, so that manufacturers who turn out the necessary fittings find
+no sale for devices that do not conform to insurance standards.
+Therefore it is difficult to go wrong in wiring a house.</p>
+
+<p>Finally, as to the added value a water-power electric plant adds to
+the selling price of a farm. Let the farmer answer this question for
+himself. If he can advertise his farm for sale, with a paragraph
+running: "Hydroelectric plant on the premises, furnishing electricity
+for light, heat, and power"&mdash;what do you suppose a wide-awake
+purchaser would be willing to pay for that? Perkins and his neighbor
+believe that $1,000 is a very modest estimate added by their electric
+plant to both places. And they talk of doing still more. They use only
+a quarter of the power of the water that is running to waste through
+the wheel. They are figuring on installing a larger dynamo, of say 30
+electrical horse-power, <span class='pagenum'><a name="Page_21" id="Page_21">[Pg 21]</a></span>which will provide clean, dry, safe heat for
+their houses even on the coldest days in winter. When they have done
+this, they will consider that they are really putting their small
+river to work.</p>
+
+
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_22" id="Page_22">[Pg 22]</a></span></p>
+<h2><a name="CHAPTER_II" id="CHAPTER_II"></a>CHAPTER II</h2>
+
+<p class="subhead2">A LITTLE PROSPECTING</p>
+
+<div class="blockquot"><p>Small amount of water required for an electric plant&mdash;Exploring, on
+a dull day&mdash;A rough and ready weir&mdash;What a little water will
+do&mdash;The water wheel and the dynamo&mdash;Electricity consumed the
+instant it is produced&mdash;The price of the average small plant, not
+counting labor.</p></div>
+
+
+<p>The average farmer makes the mistake of considering that one must have
+a river of some size to develop power of any practical use. On your
+next free day do a little prospecting. We have already said that 250
+cubic feet of water falling 10 feet a minute will provide light, heat
+and small motor power for the average farm. A single water horsepower
+will generate enough electricity to provide light for the house and
+barn. But let us take five horsepower as a desirable minimum in this
+instance.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="i22" id="i22"></a>
+<img src="images/i22.jpg" width="500" height="352" alt="" title="" />
+Measuring a small stream with a weir
+</div>
+
+<p>In your neighborhood there is a creek three or four feet wide,
+toiling along day by day, at its task of watering your fields. Find a
+wide board a little longer than the width o<span class='pagenum'><a name="Page_23" id="Page_23">[Pg 23]</a></span>f this creek you have
+scorned. Set it upright across the stream between the banks, so that
+no water flows around the ends or under it. It should be high enough
+to set the water back to a dead level for a few feet upstream, before
+it overflows. Cut a gate in this board, say three feet wide and ten
+inches deep, or according to the size of a stream. Cut this gate from
+the top, so that all the water of the stream will flow through the
+opening, and still maintain a level for several feet back of the
+board.</p>
+
+<p>This is what engineers call a weir, a handy contrivance for measuring
+the flow of small streams. Experts have figured out an elaborate
+system of tables as to weirs. All we need to do now, in this rough
+survey, is to figure out the number of square inches of water flowing
+through this opening and falling on the other side. With a rule,
+measure the depth of the overflowing water, from the bottom <span class='pagenum'><a name="Page_24" id="Page_24">[Pg 24]</a></span>of the
+opening to the top of the dead level of the water behind the board.
+Multiply this depth by the width of the opening, which will give the
+square inches of water escaping. For every square inch of this water
+escaping, engineers tell us that stream is capable of delivering,
+roughly, one cubic foot of water a minute.</p>
+
+<p>Thus, if the water is 8 inches deep in an opening 32 inches wide, then
+the number of cubic feet this stream is delivering each minute is 8
+times 32, or 256 cubic feet a minute. So, a stream 32 inches wide,
+with a uniform depth of 8 inches running through our weir is capable
+of supplying the demands of the average farm in terms of electricity.
+Providing, of course, that the lay of the land is such that this water
+can be made to fall 10 feet into a water wheel.</p>
+
+<p>Go upstream and make a rough survey of the fall. In the majority of
+instances (unless this is some sluggish stream in a flat prairie) it
+will be found feasible to divert the stream from its main channel by
+means of a race&mdash;an<span class='pagenum'><a name="Page_25" id="Page_25">[Pg 25]</a></span> artificial channel&mdash;and to convey it to a not
+far-distant spot where the necessary fall can be had at an angle of
+about 30 degrees from horizontal.</p>
+
+<p>If you find there is <i>twice</i> as much water as you need for the amount
+of power you require, a five-foot fall will give the same result. Or,
+if there is only <i>one-half</i> as much water as the 250 cubic feet
+specified, you can still obtain your theoretical five horsepower if
+the means are at hand for providing a fall of twenty feet instead of
+ten. Do not make the very common mistake of figuring that a stream is
+delivering a cubic foot a minute to each square inch of weir opening,
+simply because it <i>fills</i> a certain opening. It is the excess water,
+falling <i>over</i> the opening, after the stream has set back to a
+permanent dead level, that is to be measured.</p>
+
+<p>This farmer who spends an idle day measuring the flow of his brook
+with a notched board, may say here: "This is all very well. This is
+the spring of the year, when my brook is flowing at high-water mark.
+What am I going to do in the dry months of summer, when<span class='pagenum'><a name="Page_26" id="Page_26">[Pg 26]</a></span> there are not
+250 cubic feet of water escaping every minute?"</p>
+
+<p>There are several answers to this question, which will be taken up in
+detail in subsequent chapters. Here, let us say, even if this brook
+does flow in sufficient volume only 8 months in a year&mdash;the dark
+months, by the way,&mdash;is not electricity and the many benefits it
+provides worth having eight months in the year? My garden provides
+fresh vegetables four months a year. Because it withers and dies and
+lies covered with snow during the winter, is that any reason why I
+should not plow and manure and plant my garden when spring comes
+again?</p>
+
+<p>A water wheel, the modern turbine, is a circular fan with curved iron
+blades, revolving in an iron case. Water, forced through the blades of
+this fan by its own weight, causes the wheel to revolve on its axis;
+and the fan, in turn causes a shaft fitted with pulleys to revolve.</p>
+
+<p>The water, by giving the iron-bladed fan a turning movement as it
+rushes through, imparts <span class='pagenum'><a name="Page_27" id="Page_27">[Pg 27]</a></span>to it mechanical power. The shaft set in
+motion by means of this mechanical power is, in turn, belted to the
+pulley of a dynamo. This dynamo consists, first, of a shaft on which
+is placed a spool, wound in a curious way, with many turns of
+insulated copper wire. This spool revolves freely in an air space
+surrounded by electric magnets. The spool does not touch these
+magnets. It is so nicely balanced that the weight of a finger will
+turn it. Yet, when it is revolved by water-power at a predetermined
+speed&mdash;say 1,500 revolutions a minute&mdash;it generates electricity,
+transforms the mechanical power of the water wheel into another form
+of energy&mdash;a form of energy which can be carried for long distances on
+copper wires, which can, by touching a button, be itself converted
+into light, or heat, or back into mechanical energy again.</p>
+
+<p>If two wires be led from opposite sides of this revolving spool, and
+an electric lamp be connected from one to the other wire, the lamp
+will be lighted&mdash;will grow white hot,&mdash;hence<span class='pagenum'><a name="Page_28" id="Page_28">[Pg 28]</a></span> <i>incandescent light</i>.
+The instant this lamp is turned on, the revolving spool feels a
+stress, the magnets by which it is surrounded begin to pull back on
+it. The power of the water wheel, however, overcomes this pull. If one
+hundred lights be turned on, the backward pull of the magnets
+surrounding the spool will be one hundred times as strong as for one
+light. For every ounce of electrical energy used in light or heat or
+power, the dynamo will require a like ounce of mechanical power from
+the water wheel which drives it.</p>
+
+<p>The story is told of a canny Scotch engineer, who, in the first days
+of dynamos, not so very long ago, scoffed at the suggestion that such
+a spool, spinning in free air, in well lubricated bearings, could
+bring his big Corliss steam engine to a stop. Yet he saw it done
+simply by belting this "spool," a dynamo, to his engine and asking the
+dynamo for more power in terms of light than his steam could deliver
+in terms of mechanical power to overcome the pull of the magnets.</p>
+
+<p><span class='pagenum'><a name="Page_29" id="Page_29">[Pg 29]</a></span></p><p>Electricity must be consumed the instant it is generated (except in
+rare instances where small amounts are accumulated in storage
+batteries by a chemical process). The pressure of a button, or the
+throw of a switch causes the dynamo instantly to respond with just
+enough energy to do the work asked of it, always in proportion to the
+amount required. Having this in mind, it is rather curious to think of
+electricity as being an article of export, an item in international
+trade. Yet in 1913 hydro-electric companies in Canada "exported" by
+means of wires, to this country over 772,000,000 kilowatt-hours (over
+one billion horsepower hours) of electricity for use in factories near
+the boundary line.</p>
+
+<p>This 250 cubic feet of water per minute then, which the farmer has
+measured by means of his notched board, will transform by means of its
+falling weight mechanical power into a like amount of electrical
+power&mdash;less friction losses, which may amount to as much as 60% in
+very small machines, and 15% in larger<span class='pagenum'><a name="Page_30" id="Page_30">[Pg 30]</a></span> plants. That is, the brook
+which has been draining your pastures for uncounted ages contains the
+potential power of 3 and 4 young horses&mdash;with this difference: that it
+works 24 hours a day, runs on forever, and requires no oats or hay.
+And the cost of such an electric plant, which is ample for the needs
+of the average farm, <i>is in most cases less than the price of a good
+farm horse</i>&mdash;the $200 kind&mdash;not counting labor of installation.</p>
+
+<p>It is the purpose of these chapters to awaken the farmer to the
+possibilities of such small water-power as he or his community may
+possess; to show that the generating of electricity is a very simple
+operation, and that the maintenance and care of such a plant is within
+the mechanical ability of any American farmer or farm boy; and to show
+that electricity itself is far from being the dangerous death-dealing
+"fluid" of popular imagination. Electricity must be studied; and then
+it becomes an obedient, tireless servant. During the past decade or
+two, mathematical wizards have studied electricity, explored its
+atoms,<span class='pagenum'><a name="Page_31" id="Page_31">[Pg 31]</a></span> reduced it to simple arithmetic&mdash;and although they cannot yet
+tell us <i>why</i> it is generated, they tell us <i>how</i>. It is with this
+simple arithmetic, and the necessary manual operations that we have to
+do here.</p>
+
+
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_32" id="Page_32">[Pg 32]</a></span></p>
+<h2><a name="CHAPTER_III" id="CHAPTER_III"></a>CHAPTER III</h2>
+
+<p class="subhead2">HOW TO MEASURE WATER-POWER</p>
+
+<div class="blockquot"><p>What is a horsepower?&mdash;How the Carthaginians manufactured
+horsepower&mdash;All that goes up must come down&mdash;How the sun lifts
+water up for us to use&mdash;Water the ideal power for generating
+electricity&mdash;The weir&mdash;Table for estimating flow of streams, with a
+weir&mdash;Another method of measuring&mdash;Figuring water horsepower&mdash;The
+size of the wheel&mdash;What head is required&mdash;Quantity of water
+necessary.</p></div>
+
+
+<p>If a man were off in the woods and needed a horsepower of energy to
+work for him, he could generate it by lifting 550 pounds of stone or
+wood, or whatnot, one foot off the ground, and letting it fall back in
+the space of one second. As a man possesses capacity for work equal to
+one-fifth horsepower, it would take him five seconds to do the work of
+lifting the weight up that the weight itself accomplished in falling
+down. All that goes up must come down; and by a nice balance of<span class='pagenum'><a name="Page_33" id="Page_33">[Pg 33]</a></span>
+physical laws, a falling body hits the ground with precisely the same
+force as is required to lift it to the height from which it falls.</p>
+
+<p>The Carthaginians, and other ancients (who were deep in the woods as
+regards mechanical knowledge) had their slaves carry huge stones to
+the top of the city wall; and the stones were placed in convenient
+positions to be tipped over on the heads of any besieging army that
+happened along. Thus by concentrating the energy of many slaves in one
+batch of stones, the warriors of that day were enabled to deliver
+"horsepower" in one mass where it would do the most good. The farmer
+who makes use of the energy of falling water to generate electricity
+for light, heat, and power does the same thing&mdash;he makes use of the
+capacity for work stored in water in being lifted to a certain height.
+As in the case of the gasoline engine, which burns 14 pounds of air
+for every pound of gasoline, the engineer of the water-power plant
+does not have to concern himself with the question of how this<span class='pagenum'><a name="Page_34" id="Page_34">[Pg 34]</a></span>
+natural source of energy happened to be in a handy place for him to
+make use of it.</p>
+
+<p>The sun, shining on the ocean, and turning water into vapor by its
+heat has already lifted it up for him. This vapor floating in the air
+and blown about by winds, becomes chilled from one cause or another,
+gives up its heat, turns back into water, and falls as rain. This
+rain, falling on land five, ten, a hundred, a thousand, or ten
+thousand feet above the sea level, begins to run back to the sea,
+picking out the easiest road and cutting a channel that we call a
+brook, a stream, or a river. Our farm lands are covered to an average
+depth of about three feet a year with water, every gallon of which has
+stored in it the energy expended by the heat of the sun in lifting it
+to the height where it is found.</p>
+
+<p>The farmer, prospecting on his land for water-power, locates a spot on
+a stream which he calls Supply; and another spot a few feet down hill
+near the same stream, which he calls Power. Every gallon of water that
+falls between these two points, and is made to<span class='pagenum'><a name="Page_35" id="Page_35">[Pg 35]</a></span> escape through the
+revolving blades of a water wheel is capable of work in terms of
+foot-pounds&mdash;an amount of work that is directly proportional to the
+<i>quantity</i> of water, and to the <i>distance</i> in feet which it falls to
+reach the wheel&mdash;<i>pounds</i> and <i>feet</i>.</p>
+
+
+<p class="center padtop"><i>The Efficient Water Wheel</i></p>
+
+<p>And it is a very efficient form of work, too. In fact it is one of the
+most efficient forms of mechanical energy known&mdash;and one of the
+easiest controlled. A modern water wheel uses 85 per cent of the total
+capacity for work imparted to falling water by gravity, and delivers
+it as rotary motion. Compare this water wheel efficiency with other
+forms of mechanical power in common use: Whereas a water wheel uses 85
+per cent of the energy of its water supply, and wastes only 15 per
+cent, a gasoline engine reverses the table, and delivers only 15 per
+cent of the energy in gasoline and wastes 85 per cent&mdash;and it is
+rather a high-class gasoline engine that can deliver even 15 per cent;
+a steam engine, on<span class='pagenum'><a name="Page_36" id="Page_36">[Pg 36]</a></span> the other hand, uses about 17 per cent of the
+energy in the coal under its boilers and passes the rest up the
+chimney as waste heat and smoke.</p>
+
+<p>There is still another advantage possessed by water-power over its two
+rivals, steam and gas: It gives the most even flow of power. A gas
+engine "kicks" a wheel round in a circle, by means of successive
+explosions in its cylinders. A reciprocating steam engine "kicks" a
+wheel round in a circle by means of steam expanding first in one
+direction, then in another. A water wheel, on the other hand, is made
+to revolve by means of the pressure of water&mdash;by the constant force of
+gravity, itself&mdash;weight. Weight is something that does not vary from
+minute to minute, or from one fraction of a second to another. It is
+always the same. A square inch of water pressing on the blades of a
+water wheel weights ten, twenty, a hundred pounds, according to the
+height of the pipe conveying that water from the source of supply, to
+the wheel. So long as this column of water is<span class='pagenum'><a name="Page_37" id="Page_37">[Pg 37]</a></span> maintained at a fixed
+height, the power it delivers to the wheel does not vary by so much as
+the weight of a feather.</p>
+
+<p>This property of falling water makes it the ideal power for generating
+electricity. Electricity generated from mechanical power depends on
+constant speed for steady pressure&mdash;since the electric current, when
+analyzed, is merely a succession of pulsations through a wire, like
+waves beating against a sea wall. Water-power delivers these waves at
+a constant speed, so that electric lights made from water-power do not
+flicker and jump like the flame of a lantern in a gusty wind. On the
+other hand, to accomplish the same thing with steam or gasoline
+requires an especially constructed engine.</p>
+
+
+<p class="center padtop"><i>The Simple Weir</i></p>
+
+<p>Since a steady flow of water, and a constant head, bring about this
+ideal condition in the water wheel, the first problem that faces the
+farmer prospector is to determine the amount of water which his stream
+is capable of delivering. <span class='pagenum'><a name="Page_38" id="Page_38">[Pg 38]</a></span>This is always measured, for convenience,
+in <i>cubic feet per minute</i>. (A cubic foot of water weighs 62.5 pounds,
+and contains 7&frac12; gallons.) This measurement is obtained in several
+ways, among which probably the use of a weir is the simplest and most
+accurate, for small streams.</p>
+
+<p>A weir is, in effect, merely a temporary dam set across the stream in
+such a manner as to form a small pond; and to enable one to measure
+the water escaping from this pond.</p>
+
+<p>It may be likened to the overflow pipe of a horse trough which is
+being fed from a spring. To measure the flow of water from such a
+spring, all that is necessary is to measure the water escaping through
+the overflow when the water in the trough has attained a permanent
+level.</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d38.jpg" width="500" height="269" alt="" title="" />
+Detail of home-made weir
+</div>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d39.jpg" width="500" height="245" alt="" title="" />
+Cross-section of weir
+</div>
+
+<p>The diagrams show the cross-section and detail of a typical weir,
+which can be put<span class='pagenum'><a name="Page_39" id="Page_39">[Pg 39]</a></span> together in a few minutes with the aid of a saw and
+hammer. The cross-section shows that the lower edge of the slot
+through which the water of the temporary pond is made to escape, is
+cut on a bevel, with its sharp edge upstream. The wing on each side of
+the opening is for the purpose of preventing the stream from narrowing
+as it flows through the opening, and thus upsetting the calculations.
+This weir should be set directly across the flow of the stream,
+perfectly level, and upright. It should be so imbedded in the banks,
+and in the bottom of the stream, that no water can escape, except
+through the opening cut for that purpose. It will require a little
+experimenting with a rough model to determine just how wide and how
+deep this opening should be. It should be large enough to prevent
+water flowing over the top of the<span class='pagenum'><a name="Page_40" id="Page_40">[Pg 40]</a></span> board; and it should be small
+enough to cause a still-water pond to form for several feet behind the
+weir. Keep in mind the idea of the overflowing water trough when
+building your weir. The stream, running down from a higher level
+behind, should be emptying into a still-water pond, which in turn
+should be emptying itself through the aperture in the board at the
+same rate as the stream is keeping the pond full.</p>
+
+<p>Your weir should be fashioned with the idea of some permanency so that
+a number of measurements may be taken, extending over a period of
+time&mdash;thus enabling the prospector to make a reliable estimate not
+only of the amount of water flowing at any one time, but of its
+fluctuations.</p>
+
+<p>Under expert supervision, this simple weir is an exact
+contrivance&mdash;exact enough, in fact, for the finest calculations
+required in engineering work. To find out how many cubic feet of water
+the stream is delivering at any moment, all that is necessary is to
+measure its depth where it flows through the opening. There are<span class='pagenum'><a name="Page_41" id="Page_41">[Pg 41]</a></span>
+instruments, like the hook-gauge, which are designed to measure this
+depth with accuracy up to one-thousandth of an inch. An ordinary foot
+rule, or a folding rule, will give results sufficiently accurate for
+the water prospector in this instance. The depth should be measured
+not at the opening itself, but a short distance back of the opening,
+where the water is setting at a dead level and is moving very slowly.</p>
+
+<p>With this weir, every square inch of water flowing through the opening
+indicates roughly one cubic foot of water a minute. Thus if the
+opening is 10 inches wide and the water flowing through it is 5 inches
+deep, the number of cubic feet a minute the stream is delivering is 10
+&times; 5 = 50 square inches = 50 cubic feet a minute. This is a very small
+stream; yet, if it could be made to fall through a water wheel 10 feet
+below a pond or reservoir, it would exert a continuous pressure of
+30,000 pounds per minute on the blades of the wheel&mdash;nearly one
+theoretical horsepower.</p>
+
+<p><span class='pagenum'><a name="Page_42" id="Page_42">[Pg 42]</a></span></p><p>This estimate of one cubic foot to each square inch is a very rough
+approximation. Engineers have developed many complicated formulas for
+determining the flow of water through weirs, taking into account fine
+variations that the farm prospector need not heed. The so-called
+Francis formula, developed by a long series of actual experiments at
+Lowell, Mass., in 1852 by Mr. James B. Francis, with weirs 10 feet
+long and 5 feet 2 inches high, is standard for these calculations and
+is expressed (for those who desire to use it for special purposes) as
+follows:</p>
+
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/m42.jpg" width="500" height="72" alt="Q = 3.33 L H^(3/2) or, Q = 3.33 L H sqrt(H)," title="" />
+</div>
+
+<p>in which Q means <i>quantity</i> of water in cubic feet per second, L is
+length of opening, in feet; and H is height of opening in feet.</p>
+
+<p>The following table is figured according to the Francis formula, and
+gives the discharge in cubic feet per minute, for openings one inch
+wide:</p>
+
+
+<p><span class='pagenum'><a name="Page_43" id="Page_43">[Pg 43]</a></span></p>
+
+<p class="center"><b>TABLE OF WEIRS</b></p>
+
+<table summary="table of weirs" style="width: 60%;"><tbody>
+<tr>
+<th class="right"><i>Inches</i></th>   <th class="right">0</th>         <th class="right">&frac14;</th>        <th class="right">&frac12;</th>        <th class="right">&frac34;</th>
+</tr><tr>
+ <td class="tr" style="width: 20%;">1</td>  <td class="tr" style="width: 20%;">0.403</td>  <td class="tr" style="width: 20%;">0.563</td>  <td class="tr" style="width: 20%;">0.740</td> <td class="tr" style="width: 20%;">0.966</td>
+</tr><tr>
+ <td class="tr">2</td>  <td class="tr">1.141</td>  <td class="tr">1.360</td>  <td class="tr">1.593</td> <td class="tr">1.838</td>
+</tr><tr>
+ <td class="tr">3</td>  <td class="tr">2.094</td>  <td class="tr">2.361</td>  <td class="tr">2.639</td> <td class="tr">2.927</td>
+</tr><tr>
+ <td class="tr">4</td>  <td class="tr">3.225</td>  <td class="tr">3.531</td>  <td class="tr">3.848</td> <td class="tr">4.173</td>
+</tr><tr>
+ <td class="tr">5</td>  <td class="tr">4.506</td>  <td class="tr">4.849</td>  <td class="tr">5.200</td> <td class="tr">5.558</td>
+</tr><tr>
+ <td class="tr">6</td>  <td class="tr">5.925</td>  <td class="tr">6.298</td>  <td class="tr">6.681</td> <td class="tr">7.071</td>
+</tr><tr>
+ <td class="tr">7</td>  <td class="tr">7.465</td>  <td class="tr">7.869</td>  <td class="tr">8.280</td> <td class="tr">8.697</td>
+</tr><tr>
+ <td class="tr">8</td>  <td class="tr">9.121</td>  <td class="tr">9.552</td>  <td class="tr">9.990</td> <td class="tr">10.427</td>
+</tr><tr>
+ <td class="tr">9</td>  <td class="tr">10.884</td>  <td class="tr">11.340</td>  <td class="tr">11.804</td> <td class="tr">12.272</td>
+</tr><tr>
+<td class="tr">10</td>  <td class="tr">12.747</td>  <td class="tr">13.228</td>  <td class="tr">13.716</td> <td class="tr">14.208</td>
+</tr><tr>
+<td class="tr">11</td>  <td class="tr">14.707</td>  <td class="tr">15.211</td>  <td class="tr">15.721</td> <td class="tr">16.236</td>
+</tr><tr>
+<td class="tr">12</td>  <td class="tr">16.757</td>  <td class="tr">17.283</td>  <td class="tr">17.816</td> <td class="tr">18.352</td>
+</tr><tr>
+<td class="tr">13</td>  <td class="tr">18.895</td>  <td class="tr">19.445</td>  <td class="tr">19.996</td> <td class="tr">20.558</td>
+</tr><tr>
+<td class="tr">14</td>  <td class="tr">21.116</td>  <td class="tr">21.684</td>  <td class="tr">22.258</td> <td class="tr">22.835</td>
+</tr><tr>
+<td class="tr">15</td>  <td class="tr">23.418</td>  <td class="tr">24.007</td>  <td class="tr">24.600</td> <td class="tr">25.195</td>
+</tr><tr>
+<td class="tr">16</td>  <td class="tr">25.800</td>  <td class="tr">26.406</td>  <td class="tr">27.019</td> <td class="tr">27.634</td>
+</tr><tr>
+<td class="tr">17</td>  <td class="tr">28.256</td>  <td class="tr">28.881</td>  <td class="tr">29.512</td> <td class="tr">30.145</td>
+</tr><tr>
+<td class="tr">18</td>  <td class="tr">30.785</td>  <td class="tr">31.429</td>  <td class="tr">32.075</td> <td class="tr">32.733</td>
+</tr></tbody></table>
+
+
+<p>Thus, let us say, our weir has an opening 30 inches wide, and the
+water overflows through the opening at a uniform depth of 6&frac14;
+inches, when measured a few inches behind the board at a point before
+the overflow curve begins. Run down the first column on the left to
+"6", and cross over to the second column to the right, headed "&frac14;".
+This gives the number of cubic feet per minute for this depth one inch
+wide, as 6.298.<span class='pagenum'><a name="Page_44" id="Page_44">[Pg 44]</a></span> Since the weir is 30 inches wide, multiply 6.298 &times; 30
+= 188.94&mdash;or, say, 189 cubic feet per minute.</p>
+
+<p>Once the weir is set, it is the work of but a moment to find out the
+quantity of water a stream is delivering, simply by referring to the
+above table.</p>
+
+
+<p class="center padtop"><i>Another Method of Measuring a Stream</i></p>
+
+<p>Weirs are for use in small streams. For larger streams, where the
+construction of a weir would be difficult, the U. S. Geological Survey
+engineers recommend the following simple method:</p>
+
+<p>Choose a place where the channel is straight for 100 or 200 feet, and
+has a nearly constant depth and width; lay off on the bank a line 50
+or 100 feet in length. Throw small chips into the stream, and measure
+the time in seconds they take to travel the distance laid off on the
+bank. This gives the surface velocity of the water. Multiply the
+average of several such tests by 0.80, which will give very nearly the
+mean velocity. Then it is<span class='pagenum'><a name="Page_45" id="Page_45">[Pg 45]</a></span> necessary to find the cross-section of the
+flowing water (its average depth multiplied by width), and this
+number, in square feet, multiplied by the velocity in feet per second,
+will give the number of cubic feet the stream is delivering each
+second. Multiplied by 60 gives cubic feet a minute.</p>
+
+
+<p class="center padtop"><i>Figuring a Stream's Horsepower</i></p>
+
+<p>By one of the above simple methods, the problem of <i>Quantity</i> can
+easily be determined. The next problem is to determine what <i>Head</i> can
+be obtained. <i>Head</i> is the distance in feet the water may be made to
+fall, from the Source of Supply, to the water wheel itself. The power
+of water is directly proportional to <i>head</i>, just as it is directly
+proportional to <i>quantity</i>. Thus the typical weir measured above was
+30 inches wide and 6&frac14; deep, giving 189 cubic feet of water a
+minute&mdash;<i>Quantity.</i> Since such a stream is of common occurrence on
+thousands of farms, let us analyze briefly its possibilities for
+power: One hundred and eighty-nine cubic feet of water<span class='pagenum'><a name="Page_46" id="Page_46">[Pg 46]</a></span> weighs 189 &times;
+62.5 pounds = 11,812.5 pounds. Drop this weight one foot, and we have
+11,812.5 foot-pounds. Drop it 3 feet and we have 11,812 &times; 3 =
+35,437.5 foot-pounds. Since 33,000 foot-pounds exerted in one minute
+is one horsepower, we have here a little more than one horsepower. For
+simplicity let us call it a horsepower.</p>
+
+<div class="figcenter" style="width: 500px;">
+<a href="images/d46-big.jpg"><img src="images/d46-small.jpg" width="500" height="380" alt="" title="" /></a>
+Detail of a water-power plant, showing setting of
+wheel, and dynamo connection
+</div>
+
+<p><span class='pagenum'><a name="Page_47" id="Page_47">[Pg 47]</a></span>Now, since the work to be had from this water varies directly with
+<i>quantity</i> and <i>head</i>, it is obvious that a stream <i>one-half</i> as big
+falling <i>twice</i> as far, would still give one horsepower at the wheel;
+or, a stream of 189 cubic feet a minute falling <i>ten times</i> as far, 30
+feet, would give <i>ten times</i> the power, or <i>ten</i> horsepower; a stream
+falling <i>one hundred times</i> as far would give <i>one hundred</i>
+horsepower. Thus small quantities of water falling great distances, or
+large quantities of water falling small distances may accomplish the
+same results. From this it will be seen, that the simple formula for
+determining the theoretical horsepower of any stream, in which
+Quantity and Head are known, is as follows:</p>
+
+<p><span class='pagenum'><a name="Page_48" id="Page_48">[Pg 48]</a></span></p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/m48-1.jpg" width="500" height="84" alt="(A) Theoretical Horsepower = (Cu. Ft. per minute × Feet head × 62.5) / 33,000" title="" />
+</div>
+
+<p><i>As an example, let us say that we have a stream whose weir
+measurement shows it capable of delivering 376 cubic feet a minute,
+with a head (determined by survey) of 13 feet 6 inches. What is the
+horsepower of this stream?</i></p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/m48-2.jpg" width="500" height="95" alt="Answer: H.P. = (Cu. ft. p. m. 376 × head 13.5 × pounds 62.5) / 33,000 = 9.614 horsepower" title="" />
+</div>
+
+<p>This is <i>theoretical horsepower</i>. To determine the <i>actual</i> horsepower
+that can be counted on, in practice, it is customary, with small water
+wheels, to figure 25 per cent loss through friction, etc. In this
+instance, the actual horsepower would then be 7.2.</p>
+
+
+<p class="center padtop"><i>The Size of the Wheel</i></p>
+
+<p>Water wheels are not rated by horsepower by manufacturers, because the
+same wheel might develop one horsepower or one hundred horsepower, or
+even a thousand horsepower,<span class='pagenum'><a name="Page_49" id="Page_49">[Pg 49]</a></span> according to the conditions under which
+it is used. With a given supply of water, the head, in feet,
+determines the size of wheel necessary. The farther a stream of water
+falls, the smaller the pipe necessary to carry a given number of
+gallons past a given point in a given time.</p>
+
+<p>A small wheel, under 10 &times; 13.5 ft. head, would give the same power
+with the above 376 cubic feet of water a minute, as a large wheel
+would with 10 &times; 376 cubic feet, under a 13.5 foot head.</p>
+
+<p>This is due to the <i>acceleration of gravity</i> on falling bodies. A
+rifle bullet shot into the air with a muzzle velocity of 3,000 feet a
+second begins to diminish its speed instantly on leaving the muzzle,
+and continues to diminish in speed at the fixed rate of 32.16 feet a
+second, until it finally comes to a stop, and starts to descend. Then,
+again, its speed accelerates at the rate of 32.16 feet a second, until
+on striking the earth it has attained the velocity at which it left
+the muzzle of the rifle, less loss due to friction.</p>
+
+<p><span class='pagenum'><a name="Page_50" id="Page_50">[Pg 50]</a></span></p><p>The acceleration of gravity affects falling water in the same manner
+as it affects a falling bullet. At any one second, during its course
+of fall, it is traveling at a rate 32.16 feet a second in excess of
+its speed the previous second.</p>
+
+<p>In figuring the size wheel necessary under given conditions or to
+determine the power of water with a given nozzle opening, it is
+necessary to take this into account. The table on page 51 gives
+velocity per second of falling water, ignoring the friction of the
+pipe, in heads from 5 to 1000 feet.</p>
+
+<p>The scientific formula from which the table is computed is expressed
+as follows, for those of a mathematical turn of mind:</p>
+
+<p>Velocity (ft. per sec.) = sqrt(2gh); or, velocity is equal to the
+square root of the product (g = 32.16,&mdash;times head in feet, multiplied
+by 2).</p>
+
+
+
+<p><span class='pagenum'><a name="Page_51" id="Page_51">[Pg 51]</a></span></p>
+
+<p class="center"><b>SPOUTING VELOCITY OF WATER, IN FEET PER SECOND, IN HEADS OF FROM 5 TO
+1,000 FEET</b></p>
+
+<table summary="spouting velocity of water" style="width: 30%;"><tbody>
+<tr>
+<th class="left"><i>Head</i></th>  <th class="right"><i>Velocity</i></th></tr>
+<tr><td class="tl">5</td>  <td class="tr">17.9</td></tr>
+<tr><td class="tl">6</td>  <td class="tr">19.7</td></tr>
+<tr><td class="tl">7</td>  <td class="tr">21.2</td></tr>
+<tr><td class="tl">8</td>  <td class="tr">22.7</td></tr>
+<tr><td class="tl">9</td>  <td class="tr">24.1</td></tr>
+<tr><td class="tl">10</td>  <td class="tr">25.4</td></tr>
+<tr><td class="tl">11</td>  <td class="tr">26.6</td></tr>
+<tr><td class="tl">11.5</td>  <td class="tr">27.2</td></tr>
+<tr><td class="tl">12</td>  <td class="tr">27.8</td></tr>
+<tr><td class="tl">12.5</td>  <td class="tr">28.4</td></tr>
+<tr><td class="tl">13</td>  <td class="tr">28.9</td></tr>
+<tr><td class="tl">13.5</td>  <td class="tr">29.5</td></tr>
+<tr><td class="tl">14</td>  <td class="tr">30.0</td></tr>
+<tr><td class="tl">14.5</td>  <td class="tr">30.5</td></tr>
+<tr><td class="tl">15</td>  <td class="tr">31.3</td></tr>
+<tr><td class="tl">15.5</td>  <td class="tr">31.6</td></tr>
+<tr><td class="tl">16</td>  <td class="tr">32.1</td></tr>
+<tr><td class="tl">16.5</td>  <td class="tr">32.6</td></tr>
+<tr><td class="tl">17</td>  <td class="tr">33.1</td></tr>
+<tr><td class="tl">17.5</td>  <td class="tr">33.6</td></tr>
+<tr><td class="tl">18</td>  <td class="tr">34.0</td></tr>
+<tr><td class="tl">18.5</td>  <td class="tr">34.5</td></tr>
+<tr><td class="tl">19</td>  <td class="tr">35.0</td></tr>
+<tr><td class="tl">19.5</td>  <td class="tr">35.4</td></tr>
+<tr><td class="tl">20</td>  <td class="tr">35.9</td></tr>
+<tr><td class="tl">20.5</td>  <td class="tr">36.3</td></tr>
+<tr><td class="tl">21</td>  <td class="tr">36.8</td></tr>
+<tr><td class="tl">21.5</td>  <td class="tr">37.2</td></tr>
+<tr><td class="tl">22</td>  <td class="tr">37.6</td></tr>
+<tr><td class="tl">22.5</td>  <td class="tr">38.1</td></tr>
+<tr><td class="tl">23</td>  <td class="tr">38.5</td></tr>
+<tr><td class="tl">23.5</td>  <td class="tr">38.9</td></tr>
+<tr><td class="tl">24</td>  <td class="tr">39.3</td></tr>
+<tr><td class="tl">24.5</td>  <td class="tr">39.7</td></tr>
+<tr><td class="tl">25</td>  <td class="tr">40.1</td></tr>
+<tr><td class="tl">26</td>  <td class="tr">40.9</td></tr>
+<tr><td class="tl">27</td>  <td class="tr">41.7</td></tr>
+<tr><td class="tl">28</td>  <td class="tr">42.5</td></tr>
+<tr><td class="tl">29</td>  <td class="tr">43.2</td></tr>
+<tr><td class="tl">30</td>  <td class="tr">43.9</td></tr>
+<tr><td class="tl">31</td>  <td class="tr">44.7</td></tr>
+<tr><td class="tl">32</td>  <td class="tr">45.4</td></tr>
+<tr><td class="tl">33</td>  <td class="tr">46.1</td></tr>
+<tr><td class="tl">34</td>  <td class="tr">46.7</td></tr>
+<tr><td class="tl">35</td>  <td class="tr">47.4</td></tr>
+<tr><td class="tl">36</td>  <td class="tr">48.1</td></tr>
+<tr><td class="tl">37</td>  <td class="tr">48.8</td></tr>
+<tr><td class="tl">38</td>  <td class="tr">49.5</td></tr>
+<tr><td class="tl">39</td>  <td class="tr">50.1</td></tr>
+<tr><td class="tl">40</td>  <td class="tr">50.7</td></tr>
+<tr><td class="tl">41</td>  <td class="tr">51.3</td></tr>
+<tr><td class="tl">42</td>  <td class="tr">52.0</td></tr>
+<tr><td class="tl">43</td>  <td class="tr">52.6</td></tr>
+<tr><td class="tl">44</td>  <td class="tr">53.2</td></tr>
+<tr><td class="tl">45</td>  <td class="tr">53.8</td></tr>
+<tr><td class="tl">46</td>  <td class="tr">54.4</td></tr>
+<tr><td class="tl">47</td>  <td class="tr">55.0</td></tr>
+<tr><td class="tl">48</td>  <td class="tr">55.6</td></tr>
+<tr><td class="tl">49</td>  <td class="tr">56.2</td></tr>
+<tr><td class="tl">50</td>  <td class="tr">56.7</td></tr>
+<tr><td class="tl">55</td>  <td class="tr">59.5</td></tr>
+<tr><td class="tl">60</td>  <td class="tr">62.1</td></tr>
+<tr><td class="tl">65</td>  <td class="tr">64.7</td></tr>
+<tr><td class="tl">70</td>  <td class="tr">67.1</td></tr>
+<tr><td class="tl">75</td>  <td class="tr">69.5</td></tr>
+<tr><td class="tl">80</td>  <td class="tr">71.8</td></tr>
+<tr><td class="tl">85</td>  <td class="tr">74.0</td></tr>
+<tr><td class="tl">90</td>  <td class="tr">76.1</td></tr>
+<tr><td class="tl">95</td>  <td class="tr">78.2</td></tr>
+<tr><td class="tl">100</td>  <td class="tr">80.3</td></tr>
+<tr><td class="tl">200</td>  <td class="tr">114.0</td></tr>
+<tr><td class="tl">300</td>  <td class="tr">139.0</td></tr>
+<tr><td class="tl">400</td>  <td class="tr">160.0</td></tr>
+<tr><td class="tl">500</td>  <td class="tr">179.0</td></tr>
+<tr><td class="tl">1000</td>  <td class="tr">254.0</td></tr>
+</tbody></table>
+
+<p><span class='pagenum'><a name="Page_52" id="Page_52">[Pg 52]</a></span></p>
+
+<p><i>In the above example, we found that 376 cubic feet of water a minute,
+under 13.5 feet head, would deliver 7.2 actual horsepower. Question: What size wheel would it be necessary to install under such
+conditions?</i></p>
+
+<p>By referring to the table of velocity above, (or by using the
+formula), we find that water under a head of 13.5 feet, has a spouting
+velocity of 29.5 feet a second. This means that a solid stream of
+water 29.5 feet long would pass through the wheel in one second. <i>What
+should be the diameter of such a stream, to make its cubical contents
+376 cubic feet a minute or 376/60 = 6.27 cubic feet a second?</i> The
+following formula should be used to determine this:</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/m52-1.jpg" width="500" height="72" alt="(B) Sq. Inches of wheel = (144 × cu. ft. per second) / (Velocity in ft. per sec.)" title="" />
+</div>
+
+<p>Substituting values, in the above instance, we have:</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/m52-2.jpg" width="500" height="100" alt="Answer: Sq. Inches of wheel = (144 × 6.27 Cu. Ft. Sec.) / (29.5 Velocity in feet.) = 30.6 sq. in." title="" />
+</div>
+
+
+<p>That is, a wheel capable of using 30.6 square inches of water would
+meet these conditions.</p>
+
+
+<p><span class='pagenum'><a name="Page_53" id="Page_53">[Pg 53]</a></span></p><p class="center padtop"><i>What Head is Required</i></p>
+
+<p>Let us attack the problem of water-power in another way. <i>A farmer
+wishes to install a water wheel that will deliver 10 horsepower on the
+shaft, and he finds his stream delivers 400 cubic feet of water a
+minute. How many feet fall is required?</i> Formula:</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/m53-1.jpg" width="500" height="74" alt="(C) Head in feet = (33,000 × horsepower required) / (Cu. Ft. per minute × 62.5)" title="" />
+</div>
+
+
+<p>Since a theoretical horsepower is only 75 per cent efficient, he would
+require 10 &times; 4/3 = 13.33 theoretical horsepower of water, in this
+instance. Substituting the values of the problem in the formula, we
+have:</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/m53-2.jpg" width="500" height="57" alt="Answer: Head = (33,000 × 13.33) / (400 × 62.5) = 17.6 feet fall required." title="" />
+</div>
+
+
+<p><i>What capacity of wheel would this prospect (400 cubic feet of water a
+minute falling 17.6 feet, and developing 13.33 horsepower) require?</i></p>
+
+<p>By referring to the table of velocities, we find that the velocity for
+17.5 feet head (nearly) is 33.6 feet a second. Four hundred<span class='pagenum'><a name="Page_54" id="Page_54">[Pg 54]</a></span> feet of
+water a minute is 400/60 = 6.67 cu. ft. a second. Substituting these
+values, in formula (B) then, we have:</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/m54-1.jpg" width="500" height="88" alt="Answer: Capacity of wheel = (144 × 6.67) / 33.6 = 28.6 sq. in. of water." title="" />
+</div>
+
+
+<p class="center padtop"><i>Quantity of Water</i></p>
+
+<p>Let us take still another problem which the prospector may be called
+on to solve: <i>A man finds that he can conveniently get a fall of 27
+feet. He desires 20 actual horsepower. What quantity of water will be
+necessary, and what capacity wheel?</i></p>
+
+<p>Twenty actual horsepower will be 20 &times; 4/3 = 26.67 theoretical
+horsepower. Formula:</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/m54-2.jpg" width="500" height="56" alt="(D) Cubic feet per minute = (33,000 × Hp. required) / (Head in feet × 62.5)" title="" />
+</div>
+
+
+<p>Substituting values, then, we have:</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/m54-3.jpg" width="500" height="83" alt="Cu. Ft. per minute = (33,000 × 26.67) / (27 × 62.5) = 521.5 cubic ft. a minute." title="" />
+</div>
+
+
+<p>A head of 27 feet would give this stream a velocity of 41.7 feet a
+second, and, from<span class='pagenum'><a name="Page_55" id="Page_55">[Pg 55]</a></span> formula (B) we find that the capacity of the wheel
+should be 30 square inches.</p>
+
+<p>It is well to remember that the square inches of wheel capacity does
+not refer to the size of pipe conveying water from the head to the
+wheel, but merely to the actual nozzle capacity provided by the wheel
+itself. In small installations of low head, such as above a penstock
+at least six times the nozzle capacity should be used, to avoid losing
+effective head from friction. Thus, with a nozzle of 30 square inches,
+the penstock or pipe should be 180 square inches, or nearly 14 inches
+square inside measurement. A larger penstock would be still better.</p>
+
+
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_56" id="Page_56">[Pg 56]</a></span></p>
+<h2><a name="CHAPTER_IV" id="CHAPTER_IV"></a>CHAPTER IV</h2>
+
+<p class="subhead2">THE WATER WHEEL AND HOW TO INSTALL IT</p>
+
+<div class="blockquot"><p>Different types of water wheels&mdash;The impulse and reaction
+wheels&mdash;The impulse wheel adapted to high heads and small amount of
+water&mdash;Pipe lines&mdash;Table of resistance in pipes&mdash;Advantages and
+disadvantages of the impulse wheel&mdash;Other forms of impulse
+wheels&mdash;The reaction turbine, suited to low heads and large
+quantity of water&mdash;Its advantages and limitations&mdash;Developing a
+water-power project: the dam; the race; the flume; the penstock;
+and the tailrace&mdash;Water rights for the farmer.</p></div>
+
+
+<p>In general, there are two types of water wheels, the <i>impulse</i> wheel
+and the <i>reaction</i> wheel. Both are called turbines, although the name
+belongs, more properly, to the reaction wheel alone.</p>
+
+<p>Impulse wheels derive their power from the <i>momentum</i> of falling
+water. Reaction wheels derive their power from the <i>momentum and
+pressure</i> of falling water. The old-fashioned <i>undershot</i>, <i>overshot</i>,
+and <i>breast</i> wheels<span class='pagenum'><a name="Page_57" id="Page_57">[Pg 57]</a></span> are familiar to all as examples of impulse
+wheels. Water wheels of this class revolve in the air, with the energy
+of the water exerted on one face of their buckets. On the other hand,
+reaction wheels are enclosed in water-tight cases, either of metal or
+of wood, and the buckets are entirely surrounded by water.</p>
+
+<p>The old-fashioned undershot, overshot, and breast wheels were not very
+efficient; they wasted about 75 per cent of the power applied to them.
+A modern impulse wheel, on the other hand, operates at an efficiency
+of 80 per cent and over. The loss is mainly through friction and
+leakage, and cannot be eliminated altogether. The modern reaction
+wheel, called the <i>turbine</i>, attains an equal efficiency. Individual
+conditions govern the type of wheel to be selected.</p>
+
+
+<p class="center padtop"><i>The Impulse, or Tangential Water Wheel</i></p>
+
+<p>The modern impulse, or tangential wheel (so called because the driving
+stream of water strikes the wheel at a tangent) is best adapted to
+situations where the amount of water is<span class='pagenum'><a name="Page_58" id="Page_58">[Pg 58]</a></span> limited, and the head is
+large. Thus, a mountain brook supplying only seven cubic feet of water
+a minute&mdash;a stream less than two-and-a-half inches deep flowing over a
+weir with an opening three inches wide&mdash;would develop two actual
+horsepower, under a head of 200 feet&mdash;not an unusual head to be found
+in the hill country. Under a head of one thousand feet, a stream
+furnishing 352.6 cubic feet of water a minute would develop 534.01
+horsepower at the nozzle.</p>
+
+<p>Ordinarily these wheels are not used under heads of less than 20 feet.
+A wheel of this type, six feet in diameter, would develop six
+horsepower, with 188 cubic feet of water a minute and 20-foot head.
+The great majority of impulse wheels are used under heads of 100 feet
+and over. In this country the greatest head in use is slightly over
+2,100 feet, although in Switzerland there is one plant utilizing a
+head of over 5,000 feet.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="i58" id="i58"></a>
+<img src="images/i58-1.jpg" width="300" height="393" alt="" title="" />
+<br />
+Runner of Pelton wheel, showing peculiar shape of the buckets
+</div>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/i58-2.jpg" width="500" height="428" alt="" title="" />
+The Fitz overshoot wheel
+</div>
+
+<div class="figcenter" style="width: 500px;">
+<span class="smcap">Efficient Modern Adaptations of the Archaic Undershot and Overshot
+Water Wheels</span>
+</div>
+
+<p>The old-fashioned impulse wheels were inefficient because of the fact
+that their buckets were not constructed scientifically, and much of
+the force of the water was lost at the moment of impact. The impulse
+wheel of to-day, however, has buckets which so completely <span class='pagenum'><a name="Page_59" id="Page_59">[Pg 59]</a></span>absorb the
+momentum of water issuing from a nozzle, that the water falls into the
+tailrace with practically no velocity. When it is remembered that the
+nozzle pressure under a 2,250-foot head is nearly 1,000 pounds to the
+square inch, and that water issues from this nozzle with a velocity of
+23,000 feet a minute, the scientific precision of this type of bucket
+can be appreciated.</p>
+
+<p>A typical bucket for such a wheel is shaped like an open clam shell,
+the central line which cuts the stream of water into halves being
+ground to a sharp edge. The curves which absorb the momentum of the
+water are figured mathematically and in practice become polished like
+mirrors. So great is the eroding action of water, under great
+heads&mdash;especially when it contains sand or silt&mdash;that it is
+occasionally necessary to replace these buckets. For this reason the
+larger wheels consist merely of a spider of iron or steel, with each<span class='pagenum'><a name="Page_60" id="Page_60">[Pg 60]</a></span>
+bucket bolted separately to its circumference, so that it can be
+removed and replaced easily. Usually only one nozzle is provided; but
+in order to use this wheel under low heads&mdash;down to 10 feet&mdash;a number
+of nozzles are used, sometimes five, where the water supply is
+plentiful.</p>
+
+<p>The wheel is keyed to a horizontal shaft running in babbited bearings,
+and this same shaft is used for driving the generator, either by
+direct connection, or by means of pulleys and a belt. The wheel may be
+mounted on a home-made timber base, or on an iron frame. It takes up
+very little room, especially when it is so set that the nozzle can be
+mounted under the flooring. The wheel itself is enclosed, above the
+floor, in a wooden box, or a casing made of cast or sheet iron, which
+should be water-tight.</p>
+
+<p>Since these wheels are usually operated under great heads, the problem
+of regulating their water supply requires special consideration. A
+gate is always provided at the upper, or intake end, where the water
+pipe leaves the<span class='pagenum'><a name="Page_61" id="Page_61">[Pg 61]</a></span> flume. Since the pressure reaches 1,000 pounds the
+square inch and more, there would be danger of bursting the pipe if
+the water were suddenly shut off at the nozzle itself. For this reason
+it is necessary to use a needle valve, similar to that in an ordinary
+garden hose nozzle; and by such a valve the amount of water may be
+regulated to a nicety. Where the head is so great that even such a
+valve could not be used safely, provision is made to deflect the
+nozzle. These wheels have a speed variation amounting to as much as 25
+per cent from no-load to full load, in generating electricity, and
+since the speed of the prime mover&mdash;the water wheel&mdash;is reflected
+directly in the voltage or pressure of electricity delivered, the
+wheel must be provided with some form of automatic governor. This
+consists usually of two centrifugal balls, similar to those used in
+governing steam engines; these are connected by means of gears to the
+needle valve or the deflector.</p>
+
+<p>As the demand for farm water-powers in our hill sections becomes more
+general, the<span class='pagenum'><a name="Page_62" id="Page_62">[Pg 62]</a></span> tangential type of water wheel will come into common use
+for small plants. At present it is most familiar in the great
+commercial installations of the Far West, working under enormous
+heads. These wheels are to be had in the market ranging in size from
+six inches to six feet and over. Wheels ranging in size from six
+inches to twenty-four inches are called water motors, and are to be
+had in the market, new, for $30 for the smallest size, and $275 for
+the largest. Above three feet in diameter, the list prices will run
+from $200 for a 3-foot wheel to $800 for a 6-foot wheel. Where one has
+a surplus of water, it is possible to install a multiple nozzle wheel,
+under heads of from 10 to 100 feet, the cost for 18-inch wheels of
+this pattern running from $150 to $180 list, and for 24-inch wheels
+from $200 to $250. A 24-inch wheel, with a 10-foot head would give
+1.19 horsepower, enough for lighting the home, and using an electric
+iron. Under a 100-foot head this same wheel would provide 25.9
+horsepower, to meet the requirements of a bigger-than-average farm
+plant.</p>
+
+
+<p><span class='pagenum'><a name="Page_63" id="Page_63">[Pg 63]</a></span></p><p class="center padtop"><i>The Pipe Line</i></p>
+
+<p>The principal items of cost in installing an impulse wheel are in
+connection with the pipe line, and the governor. In small heads, that
+is, under 100 feet, the expense of pipe line is low. Frequently,
+however, the governor will cost more than the water motor itself,
+although cheaper, yet efficient, makes are now being put on the market
+to meet this objection. In a later chapter, we will take up in detail
+the question of governing the water wheel, and voltage regulation, and
+will attempt to show how this expense may be practically eliminated by
+the farmer.</p>
+
+<p>To secure large heads, it is usually necessary to run a pipe line many
+hundreds (and in many cases, many thousands) of feet from the flume to
+the water wheel. Water flowing through pipes is subject to loss of
+head, by friction, and for this reason the larger the pipe the less
+the friction loss. Under no circumstances is it recommended to use a
+pipe of less than two inches in diameter, even for the smallest water<span class='pagenum'><a name="Page_64" id="Page_64">[Pg 64]</a></span>
+motors; and with a two-inch pipe, the run should not exceed 200 feet.
+Where heavy-pressure mains, such as those of municipal or commercial
+water systems, are available, the problem of both water supply and
+head becomes very simple. Merely ascertain the pressure of the water
+in the mains <i>when flowing</i>, determine the amount of power required
+(as illustrated in a succeeding chapter of this book), and install the
+proper water motor with a suitably sized pipe.</p>
+
+<p>Where one has his own water supply, however, and it is necessary to
+lay pipe to secure the requisite fall, the problem is more difficult.
+Friction in pipes acts in the same way as cutting down the head a
+proportional amount; and by cutting down the head, your water motor
+loses power in direct proportion to the number of feet head lost. This
+head, obtained by subtracting friction and other losses from the
+surveyed head, is called the <i>effective head</i>, and determines the
+amount of power delivered at the nozzle.</p>
+
+<p>The tables on pages 66-67 show the friction<span class='pagenum'><a name="Page_65" id="Page_65">[Pg 65]</a></span> loss in pipes up to 12
+inches in diameter, according to the amount of water, and the length
+of pipe.</p>
+
+<p>In this example it is seen that a 240-foot static head is reduced by
+friction to 230.1 feet effective head. By referring to the table we
+find the wheel fitting these conditions has a nozzle so small that it
+cuts down the rate of flow of water in the big pipe to 4.4 feet a
+second, and permits the flow of only 207 cubic feet of water a minute.
+The actual horsepower of this tube and nozzle, then, can be figured by
+applying formula (A), Chapter III, allowing 80 per cent for the
+efficiency of the wheel. Thus:</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/m65.jpg" width="500" height="82" alt="Actual horsepower = (207 × 230.1 × 62.5) / 33,000 = 90.21 × .80 = 72.168 Hp." title="" />
+</div>
+
+
+
+<p>To calculate what the horsepower of this tube 12 inches in diameter
+and 900 feet long, would be without a nozzle, under a head of 240
+feet, introduces a new element of friction losses, which is too
+complicated to figure here. Such a condition would not be met<span class='pagenum'><a name="Page_66" id="Page_66">[Pg 66]</a></span> with in
+actual practice, in any event. The largest nozzles used, even in the
+jumbo plants of the Far West, rarely exceed 10 inches in diameter; and
+the pipe conveying water to such a nozzle is upwards of eight feet in
+diameter.</p>
+
+
+<p class="subhead2 padtop">PIPE FRICTION TABLES</p>
+
+<p class="subhead3">INDICATING THE CALCULATED LOSS OF HEAD DUE TO FRICTION IN RIVETED
+STEEL PIPE WITH VARIOUS WATER QUANTITIES AND VELOCITIES</p>
+
+<p class="subhead3">[Courtesy of the Pelton Water Wheel Company]</p>
+
+<p style="margin-left: 20%;">Heavy-faced figures = Loss of head in feet for each one thousand feet
+of pipe.<br />
+Light-faced figures = Water quantity in cubic feet per minute.</p>
+
+
+
+
+
+<div class='center'>
+<table border="0" cellpadding="4" cellspacing="0" summary="">
+<tr><td align='left'>Pipe<br />Diameter</td><td align='left' colspan="13"> <span class="smcap">Velocity in Feet per Second</span></td></tr>
+<tr><td align='left'></td><td align='left'> 2.0</td><td align='left'> 2.2</td><td align='left'> 2.4</td><td align='left'> 2.6</td><td align='left'> 2.8</td><td align='left'> 3.0</td><td align='left'> 3.2</td><td align='left'> 3.4</td><td align='left'> 3.6</td><td align='left'> 3.8</td><td align='left'> 4.0</td><td align='left'> 4.2</td><td align='left'> 4.4</td></tr>
+<tr><td align='left'></td><td align='left'><b>17.1</b></td><td align='left'><b>20.0</b></td><td align='left'><b>25.6</b></td><td align='left'><b>28.3</b></td><td align='left'><b>32.0</b></td><td align='left'><b>37.3</b></td><td align='left'><b>40.9</b></td><td align='left'><b>45.8</b></td><td align='left'><b>50.4</b></td><td align='left'><b>56.0</b></td><td align='left'><b>62.3</b></td><td align='left'><b>68.1</b></td><td align='left'><b>74.9</b></td></tr>
+<tr><td align='left'>3"</td><td align='left'> 5.9</td><td align='left'> 6.5</td><td align='left'> 7.1</td><td align='left'> 7.7</td><td align='left'> 8.3</td><td align='left'> 8.9</td><td align='left'> 9.4</td><td align='left'> 10.0</td><td align='left'> 10.6</td><td align='left'> 11.2</td><td align='left'> 11.8</td><td align='left'> 12.4</td><td align='left'> 13.0</td></tr>
+<tr><td align='left'></td><td align='left'><b>11.0</b></td><td align='left'><b>13.0</b></td><td align='left'><b>15.0</b></td><td align='left'><b>17.3</b></td><td align='left'><b>20.2</b></td><td align='left'><b>23.2</b></td><td align='left'><b>26.2</b></td><td align='left'><b>29.6</b></td><td align='left'><b>33.0</b></td><td align='left'><b>36.5</b></td><td align='left'><b>41.0</b></td><td align='left'><b>45.4</b></td><td align='left'><b>49.2</b></td></tr>
+<tr><td align='left'>4"</td><td align='left'> 10.5</td><td align='left'> 11.5</td><td align='left'> 12.6</td><td align='left'> 13.6</td><td align='left'> 14.7</td><td align='left'> 15.7</td><td align='left'> 16.8</td><td align='left'> 17.8</td><td align='left'> 18.8</td><td align='left'> 19.9</td><td align='left'> 21.0</td><td align='left'> 22.0</td><td align='left'> 23.0</td></tr>
+<tr><td align='left'></td><td align='left'> <b>7.7</b></td><td align='left'> <b>9.4</b></td><td align='left'><b>11.0</b></td><td align='left'><b>12.9</b></td><td align='left'><b>14.9</b></td><td align='left'><b>16.9</b></td><td align='left'><b>19.5</b></td><td align='left'><b>21.6</b></td><td align='left'><b>24.0</b></td><td align='left'><b>27.0</b></td><td align='left'><b>29.8</b></td><td align='left'><b>32.9</b></td><td align='left'><b>36.0</b></td></tr>
+<tr><td align='left'>5"</td><td align='left'> 16.4</td><td align='left'> 18.0</td><td align='left'> 19.6</td><td align='left'> 21.2</td><td align='left'> 22.9</td><td align='left'> 24.5</td><td align='left'> 26.1</td><td align='left'> 27.8</td><td align='left'> 29.5</td><td align='left'> 31.0</td><td align='left'> 32.7</td><td align='left'> 34.3</td><td align='left'> 36.0</td></tr>
+<tr><td align='left'></td><td align='left'> <b>6.0</b></td><td align='left'> <b>7.2</b></td><td align='left'> <b>8.6</b></td><td align='left'> <b>9.9</b></td><td align='left'><b>11.7</b></td><td align='left'><b>13.0</b></td><td align='left'><b>14.6</b></td><td align='left'><b>16.6</b></td><td align='left'><b>19.0</b></td><td align='left'><b>21.5</b></td><td align='left'><b>23.4</b></td><td align='left'><b>25.5</b></td><td align='left'><b>27.8</b></td></tr>
+<tr><td align='left'>6"</td><td align='left'> 23.5</td><td align='left'> 25.9</td><td align='left'> 28.2</td><td align='left'> 30.6</td><td align='left'> 32.9</td><td align='left'> 35.3</td><td align='left'> 37.7</td><td align='left'> 40.0</td><td align='left'> 42.4</td><td align='left'> 44.7</td><td align='left'> 47.1</td><td align='left'> 49.5</td><td align='left'> 51.8</td></tr>
+<tr><td align='left'></td><td align='left'> <b>4.9</b></td><td align='left'> <b>6.9</b></td><td align='left'> <b>7.0</b></td><td align='left'> <b>8.1</b></td><td align='left'> <b>9.3</b></td><td align='left'><b>10.6</b></td><td align='left'><b>12.0</b></td><td align='left'><b>13.6</b></td><td align='left'><b>15.2</b></td><td align='left'><b>17.0</b></td><td align='left'><b>19.0</b></td><td align='left'><b>21.0</b></td><td align='left'><b>23.0</b></td></tr>
+<tr><td align='left'>7"</td><td align='left'> 32.0</td><td align='left'> 35.3</td><td align='left'> 38.5</td><td align='left'> 41.7</td><td align='left'> 44.9</td><td align='left'> 48.1</td><td align='left'> 51.3</td><td align='left'> 54.5</td><td align='left'> 57.7</td><td align='left'> 60.9</td><td align='left'> 64.1</td><td align='left'> 67.3</td><td align='left'> 70.5</td></tr>
+<tr><td align='left'></td><td align='left'> <b>4.0</b></td><td align='left'> <b>4.9</b></td><td align='left'> <b>6.0</b></td><td align='left'> <b>6.9</b></td><td align='left'> <b>7.8</b></td><td align='left'> <b>9.1</b></td><td align='left'><b>10.0</b></td><td align='left'><b>10.2</b></td><td align='left'><b>13.0</b></td><td align='left'><b>14.4</b></td><td align='left'><b>15.9</b></td><td align='left'><b>17.2</b></td><td align='left'><b>19.2</b></td></tr>
+<tr><td align='left'>8"</td><td align='left'> 41.9</td><td align='left'> 46.1</td><td align='left'> 50.2</td><td align='left'> 54.4</td><td align='left'> 58.6</td><td align='left'> 62.8</td><td align='left'> 67.0</td><td align='left'> 71.2</td><td align='left'> 75.4</td><td align='left'> 79.6</td><td align='left'> 83.7</td><td align='left'> 87.9</td><td align='left'> 92.1</td></tr>
+<tr><td align='left'></td><td align='left'> <b>3.4</b></td><td align='left'> <b>4.2</b></td><td align='left'> <b>5.1</b></td><td align='left'> <b>5.9</b></td><td align='left'> <b>6.7</b></td><td align='left'> <b>7.7</b></td><td align='left'> <b>8.9</b></td><td align='left'> <b>9.8</b></td><td align='left'><b>11.0</b></td><td align='left'><b>12.2</b></td><td align='left'><b>13.8</b></td><td align='left'><b>15.0</b></td><td align='left'><b>16.0</b></td></tr>
+<tr><td align='left'>9"</td><td align='left'> 53.0</td><td align='left'> 58.3</td><td align='left'> 63.6</td><td align='left'> 68.9</td><td align='left'> 74.2</td><td align='left'> 79.5</td><td align='left'> 84.8</td><td align='left'> 90.1</td><td align='left'> 95.4</td><td align='left'>101</td><td align='left'>106</td><td align='left'>111</td><td align='left'>116</td></tr>
+<tr><td align='left'></td><td align='left'> <b>2.9</b></td><td align='left'> <b>3.7</b></td><td align='left'> <b>4.4</b></td><td align='left'> <b>5.1</b></td><td align='left'> <b>5.9</b></td><td align='left'> <b>6.7</b></td><td align='left'> <b>7.5</b></td><td align='left'> <b>8.6</b></td><td align='left'> <b>9.5</b></td><td align='left'><b>10.6</b></td><td align='left'><b>12.1</b></td><td align='left'><b>13.1</b></td><td align='left'><b>14.1</b></td></tr>
+<tr><td align='left'>10"</td><td align='left'> 65.4</td><td align='left'> 72.0</td><td align='left'> 78.5</td><td align='left'> 85.1</td><td align='left'> 91.6</td><td align='left'> 98.2</td><td align='left'>105</td><td align='left'>111</td><td align='left'>118</td><td align='left'>124</td><td align='left'>131</td><td align='left'>137</td><td align='left'>144</td></tr>
+<tr><td align='left'></td><td align='left'> <b>2.6</b></td><td align='left'> <b>3.2</b></td><td align='left'> <b>3.8</b></td><td align='left'> <b>4.4</b></td><td align='left'> <b>5.1</b></td><td align='left'> <b>5.9</b></td><td align='left'> <b>6.6</b></td><td align='left'> <b>7.5</b></td><td align='left'> <b>8.4</b></td><td align='left'> <b>9.5</b></td><td align='left'><b>10.3</b></td><td align='left'><b>10.1</b></td><td align='left'><b>12.5</b></td></tr>
+<tr><td align='left'>11"</td><td align='left'> 79</td><td align='left'> 87</td><td align='left'> 95</td><td align='left'>103</td><td align='left'>111</td><td align='left'>119</td><td align='left'>127</td><td align='left'>134</td><td align='left'>142</td><td align='left'>150</td><td align='left'>158</td><td align='left'>166</td><td align='left'>174</td></tr>
+<tr><td align='left'></td><td align='left'> <b>2.36</b></td><td align='left'> <b>2.9</b></td><td align='left'> <b>3.4</b></td><td align='left'> <b>3.9</b></td><td align='left'> <b>4.5</b></td><td align='left'> <b>5.2</b></td><td align='left'> <b>5.9</b></td><td align='left'> <b>6.7</b></td><td align='left'> <b>7.5</b></td><td align='left'> <b>8.5</b></td><td align='left'> <b>9.4</b></td><td align='left'><b>10.0</b></td><td align='left'><b>11.0</b></td></tr>
+<tr><td align='left'>12"</td><td align='left'>94</td><td align='left'>103</td><td align='left'>113</td><td align='left'>122</td><td align='left'>132</td><td align='left'>141</td><td align='left'>151</td><td align='left'>160</td><td align='left'>169</td><td align='left'>179</td><td align='left'>188</td><td align='left'>198</td><td align='left'>207</td></tr>
+</table>
+</div>
+
+
+<p><span class='pagenum'><a name="Page_67" id="Page_67">[Pg 67]</a></span></p>
+
+
+
+<div class='center'>
+<table border="0" cellpadding="4" cellspacing="0" summary="">
+<tr><td align='left'>Pipe<br />Diameter</td><td align='left' colspan="12"> <span class="smcap">Velocity in Feet per Second</span></td></tr>
+<tr><td align='left'></td><td align='left'> 4.6</td><td align='left'> 4.8</td><td align='left'> 5.0</td><td align='left'> 5.2</td><td align='left'> 5.4</td><td align='left'> 5.6</td><td align='left'> 5.8</td><td align='left'> 6.0</td><td align='left'> 7.0</td><td align='left'> 8.0</td><td align='left'> 9.0</td><td align='left'> 10.0</td></tr>
+<tr><td align='left'></td><td align='left'><b>78.1</b></td><td align='left'><b>82.0</b></td><td align='left'><b>89.5</b></td><td align='left'><b>98.9</b></td><td align='left'><b>105.0</b></td><td align='left'><b>113.2</b></td><td align='left'><b>120.8</b></td><td align='left'><b>130.0</b></td><td align='left'><b>162.8</b></td><td align='left'><b>216.0</b></td><td align='left'><b>270.</b></td><td align='left'><b>323.</b></td></tr>
+<tr><td align='left'> 3"</td><td align='left'> 13.6</td><td align='left'> 14.2</td><td align='left'> 14.8</td><td align='left'> 15.3</td><td align='left'> 15.9</td><td align='left'> 16.5</td><td align='left'> 17.1</td><td align='left'> 17.7</td><td align='left'> 20.6</td><td align='left'> 23.5</td><td align='left'> 26.5</td><td align='left'> 29.5</td></tr>
+<tr><td align='left'></td><td align='left'><b>52.3</b></td><td align='left'><b>57.0</b></td><td align='left'><b>61.5</b></td><td align='left'><b>68.0</b></td><td align='left'> <b>72.5</b></td><td align='left'> <b>78.2</b></td><td align='left'> <b>83.1</b></td><td align='left'> <b>89.5</b></td><td align='left'><b>121.</b></td><td align='left'><b>155.</b></td><td align='left'><b>198.</b></td><td align='left'><b>242.</b></td></tr>
+<tr><td align='left'> 4"</td><td align='left'> 24.1</td><td align='left'> 25.1</td><td align='left'> 26.2</td><td align='left'> 27.2</td><td align='left'> 28.3</td><td align='left'> 29.3</td><td align='left'> 30.4</td><td align='left'> 31.5</td><td align='left'> 36.6</td><td align='left'> 41.9</td><td align='left'> 47.2</td><td align='left'> 52.4</td></tr>
+<tr><td align='left'></td><td align='left'><b>39.2</b></td><td align='left'><b>42.3</b></td><td align='left'><b>46.0</b></td><td align='left'><b>49.8</b></td><td align='left'> <b>53.5</b></td><td align='left'> <b>58.0</b></td><td align='left'> <b>62.0</b></td><td align='left'> <b>67.0</b></td><td align='left'> <b>89.</b></td><td align='left'><b>118.</b></td><td align='left'><b>148.</b></td><td align='left'><b>182.</b></td></tr>
+<tr><td align='left'> 5"</td><td align='left'> 37.6</td><td align='left'> 39.2</td><td align='left'> 40.9</td><td align='left'> 42.5</td><td align='left'> 44.1</td><td align='left'> 45.8</td><td align='left'> 47.5</td><td align='left'> 49.1</td><td align='left'> 57.1</td><td align='left'> 65.4</td><td align='left'> 73.7</td><td align='left'> 82.0</td></tr>
+<tr><td align='left'></td><td align='left'><b>30.6</b></td><td align='left'><b>33.1</b></td><td align='left'><b>35.6</b></td><td align='left'><b>39.0</b></td><td align='left'> <b>41.6</b></td><td align='left'> <b>44.6</b></td><td align='left'> <b>48.0</b></td><td align='left'> <b>51.6</b></td><td align='left'> <b>69.0</b></td><td align='left'> <b>89.0</b></td><td align='left'><b>114.</b></td><td align='left'><b>140.</b></td></tr>
+<tr><td align='left'> 6"</td><td align='left'> 54.1</td><td align='left'> 56.5</td><td align='left'> 58.9</td><td align='left'> 61.2</td><td align='left'> 63.6</td><td align='left'> 65.9</td><td align='left'> 68.3</td><td align='left'> 70.7</td><td align='left'> 82.4</td><td align='left'> 94.3</td><td align='left'> 106</td><td align='left'> 118</td></tr>
+<tr><td align='left'></td><td align='left'><b>25.1</b></td><td align='left'><b>27.3</b></td><td align='left'><b>29.5</b></td><td align='left'><b>32.0</b></td><td align='left'> <b>34.5</b></td><td align='left'> <b>37.1</b></td><td align='left'> <b>40.0</b></td><td align='left'> <b>43.0</b></td><td align='left'> <b>58.0</b></td><td align='left'> <b>75.0</b></td><td align='left'> <b>95.0</b></td><td align='left'><b>116.</b></td></tr>
+<tr><td align='left'> 7"</td><td align='left'> 73.7</td><td align='left'> 76.9</td><td align='left'> 80.2</td><td align='left'> 83.3</td><td align='left'> 86.6</td><td align='left'> 89.8</td><td align='left'> 93.0</td><td align='left'> 96.2</td><td align='left'> 112</td><td align='left'> 128</td><td align='left'> 145</td><td align='left'> 161</td></tr>
+<tr><td align='left'></td><td align='left'><b>20.0</b></td><td align='left'><b>22.5</b></td><td align='left'><b>24.9</b></td><td align='left'><b>27.0</b></td><td align='left'> <b>28.8</b></td><td align='left'> <b>30.6</b></td><td align='left'> <b>32.8</b></td><td align='left'> <b>35.5</b></td><td align='left'> <b>47.5</b></td><td align='left'> <b>61.2</b></td><td align='left'> <b>78.6</b></td><td align='left'> <b>95.1</b></td></tr>
+<tr><td align='left'> 8"</td><td align='left'> 96.3</td><td align='left'>101</td><td align='left'>105</td><td align='left'>109</td><td align='left'> 113</td><td align='left'> 117</td><td align='left'> 121</td><td align='left'> 125</td><td align='left'> 146</td><td align='left'> 168</td><td align='left'> 189</td><td align='left'> 210</td></tr>
+<tr><td align='left'></td><td align='left'><b>17.1</b></td><td align='left'><b>19.2</b></td><td align='left'><b>21.0</b></td><td align='left'><b>22.9</b></td><td align='left'> <b>24.6</b></td><td align='left'> <b>26.2</b></td><td align='left'> <b>28.0</b></td><td align='left'> <b>30.1</b></td><td align='left'> <b>40.1</b></td><td align='left'> <b>52.1</b></td><td align='left'> <b>66.6</b></td><td align='left'> <b>82.0</b></td></tr>
+<tr><td align='left'> 9"</td><td align='left'>122</td><td align='left'>127</td><td align='left'>132</td><td align='left'>138</td><td align='left'> 143</td><td align='left'> 148</td><td align='left'> 154</td><td align='left'> 159</td><td align='left'> 185</td><td align='left'> 212</td><td align='left'> 238</td><td align='left'> 265</td></tr>
+<tr><td align='left'></td><td align='left'><b>14.8</b></td><td align='left'><b>16.7</b></td><td align='left'><b>17.9</b></td><td align='left'><b>19.9</b></td><td align='left'> <b>21.0</b></td><td align='left'> <b>22.7</b></td><td align='left'> <b>24.3</b></td><td align='left'> <b>25.9</b></td><td align='left'> <b>34.8</b></td><td align='left'> <b>45.9</b></td><td align='left'> <b>58.0</b></td><td align='left'> <b>70.1</b></td></tr>
+<tr><td align='left'> 10"</td><td align='left'>150</td><td align='left'>157</td><td align='left'>163</td><td align='left'>170</td><td align='left'> 177</td><td align='left'> 183</td><td align='left'> 190</td><td align='left'> 196</td><td align='left'> 229</td><td align='left'> 261</td><td align='left'> 295</td><td align='left'> 327</td></tr>
+<tr><td align='left'></td><td align='left'><b>13.0</b></td><td align='left'><b>14.7</b></td><td align='left'><b>15.9</b></td><td align='left'><b>17.1</b></td><td align='left'> <b>18.2</b></td><td align='left'> <b>20.1</b></td><td align='left'> <b>21.3</b></td><td align='left'> <b>22.6</b></td><td align='left'> <b>30.7</b></td><td align='left'> <b>40.0</b></td><td align='left'> <b>50.8</b></td><td align='left'> <b>62.0</b></td></tr>
+<tr><td align='left'> 11"</td><td align='left'>182</td><td align='left'>190</td><td align='left'>198</td><td align='left'>206</td><td align='left'> 214</td><td align='left'> 222</td><td align='left'> 229</td><td align='left'> 237</td><td align='left'> 277</td><td align='left'> 316</td><td align='left'> 356</td><td align='left'> 396</td></tr>
+<tr><td align='left'></td><td align='left'><b>11.6</b></td><td align='left'><b>13.0</b></td><td align='left'><b>14.0</b></td><td align='left'><b>15.1</b></td><td align='left'> <b>16.1</b></td><td align='left'> <b>17.8</b></td><td align='left'> <b>19.1</b></td><td align='left'> <b>20.2</b></td><td align='left'> <b>27.1</b></td><td align='left'> <b>35.9</b></td><td align='left'> <b>45.4</b></td><td align='left'> <b>55.9</b></td></tr>
+<tr><td align='left'> 12"</td><td align='left'>217</td><td align='left'>226</td><td align='left'>235</td><td align='left'>245</td><td align='left'> 254</td><td align='left'> 264</td><td align='left'> 273</td><td align='left'> 283</td><td align='left'> 330</td><td align='left'> 377</td><td align='left'> 425</td><td align='left'> 472</td></tr>
+</table></div>
+
+<p class="subhead3">EXAMPLE</p>
+
+<div class="blockquot">
+<p>Assume the surveyed head as 240 feet, the water quantity as 207 cubic
+feet per minute and a pipe line 12 inches in diameter 900 feet long.
+To ascertain the friction loss, refer to column of pipe diameter and
+follow across the column for 12 inches diameter to the quantity, 207
+cubic feet per minute. The heavy-faced figures above 207 indicate that
+the loss per 1000 feet of pipe length is 11 feet. Therefore, since the
+pipe in the example is 900 feet long, the loss will be
+11.' &times; 900/1000 or 9.9 feet, and the effective head will be 240' - 9.9'
+= 230.1'</p>
+</div>
+
+<p><span class='pagenum'><a name="Page_68" id="Page_68">[Pg 68]</a></span></p>
+
+<p class="padtop">Steel tubing for supply pipes, from 3 to 12 inches in diameter is
+listed at from 20 cents to $1.50 a foot, according to the diameter and
+thickness of the material. Discounts on these prices will vary from 25
+to 50 per cent. The farmer can cut down the cost of this pipe by
+conveying his supply water from its natural source to a pond, by means
+of an open race, or a wooden flume. An ingenious mechanic can even
+construct his own pipe out of wood, though figuring labor and
+materials, it is doubtful if anything would be saved over a riveted
+steel pipe, purchased at the regular price. This pipe, leading from
+the pond, or forebay, to the water wheel, should be kept as short as
+possible; at the same time, the fall should not be too sharp. An angle
+of 30&deg; will be found very satisfactory, <span class='pagenum'><a name="Page_69" id="Page_69">[Pg 69]</a></span>although pipe is frequently
+laid at angles up to 50&deg;.</p>
+
+
+<p class="center padtop"><i>Other Types of Impulse Wheels</i></p>
+
+<p>In recent years more efficient forms of the old-fashioned overshoot,
+pitch-back breast, and undershoot wheels have been developed, by
+substituting steel or other metal for wood, and altering the shape of
+the buckets to make better use of the power of falling water.</p>
+
+<p>In some forms of overshoot wheels, an efficiency of over 90 per cent
+is claimed by manufacturers; and this type offers the additional
+advantage of utilizing small quantities of water, as well as being
+efficient under varying quantities of water. They utilize the falling
+weight of water, although by giving the water momentum at the point of
+delivery, by means of the proper fall, impulse too is utilized in some
+measure. The modern steel overshoot wheel receives water in its
+buckets from a spout set a few degrees back of dead center; and its
+buckets are so shaped that the water is retained a full
+half-revolution <span class='pagenum'><a name="Page_70" id="Page_70">[Pg 70]</a></span>of the wheel. The old-style overshoot wheel was
+inefficient principally because the buckets began emptying themselves
+at the end of a quarter-revolution. Another advantage claimed for
+these wheels over the old style is that, being made of thin metal,
+their buckets attain the temperature of the water itself, thus
+reducing the danger of freezing to a minimum. They are manufactured in
+sizes from 6 feet in diameter to upwards of fifty feet; and with
+buckets of from 6 inches to 10 feet in width. In practice it is usual
+to deliver water to the buckets by means of a trough or pipe, through
+a suitable spout and gate, at a point two feet above the crown of the
+wheel. For this reason, the diameter of the wheel corresponds very
+closely to the head in feet.</p>
+
+
+<p class="center padtop"><i>The Reaction Turbine</i></p>
+
+<p>The reaction turbine is best adapted to low heads, with a large supply
+of water. It is not advisable, under ordinary circumstances, to use it
+under heads exceeding 100 feet, as<span class='pagenum'><a name="Page_71" id="Page_71">[Pg 71]</a></span> its speed is then excessive. It
+may be used under falls as low as two feet. Five thousand cubic feet
+of water a minute would give approximately 14 actual horsepower under
+such a head. A sluggish creek that flows in large volume could thus be
+utilized for power with the reaction turbine, whereas it would be
+useless with an impulse wheel. Falls of from five to fifteen feet are
+to be found on thousands of farm streams, and the reaction turbine is
+admirably adapted to them.</p>
+
+<p>Reaction turbines consist of an iron "runner" which is in effect a
+rotary fan, the pressure and momentum of the column of water pressing
+on the slanted blades giving it motion and power. These wheels are
+manufactured in a great variety of forms and sizes; and are to be
+purchased either as the runner (set in bearings) alone, or as a runner
+enclosed in an iron case. In case the runner alone is purchased, the
+owner must enclose it, either with iron or wood. They vary in price
+according to size, and the means by which the flow of water is
+controlled. A simple 12-inch reaction<span class='pagenum'><a name="Page_72" id="Page_72">[Pg 72]</a></span> turbine wheel, such as would be
+suitable for many power plants can be had for $75. A twelve-inch
+wheel, using 18 or 20 square inches of water, would generate about
+7&frac12; horsepower under a 20-foot head, with 268 cubic feet of water a
+minute. Under a 30-foot head, and with 330 cubic feet of water such a
+wheel will give 14 horsepower. A 36-inch wheel, under a 5-foot head,
+would use 2,000 cubic feet of water, and give 14 horsepower. Under a
+30-foot head, this same wheel, using 4,900 cubic feet of water a
+minute, would develop over 200 horsepower. If the farmer is confronted
+by the situation of a great deal of water and small head, a large
+wheel would be necessary. Thus he could secure 35 horsepower with only
+a 3-foot head, providing his water supply is equal to the draft of
+8,300 cubic feet a minute.</p>
+
+<p><span class='pagenum'><a name="Page_73" id="Page_73">[Pg 73]</a></span></p>
+
+
+<div class="figcenter" style="width: 400px;">
+<img src="images/i73.jpg" width="400" height="590" alt="" title="" />
+A typical vertical turbine
+</div>
+
+<p>From these sample figures, it will be seen
+that the reaction turbine will meet the requirements of widely varying
+conditions up to, say a head of 100 feet. The farmer prospector should
+measure first the quantity of water to be depended on, and then the
+number of feet fall to be had. <span class='pagenum'><a name="Page_74" id="Page_74">[Pg 74]</a></span>The higher the fall, with certain
+limits, the smaller the expense of installation, and the less water
+required. When he has determined <i>quantity</i> and <i>head</i>, the catalogue
+of a reputable manufacturer will supply him with what information is
+necessary to decide on the style and size wheel he should install. In
+the older settled communities, especially in New England, a farmer
+should be able to pick up a second-hand turbine, at half the price
+asked for a new one; and since these wheels do not depreciate rapidly,
+it would serve his purpose as well, in most cases, as a new one.</p>
+
+
+<p>Reaction turbines may be either horizontal or vertical. If they are
+vertical, it is necessary to connect them to the main shaft by means
+of a set of bevel gears. These gears should be substantially large,
+and if the teeth are of hard wood (set in such a manner that they can
+be replaced when worn) they will be found more satisfactory than if of
+cast or cut metal.</p>
+
+<p><span class='pagenum'><a name="Page_75" id="Page_75">[Pg 75]</a></span></p>
+
+<div class="figcenter" style="width: 682px;">
+<img src="images/i75.jpg" width="682" height="200" alt="" title="" />
+Two wheels on a horizontal shaft<br />
+(<i>Courtesy of the C. P. Bradway Company, West Stafford, Conn.</i>)
+</div>
+
+
+<p>The horizontal turbine is keyed to its shaft, like the impulse wheel,
+so that the wheel shaft itself is used for driving, without gears or a
+quarter-turn belt. (The latter is to be avoided, wherever possible.)
+There are many forms of horizontal turbines; they are to be had of the
+duplex type, that is, two wheels on one shaft. These are arranged so
+that either wheel may be run separately, or both together, thus
+permitting one to take advantage of the seasonal fluctuation in water
+supply. A convenient form of these wheels includes draft tubes, by
+which the wheel may be set several feet above the tailrace, and the
+advantage of this additional fall still be preserved. In this case the
+draft tube must be airtight so as to form suction, when<span class='pagenum'><a name="Page_76" id="Page_76">[Pg 76]</a></span> filled with
+escaping water, and should be proportioned to the size of the wheel.
+Theoretically these draft tubes might be 34 feet long, but in practice
+it has been found that they should not exceed 10 or 12 feet under
+ordinary circumstances. They permit the wheel to be installed on the
+main floor of the power station, with the escape below, instead of
+being set just above the tailrace level itself, as is the case when
+draft tubes are not used.</p>
+
+<p>Reaction turbines when working under a variable load require water
+governors (like impulse wheels) although where the supply of water is
+large, and the proportion of power between water wheel and dynamo is
+liberal&mdash;say two to one, or more&mdash;this necessity is greatly reduced.
+Reaction wheels as a rule govern themselves better than impulse
+wheels, due both to the fact that they use more water, and that they
+operate in a small airtight case. The centrifugal ball governor is the
+type usually used with reaction wheels as well as with impulse wheels.
+This subject will be discussed more fully later.</p>
+
+
+<p><span class='pagenum'><a name="Page_77" id="Page_77">[Pg 77]</a></span></p><p class="center padtop"><i>Installing a Power Plant</i></p>
+
+<p>In developing a power prospect, the dam itself is usually not the site
+of the power plant. In fact, because of danger from flood water and
+ice, it is better to locate it in a more protected spot, leading the
+water to the wheel by means of a race and flume.</p>
+
+<div class="figcenter" style="width: 500px;">
+<a href="images/d78-big.jpg"><img src="images/d78-small.jpg" width="500" height="409" alt="" title="" /></a>
+Bird's-eye view of a developed water-power plant
+</div>
+
+
+<p>A typical crib dam, filled with stone, is shown in section in the
+diagram, and the half-tone illustration shows such a dam in course of
+construction. The first bed of timbers should be laid on hard-pan or<span class='pagenum'><a name="Page_78" id="Page_78">[Pg 78]</a></span>
+solid rock in the bed of the stream parallel to its flow. The second
+course, across the stream, is then begun, being spiked home by means
+of rods cut to length and sharpened by the local blacksmith, from
+&frac34;-inch Norway iron. Hemlock logs are suitable for building the crib;
+and as the timbers are finally laid, it should be filled in and made
+solid with boulders. This filling in should proceed section by
+section, as the planking goes forward, otherwise there will be no
+escape for the water of the stream, until it rises and spills over
+the top timbers. The planking should be of two-inch<span class='pagenum'><a name="Page_79" id="Page_79">[Pg 79]</a></span> chestnut, spiked
+home with 60 penny wire spikes. When the last section of the crib is
+filled with boulders and the water rises, the remaining planks may be
+spiked home with the aid of an iron pipe in which to drive the spike
+by means of a plunger of iron long enough to reach above the level of
+the water. When the planking is completed, the dam should be well
+gravelled, to within a foot or two of its crest. Such dams are
+substantial, easily made with the aid of unskilled labor, and the
+materials are to be had on the average farm with the exception of the
+hardware.</p>
+
+<div class="figcenter" style="width: 500px;">
+<a href="images/d79-big.jpg"><img src="images/d79-small.jpg" width="500" height="202" alt="" title="" /></a>
+Cross-section of a rock and timber dam
+</div>
+
+
+<p>This dam forms a pond from which the race<span class='pagenum'><a name="Page_80" id="Page_80">[Pg 80]</a></span> draws its supply of water
+for the wheel. It also serves as a spillway over which the surplus
+water escapes. The race should enter the pond at some convenient
+point, and should be protected at or near its point of entrance by a
+bulkhead containing a gate, so that the supply of water may be cut off
+from the race and wheel readily. The lay of the land will determine
+the length and course of the race. The object of the race is to secure
+the required head by carrying a portion of the available water to a
+point where it can escape, by a fall of say 30&deg; to the tailrace. It
+may be feasible to carry the race in a line almost at right angles to
+the stream itself, or, again, it may be necessary to parallel the
+stream. If the lay of the land is favorable, the race may be dug to a
+distance of a rod or so inshore, and then be permitted to cut its own
+course along the bank, preventing the water escaping back to the river
+or brook before the site of the power plant is reached, by building
+suitable retaining embankments. The race should be of ample size for
+conveying the water required<span class='pagenum'><a name="Page_81" id="Page_81">[Pg 81]</a></span> without too much friction. It should end
+in a flume constructed stoutly of timbers. It is from this flume that
+the penstock draws water for the wheel. When the wheel gate is closed
+the water in the mill pond behind the dam, and in the flume itself
+should maintain an approximate level. Any surplus flow is permitted to
+escape over flushboards in the flume; these same flushboards maintain
+a constant head when the wheel is in operation by carrying off what
+little surplus water the race delivers from the pond.</p>
+
+<div class="figleft" style="width: 400px;">
+<a href="images/d81-big.jpg"><img src="images/d81-small.jpg" width="400" height="493" alt="" title="" /></a>
+Detail of bulkhead gate
+</div>
+
+<p>At some point in the race or flume, the flow should be protected from
+leaves and other trash by means of a rack. This rack is best made of
+&frac14; or<span class='pagenum'><a name="Page_82" id="Page_82">[Pg 82]</a></span> &frac12;-inch battens from 1&frac12; to 3 inches in width, bolted
+together on their flat faces and separated a distance equal to the
+thickness of the battens by means of iron washers. This rack will
+accumulate leaves and trash, varying with the time of year and should
+be kept clean, so as not to cut down the supply of water needed by the
+wheel.</p>
+
+<p>The penstock, or pipe conveying water from the flume to the wheel,
+should be constructed of liberal size, and substantially, of two-inch
+chestnut planking, with joints caulked with oakum, and the whole well
+bound together to resist the pressure of the water. Means should be
+provided near the bottom for an opening through which to remove any
+obstructions that may by accident pass by the rack. Many wheels have
+plates provided in their cases for this purpose.</p>
+
+<p>The tailrace should be provided with enough fall to carry the escaping
+water back to the main stream, without backing up on the wheel itself
+and thus cutting down the head.</p>
+
+<p>It is impossible to make any estimates of the<span class='pagenum'><a name="Page_83" id="Page_83">[Pg 83]</a></span> cost of such a
+water-power plant. The labor required will in most instances be
+supplied by the farmer himself, his sons, and his help, during times
+when farm operations are slack.</p>
+
+
+<p class="center padtop"><i>Water Rights of the Farmer</i></p>
+
+<p>The farmer owns the bed of every stream not navigable, lying within
+the boundary lines of the farm; and his right to divert and make use
+of the water of such streams is determined in most states by common
+law. In the dry-land states where water is scarce and is valuable for
+irrigation, a special set of statutes has sprung up with the
+development of irrigation in this country.</p>
+
+<p>A stream on the farm is either public or private; its being navigable
+or "floatable" (suitable for floating logs) determining which. Water
+rights are termed in law "riparian" rights, and land is riparian only
+when water flows over it or along its borders.</p>
+
+<p>Green (Law for the American Farmer) says:</p>
+
+<p>"Water is the common and equal property of every one through whose
+land it flows,<span class='pagenum'><a name="Page_84" id="Page_84">[Pg 84]</a></span> and the right of each land-owner to use and consume it
+without destroying, or unreasonably impairing the rights of others, is
+the same. An owner of land bordering on a running stream has the right
+to have its waters flow naturally, and none can lawfully divert them
+without his consent. Each riparian proprietor has an equal right with
+all the others to have the stream flow in its natural way without
+substantial reduction in volume, or deterioration in quality, subject
+to a proper and reasonable use of its waters for domestic,
+agricultural and manufacturing purposes, and he is entitled to use it
+himself for such purposes, but in doing so must not substantially
+injure others. In addition to the right of drawing water for the
+purposes just mentioned, a riparian proprietor, if he duly regards the
+rights of others, and does not unreasonably deplete the supply, has
+also the right to take the water for some other proper uses."</p>
+
+<p>Thus, the farmer who seeks to develop water-power from a stream
+flowing across his own<span class='pagenum'><a name="Page_85" id="Page_85">[Pg 85]</a></span> land, has the right to divert such a stream
+from its natural channel&mdash;providing it is not a navigable or floatable
+stream&mdash;but in so doing, he must return it to its own channel for
+lower riparian owners. The generation of water-power does not pollute
+the water, nor does it diminish the water in quantity, therefore the
+farmer is infringing on no other owner's rights in using the water for
+such a purpose.</p>
+
+<p>When a stream is a dividing line between two farms, as is frequently
+the case, each proprietor owns to the middle of the stream and
+controls its banks. Therefore to erect a dam across such a private
+stream and divert all or a part of the water for power purposes,
+requires the consent of the neighboring owner. The owner of the dam is
+responsible for damage due to flooding, to upstream riparian owners.</p>
+
+
+<p><span class='pagenum'><a name="Page_86" id="Page_86">[Pg 86]</a></span></p>
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_87" id="Page_87">[Pg 87]</a></span></p>
+<h2><a name="PART_II" id="PART_II"></a>PART II</h2>
+
+<p class="subhead1">ELECTRICITY</p>
+
+
+<p><span class='pagenum'><a name="Page_88" id="Page_88">[Pg 88]</a></span></p>
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_89" id="Page_89">[Pg 89]</a></span></p>
+<h2><a name="CHAPTER_V" id="CHAPTER_V"></a>CHAPTER V</h2>
+
+<p class="subhead2">THE DYNAMO; WHAT IT DOES, AND HOW</p>
+
+<div class="blockquot"><p>Electricity compared to the heat and light of the Sun&mdash;The simple
+dynamo&mdash;The amount of electric energy a dynamo will generate&mdash;The
+modern dynamo&mdash;Measuring power in terms of electricity&mdash;The
+volt&mdash;The ampere&mdash;The ohm&mdash;The watt and the kilowatt&mdash;Ohm's Law of
+the electric circuit, and some examples of its application&mdash;Direct
+current, and alternating current&mdash;Three types of direct-current
+dynamos: series, shunt, and compound.</p></div>
+
+
+<p>What a farmer really does in generating electricity from water that
+would otherwise run to waste in his brook, is to install a private Sun
+of his own&mdash;which is on duty not merely in daylight, but twenty-four
+hours a day; a private Sun which is under such simple control that it
+shines or provides heat and power, when and where wanted, simply by
+touching a button.</p>
+
+<p>This is not a mere fanciful statement. When you come to look into it
+you find that<span class='pagenum'><a name="Page_90" id="Page_90">[Pg 90]</a></span> electricity actually is the life-giving power of the
+Sun's rays, so transformed that it can be handily conveyed from place
+to place by means of wires, and controlled by mechanical devices as
+simple as the spigot that drains a cask.</p>
+
+<p>Nature has the habit of traveling in circles. Sometimes these circles
+are so big that the part of them we see looks like a straight line,
+but it is not. Even parallel lines, according to the mathematicians,
+"meet in infinity." Take the instance of the water wheel which the
+farmer has installed under the fall of his brook. The power which
+turns the wheel has the strength of many horses. It is there in a
+handy place for use, because the Sun brought it there. The Sun, by its
+heat, lifted the water from sea-level, to the pond where we find
+it&mdash;and we cannot get any more power out of this water by means of a
+turbine using its pressure and momentum in falling, than the Sun
+itself expended in raising the water against the force of gravity.</p>
+
+<p>Once we have installed the wheel to change the energy of falling water
+into mechanical<span class='pagenum'><a name="Page_91" id="Page_91">[Pg 91]</a></span> power, the task of the dynamo is to turn this
+mechanical power into another mode of motion&mdash;electricity. And the
+task of electricity is to change this mode of motion back into the
+original heat and light of the Sun&mdash;which started the circle in the
+beginning.</p>
+
+<p>Astronomers refer to the Sun as "he" and "him" and they spell his name
+with a capital letter, to show that he occupies the center of our
+small neighborhood of the universe at all times.</p>
+
+
+<p class="center padtop"><i>Magnets and Magnetism</i></p>
+
+<p>The dynamo is a mechanical engine, like the steam engine, the water
+turbine or the gas engine; and it converts the mechanical motion of
+the driven wheel into electrical motion, with the aid of a magnet.
+Many scientists say that the full circle of energy that keeps the
+world spinning, grows crops, and paints the sky with the Aurora
+Borealis, begins and ends with magnetism&mdash;that the sun's rays are
+magnetic rays. Magnetism is the force that keeps the compass needle
+pointing north<span class='pagenum'><a name="Page_92" id="Page_92">[Pg 92]</a></span> and south. Take a steel rod and hold it along the
+north and south line, slightly inclined towards the earth, and strike
+it a sharp blow with a hammer, and it becomes a magnet&mdash;feeble, it is
+true, but still a magnet.</p>
+
+<p>Take a wire connected with a common dry battery and hold a compass
+needle under it and the needle will immediately turn around and point
+directly across the wire, showing that the wire possesses magnetism
+encircling it in invisible lines, stronger than the magnetism of the
+earth.</p>
+
+<div class="figcenter" style="width: 765px;"><a name="i92" id="i92"></a>
+<img src="images/i92.jpg" width="765" height="400" alt="" title="" />
+A direct-current dynamo or motor, showing details of construction<br />
+
+(<i>Courtesy of the Crocker-Wheeler Company</i>)
+</div>
+
+<p>Insulate this wire by covering it with cotton thread, and wind it
+closely on a spool. Connect the two loose ends to a dry battery, and
+you will find that you have multiplied the magnetic strength of a
+single loop of wire by the number of turns on the spool&mdash;concentrated
+all the magnetism of the length of that wire into a small space. Put
+an iron core in the middle of this spool and the magnet seems still
+more powerful. Lines of force which otherwise would escape in great
+circles into space, are now concentrated in the iron. The iron core
+is a magnet. Shut off the current from the battery and the iron is
+still a magnet&mdash;weak, true, but it will always retain a<span class='pagenum'><a name="Page_93" id="Page_93">[Pg 93]</a></span> small portion
+of its magnetism. Soft iron retains very little of its magnetism. Hard
+steel retains a great deal, and for this reason steel is used for
+permanent magnets, of the horseshoe type so familiar.</p>
+
+
+<p class="center padtop"><i>A Simple Dynamo</i></p>
+
+<p>A dynamo consists, first, of a number of such magnets, wound with
+insulated wire. Their iron cores point towards the center of a circle
+like the spokes of a wheel; and their curved inner faces form a circle
+in which a spool, wound with wire in another way, may be spun by the
+water wheel.</p>
+
+<p>Now take a piece of copper wire and make a loop of it. Pass one side
+of this loop in front of an electric magnet.</p>
+
+<p>As the wire you hold in your hands passes the iron face of the magnet,
+a wave of energy that is called electricity flows around this loop at
+the rate of 186,000 miles a second&mdash;the<span class='pagenum'><a name="Page_94" id="Page_94">[Pg 94]</a></span> same speed as light comes to
+us from the sun. As you move the wire away from the magnet, a second
+wave starts through the wire, flowing in the opposite direction. You
+can prove this by holding a compass needle under the wire and see it
+wag first in one direction, then in another.</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d94.jpg" width="500" height="168" alt="" title="" />
+A wire "cutting" the lines of force of an
+electro-magnet
+</div>
+
+
+<p>This is a simple dynamo. A wire "cutting" the invisible lines of
+force, that a magnet is spraying out into the air, becomes
+"electrified." Why this is true, no one has ever been able to explain.</p>
+
+<p>The amount of electricity&mdash;its capacity for work&mdash;which you have
+generated with the magnet and wire, does not depend alone on the
+pulling power of that simple magnet. Let us say the magnet is very
+weak&mdash;has not enough power to lift one ounce of iron. Nevertheless,
+<span class='pagenum'><a name="Page_95" id="Page_95">[Pg 95]</a></span>if you possessed the strength of Hercules, and could pass that wire
+through the field of force of the magnet many thousands of times a
+second, you would generate enough electricity in the wire to cause the
+wire to melt in your hands from heat.</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d95.jpg" width="500" height="346" alt="" title="" />
+Cross-section of an armature revolving in its field
+</div>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d96.jpg" width="500" height="152" alt="" title="" />
+Forms of annealed steel discs used in armature
+construction
+</div>
+
+<p>This experiment gives the theory of the dynamo. Instead of passing
+only one wire through the field of force of a magnet, we have hundreds
+bound lengthwise on a revolving drum called an armature. Instead of
+one magnetic pole in a dynamo we have two, or<span class='pagenum'><a name="Page_96" id="Page_96">[Pg 96]</a></span> four, or twenty
+according to the work the machine is designed for&mdash;always in pairs, a
+North pole next to a South pole, so that the lines of force may flow
+out of one and into another, instead of escaping in the surrounding
+air. If you could see these lines of force, they would appear in
+countless numbers issuing from each pole face of the field magnets,
+pressing against the revolving drum like hair brush bristles&mdash;trying
+to hold it back. This drum, in practice, is built up of discs of
+annealed steel, and the wires extending lengthwise on its face are
+held in place by slots to prevent them from flying off when the drum
+is whirled at high speed. The drum does not touch the face of the
+magnets, but revolves in an air space. If we give the electric
+impulses generated in these wires a chance to flow in a<span class='pagenum'><a name="Page_97" id="Page_97">[Pg 97]</a></span> circuit&mdash;flow
+out of one end of the wires, and in at the other, the drum will
+require more and more power to turn it, in proportion to the amount of
+electricity we permit to flow. Thus, if one electric light is turned
+on, the drum will press back with a certain strength on the water
+wheel; if one hundred lights are turned on it will press back one
+hundred times as much. Providing there is enough power in the water
+wheel to continue turning the drum at its predetermined speed, the
+dynamo will keep on giving more and more electricity if asked to,
+until it finally destroys itself by fire. You cannot take more power,
+in terms of electricity, out of a dynamo that you put into it, in
+terms of mechanical motion. In fact,<span class='pagenum'><a name="Page_98" id="Page_98">[Pg 98]</a></span> to insure flexibility and
+constant speed at all loads, it is customary to provide twice as much
+water wheel, or engine, power as the electrical rating of the dynamo.</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d97.jpg" width="500" height="233" alt="" title="" />
+An armature partly wound, showing slots and commutator
+</div>
+
+
+<p>We have seen that a water wheel is 85 per cent efficient under ideal
+conditions. A dynamo's efficiency in translating mechanical motion
+into electricity, varies with the type of machine and its size. The
+largest machines attain as high as 90 per cent efficiency; the
+smallest ones run as low as 40 per cent.</p>
+
+
+<p class="center padtop"><i>Measuring Electric Power</i></p>
+
+<p>The amount of electricity any given dynamo can generate depends,
+generally speaking, on two factors, i. e., (1) the power of the water
+wheel, or other mechanical engine that turns the armature; and (2) the
+size (carrying capacity) of the wires on this drum.</p>
+
+<p>Strength, of electricity, is measured in <i>amperes</i>. An ampere of
+electricity is the unit of the rate of flow and may be likened to a
+gallon of water per minute.</p>
+
+<p>In surveying for water-power, in Chapter<span class='pagenum'><a name="Page_99" id="Page_99">[Pg 99]</a></span> III, we found that the
+number of gallons or cubic feet of water alone did not determine the
+amount of power. We found that the number of gallons or cubic feet
+multiplied by the distance in feet it falls in a given time, was the
+determining factor&mdash;pounds (quantity) multiplied by feet per
+second&mdash;(velocity).</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d99.jpg" width="500" height="217" alt="" title="" />
+Showing the analogy of water to volts and amperes of
+electricity
+</div>
+
+
+<p>The same is true in figuring the power of electricity. We multiply the
+<i>amperes</i> by the number of electric impulses that are created in the
+wire in the course of one second. The unit of velocity, or pressure of
+the electric current is called a <i>volt</i>. Voltage is the pressure which
+causes electricity to flow. A volt may be likened to the velocity in
+feet per second of water in falling past a certain point. If you<span class='pagenum'><a name="Page_100" id="Page_100">[Pg 100]</a></span>
+think a moment you will see that this has nothing to do with quantity.
+A pin-hole stream of water under 40 pounds pressure has the same
+velocity as water coming from a nozzle as big as a barrel, under the
+same pressure. So with electricity under the pressure of one volt or
+one hundred volts.</p>
+
+<p>One volt is said to consist of a succession of impulses caused by <i>one
+wire cutting 100,000,000 lines of magnetic force in one second</i>. Thus,
+if the strength of a magnet consisted of one line of force, to create
+the pressure of one volt we would have to "cut" that line of force
+100,000,000 times a second, with one wire; or 100,000 times a second
+with one thousand wires. Or, if a magnet could be made with
+100,000,000 lines of force, a single wire cutting those lines once in
+a second would create one volt pressure. In actual practice, field
+magnets of dynamos are worked at densities up to and over 100,000
+lines of force to the square inch, and armatures contain several
+hundred conductors to "cut" these magnetic lines. The voltage then
+depends on the speed at<span class='pagenum'><a name="Page_101" id="Page_101">[Pg 101]</a></span> which the armature is driven. In machines for
+isolated plants, it will be found that the speed varies from 400
+revolutions per minute, to 1,800, according to the design of dynamo
+used.</p>
+<div class="figcenter" style="width: 500px;">
+<img src="images/d101.jpg" width="500" height="168" alt="" title="" />
+Pressure determines volume of flow in a given time
+</div>
+
+
+<p>Multiplying amperes (strength) by volts (pressure), gives us <i>watts</i>
+(power). Seven hundred and forty-six watts of electrical energy is
+equal to one horsepower of mechanical energy&mdash;will do the same work.
+Thus an electric current under a pressure of 100 volts, and a density
+of 7.46 amperes, is one horsepower; as is 74.6 amperes, at 10 volts
+pressure; or 746 amperes at one volt pressure. For convenience (as a
+watt is a small quantity) electricity is measured in <i>kilowatts</i>, or
+1,000 watts. Since 746 watts is one horsepower, 1,000 watts or one
+kilowatt is 1.34 horsepower. The work of such a current for one hour
+is called a <i>kilowatt-hour</i>, and in our cities, where electricity is
+generated from steam, the retail<span class='pagenum'><a name="Page_102" id="Page_102">[Pg 102]</a></span> price of a kilowatt-hour varies from
+10 to 15 cents.</p>
+
+<p>Now as to how electricity may be controlled, so that a dynamo will not
+burn itself up when it begins to generate.</p>
+
+<p>Again we come back to the analogy of water. The amount of water that
+passes through a pipe in any given time, depends on the size of the
+pipe, if the pressure is maintained uniform. In other words the
+<i>resistance</i> of the pipe to the flow of water determines the amount.
+If the pipe be the size of a pin-hole, a very small amount of water
+will escape. If the pipe is as big around as a barrel, a large amount
+will force its way through. So with electricity. Resistance,
+introduced in the electric circuit, controls the amount of current
+that flows. A wire as fine as a hair will permit only a small quantity
+to pass, under a given pressure. A wire as big as one's thumb will
+permit a correspondingly greater quantity to pass, the pressure
+remaining the same. The unit of electrical resistance is called the
+<i>ohm</i>&mdash;named after a man, as are all electrical units.</p>
+
+
+<p><span class='pagenum'><a name="Page_103" id="Page_103">[Pg 103]</a></span></p><p class="center padtop"><i>Ohm's Law</i></p>
+
+<p>The <i>ohm</i> is that amount of <i>resistance</i> that will permit the passage
+of <i>one ampere</i>, under the pressure of <i>one volt</i>. It would take two
+volts to force two amperes through one ohm; or 100 volts to force 100
+amperes through the resistance of one ohm. From this we have Ohm's
+Law, a simple formula which is the beginning and end of all electric
+computations the farmer will have to make in installing his
+water-power electric plant. Ohm's Law tells us that the density of
+current (amperes) that can pass through a given resistance in ohms (a
+wire, a lamp, or an electric stove) equals <i>volts</i> divided by
+<i>ohms</i>&mdash;or <i>pressure</i> divided by <i>resistance</i>. This formula may be
+written in three ways, thus:</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/m103.jpg" width="500" height="45" alt="C = E/R, or R = E/C or, E = C × R." title="" />
+</div>
+
+<p>Or to express the same thing in
+words, <i>current</i> equals <i>volts</i> divided by <i>ohms</i>; <i>ohms</i> equals
+<i>volts</i> divided by <i>current</i>; or <i>volts</i> equals <i>current</i> multiplied
+by <i>ohms</i>. So, with any two of these three determining factors known,
+we can find the third.<span class='pagenum'><a name="Page_104" id="Page_104">[Pg 104]</a></span> As we have said, this simple law is the
+beginning and end of ordinary calculations as to electric current, and
+it should be thoroughly understood by any farmer who essays to be his
+own electrical engineer. Once understood and applied, the problem of
+the control of the electric current becomes simple a b c.</p>
+
+
+<p class="center padtop"><i>Examples of Ohm's Law</i></p>
+
+<p>Let us illustrate its application by an example. The water wheel is
+started and is spinning the dynamo at its rated speed, say 1,500
+r.p.m. Two heavy wires, leading from brushes which collect electricity
+from the revolving armature, are led, by suitable insulated supports
+to the switchboard, and fastened there. They do not touch each other.
+Dynamo mains must not be permitted to touch each other <i>under any
+conditions</i>. They are separated by say four inches of air. Dry air is
+a very poor conductor of electricity. Let us say, for the example,
+that dry air has a resistance to the flow of an electric current, of
+1,000,000 ohms to the inch&mdash;that would be<span class='pagenum'><a name="Page_105" id="Page_105">[Pg 105]</a></span> 4,000,000 ohms. How much
+electricity is being permitted to escape from the armature of this
+110-volt dynamo, when the mains are separated by four inches of dry
+air? Apply Ohm's law, C equals E divided by R. E, in this case is 110;
+R is 4,000,000; therefore C (amperes) equals 110/4,000,000&mdash;an
+infinitesimal amount&mdash;about .0000277 ampere.</p>
+
+<p>Let us say that instead of separating these two mains by air we
+separated them by the human body&mdash;that a man took hold of the bare
+wires, one in each hand. The resistance of the human body varies from
+5,000 to 10,000 ohms. In that case C (amperes) equals 110/5,000, or
+110/10,000&mdash;about 1/50th, or 1/100th of an ampere. This illustrates
+why an electric current of 110 volts pressure is not fatal to human
+beings, under ordinary circumstances. The body offers too much
+resistance. But, if the volts were 1,100 instead of the usual 110 used
+in commercial and private plants for domestic use, the value of C, by
+this formula at 5,000 ohms, would be nearly 1/5th ampere. To drive
+1/5th<span class='pagenum'><a name="Page_106" id="Page_106">[Pg 106]</a></span> ampere of electricity through the human body would be fatal in
+many instances. The higher the voltage, the more dangerous the
+current. In large water-power installations in the Far West, where the
+current must be transmitted over long distances to the spot where it
+is to be used, it is occasionally generated at a pressure of 150,000
+volts. Needless to say, contact with such wires means instant death.
+Before being used for commercial or domestic purposes, in such cases,
+the voltage is "stepped down" to safe pressures&mdash;to 110, or to 220, or
+to 550 volts&mdash;always depending on the use made of it.</p>
+
+<p>Now, if instead of interposing four inches of air, or the human body,
+between the mains of our 110-volt dynamo, we connected an incandescent
+lamp across the mains, how much electricity would flow from the
+generator? An incandescent lamp consists of a vacuum bulb of glass, in
+which is mounted a slender thread of carbonized fibre, or fine
+tungsten wire. To complete a circuit, the current must flow through
+this wire or filament. <span class='pagenum'><a name="Page_107" id="Page_107">[Pg 107]</a></span>In flowing through it, the electric current
+turns the wire or filament white hot&mdash;incandescent&mdash;and thus turns
+electricity back into light, with a small loss in heat. In an ordinary
+16 candlepower carbon lamp, the resistance of this filament is 220
+ohms. Therefore the amount of current that a 110-volt generator can
+force through that filament is 110/220, or &frac12; ampere.</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d107.jpg" width="500" height="294" alt="" title="" />
+Armature and field coils of a direct current dynamo
+</div>
+
+
+<p>One hundred lamps would provide 100 paths of 220 ohms resistance each
+to carry current, and the amount required to light 100 such lamps
+would be 100 &times; &frac12; or 50 amperes. Every electrical device&mdash;a lamp,<span class='pagenum'><a name="Page_108" id="Page_108">[Pg 108]</a></span> a
+stove, an iron, a motor, etc.,&mdash;must, by regulations of the Fire
+Underwriters' Board be plainly marked with the voltage of the current
+for which it is designed and the amount of current it will consume.
+This is usually done by indicating its capacity in watts, which as we
+have seen, means volts times amperes, and from this one can figure
+ohms, by the above formulas.</p>
+
+
+<p class="center padtop"><i>A Short Circuit</i></p>
+
+<p>We said a few paragraphs back that under no conditions must two bare
+wires leading from electric mains be permitted to touch each other,
+without some form of resistance being interposed in the form of lamps,
+or other devices. Let us see what would happen if two such bare wires
+did touch each other. Our dynamo as we discover by reading its plate,
+is rated to deliver 50 amperes, let us say, at 110 volts pressure.
+Modern dynamos are rated liberally, and can stand 100% overload for
+short periods of time, without dangerous overheating. Let us say that
+the<span class='pagenum'><a name="Page_109" id="Page_109">[Pg 109]</a></span> mains conveying current from the armature to the switchboard are
+five feet long, and of No. 2 B. &amp; S. gauge copper wire, a size which
+will carry 50 amperes without heating appreciably. The resistance of
+this 10 feet of No. 2 copper wire, is, as we find by consulting a wire
+table, .001560 ohms. If we touch the ends of these two five-foot wires
+together, we instantly open a clear path for the flow of electric
+current, limited only by the carrying capacity of the wire and the
+back pressure of .001560 ohms resistance. Using Ohm's Law, C equals E
+divided by R, we find that C (amperes) equals 110/.001560 or <i>70,515
+amperes</i>!</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d109.jpg" width="500" height="348" alt="" title="" />
+A direct current dynamo
+</div>
+
+<p>Unless this dynamo were properly protected, the effect of such a
+catastrophe would be immediate and probably irreparable. In effect, it
+would be suddenly exerting a force of nearly 10,000 horsepower against
+the little 10 horsepower water wheel that is driving this<span class='pagenum'><a name="Page_110" id="Page_110">[Pg 110]</a></span> dynamo. The
+mildest thing that could happen would be to melt the feed-wire or to
+snap the driving belt, in which latter case the dynamo would come to a
+stop. If by any chance the little water wheel was given a chance to
+maintain itself against the blow for an instant, the dynamo, rated at
+50 amperes, would do its best to deliver the 70,515 amperes you called
+for&mdash;and the result would be a puff of smoke, and a ruined dynamo.
+This is called a "short circuit"&mdash;one of the first "don'ts" in
+handling electricity.</p>
+
+<p>As a matter of fact every dynamo is protected against such a calamity
+by means of safety devices, which will be described in a later
+chapter&mdash;because no matter how careful a person may be, a partial
+short circuit is apt to occur. Happily, guarding against its
+disastrous effects is one of the simplest problems in connection with
+the electric plant.</p>
+
+
+<p class="center padtop"><i>Direct Current and Alternating Current</i></p>
+
+<p>When one has mastered the simple Ohm's Law of the electric circuit,
+the next step is to<span class='pagenum'><a name="Page_111" id="Page_111">[Pg 111]</a></span> determine what type of electrical generator is
+best suited to the requirements of a farm plant.</p>
+
+<p>In the first place, electric current is divided into two classes of
+interest here&mdash;<i>alternating</i>, and <i>direct</i>.</p>
+
+<p>We have seen that when a wire is moved through the field of a magnet,
+there is induced in it two pulsations&mdash;first in one direction, then in
+another. This is an <i>alternating</i> current, so called because it
+changes its direction. If, with our armature containing hundreds of
+wires to "cut" the lines of force of a group of magnets, we connected
+the beginning of each wire with one copper ring, and the end of each
+wire with another copper ring, we would have what is called an
+<i>alternating-current</i> dynamo. Simply by pressing a strap of flexible
+copper against each revolving copper ring, we would gather the sum of
+the current of these conductors. Its course would be represented by
+the curved line in the diagram, one loop on each side of the middle
+line (which represents time) would be a <i>cycle</i>. The number <span class='pagenum'><a name="Page_112" id="Page_112">[Pg 112]</a></span>of
+<i>cycles</i> to the second depends on the speed of the armature; in
+ordinary practice it is usually twenty-five or sixty. Alternating
+current has many advantages, which however, do not concern us here.
+Except under very rare conditions, a farmer installing his own plant
+should not use this type of machine.</p>
+
+<div class="figcenter" style="width: 500px;">
+<a href="images/d112-big.jpg"><img src="images/d112-small.jpg" width="500" height="158" alt="" title="" /></a>
+Diagram of alternating and direct current
+</div>
+
+
+<p>If, however, instead of gathering all the current with brushes bearing
+on two copper rings, we collected all the current traveling in one
+direction, on one set of brushes&mdash;and all the current traveling in the
+other direction on another set of brushes,&mdash;we would straighten out
+this current, make it all travel in one direction. Then we would have
+a <i>direct current</i>. A direct current dynamo, the type generally used
+in private plants, does<span class='pagenum'><a name="Page_113" id="Page_113">[Pg 113]</a></span> this. Instead of having two copper rings for
+collecting the current, it has a single ring, made up of segments of
+copper bound together, but insulated from each other, one segment for
+each set of conductors on the armature. This ring of many segments, is
+called a <i>commutator</i>, because it commutates, or changes, the
+direction of the electric impulses, and delivers them all in one
+direction. In effect, it is like the connecting rod of a steam engine
+that straightens out the back-and-forth motion of the piston in the
+steam cylinder and delivers the motion to a wheel running in one
+direction.</p>
+
+<p>Such a current, flowing through a coil of wire would make a magnet,
+one end of which would always be the north end, and the other end the
+south end. An alternating current, on the other hand, flowing through
+a coil of wire, would make a magnet that changed its poles with each
+half-cycle. It would no sooner begin to pull another magnet to it,
+than it would change about and push the other magnet away from it, and
+so on, as long as it continued to flow. This<span class='pagenum'><a name="Page_114" id="Page_114">[Pg 114]</a></span> is one reason why a
+direct current dynamo is used for small plants. Alternating current
+will light the same lamps and heat the same irons as a direct current;
+but for electric power it requires a different type of motor.</p>
+
+
+<p class="center padtop"><i>Types of Direct Current Dynamos</i></p>
+
+<p>Just as electrical generators are divided into two classes,
+alternating and direct, so direct current machines are divided into
+three classes, according to the manner in which their output, in
+amperes and volts, is regulated. They differ as to the manner in which
+their field magnets (in whose field of force the armature spins) are
+excited, or made magnetic. They are called <i>series</i>, <i>shunt</i>, and
+<i>compound</i> machines.</p>
+
+
+<p class="center padtop"><i>The Series Dynamo</i></p>
+
+<p>By referring to the diagram, it will be seen that the current of a
+<i>series</i> dynamo issues from the armature mains, and passes through the
+coils of the field magnets before passing into the external circuit to
+do its work. The<span class='pagenum'><a name="Page_115" id="Page_115">[Pg 115]</a></span> residual magnetism, or the magnetism left in the
+iron cores of the field magnets from its last charge, provides the
+initial excitation, when the machine is started. As the resistance of
+the external circuit is lowered, by turning on more and more lights,
+more and more current flows from the armature, through the field
+magnets. Each time the resistance is lowered, therefore, the current
+passing through the field magnets becomes more dense in amperes, and
+makes the field magnets correspondingly stronger.</p>
+
+<p>We have seen that the voltage depends on the number of lines of
+magnetic force cut by the armature conductors in a given time. If the
+speed remains constant then, and the magnets grow stronger and
+stronger, the voltage will rise in a straight line. When no current is
+drawn, it is 0; at full load, it may be 100 volts, or 500, or 1,000
+according to the machine. This type of machine is used only in street
+lighting, in cities, with the lights connected in "series," or one
+after another on the same wire, the last lamp finally returning<span class='pagenum'><a name="Page_116" id="Page_116">[Pg 116]</a></span> the
+wire to the machine to complete the circuit. This type of dynamo has
+gained the name for itself of "mankiller," as its voltage becomes
+enormous at full load. It is unsuitable, in every respect, for the
+farm plant. Its field coils consist of a few turns of very heavy wire,
+enough to carry all the current of the external circuit, without
+heating.</p>
+
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d116.jpg" width="500" height="402" alt="" title="" />
+Connections of a series dynamo
+</div>
+
+
+<p class="center padtop"><i>The Shunt Dynamo</i></p>
+
+<p>The shunt dynamo, on the other hand, has field coils connected
+directly <i>across</i> the circuit, from one wire to another, instead of in
+"series." These coils consist of a great many turns of very fine wire,
+thus introducing <i>resistance</i> into the circuit, which limits the
+amount of current (amperes) that can be forced through them at any
+given voltage. As a shunt dynamo is brought up to its rated speed, its
+voltage gradually rises until a condition <span class='pagenum'><a name="Page_117" id="Page_117">[Pg 117]</a></span>of balance occurs between
+the field coils and the armature. There it remains constant. When
+resistance on the external circuit is lowered, by means of turning on
+lamps or other devices, the current from the armature increases in
+working power, by increasing its amperes. Its voltage remains
+stationary; and, since the resistance of its field coils never
+changes, the magnets do not vary in strength.</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d117.jpg" width="500" height="384" alt="" title="" />
+Connections of a shunt dynamo
+</div>
+
+<p>The objection to this type of machine for a farm plant is that, in
+practice, the armature begins to exercise a de-magnetizing effect on
+the field magnets after a certain point is reached&mdash;weakens them;
+consequently the voltage begins to fall. The voltage of a shunt dynamo
+begins to fall after half-load is reached; and at full load, it has
+fallen possibly 20 per cent. A rheostat, or resistance<span class='pagenum'><a name="Page_118" id="Page_118">[Pg 118]</a></span> box on the
+switchboard, makes it possible to cut out or switch in additional
+resistance in the field coils, thus varying the strength of the field
+coils, within a limit of say 15 per cent, to keep the voltage
+constant. This, however, requires a constant attendance on the
+machine. If the voltage were set right for 10 lights, the lights would
+grow dim when 50 lights were turned on; and if it were adjusted for 50
+lights, the voltage would be too high for only ten lights&mdash;would cause
+them to "burn out."</p>
+
+<p>Shunt dynamos are used for charging storage batteries, and are
+satisfactory for direct service only when an attendant is constantly
+at hand to regulate them.</p>
+
+
+<p class="center padtop"><i>The Compound Dynamo</i></p>
+
+<p>The ideal between these two conditions would be a compromise, which
+included the characteristics of both <i>series</i> and <i>shunt</i> effects.
+That is exactly what the <i>compound</i> dynamo effects.</p>
+
+<p>A compound dynamo is a shunt dynamo<span class='pagenum'><a name="Page_119" id="Page_119">[Pg 119]</a></span> with just enough series turns on
+its field coils, to counteract the de-magnetizing effect of the
+armature at full load. A machine can be designed to make the voltage
+rise gradually, or swiftly, by combining the two systems. For country
+homes, the best combination is a machine that will keep the voltage
+constant from no load to full load. A so-called <i>flat-compounded</i>
+machine does this. In actual practice, this voltage rises slightly at
+the half-load line&mdash;only two or three volts, which will not damage the
+lamps in a 110-volt circuit.</p>
+
+<p>The compound dynamo is therefore self-regulating, and requires no
+attention, except as to lubrication, and the incidental care given to
+any piece of machinery. Any shunt dynamo can be made into a compound
+dynamo, by winding a few turns of heavy insulated wire around the
+shunt coils, and connecting them in "series" with the external
+circuit. How many turns are necessary depends on conditions. Three or
+four turns to each coil usually are sufficient for "flat compounding."
+If the generating plant is a long<span class='pagenum'><a name="Page_120" id="Page_120">[Pg 120]</a></span> distance from the farm house where
+the light, heat, and power are to be used, the voltage drops at full
+load, due to resistance of the transmission wires. To overcome this,
+enough turns can be wound on top of the shunt coils to cause the
+voltage to rise at the switchboard, but remain stationary at the spot
+where the current is used. The usual so-called flat-compounded dynamo,
+turned out by manufacturers, provides for constant voltage at the
+switchboard. Such a dynamo is eminently fitted for the farm electric
+plant. Any other type of machine is bound to cause constant trouble
+and annoyance.</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d120.jpg" width="500" height="414" alt="" title="" />
+Connections of a compound dynamo
+</div>
+
+
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_121" id="Page_121">[Pg 121]</a></span></p>
+<h2><a name="CHAPTER_VI" id="CHAPTER_VI"></a>CHAPTER VI</h2>
+
+<p class="subhead2">WHAT SIZE PLANT TO INSTALL</p>
+
+<div class="blockquot"><p>The farmer's wife his partner&mdash;Little and big plants&mdash;Limiting
+factors&mdash;Fluctuations in water supply&mdash;The average plant&mdash;The
+actual plant&mdash;Amount of current required for various
+operations&mdash;Standard voltage&mdash;A specimen allowance for electric
+light&mdash;Heating and cooking by electricity&mdash;Electric power: the
+electric motor.</p></div>
+
+
+<p>The farmer's wife becomes his partner when he has concluded the
+preliminary measurements and surveys for building his water-power
+electric plant. Now the question is, how big a plant is necessary, or
+how small a plant can he get along with. Electricity may be used for a
+multitude of purposes on the farm, in its sphere of furnishing
+portable light, heat and power; but when this multitude of uses has
+been enumerated, it will be found that the wife shares in the benefits
+no less than the farmer himself. The greatest dividend of all,<span class='pagenum'><a name="Page_122" id="Page_122">[Pg 122]</a></span>
+whether dividends are counted in dollars or happiness, is that
+electricity takes the drudgery out of housework. Here, the work of the
+farmer himself ends when he has brought electricity to the house, just
+as his share in housework ends when he has brought in the kerosene,
+and filled the woodbox. Of the light and heat, she will use the lion's
+share; and for the power, she will discover heretofore undreamed-of
+uses. So she must be a full partner when it comes to deciding how much
+electricity they need.</p>
+
+<p>How much electricity, in terms of light, heat, and power, will the
+farmer and his wife have use for? How big a plant should be installed
+to meet the needs of keeping house and running the farm?</p>
+
+<p>The answer hangs mainly on how much water-power there is available,
+through all the seasons of the year, with which to generate
+electricity. Beyond that, it is merely a question of the farmer's
+pocketbook. How much money does he care to spend? Electricity is a
+cumulative "poison." The more one uses<span class='pagenum'><a name="Page_123" id="Page_123">[Pg 123]</a></span> it, the more he wants to use
+it. After a plant has been in operation a year, the family have
+discovered uses for electricity which they did not think of in the
+beginning. For this reason, it is well to put in a plant larger than
+the needs of the moment seem to require. An electrical horsepower or
+two one way or another will not greatly change the first cost, and you
+will always find use for any excess.</p>
+
+<p>Once for all, to settle the question of water-power, the water wheel
+should be twice the normal capacity of the dynamo it drives, in terms
+of power. This allows for overload, which is bound to occur
+occasionally; and it also insures smooth running, easy governing, and
+the highest efficiency. Since the electric current, once the plant is
+installed, will cost practically nothing, the farmer can afford to
+ignore the power going to waste, and consider only how to get the best
+service.</p>
+
+
+<p class="center padtop"><i>The Two Extremes</i></p>
+
+<p>The amount of water to be had to be turned into electricity, will vary
+with location, and<span class='pagenum'><a name="Page_124" id="Page_124">[Pg 124]</a></span> with the season. It may be only enough, the
+greater part of the year, for a "toy" plant&mdash;a very practical toy, by
+the way&mdash;one that will keep half a dozen lights burning in the house
+and barn at one time; under some conditions water may be so scarce
+that it must be stored for three or four days to get enough power to
+charge a storage battery for these six or eight lights. A one-quarter,
+or a one-half kilowatt electrical generator, with a one horsepower (or
+smaller) wheel, will light a farmstead very satisfactorily&mdash;much
+better than kerosene lamps.</p>
+
+<p>On the other hand, the driving power of your wheel may be sufficient
+to furnish 50 or 100 lights for the house, barn, and out-buildings,
+and barn-yard and drives; to provide ample current for irons,
+toasters, vacuum cleaners, electric fans, etc.; to do all the cooking
+and baking and keep the kitchen boiler hot; and to heat the house in
+the coldest weather with a dry clean heat that does not vitiate the
+air, with no ashes, smoke or dust or woodchopping&mdash;nothing but an
+electric switch<span class='pagenum'><a name="Page_125" id="Page_125">[Pg 125]</a></span> to turn on and off; and to provide power for motors
+ranging from tiny ones to run the sewing machine, to one of 15
+horsepower to do the threshing. A plant capable of developing from 30
+to 50 kilowatts of electricity, and requiring from 50 to 100
+horsepower at the water wheel, would do all this, depending on the
+size of the farmstead. One hundred horsepower is a very small water
+project, in a commercial way; and there are thousands of farms
+possessing streams of this capacity.</p>
+
+
+<p class="center padtop"><i>Fluctuations in Water Supply</i></p>
+
+<p>It would be only during the winter months that such a plant would be
+driven to its full capacity; and since water is normally plentiful
+during these months, the problem of power would be greatly simplified.
+The heaviest draft on such a plant in summer would be during
+harvesting; otherwise it would be confined to light, small power for
+routine work, and cooking. Thus, a plant capable of meeting all the
+ordinary requirements of the four dry months of summer, when water is
+apt to<span class='pagenum'><a name="Page_126" id="Page_126">[Pg 126]</a></span> be scarce, doubles or quadruples its capacity during the
+winter months, to meet the necessities of heat for the house.</p>
+
+<p>A dynamo requires only as much power to drive it, at any given time,
+as is being used in terms of electricity. There is some small loss
+through friction, of course, but aside from this the power required of
+the prime mover (the water wheel) is always in proportion to the
+amount of current flowing. When water is scarce, and the demands for
+current for heating are low, it is good practice to close a portion of
+the buckets of the turbine wheel with wooden blocks provided for this
+purpose. It is necessary to keep the speed of the dynamo uniform under
+all water conditions; and where there is a great fluctuation between
+high and low water periods, it is frequently necessary to have a
+separate set of pulleys for full gate and for half-gate. The head must
+remain the same, under all conditions. Changing the gate is in effect
+choking or opening the nozzle supplying the wheel, to cut down or
+increase its consumption of water.</p>
+
+
+<p><span class='pagenum'><a name="Page_127" id="Page_127">[Pg 127]</a></span></p>
+
+<p class="center padtop"><i>The Average Plant</i></p>
+
+<p>It will be the exceptional plant, however, among the hundreds of
+thousands to be had on our farms, which will banish not only the oil
+lamp and kitchen stove, but all coal or wood burning stoves as
+well&mdash;which will heat the house in below-zero weather, and provide
+power for the heavier operations of the farm. Also, on the other hand,
+it will be the exceptional plant whose capacity is limited to
+furnishing a half-dozen lights and no more.</p>
+
+<p>A happy medium between these two conditions is the plant large enough
+to supply between five and ten electrical horsepower, in all seasons.
+Such a plant will meet the needs of the average farm, outside of
+winter heating and large power operations, and will provide an excess
+on which to draw in emergencies, or to pass round to one's neighbors.
+It is such a plant that we refer to when we say that (not counting
+labor) its cost, under ordinary conditions should not greatly exceed
+the price of one sound young horse for farm work.</p>
+
+<p><span class='pagenum'><a name="Page_128" id="Page_128">[Pg 128]</a></span></p><p>Since the plant we described briefly in the first chapter, meets the
+requirements of this "average plant" let us inquire a little more
+fully into its installation, maintenance, and cost.</p>
+
+
+<p class="center padtop"><i>An Actual Plant</i></p>
+
+<p>In this instance, the water-power was already installed, running to
+waste, in fact. The wheel consists of the so-called thirty-six inch
+vertical turbine, using 185 square inches of water, under a 14-foot
+head. Water is supplied to this wheel by a wooden penstock 33 inches
+square, inside measurements, and sloping at an angle of 30&deg; from the
+flume to the wheel.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="i128" id="i128"></a>
+<img src="images/i128.jpg" width="400" height="472" alt="" title="" />
+Details of voltmeter or ammeter
+</div>
+
+<p>This wheel, under a 14-foot head, takes 2,312 cubic feet of water a
+minute; and it develops 46.98 actual horsepower (as may be figured by
+using the formulas of Chapter III). The water supply is provided by a
+small mountain river. The dam is 10 feet high, and the race, which
+feeds the flume from the mill pond is 75 yards long. The race has two
+spillways, one near the dam, and the second at the flume itself, to
+maintain an even head of water at all times.</p>
+
+
+<p><span class='pagenum'><a name="Page_129" id="Page_129">[Pg 129]</a></span></p><p class="center padtop"><i>Half-Gate</i></p>
+
+<p>Since the water supply varies with the seasons, it has been found
+practical to run the wheel at half-gate&mdash;that is, with the gate only
+half-open. A set of bevel gears work the main shaft, which runs at
+approximately 200 revolutions per minute; and the dynamo is worked up
+to its required speed of 1,500 revolutions per minute through a
+countershaft.</p>
+
+<p>The dynamo is a modern four-pole machine, compound-wound, with a rated
+output of 46 amperes, at 125 volts&mdash;in other words a dynamo of 5.75
+kilowatts capacity, or 7.7 electrical horsepower. At full load this
+dynamo would require a driving power of 10 horsepower, counting it as
+75 per cent efficient; and, to conform to our rule of two water
+horsepower to one electrical horsepower, the wheel should be capable
+of developing 20 horsepower. As a matter of fact, in this<span class='pagenum'><a name="Page_130" id="Page_130">[Pg 130]</a></span> particular
+instance, shutting down the wheel to half-gate more than halves the
+rated power of the wheel, and little more than 15 horsepower is
+available. This allowance has proved ample, under all conditions met
+with, in this plant.</p>
+
+<div class="figleft" style="width: 200px;">
+<img src="images/d131.jpg" width="200" height="535" alt="" title="" />
+ A switchboard and its connections: <i>G.</i> Dynamo; <i>A.</i>
+Shunt field coils; <i>B.</i> Series coils; <i>DD.</i> Fuses; <i>FF.</i> Main switch;
+<i>F.</i> Field switch; <i>C.</i> Ammeter; <i>V.</i> Voltmeter; <i>E.</i> Lamp; <i>R.</i>
+Rheostat. Dotted lines show connections on back of board
+</div>
+
+<p>The dynamo is mounted on a firm floor foundation; and it is belted
+from the countershaft by an endless belt running diagonally. A
+horizontal belt drive is the best. Vertical drive should be avoided
+wherever possible.</p>
+
+
+
+
+<p class="center padtop"><i>The Switchboard</i></p>
+
+<p>The switchboard originally consisted of a wooden frame on which were
+screwed ordinary asbestos shingles, and the instruments were mounted
+on these. Later, a sheet of electric insulating fibre was substituted,
+for look's sake. The main requisite is something substantial&mdash;and
+fireproof. The switchboard instruments consist of a voltmeter, with a
+range of from 0 to 150 volts; an ammeter, with a range, 0 to 75
+amperes; a field regulating rheostat (which came with the dynamo); a
+main switch, with<span class='pagenum'><a name="Page_131" id="Page_131">[Pg 131]</a></span> cartridge fuses protecting the machine against a
+draft of current over 60 amperes; and two line switches for the two
+owners, one fuse at 20 amperes, and the other at 40 amperes. Electric
+fuses are either cartridges or plugs, enclosing lead wire of a size
+corresponding to their rating. All the current of the line they
+protect passes through this lead wire. If the current drawn exceeds
+the capacity of the lead wire, it melts from the heat, and thus opens
+the circuit, and cuts off the current.</p>
+
+
+
+
+<p class="center padtop"><i>Items of Cost</i></p>
+
+<p>This water wheel would cost $250 new. There is a duplicate in the
+neighborhood bought at second-hand, for $125. The<span class='pagenum'><a name="Page_132" id="Page_132">[Pg 132]</a></span> dynamo cost $90,
+and was picked up second-hand in New York City. New it would cost
+$150. The voltmeter cost $7, and the ammeter $10; and the switches and
+fuses could be had for $5. A wheel one-half the size, using one-half
+the amount of water at full gate, would do the work required, and the
+cost would be correspondingly less.</p>
+
+
+<p class="center padtop"><i>Capacity</i></p>
+
+<p>This plant supplies two farms with electric light. One farm (that of
+the owner of the wheel) has 30 lamps, of 16 candlepower each, and two
+barn-yard lamps of 92 candlepower each. His wife has an electric iron
+and an electric water heater. Needless to say, all these lamps, and
+the iron and water heater are not in use at one time.</p>
+
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d132.jpg" width="500" height="390" alt="" title="" />
+Carbon Lamps Gem Type (&frac14; scale)
+</div>
+
+
+<p>The partner who owns the electric part of the plant has 30 lamps in
+his house and barn,<span class='pagenum'><a name="Page_133" id="Page_133">[Pg 133]</a></span> many of them being 25 watt tungsten, which give
+more light for less power, but cost more to buy. They are not all in
+use at one time, though (since the current costs nothing) the
+inclination is to turn them on at night and let them burn. In his
+kitchen he has an electric range, and a water heater for the 40 gallon
+boiler. In addition to this he has all sorts of appliances,&mdash;irons,
+toasters, grills, a vacuum cleaner, a vibrator, etc. Naturally all
+these appliances are not in use at one time, else the draft on the
+plant would be such as to "blow" the fuses. For instance, all the
+baking is done in daylight; and when the oven is used after dark, they
+are careful to turn off all lights not needed. An ideal plant, of
+course, would be a plant big enough to take care of the sum of lamps
+and handy devices used at one time.</p>
+
+<p>To make this plant ideal, (for, being an actual affair, it has
+developed some short-comings, with the extension of the use of
+electricity) it would require a dynamo whose capacity can be figured,
+from the following:</p>
+
+<p><span class='pagenum'><a name="Page_134" id="Page_134">[Pg 134]</a></span></p>
+
+
+<table summary="watts used" style="width: 50%;"><tbody>
+<tr><td></td>                                                   <td class="tr"><i>Watts</i></td></tr>
+<tr><td class="tl">15 carbon lamps, 16 candlepower, @60 watts each    </td>  <td class="tr">900</td></tr>
+<tr><td class="tl">10 tungsten lamps, 20 candlepower, @25 watts each  </td>  <td class="tr">250</td></tr>
+<tr><td class="tl">2 tungsten lamps, 92 candlepower, @100 watts each  </td>  <td class="tr">200</td></tr>
+<tr><td class="tl">Water heater, continuous service                   </td>  <td class="tr">800</td></tr>
+<tr><td class="tl">Toaster, occasional service                        </td>  <td class="tr">600</td></tr>
+<tr><td class="tl">Iron, occasional service                           </td>  <td class="tr">400</td></tr>
+<tr><td class="tl">Oven-baking, roasting, etc                       </td>  <td class="tr">2,000</td></tr>
+<tr><td class="tl">2 stove plates @1,000 watts each                 </td>  <td class="tr">2,000</td></tr>
+<tr><td class="tl">1 stove plate                                      </td>  <td class="tr">400</td></tr>
+<tr><td class="tl">Vacuum cleaner, occasional service                 </td>  <td class="tr">200</td></tr>
+<tr><td class="tl">Vibrator, occasional service                       </td>  <td class="tr">100</td></tr>
+<tr><td class="tl">Small water heater, quart capacity                 </td>  <td class="tr">400</td></tr>
+<tr><td class="tl">Small motor, &frac14; horsepower, occasional            </td>  <td class="tr">250</td></tr>
+<tr><td class="tl">Motor, &frac12; hp, pumping water, etc                  </td>  <td class="tr">500</td></tr>
+<tr><td class="tl">Electric fan, occasional service                   </td>  <td class="tr">100</td></tr>
+<tr><td></td>                                                 <td class="tr">&mdash;&mdash;&mdash;</td></tr>
+         <tr><td class="tl">Total current, one house<br />&nbsp;</td>                 <td style="text-align: right; vertical-align: top;">9,100</td></tr>
+
+
+<tr><td class="tl">30 carbon lamps, 16 candlepower, @60             </td>  <td class="tr">1,800</td></tr>
+<tr><td class="tl">2 lamps, 100 watt tungsten                         </td>  <td class="tr">200</td></tr>
+<tr><td class="tl">Electric iron                                      </td>  <td class="tr">400</td></tr>
+<tr><td class="tl">Small water or milk heater                         </td>  <td class="tr">600</td></tr>
+<tr><td></td>                                                 <td class="tr">&mdash;&mdash;&mdash;</td></tr>
+         <tr><td class="tl">Total current, 2nd house</td>                 <td class="tr">3,000</td></tr>
+                        <tr><td class="tl">1st house</td>                 <td class="tr">9,100</td></tr>
+<tr><td></td>                                                 <td class="tr">&mdash;&mdash;&mdash;</td></tr>
+<tr><td></td>                                                 <td class="tr">12,100</td></tr>
+</tbody></table>
+
+<p>Thus, in this plant, if every electrical device were turned on at
+once, the demand on the dynamo would be for 12.1 kilowatts, or an
+overload of over 100 per cent. The main-switch fuse, being for 60
+amperes, would "blow" or melt, and cut off all current for the<span class='pagenum'><a name="Page_135" id="Page_135">[Pg 135]</a></span>
+moment. To repair the damage would be merely the work of a second&mdash;and
+at a cost of a few cents&mdash;simply insert a new fuse, of which there
+must be a supply on hand at all times. Or, if either owner exceeded
+his capacity, the line fuses (one for 20 amperes, and the other for 40
+amperes) would instantly cut off all current from the greedy one.</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d135.jpg" width="500" height="394" alt="" title="" />
+ 25 and 40 watt Mazda tungsten lamps (&frac14; scale)
+</div>
+
+
+
+<p class="center padtop"><i>Lessons From This Plant</i></p>
+
+<p>The story of this plant illustrates two things which the farmer and
+his wife must take into account when they are figuring how much
+electricity they require. First, it illustrates how one uses more and
+more current, as he finds it so serviceable and labor-saving, and at
+the same time free. The electric range and the water boiler, in the
+above instance, were later acquisitions not counted on in figuring the
+original installation. Second, it illustrates,<span class='pagenum'><a name="Page_136" id="Page_136">[Pg 136]</a></span> that while the normal
+load of this generator is <i>5.75</i> kilowatts, one does not have to limit
+the electrical conveniences in the home to this amount. True, he
+cannot use more electricity than his plant will produce <i>at any one
+time</i>,&mdash;but it is only by a stretch of the imagination that one may
+conceive the necessity of using them all at once. Ironing, baking, and
+the use of small power are usually limited to daylight hours when no
+lights are burning.</p>
+
+<p>As a matter of fact, this plant has proved satisfactory in every way;
+and only on one or two occasions have fuses been "blown", and then it
+was due to carelessness. A modern dynamo is rated liberally. It will
+stand an overload of as much as 100 per cent for a short time&mdash;half an
+hour or so. The danger from overloading is from heating. When the
+machine grows too hot for the hand, it is beginning to char its
+insulation, to continue which, of course would ruin it. The best plant
+is that which works under one-half or three-quarters load, under
+normal demands.</p>
+
+
+<p><span class='pagenum'><a name="Page_137" id="Page_137">[Pg 137]</a></span></p><p class="center padtop"><i>Standard Voltage</i></p>
+
+<p>We are assuming the farmer's plant to be, in 99 cases out of 100, the
+standard 110-volt, direct current type. Such a plant allows for at
+least a 10 per cent regulation, in voltage, up or down the scale;
+supplies for this voltage are to be had without delay in even the more
+remote parts of the country, and (being sold in greater volume) they
+are cheaper than those for other voltages.</p>
+
+<p>There are two general exceptions to this rule as to 110-volt plants:
+(1) If the plant is located at a distance greater than a quarter of a
+mile from the house, it will be found cheaper (in cost of transmission
+line, as will be shown later) to adopt the 220-volt plant; (2), If the
+water supply is so meagre that it must be stored for many hours at a
+time, and then used for charging storage batteries, it will be found
+most economical to use a 30-volt plant. A storage battery is made up
+of cells of approximately 2 volts each; and, since more than 55 such
+cells would be required for a<span class='pagenum'><a name="Page_138" id="Page_138">[Pg 138]</a></span> 110-volt installation, its cost would
+be prohibitive, with many farmers.</p>
+
+<p>So we will assume that this plant is a 110-volt plant, to be run
+without storage battery. It will be well to make a chart, dividing the
+farm requirements into three heads&mdash;light, heat, and power.</p>
+
+
+<p class="center padtop"><i>Light</i></p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d138.jpg" width="500" height="357" alt="" title="" />
+60 and 100 watt Mazda tungsten lamp. These lamps may be
+had in sizes from 10 to 500 watts (&frac14; scale)
+</div>
+
+<div class="figcenter" style="width: 300px;">
+<img src="images/d139.jpg" width="300" height="526" alt="" title="" />
+The lamp of the future. A 1000 watt Mazda nitrogen
+lamp, giving 2000 candlepower (&frac14; scale)
+</div>
+
+<p>Light is obtained by means of incandescent lamps. There are two styles
+in common use, the carbon and the tungsten lamp. It requires 3.5 to 4
+watts of electricity to produce one candlepower in a carbon lamp. It
+requires<span class='pagenum'><a name="Page_139" id="Page_139">[Pg 139]</a></span> from 1 to 1.25 watt to produce one candlepower in the
+tungsten lamp. The new nitrogen lamp, not yet in general use, requires
+only &frac12; watt to the candlepower. Since tungsten lamps give three
+times the light of the carbon lamp, they are the most economical to
+use in the city or town where one is paying for commercial current.
+But, in the country where water-power furnishes current for nothing,
+it will be found most economical to use the carbon lamp, since its
+cost at retail is 16 cents, as compared with 30 cents for a
+corresponding size in tungsten. A 60 watt carbon lamp, of 16
+candlepower; or a 25 watt tungsten lamp, of 20<span class='pagenum'><a name="Page_140" id="Page_140">[Pg 140]</a></span> candlepower, are the
+sizes to use. In hanging lamps, as over the dining room table, a 100
+watt tungsten lamp, costing 70 cents, and giving 92 candlepower light
+is very desirable; and for lighting the barn-yard, these 100 watt
+tungsten lamps should be used. For reading lamps, the tungsten style,
+of 40 or 60 watt capacity, will be found best. Otherwise, in all
+locations use the cheaper carbon lamp. Both styles have a rated life
+of 1,000 hours, after which they begin to fall off in efficiency. Here
+again, the farmer need not worry over lack of highest efficiency, as a
+lamp giving only 80 per cent of its rated candlepower is still
+serviceable when he is not paying for the current. With care not to
+use them at voltages beyond their ratings, lamps will last for years.</p>
+
+
+<p class="center padtop"><i>A Specimen Light Allowance</i></p>
+
+<p>Below is a typical table of lights for a large farm house, the barns
+and barn-yard. It is given merely as a guide, to be varied for each
+individual case:</p>
+
+<p><span class='pagenum'><a name="Page_141" id="Page_141">[Pg 141]</a></span></p>
+
+
+<table summary="watts used" style="width: 50%;"><tbody>
+
+<tr><td></td>                                                            <td class="tr"><i>Watts</i></td></tr>
+<tr><td class="tl">Kitchen, 2 lights @60 watts                                 </td>  <td class="tr">120</td></tr>
+<tr><td class="tl">Dining room, 1 light, tungsten                              </td>  <td class="tr">100</td></tr>
+<tr><td class="tl">Living room, table lamp with 3 tungstens @40                </td>  <td class="tr">120</td></tr>
+<tr><td class="tl">Living room, 2 wall fixtures, 4 lamps @60 watts             </td>  <td class="tr">240</td></tr>
+<tr><td class="tl">Parlor, same as living room                                 </td>  <td class="tr">360</td></tr>
+<tr><td class="tl">Pantry, 1 hanging lamp                                       </td>  <td class="tr">60</td></tr>
+<tr><td class="tl">Cellar, one portable lamp                                    </td>  <td class="tr">60</td></tr>
+<tr><td class="tl">Woodshed, 1 hanging lamp                                     </td>  <td class="tr">60</td></tr>
+<tr><td class="tl">2 bedrooms, 2 lights each @ 60                              </td>  <td class="tr">240</td></tr>
+<tr><td class="tl">2 bed rooms, 1 light each @60                               </td>  <td class="tr">120</td></tr>
+<tr><td class="tl">Bathroom, 1 "turn-down" light, @60                           </td>  <td class="tr">60</td></tr>
+<tr><td class="tl">Hall, downstairs, 2 lights @60                              </td>  <td class="tr">120</td></tr>
+<tr><td class="tl">Hall, upstairs, 1 light                                      </td>  <td class="tr">60</td></tr>
+<tr><td class="tl">Attic, 1 light                                               </td>  <td class="tr">60</td></tr>
+<tr><td class="tl">Porch, 1 light                                               </td>  <td class="tr">60</td></tr>
+<tr><td class="tl">Barn and barn-yard:</td> <td></td></tr>
+<tr><td class="tl">Barn-yard entrance, 1 tungsten                              </td>  <td class="tr">100</td></tr>
+<tr><td class="tl">Watering trough,    1 tungsten                                  </td>  <td class="tr">100</td></tr>
+<tr><td class="tl">Front gate,         1 tungsten                                  </td>  <td class="tr">100</td></tr>
+<tr><td class="tl">Horse barn, 4 lights @60                                    </td>  <td class="tr">240</td></tr>
+<tr><td class="tl">Cow barn, 4 lights @60                                      </td>  <td class="tr">240</td></tr>
+<tr><td class="tl">Pig house, 1 light                                           </td>  <td class="tr">60</td></tr>
+<tr><td class="tl">Hay barn, 2 lights, @60                                     </td>  <td class="tr">120</td></tr>
+<tr><td></td>                                                          <td class="tr">&mdash;&mdash;&mdash;</td></tr>
+<tr><td class="tl">Total for farmstead</td>  <td class="tr">2,800</td></tr>
+</tbody></table>
+
+<p>This provides for 44 lights, an extremely liberal allowance. How many
+of these lights will be burning at any one time? Probably not one-half
+of them; yet the ideal plant is that which permits all fixtures to be
+in service at one time on the rare occasions when necessary. Thus, for
+lighting only, 2,800<span class='pagenum'><a name="Page_142" id="Page_142">[Pg 142]</a></span> watts maximum service would require a 4 kilowatt
+generator, and 10 water horsepower, on the liberal rating of two to
+one. A 3 kilowatt generator would take care of these lights, with a 30
+per cent overload (which is not excessive) for maximum service. The
+above liberal allowance of lights may be cut in two, or four&mdash;or even
+eight&mdash;and still throw a kerosene lamp in shadow. It all depends on
+the number of lights one wants burning at one time; and the power of
+the water wheel.</p>
+
+<p>If the 36 carbon lights in the above table were replaced by 25 watt
+tungsten lights, the saving in power would be 35 watts each, or 1,260
+watts, nearly two electrical horsepower; while the added first cost
+would be 14 cents a light, or $5.04. A generator of 2 kilowatt
+capacity would take care of all these lights then, with 460 watts to
+spare.</p>
+
+
+<p class="center padtop"><i>Heating</i></p>
+
+<p>Electric heating and cooking is in its infancy, due to the prohibitive
+cost of commercial <span class='pagenum'><a name="Page_143" id="Page_143">[Pg 143]</a></span>current in our cities. Here the farmer has the
+advantage again, with his cheap current.</p>
+
+<p>For heating the house, it is calculated that 2 watts is required for
+each cubic foot of air space in a room, during ordinary winter
+weather. Thus, a room 10 &times; 12, and 8 feet high, would contain 960
+cubic feet, and would require 1,820 watts energy to heat it in cold
+weather. Five such rooms would require 9.1 kilowatts; and 10 such
+rooms, or their equivalent, would require 18.2 kilowatts.</p>
+
+<p>Electric heating devices are divided into two classes: (1) those which
+can be used on lamp circuits, <i>and do not draw more than 660 watts
+each</i>; and (2) those which draw more than 660, therefore <i>require
+special wiring</i>. The capacity of these devices is approximately as
+follows:</p>
+
+
+<p style="margin-left: 20%;">Lamp circuit devices:</p>
+
+<table summary="circuit devices and watts" style="width: 40%;"><tbody>
+<tr><td></td>    <td class="tr"><i>Watts</i></td></tr>
+<tr><td class="tl">Electric iron</td>  <td class="tr">400 to 660</td></tr>
+<tr><td class="tl">Toaster</td>  <td class="tr">350 to 660</td></tr>
+<tr><td class="tl">Vacuum cleaner</td>  <td class="tr">200 to 400</td></tr>
+<tr><td class="tl">Grill</td>  <td class="tr">400 to 660</td></tr>
+<tr><td class="tl">Small water heater</td>  <td class="tr">400 to 660</td></tr>
+<tr><td class="tl">Hot plates</td>  <td class="tr">400 to 660</td></tr>
+</tbody></table>
+
+<p><span class='pagenum'><a name="Page_144" id="Page_144">[Pg 144]</a></span></p>
+
+<p style="margin-left: 20%;">Lamp circuit devices:</p>
+
+<table summary="circuit devices and watts" style="width: 40%;"><tbody>
+<tr><td class="tl">Coffee percolator</td>  <td class="tr">400 to 660</td></tr>
+<tr><td class="tl">Chafing dish</td>  <td class="tr">400 to 660</td></tr>
+<tr><td class="tl">Electric fan</td>  <td class="tr">100 to 250</td></tr>
+</tbody></table>
+
+<p style="margin-left: 20%;">Special circuit devices:</p>
+
+<table summary="circuit devices and watts" style="width: 40%;"><tbody>
+<tr><td class="tl">Hot water boiler heater</td>       <td class="tr">800 to  1,200</td></tr>
+<tr><td class="tl">Small ovens</td>                   <td class="tr">660 to  1,200</td></tr>
+<tr><td class="tl">Range ovens</td>                 <td class="tr">1,200 to  3,000</td></tr>
+<tr><td class="tl">Range, hot plates</td>             <td class="tr">400 to  1,300</td></tr>
+<tr><td class="tl">Radiators (small)</td>             <td class="tr">750 to  1,500</td></tr>
+<tr><td class="tl">Radiators (large)</td>            <td class="tr">1,500 to 6,000</td></tr>
+</tbody></table>
+
+<p>The only device in the above list which is connected continuously, is
+the hot water boiler, and this can be credited with at least one
+electrical horsepower 24 hours a day. It is a small contrivance, not
+much bigger than a quart can, attached to the back of the kitchen
+boiler, and it keeps the water hot throughout the house at all hours.
+Its cost will vary with the make, ranging from $8 to $15; and since it
+is one of the real blessings of the farm kitchen and bathroom, it
+should be included in all installations where power permits. Electric
+radiators will be used 24 hours a day in winter, and not at all in
+summer. They are portable, and can<span class='pagenum'><a name="Page_145" id="Page_145">[Pg 145]</a></span> be moved from room to room, and
+only such rooms as are in actual use need be heated. The other devices
+are for intermittent service, many of them (like the iron) for only a
+few hours each week.</p>
+
+<p>The grill, chafing dish, coffee percolator, etc., which are used on
+the dining room table while the family is at meals, each draw an
+equivalent of from 6 to 10 carbon lights. By keeping this in view and
+turning off spare lights, one can have the use of them, with even a
+small plant. Thus, a one kilowatt plant permits the use of any one of
+these lamp circuit devices at a time, with a few lights in addition.</p>
+
+
+<p class="center padtop"><i>Power</i></p>
+
+<p>Electric power is to be had through motors. A direct current dynamo
+and a direct current motor are identical in construction. That is, a
+motor becomes a generator if belted to power; and a generator becomes
+a motor, if connected to electric mains. This is best illustrated by
+citing the instance of a trans-continental<span class='pagenum'><a name="Page_146" id="Page_146">[Pg 146]</a></span> railroad which crosses the
+Bitter Root Mountains by means of electric power. Running 200 miles up
+a 2 per cent grade, it is drawn<span class='pagenum'><a name="Page_147" id="Page_147">[Pg 147]</a></span> by its motors. Coasting 200 miles
+down the 2 per cent grade on the other side of the mountains, its
+motors become generators. They act as brakes, and at the same time
+they pump the power of the coasting weight of this train back into the
+wires to help a train coming up the other side of the mountains.</p>
+
+<div class="figcenter" style="width: 400px;">
+<img src="images/d146.jpg" width="400" height="503" alt="" title="" />
+Connections of shunt motor and starting rheostat
+</div>
+
+
+<p>Just as there are three types of direct current generators, so there
+are three types of direct current motors: <i>series</i>, <i>shunt</i>, and
+<i>compound</i>, with features already explained in the case of generators.
+Motors are rated by horsepower, and generators are rated by kilowatts.
+Thus a one kilowatt generator has a capacity of 1,000 watts; as a
+motor, it would be rated as 1000/746 horsepower, or 1.34 horsepower.
+Their efficiency varies with their size, ranging from 40 to 60 per
+cent in very small motors, and up to 95 per cent in very large ones.
+The following table may be taken as a guide in calculating the power
+required by motors, on 110-volt circuits:</p>
+
+<p><span class='pagenum'><a name="Page_148" id="Page_148">[Pg 148]</a></span></p>
+
+
+<table summary="power required by motors" style="width: 40%;"><tbody>
+<tr><td class="tl">&frac14; Horsepower</td>     <td class="center">2&frac12; amperes, or 275 watts</td></tr>
+<tr><td class="tl">&frac12; hp</td>             <td class="center">4&frac12; amperes, or 500 watts</td></tr>
+<tr><td class="tl">1  hp</td>             <td class="center">9     amperes, or 990 watts</td></tr>
+<tr><td class="tl">2  hp</td>            <td class="center">17     amperes, or 1.97 kilowatts</td></tr>
+<tr><td class="tl">3  hp</td>            <td class="center">26     amperes, or 2.86 kilowatts</td></tr>
+<tr><td class="tl">5  hp</td>            <td class="center">40     amperes, or 4.40 kilowatts</td></tr>
+<tr><td class="tl">7&frac12; hp</td>           <td class="center">60     amperes, or 6.60 kilowatts</td></tr>
+<tr><td class="tl">10  hp</td>            <td class="center">76     amperes, or 8.36 kilowatts</td></tr>
+<tr><td class="tl">15  hp</td>           <td class="center">112     amperes, or 12.32 kilowatts</td></tr>
+</tbody></table>
+
+<p>An electric motor, in operation, actually generates electricity, which
+it pushes back into the line as a counter-electromotive-force. The
+strength of this counter force, in volts, depends on the motor's
+speed, the same as if it were running as a dynamo. For this reason,
+when a motor is started, and before it comes up to speed, there would
+be a rush of current from the line, with nothing to hold it back, and
+the motor would be burned out unless some means were provided to
+protect it for the moment. This is done by means of a starting
+rheostat, similar to the regulating rheostat on the dynamo
+switchboard. This resistance box is connected in "series" with the
+armature, in the case of shunt and compound motors; and with the
+entire<span class='pagenum'><a name="Page_149" id="Page_149">[Pg 149]</a></span> motor circuit in the case of a series machine.</p>
+
+<p>A <i>series</i> motor has a powerful starting torque, and adjusts its speed
+to the load. It is used almost altogether in street cars. It can be
+used in stump pulling, or derrick work, such as using a hay fork. It
+must always be operated under load, otherwise, it would increase in
+speed until it tore itself to pieces through mechanical strain. The
+ingenious farmer who puts together an electric plow, with the mains
+following behind on a reel, will use a series motor.</p>
+
+<p>A <i>shunt</i> motor should be used in all situations where a fairly
+uniform speed under load is required, such as separating, in milking
+machines, running a lathe, an ensilage cutter, vacuum cleaners,
+grinders, etc.</p>
+
+<p>The <i>compound</i> motor has the characteristics of the series and shunt
+motors, giving an increased starting torque, and a more nearly
+constant speed under varying loads than the shunt motor, since the
+latter drops off slightly in speed with increasing load.</p>
+
+
+<p><span class='pagenum'><a name="Page_150" id="Page_150">[Pg 150]</a></span></p><p class="center padtop"><i>Flexible Power</i></p>
+
+<p>An electric motor is an extremely satisfactory form of power because
+it is so flexible. Thus, one may use a five horsepower motor for a one
+horsepower task, and the motor will use only one electrical horsepower
+in current&mdash;just enough to overcome the task imposed on it. For this
+reason, a large-sized motor may be used for any operation, from one
+requiring small power, up to its full capacity. It will take an
+overload, the same as a dynamo. In other words it is "eager" for any
+task imposed on it; therefore it must be protected by fuses, or it
+will consume itself, if too big an overload is imposed on it.</p>
+
+<p>A one horsepower shunt or compound motor is very serviceable for
+routine farm operations, such as operating the separator, the churn,
+the milking machine, grinder, pump, and other small power jobs. Motors
+of &frac14; horsepower are handy in the kitchen, for grinding knives,
+polishing silver, etc., and can be used also for vacuum cleaners, and
+running the sewing<span class='pagenum'><a name="Page_151" id="Page_151">[Pg 151]</a></span> machine. For the larger operations, motors will
+vary from three horsepower for cutting ensilage, to fifteen horsepower
+for threshing. They can be mounted on trucks and conveyed from one
+point to another, being fed current from the mains by means of
+suitable wires wound on reels.</p>
+
+<p>Remember, in estimating the size of your plant for light, heat, and
+power, that it does not have to be big enough to use all the devices
+at one time. Also remember, that two water horsepower to one
+electrical horsepower is a very liberal allowance; and that a
+generator working under one-half or two-thirds capacity at normal
+loads will require less attention than a machine constantly being
+worked above its capacity. Therefore, let your generator be of liberal
+size, because the difference in cost between a 5 and 10 kilowatt
+machine is not in proportion to their capacity. In fact (especially
+among second-hand machines), the difference in cost is very small. The
+mere fact that the generator is of 110 electrical horsepower capacity
+does not require<span class='pagenum'><a name="Page_152" id="Page_152">[Pg 152]</a></span> a turbine of 20 horsepower. The chances are that
+(unless you wish to heat your house and do large power jobs) you will
+not use more than 3 to 5 electrical horsepower normally; therefore an
+allowance of 10 water horsepower, in this case, would be ample. A
+plant used simply for lighting the house and barn, for irons, and
+toasters, and one horsepower motors, need not exceed 2 or 2&frac12;
+kilowatts for the generator, and 5 or 6 horsepower for the turbine
+wheel. Normally it would not use one-half this capacity.</p>
+
+
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_153" id="Page_153">[Pg 153]</a></span></p>
+<h2><a name="CHAPTER_VII" id="CHAPTER_VII"></a>CHAPTER VII</h2>
+
+<p class="subhead2">TRANSMISSION LINES</p>
+
+<div class="blockquot"><p>Copper wire&mdash;Setting of poles&mdash;Loss of power in transmission&mdash;Ohm's
+Law and examples of how it is used in figuring size of
+wire&mdash;Copper-wire tables&mdash;Examples of transmission lines&mdash;When to
+use high voltages&mdash;Over-compounding a dynamo to overcome
+transmission loss.</p></div>
+
+
+<p>Having determined on the location of the farm water-power electric
+plant, and its capacity, in terms of electricity, there remains the
+wiring, for the transmission line, and the house and barn.</p>
+
+<p>For transmission lines, copper wire covered with waterproof braid&mdash;the
+so-called weatherproof wire of the trade&mdash;is used. Under no
+circumstances should a wire smaller than No. 8, B. &amp; S. gauge be used
+for this purpose, as it would not be strong enough mechanically. The
+poles should be of chestnut or cedar, 25 feet long, and set four feet
+in the ground. Where it is necessary to follow highways, they<span class='pagenum'><a name="Page_154" id="Page_154">[Pg 154]</a></span> should
+be set on the fence line; and in crossing public highways, the
+ordinance of your own town must guide you. Some towns prescribe a
+height of 19 feet above the road, others 27 feet, some 30. Direct
+current, such as is advised for farm installations, under ordinary
+circumstances, does not affect telephone wires, and therefore
+transmission lines may be strung on telephone poles. Poles are set at
+an average distance of 8 rods; they are set inclined outward on
+corners. Sometimes it is necessary to brace them with guy wires or
+wooden braces. Glass insulators are used to fasten the wires to the
+cross-arms of the poles, and the tie-wires used for this purpose must
+be the same size as the main wire and carry the same insulation.</p>
+
+
+<p class="center padtop"><i>Size of Wire for Transmission</i></p>
+
+<p>To determine the size of the transmission wires will require knowledge
+of the strength of current (in amperes) to be carried, and the
+distance in feet. In transmission, the electric current is again
+analogous to water flowing in<span class='pagenum'><a name="Page_155" id="Page_155">[Pg 155]</a></span> pipes. It is subject to resistance,
+which cuts down the amount of current (in watts) delivered.</p>
+
+<div class="figcenter" style="width: 500px;">
+<a href="images/d155-big.jpg"><img src="images/d155-small.jpg" width="500" height="337" alt="" title="" /></a>
+Bringing wires into the house or barn
+</div>
+
+<p>The loss in transmission is primarily measured in volts; and since the
+capacity of an electric current for work equals the <i>volts</i> multiplied
+by <i>amperes</i>, which gives <i>watts</i>, every volt lost reduces the working
+capacity of the current by so much. This loss is referred to by
+electrical engineers as the "C^2R loss," which is another way of
+saying that the loss is equal to the <i>square of the current in
+amperes</i>, multiplied by <i>ohms</i> resistance. Thus, if the<span class='pagenum'><a name="Page_156" id="Page_156">[Pg 156]</a></span> amperes
+carried is 10, and the ohms resistance of the line is 5, then the loss
+in watts to convey that current would be (10 &times; 10) &times; 5, or 500 watts,
+nearly a horsepower.</p>
+
+<p>The pressure of <i>one volt</i> (as we have seen in another chapter) is
+sufficient to force <i>one ampere</i>, through a resistance of <i>one ohm</i>.
+Such a current would have no capacity for work, since its pressure
+would be consumed in the mere act of transmission.</p>
+
+<p>If, however, the pressure were <i>110 volts</i>, and the current <i>one
+ampere</i>, and the resistance <i>one ohm</i>, the effective pressure after
+transmission would be 110-1, or 109 volts.</p>
+
+<p>To force a 110-volt current of <i>50 amperes</i> through the resistance of
+<i>one ohm</i>, would require the expenditure of <i>50 volts</i> pressure. Its
+capacity for work, after transmission, would be 110-50, or <i>60 volts,
+&times; 50 amperes</i>, or 3,000 watts. As this current consisted of <i>110 &times;
+50</i>, or 5,500 watts at the point of starting, the loss would be 2,500
+watts, or about 45 per cent. It is bad engineering to allow more than
+10 per cent loss in transmission.</p>
+
+<p><span class='pagenum'><a name="Page_157" id="Page_157">[Pg 157]</a></span></p><p>There are two ways of keeping this loss down. One is by increasing
+the size of the transmission wires, thus cutting down the resistance
+in ohms; the other way is by raising the voltage, thus cutting down
+the per cent loss. For instance, suppose the pressure was 1,100 volts,
+instead of 110 volts. Five amperes at 1,100 volts pressure, gives the
+same number of watts, power, as 50 amperes, at 110 volts pressure.
+Therefore it would be necessary to carry only 5 amperes, at this rate.
+The loss would be 5 volts, or less than &frac12; of 1 per cent, as compared
+with 45 per cent with 110 volts.</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d157.jpg" width="500" height="54" alt="" title="" />
+Splicing transmission wire
+</div>
+
+
+<p>In large generating stations, where individual dynamos frequently
+generate as much as 20,000 horsepower, and the current must be
+transmitted over several hundred miles of territory, the voltage is
+frequently as high as 150,000, with the amperes reduced in proportion.
+Then the voltage is lowered to a suitable rate, and the amperage
+raised in proportion, by special machinery, at the point of use.</p>
+
+<p>It is the principle of the C^2R loss, which the<span class='pagenum'><a name="Page_158" id="Page_158">[Pg 158]</a></span> farmer must apply in
+determining the size of wire he is to use in transmitting his current
+from the generator switchboard to his house or barn. The wire table on
+page 159, together with the formula to be used in connection with it,
+reduce the calculations necessary to simple arithmetic. In this table
+the resistance of the various sizes of wire is computed from the fact
+that a wire of pure copper 1 foot long, and 1/1000 inch in diameter
+(equal to one circular mill) offers a resistance of 10.6 ohms to the
+foot. The principle of the C^2R loss is founded on Ohm's Law, which is
+explained in Chapter V.</p>
+
+<p>The formula by which the size of transmission wire is determined, for
+any given distance, and a given number of amperes, is as follows:</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/m158.jpg" width="500" height="68" alt="(Distance ft. one way × 22 × No. of amperes) / (Number of volts lost) = circular mills." title="" />
+</div>
+
+<p>In other words, multiply the <i>distance in feet</i> from mill to house by
+22, and multiply this product by the <i>number of amperes</i> to be<span class='pagenum'><a name="Page_159" id="Page_159">[Pg 159]</a></span>
+carried. Then divide the product by the <i>number of volts</i> to be lost;
+and the result will be the diameter of the wire required <i>in circular
+mills</i>. By referring to the table above, the B. &amp; S. gauge of the wire
+necessary for transmission, can be found from the nearest
+corresponding number under the second column, entitled "circular mills
+area."</p>
+
+
+<p class="subhead2 padtop">COPPER WIRE TABLE</p>
+
+<table summary="copper wire table" style="width: 75%;"><tbody>
+<tr><td class="tr"><i>B.&amp; S.<br />Gauge</i></td>   <td class="tr"><i>Feet per Lb.</i></td>     <td class="tr"><i>Area in<br />circular mills</i></td>   <td class="tr"><i>(R) Ohms<br />per 1,000 feet</i></td>   <td class="tr"><i>Feet<br />per Ohm</i></td>      <td class="tr"><i>(R) Ohms<br />per pound</i></td></tr>
+<tr><td class="tr">0000</td>  <td class="tr">1.561</td>  <td class="tr">211,600.0</td>  <td class="tr">.04904</td>  <td class="tr">20,392.90</td>  <td class="tr">.00007653</td></tr>
+<tr><td class="tr">000</td>  <td class="tr">1.969</td>  <td class="tr">167,805.0</td>  <td class="tr">.06184</td>  <td class="tr">16,172.10</td>  <td class="tr">.00012169</td></tr>
+<tr><td class="tr">00</td>  <td class="tr">2.482</td>  <td class="tr">133,079.0</td>  <td class="tr">.07797</td>  <td class="tr">12,825.40</td>  <td class="tr">.00019438</td></tr>
+<tr><td class="tr">0</td>  <td class="tr">3.130</td>  <td class="tr">105,534.0</td>  <td class="tr">.09829</td>  <td class="tr">10,176.40</td>  <td class="tr">.00030734</td></tr>
+<tr><td class="tr">1</td>  <td class="tr">3.947</td>  <td class="tr">83,694.0</td>  <td class="tr">.12398</td>  <td class="tr">8,066.00</td>  <td class="tr">.00048920</td></tr>
+<tr><td class="tr">2</td>  <td class="tr">4.977</td>  <td class="tr">66,373.0</td>  <td class="tr">.15633</td>  <td class="tr">6,396.70</td>  <td class="tr">.00077784</td></tr>
+<tr><td class="tr">3</td>  <td class="tr">6.276</td>  <td class="tr">52,634.0</td>  <td class="tr">.19714</td>  <td class="tr">5,072.50</td>  <td class="tr">.00123700</td></tr>
+<tr><td class="tr">4</td>  <td class="tr">7.914</td>  <td class="tr">41,742.0</td>  <td class="tr">.24858</td>  <td class="tr">4,022.90</td>  <td class="tr">.00196660</td></tr>
+<tr><td class="tr">5</td>  <td class="tr">9.980</td>  <td class="tr">33,102.0</td>  <td class="tr">.31346</td>  <td class="tr">3,190.20</td>  <td class="tr">.00312730</td></tr>
+<tr><td class="tr">6</td>  <td class="tr">12.58</td>  <td class="tr">26,250.0</td>  <td class="tr">.39528</td>  <td class="tr">2,529.90</td>  <td class="tr">.00497280</td></tr>
+<tr><td class="tr">7</td>  <td class="tr">15.87</td>  <td class="tr">20,816.0</td>  <td class="tr">.49845</td>  <td class="tr">2,006.20</td>  <td class="tr">.00790780</td></tr>
+<tr><td class="tr">8</td>  <td class="tr">20.01</td>  <td class="tr">16,509.0</td>  <td class="tr">.62840</td>  <td class="tr">1,591.10</td>  <td class="tr">.01257190</td></tr>
+<tr><td class="tr">9</td>  <td class="tr">25.23</td>  <td class="tr">13,094.0</td>  <td class="tr">.79242</td>  <td class="tr">1,262.00</td>  <td class="tr">.01998530</td></tr>
+<tr><td class="tr">10</td>  <td class="tr">31.82</td>  <td class="tr">10,381.0</td>  <td class="tr">.99948</td>  <td class="tr">1,000.50</td>  <td class="tr">.03178460</td></tr>
+<tr><td class="tr">11</td>  <td class="tr">40.12</td>  <td class="tr">8,234.0</td>  <td class="tr">1.26020</td>  <td class="tr">793.56</td>  <td class="tr">.05054130</td></tr>
+<tr><td class="tr">12</td>  <td class="tr">50.59</td>  <td class="tr">6,529.9</td>  <td class="tr">1.58900</td>  <td class="tr">629.32</td>  <td class="tr">.08036410</td></tr>
+<tr><td class="tr">13</td>  <td class="tr">63.79</td>  <td class="tr">5,178.4</td>  <td class="tr">2.00370</td>  <td class="tr">499.06</td>  <td class="tr">.12778800</td></tr>
+<tr><td class="tr">14</td>  <td class="tr">80.44</td>  <td class="tr">4,106.8</td>  <td class="tr">2.52660</td>  <td class="tr">395.79</td>  <td class="tr">.20318000</td></tr>
+<tr><td class="tr">15</td>  <td class="tr">101.4</td>  <td class="tr">3,256.7</td>  <td class="tr">3.18600</td>  <td class="tr">313.87</td>  <td class="tr">.32307900</td></tr>
+<tr><td class="tr">16</td>  <td class="tr">127.9</td>  <td class="tr">2,582.9</td>  <td class="tr">4.01760</td>  <td class="tr">248.90</td>  <td class="tr">.51373700</td></tr>
+<tr><td class="tr">17</td>  <td class="tr">161.3</td>  <td class="tr">2,048.2</td>  <td class="tr">5.06600</td>  <td class="tr">197.39</td>  <td class="tr">.81683900</td></tr>
+<tr><td class="tr">18</td>  <td class="tr">203.4</td>  <td class="tr">1,624.3</td>  <td class="tr">6.38800</td>  <td class="tr">156.54</td>  <td class="tr">1.29876400</td></tr>
+</tbody></table>
+
+
+<p class="subhead2">CARRYING CAPACITY OF WIRES AND WEIGHT</p>
+
+<table summary="carrying capacity" style="width: 75%;"><tbody>
+
+<tr><td class="tr"><i>B. &amp; S.<br />Gauge No.</i></td>    <td class="tr"><i>Weight 1,000 ft.<br />Weatherproof (Pounds)</i></td>     <td class="tr"><i>Carrying capacity<br />Weatherproof (Amperes)</i></td>       <td class="tr"><i>Carrying capacity<br />rubber cov. (Amperes)</i></td></tr>
+<tr><td class="tr">0000</td>  <td class="tr">800</td>  <td class="tr">312</td>  <td class="tr">175</td></tr>
+<tr><td class="tr">000</td>  <td class="tr">666</td>  <td class="tr">262</td>  <td class="tr">145</td></tr>
+<tr><td class="tr">00</td>  <td class="tr">500</td>  <td class="tr">220</td>  <td class="tr">120</td></tr>
+<tr><td class="tr">0</td>  <td class="tr">363</td>  <td class="tr">185</td>  <td class="tr">100</td></tr>
+<tr><td class="tr">1</td>  <td class="tr">313</td>  <td class="tr">156</td>  <td class="tr">95</td></tr>
+<tr><td class="tr">2</td>  <td class="tr">250</td>  <td class="tr">131</td>  <td class="tr">70</td></tr>
+<tr><td class="tr">3</td>  <td class="tr">200</td>  <td class="tr">110</td>  <td class="tr">60</td></tr>
+<tr><td class="tr">4</td>  <td class="tr">144</td>  <td class="tr">92</td>  <td class="tr">50</td></tr>
+<tr><td class="tr">5</td>  <td class="tr">125</td>  <td class="tr">77</td>  <td class="tr">45</td></tr>
+<tr><td class="tr">6</td>  <td class="tr">105</td>  <td class="tr">65</td>  <td class="tr">35</td></tr>
+<tr><td class="tr">7</td>  <td class="tr">87</td>  <td class="tr">55</td>  <td class="tr">30</td></tr>
+<tr><td class="tr">8</td>  <td class="tr">69</td>  <td class="tr">46</td>  <td class="tr">25</td></tr>
+<tr><td class="tr">10</td>  <td class="tr">50</td>  <td class="tr">32</td>  <td class="tr">20</td></tr>
+<tr><td class="tr">12</td>  <td class="tr">31</td>  <td class="tr">23</td>  <td class="tr">15</td></tr>
+<tr><td class="tr">14</td>  <td class="tr">22</td>  <td class="tr">16</td>  <td class="tr">10</td></tr>
+<tr><td class="tr">16</td>  <td class="tr">14</td>  <td class="tr">8</td>  <td class="tr">5</td></tr>
+<tr><td class="tr">18</td>  <td class="tr">11</td>  <td class="tr">5</td>  <td class="tr">3</td></tr>
+</tbody></table>
+
+<p><span class='pagenum'><a name="Page_160" id="Page_160">[Pg 160]</a></span></p><p class="padtop">Since two wires are required for electrical transmission, the above
+formula is made simple by counting the distance only one way, in feet,
+and doubling the resistance constant, 10.6, which, for convenience is
+taken as 22, instead of 21.2.</p>
+
+
+<p class="center padtop"><i>Examples of Transmission Lines</i></p>
+
+<p>As an example, let us say that Farmer Jones has installed a
+water-power electric plant on his brook, <i>200 yards distant</i> from his
+house. The generator is a 5 kilowatt machine, capable of producing <i>45
+amperes</i> at <i>110 volts pressure</i>. He has a 3 horsepower motor, drawing
+26 amperes at full load; he has 20 lights of varying capacities,
+requiring<span class='pagenum'><a name="Page_161" id="Page_161">[Pg 161]</a></span> 1,200 watts, or 10 amperes when all on; and his wife uses
+irons, toasters, etc., which amount to another 9 or 10 amperes&mdash;say 45
+altogether. The chances are that he will never use all of the
+apparatus at one time; but for flexibility, and his own satisfaction
+in not having to stop to think if he is overloading his wires, he
+would like to be able to draw the full <i>45 amperes</i> if he wishes to.
+He is willing to allow <i>5 per cent loss</i> in transmission. <i>What size
+wires will be necessary, and what will they cost?</i> Substituting these
+values in the above formula, the result is:</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/m161.jpg" width="500" height="69" alt="Answer: (600 × 22 × 45) / 5.5 = 108,000 circular mills." title="" />
+</div>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d161.jpg" width="500" height="132" alt="" title="" />
+Transmission wire on glass insulator
+</div>
+
+
+<p>Referring to the table, No. 0 wire is 105,534 circular mills, and is
+near enough; so this wire would be used. It would require 1,200 feet,<span class='pagenum'><a name="Page_162" id="Page_162">[Pg 162]</a></span>
+which would weigh, by the second table, 435.6 pounds. At 19 cents a
+pound, it would cost $82.76.</p>
+
+<p>Farmer Jones says this is more money than he cares to spend for
+transmission. As a matter of fact, he says, he never uses his motor
+except in the daytime, when his lights are not burning; so the maximum
+load on his line at any one time would be <i>26 amperes</i>, not 45. <i>What
+size wire would he use in this instance?</i></p>
+
+<p>Substituting 26 for 45 in the equation, the result is 61,300 circular
+mills, which corresponds to No. 2 wire. It would cost $57.00.</p>
+
+<p>Now, if Farmer Jones, in an emergency, wished to use his motor at the
+same time he was using all his lights and his wife was ironing and
+making toast&mdash;in other words, if he wanted to use the <i>45 amperes</i>
+capacity of his dynamo, <i>how many volts would he lose?</i> To get this
+answer, we change the formula about, until it reads as follows:</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/m162.jpg" width="500" height="55" alt="(Distance in feet × 22 × amperes) / circular mills = Number of volts lost" title="" />
+</div>
+
+<p><span class='pagenum'><a name="Page_163" id="Page_163">[Pg 163]</a></span></p><p>Substituting values, we have, in this case,</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/m163.jpg" width="500" height="99" alt="(600 × 22 × 45) / 66,373 (No. 2) = 9 volts," title="" />
+</div>
+
+<p>nearly, less than 10 per cent. This is a very efficient
+line, under the circumstances. Now if he is willing to lose 10 per
+cent on <i>half-load</i>, instead of full load, he can save still more
+money in line wire. In that case (as you can find by applying the
+formula again), he could use No. 5 wire, at a cost of $28.50. He would
+lose 11 volts pressure drawing 26 amperes; and he would lose 18 volts
+pressure drawing 45 amperes, if by any chance he wished to use full
+load.</p>
+
+<p>In actual practice, this dynamo would be regulated, by means of the
+field resistance, to register 110 plus 11 volts, or 121 volts at the
+switchboard to make up for the loss at half-load. At full load, his
+voltage at the end of the line would be 121 minus 18, or 103 volts;
+his motor would run a shade slower, at this voltage, and his lights
+would be slightly dimmer. He would probably not notice the difference.
+If he did, he could walk over to his generating station, and raise<span class='pagenum'><a name="Page_164" id="Page_164">[Pg 164]</a></span>
+the voltage a further 7 volts by turning the rheostat handle another
+notch.</p>
+
+<div class="figcenter" style="width: 400px;">
+<img src="images/d164.jpg" width="400" height="604" alt="" title="" />
+A barn-yard light
+</div>
+
+
+<p>Thousands of plants can be located within 100 feet of the house. If
+Farmer Jones could do this, he could use No. 8 wire, costing $2.62.
+The drop in pressure would be 5.99 volts at full load&mdash;so small it
+could be ignored entirely. In this case the voltmeter should be made
+to read 116 volts at the switchboard, by means of the rheostat.</p>
+
+<p>If, on the other hand, this plant were 1,000 feet away from the house
+and the loss 10 volts the size wire would be</p>
+
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/m164.jpg" width="500" height="79" alt="(1,000 × 22 × 45) / 10 = 99,000 circular mills;" title="" />
+</div>
+
+<p>a No. 0 wire comes nearest to this figure, and its cost, for 2,000
+feet, at 19 cents a pound, would be $137.94.<span class='pagenum'><a name="Page_165" id="Page_165">[Pg 165]</a></span> A No. 0000 wire, costing
+$294.00, would give a 5 per cent drop at full load. In this case, the
+cost of transmission can be reduced to a much lower figure, by
+allowing a bigger drop at half-load, with regulation at the
+switchboard. Thus, a No. 2 wire here, costing but $95, would be
+satisfactory in every way. The loss at half-load would be about 9
+volts, and the rheostat would be set permanently for 119 or 120 volts.
+A modern dynamo can be regulated in voltage by over 25 per cent in
+either direction, without harm, if care is taken not to overload it.</p>
+
+
+<p class="center padtop"><i>Benefit of Higher Voltages</i></p>
+
+<p>If Farmer Jones' plant is a half of a mile away from the house, he
+faces a more serious proposition in the way of transmission. Say he
+wishes to transmit 26 amperes with a loss of 10 volts. What size wire
+will be necessary?</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/m165.jpg" width="500" height="60" alt="Thus: (2640 × 22 × 26) / 10 = 151,000 circular mills." title="" />
+</div>
+
+<p>A No. 000 wire is nearest this size, and 5,280 feet of it would cost
+over $650.00. This cost<span class='pagenum'><a name="Page_166" id="Page_166">[Pg 166]</a></span> would be prohibitive. If, however, he
+installed a 220-volt dynamo&mdash;at no increase in cost&mdash;then he would
+have to transmit only a half of 26 amperes, or 13 amperes, and he
+could allow 22 volts loss, counting 10 per cent. In this case, the
+problem would work out as follows:</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/m166.jpg" width="500" height="65" alt="(2640 × 22 × 13) / 22 = 34,320 circular mills," title="" />
+</div>
+
+<p>or approximately a No. 5 wire which, at 19 cents a pound, would cost
+$120.65.</p>
+
+<p>Install a 550-volt generator, instead of a 220-volt machine and the
+amperes necessary would be cut to 5.2, and the volts lost would be
+raised to 55. In this case a No. 12 wire would carry the current; but
+since it would not be strong enough for stringing on poles, a No. 8
+wire would be used, costing about $63.</p>
+
+<p>It will be readily seen from these examples how voltage influences the
+efficiency of transmission. Current generated at a pressure in excess
+of 550 volts is not to be recommended for farm plants unless an expert
+is in charge.<span class='pagenum'><a name="Page_167" id="Page_167">[Pg 167]</a></span> A safer rule is not to exceed 220 volts, for while 550
+volts is not necessarily deadly, it is dangerous. When one goes into
+higher voltages, it is necessary to change the type of dynamo to
+<i>alternating current</i>, so that the current can be transformed to safe
+voltages at the point where it is used. Since only the occasional farm
+plant requires a high-tension system, the details of such a plant will
+not be gone into here.</p>
+
+<p>In transmitting the electric current over miles of territory,
+engineers are accustomed to figure 1,000 volts for each mile. Since
+this is a deadly pressure, it should not be handled by any one not an
+expert, which, in this case, the farmer is not.</p>
+
+
+<p class="center padtop"><i>Over-Compounding the Generator</i></p>
+
+<p>One can absorb the loss in transmission frequently, by
+over-compounding the machine. In describing the compound machine, in
+Chapter Five, it is shown that the usual compound dynamo on the market
+is the so-called flat-compounded type. In such a dynamo, the<span class='pagenum'><a name="Page_168" id="Page_168">[Pg 168]</a></span> voltage
+remains constant at the switchboard, from no load to full load,
+allowing for a slight curve which need not be taken into account.</p>
+
+<p>Now, by adding a few more turns to the series wires on the field coils
+of such a dynamo, a machine is to be had which gradually raises its
+voltage as the load comes on in increasing volume. Thus, one could
+secure such a machine, which would begin generating at 110 volts, and
+would gradually rise to 150 at full load. Yet the voltage would remain
+constant at the point of use, the excess being absorbed in
+transmission. A machine of this type can be made to respond to any
+required rise in voltage.</p>
+
+<p>As an example of how to take advantage of this very valuable fact, let
+us take an instance:</p>
+
+<p>Say that Farmer Jones has a transmission line 1,000 feet long strung
+with No. 7 copper wire. This 2,000 feet of wire would introduce a
+resistance of one ohm in the circuit. That is, every ampere of current
+drawn at his house would cause the working voltage there to fall<span class='pagenum'><a name="Page_169" id="Page_169">[Pg 169]</a></span> one
+volt. If he drew 26 amperes, the voltage would fall, at the house, 26
+volts. If his switchboard voltage was set at say 120, the voltage at
+his house, at 26 amperes of load, would fall to 94 volts, which would
+cause his lights to dim considerably. It would be a very
+unsatisfactory transmission line, with a flat-compounded dynamo.</p>
+
+<p>On the other hand, if his dynamo was over-compounded 25 per cent&mdash;that
+is, if it gained 28 volts from no load to full load, the system would
+be perfect. In this case, the dynamo would be operated at 110 volts
+pressure at the switchboard with no load. At full load the voltmeter
+would indicate 110 plus 26, or 136 volts. The one or two lights burned
+at the power plant would be subject to a severe strain; but the 50 or
+100 lights burned at the house and barn would burn at constant
+voltage, which is very economical for lamps.</p>
+
+<p>The task of over-compounding a dynamo can be done by any trained
+electrician. The farmer himself, if he progresses far enough in his
+study of electricity, can do it. It is necessary <span class='pagenum'><a name="Page_170" id="Page_170">[Pg 170]</a></span>to remove the top or
+"series" winding from the field coils. Count the number of turns of
+this wire to each spool. Then procure some identical wire in town and
+begin experimenting. Say you found four turns of field wire to each
+spool. Now wind on five, or six, being careful to wind it in the same
+direction as the coils you removed and connect it in the same way. If
+this additional number of turns does not raise the voltage enough, in
+actual practice, when the dynamo is running from no load to full load,
+add another turn or two. With patience, the task can be done by any
+careful mechanic. The danger is in not winding the coils the same way
+as before, and getting the connections wrong. To prevent this mistake,
+make a chart of the "series" coils as you take them off.</p>
+
+<p>To make the task of over-compounding your own dynamo even more simple,
+write to the manufacturers, giving style and factory number of your
+machine. Tell them how much voltage rise you wish to secure, and ask
+them how many turns of "series" wire should<span class='pagenum'><a name="Page_171" id="Page_171">[Pg 171]</a></span> be wound on each spool in
+place of the old "series" coil. They could tell you exactly, since
+they have mathematical diagrams of each machine they make.</p>
+
+<p>Avoid overloading an over-compounded machine. Since its voltage is
+raised automatically, its output in watts is increased a similar
+amount at the switchboard, and, for a given resistance, its output in
+amperes would be increased the same amount, as can be ascertained by
+applying Ohm's Law. Your ammeter is the best guide. Your machine is
+built to stand a certain number of amperes, and this should not be
+exceeded in general practice.</p>
+
+
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_172" id="Page_172">[Pg 172]</a></span></p>
+<h2><a name="CHAPTER_VIII" id="CHAPTER_VIII"></a>CHAPTER VIII</h2>
+
+<p class="subhead2">WIRING THE HOUSE</p>
+
+<div class="blockquot"><p>The insurance code&mdash;Different kinds of wiring described&mdash;Wooden
+moulding cheap and effective&mdash;The distributing panel&mdash;Branch
+circuits&mdash;Protecting the circuits&mdash;The use of porcelain tubes and
+other insulating devices&mdash;Putting up chandeliers and wall
+brackets&mdash;"Multiple" connections&mdash;How to connect a wall
+switch&mdash;Special wiring required for heat and power circuits&mdash;Knob
+and cleat wiring, its advantages and drawbacks.</p></div>
+
+
+<p>The task of wiring your house is a simple one, with well-defined rules
+prescribed by your insurance company. Electricity, properly installed,
+is much safer than oil lamps&mdash;so much so indeed that insurance
+companies are ready to quote especial rates. But they require that the
+wiring be done in accordance with rules laid down by their experts,
+who form a powerful organization known as the National Board of Fire
+Underwriters. Ask your insurance agent for a copy of the code rules.</p>
+
+<p><span class='pagenum'><a name="Page_173" id="Page_173">[Pg 173]</a></span></p><p>Danger of fire from an electric current comes from the "short
+circuit," partial or complete; and it is against this danger that the
+rules guard one. The amount of electricity flowing through a short
+circuit is limited only by the fuse protecting that line; and since
+there is no substance known that can withstand the heat of the
+electric arc, short circuits must be guarded against. Happily the
+current is so easily controlled that the fire hazard is eliminated
+entirely&mdash;something which cannot be done with oil lamps.</p>
+
+<p>In house-wiring for farm plants, the wire should be rubber-covered,
+and not smaller than No. 14 B. &amp; S. gauge. This is the wire to use on
+all lamp circuits. It costs about $0.85 cents per 100 feet. There are
+four kinds of wiring permitted, under the insurance code:</p>
+
+<p>(1) <i>Flexible armoured cable</i>: This consists of two-wire cable,
+protected with a covering of flexible steel. It is installed out of
+sight between the walls, and provides suitable outlets for lamps,
+etc., by means of metal boxes<span class='pagenum'><a name="Page_174" id="Page_174">[Pg 174]</a></span> set flush with the plaster. It is
+easily installed in a house being built, but requires much tearing
+down of plaster for an old house. Since its expense prohibits it in
+the average farm house, this system will not be described in detail
+here.</p>
+
+<p>(2) <i>Rigid and flexible conduit</i>: As the name implies this system
+consists of iron pipe, in connection with flexible conduit, run
+between the walls. It differs from the above system, in that the pipes
+with their fittings and outlet boxes are installed first, and the
+wires are then "fished" through them. Duplex wires&mdash;the two wires of
+the circuit woven in one braid&mdash;are used; and a liberal amount of
+soapstone, and occasionally kerosene, are used to make the wires slip
+easily into place. This is the most expensive system, and the best;
+but it is difficult to install it in an old house without tearing down
+a good deal of plaster. It has the advantage of being absolutely
+waterproof and fireproof.</p>
+
+<p><span class='pagenum'><a name="Page_175" id="Page_175">[Pg 175]</a></span></p><p>(3) <i>Wooden moulding</i>: This is simply moulding, providing two
+raceways for the insulated wires to run in, and covered with a
+capping. It is nailed or screwed firmly to the wall, on top of the
+plaster; and when the wires have been installed in their respective
+slots and the capping tacked on, the moulding is given a coat of paint
+to make it in harmony with the other moulding in the room. This system
+is cheap, safe, and easily installed, and will be described in detail
+here.</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d175.jpg" width="500" height="348" alt="" title="" />
+Detail of wooden moulding
+</div>
+
+
+<p>(4) <i>Open wiring</i>: In open wiring, the wires are stretched from one
+support to another (such as beams) and held by means of porcelain
+cleats, or knobs. It is the simplest to install; but it has the
+objection of leaving the wires unprotected, and is ugly. It is very
+satisfactory in barns or out-buildings however.</p>
+
+
+<p><span class='pagenum'><a name="Page_176" id="Page_176">[Pg 176]</a></span></p><p class="center padtop"><i>The Distributing Panel</i></p>
+
+<p>The first point to consider in wiring a house with wooden moulding is
+the distribution board. It should be located centrally, on the wall
+near the ceiling, so as to be out of ordinary reach. It consists of a
+panel of wood&mdash;though fireproof material is better&mdash;firmly screwed to
+the wall, and containing in a row, the porcelain cut-outs, as shown in
+the cut, from which the various branch circuits are to be led. Each
+cut-out provides for two branch circuits; and each branch contains
+receptacles for two plug fuses. These fuses should be of 6 amperes
+each. The Insurance Code limits the amount of electricity that may be
+drawn on any branch lamp circuit to 660 watts; and these fuses protect
+the circuit from drafts beyond this amount.</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d176.jpg" width="500" height="241" alt="" title="" />
+Porcelain cut-out and plug fuse
+</div>
+
+
+<p>The mains, leading from the entrance switch, as shown in the diagram,
+to the panel<span class='pagenum'><a name="Page_177" id="Page_177">[Pg 177]</a></span> board, should be of the same size as the transmission
+wire itself, and rubber-covered. These mains terminate at the
+distributing board. They are connected to the terminals of the
+cut-outs by means of heavy brass screws.</p>
+
+
+<p class="center padtop"><i>Wire Joints</i></p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d177.jpg" width="500" height="213" alt="" title="" />
+Examples of cleat and knob wiring, 1, 2, 3; wire
+joints, 4; flexible armoured conductor, 5
+</div>
+
+
+<p>The branch circuits are, as has been said, of No. 14 rubber-covered
+wire, running concealed in wooden moulding. All joints or splices in
+this wire are made, as shown in the illustration, by first scraping
+the wires bright, and fastening them stoutly together. This joint is
+then soldered, to make the connection electrically perfect. Soft
+solder is used, with<span class='pagenum'><a name="Page_178" id="Page_178">[Pg 178]</a></span> ordinary soldering salts. There are several
+compounds on the market, consisting of soft solder in powder form,
+ready-mixed with flux. Coat the wire joint with this paste and apply
+the flame of an alcohol lamp. The soldered joint is then covered with
+rubber tape, and over this ordinary friction tape is wound on. A neat
+joint should not be larger than the diameter of the wire before
+insulation is removed.</p>
+
+
+<p class="center padtop"><i>Branch Circuits</i></p>
+
+<p>First, make a diagram of your rooms and indicate where you wish lamps,
+or outlets for other purposes. Since wooden moulding can be run across
+ceilings, and up or down walls, lamps may be located in places where
+they are out of the way. In planning the circuit, remember that you
+will want many outlets in handy places on the walls, from which
+portable cords will convey current to table lamps, to electric irons
+and toasters and other handy devices which can be used on the lamp
+circuit. These outlets are made of porcelain,<span class='pagenum'><a name="Page_179" id="Page_179">[Pg 179]</a></span> in two pieces. One
+piece is merely a continuation of the moulding itself; and the other
+is a cap to connect permanently to the end of the lamp or iron cord,
+which may be snapped into place in a second. Since there are a great
+many designs of separable current taps on the market, it is well to
+select one design and stick to it throughout the house, so that any
+device can be connected to any outlet.</p>
+
+<p>The code permits 660 watts on each circuit. This would allow 12 lamps
+of 55 watts each. It is well to limit any one circuit to 6 lamps; this
+will give leeway for the use of small stoves, irons, toasters, etc.
+without overloading the circuit and causing a fuse to blow.</p>
+
+<p>Having installed your distributing board, with its cut-outs, figure
+out the course of your first branch circuit. Let us say it will
+provide lights and outlets for the dining room and living room. It
+will be necessary to run the wires through the partitions or floors in
+several places. For this purpose porcelain tubes should be used,
+costing one to three cents each. Knock holes in the plaster at the
+determined<span class='pagenum'><a name="Page_180" id="Page_180">[Pg 180]</a></span> point, insert the tubes so they project &frac34; inch on each
+side, and fill up the ragged edge of the hole neatly with plaster.</p>
+
+<div class="figcenter" style="width: 500px;">
+<a href="images/d180-big.jpg"><img src="images/d180-small.jpg" width="500" height="433" alt="" title="" /></a>
+The distributing panel
+</div>
+
+
+<p>When all the tubes have been set in place, begin laying the moulding.
+Run it in a straight line, on the wall against the ceiling wherever
+possible, mitering the joints neatly. Whenever it is necessary to
+change the run from the ceiling to the wall and a miter cannot be
+made, the wires should be protected in<span class='pagenum'><a name="Page_181" id="Page_181">[Pg 181]</a></span> passing from one slot to the
+other by being enclosed in non-metallic flexible conduit, called
+circular loom.</p>
+
+<p>In running wooden moulding, avoid brick walls liable to sweat or draw
+dampness; keep away from places where the heat of a stove might
+destroy the rubber insulation of the wires; do not pass nearer than
+six inches to water pipes when possible&mdash;and when it is necessary to
+pass nearer than this, the wooden moulding should pass above the pipe,
+not below it, with at least an inch of air space intervening, thus
+avoiding dampness from sweating of pipes.</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d181.jpg" width="500" height="186" alt="" title="" />
+Snap switch connections
+</div>
+
+
+<p>Places where chandeliers or wall bracket lamps are to be installed
+permanently are fitted with wooden terminal blocks, which fit<span class='pagenum'><a name="Page_182" id="Page_182">[Pg 182]</a></span> over
+the moulding and flush with the plaster. These, after holes have been
+bored in them for the wires, and the wires drawn through, should be
+screwed firmly to the wall or ceiling, always choosing a joist or beam
+for support. Then a crow's-foot, or tripod of iron, tapped and
+threaded for iron pipe, is screwed to the terminal block. The iron
+pipe of the chandelier or wall bracket is then screwed home in this
+crow's-foot.</p>
+
+<div class="figleft" style="width: 400px;">
+<a href="images/d183-big.jpg"><img src="images/d183-small.jpg" width="400" height="553" alt="" title="" /></a>
+Detail of wooden moulding
+</div>
+
+<p>Do not begin stringing wires until all the moulding of the circuit has
+been laid. Then thread the wires through the wall or floor tubes and
+lay them in their respective slots. If trouble be found making them
+stay in place before the capping is put on, small tacks may be driven
+into the moulding beside them to hold them. When a terminal block is
+reached, a loop is made of each wire, through the hole cut in the
+block, if the circuit is to continue in the same direction. If it is
+to end there, the two wires are drawn through taut, and cut off at a
+length of 5 or 6 inches. These end wires, or loops, are then scraped
+bare and<span class='pagenum'><a name="Page_183" id="Page_183">[Pg 183]</a></span> spliced to the two wires coming out of the chandelier or
+wall bracket. This joint is then soldered and covered with tape, and
+the shell of the chandelier is screwed into place, covering the joint.</p>
+
+
+
+
+<p><span class='pagenum'><a name="Page_184" id="Page_184">[Pg 184]</a></span></p><p>If the moulding is run along the walls flush with the ceiling, as is
+usual, a branch is made for a wall light, or wall tap, by means of a
+porcelain "T," or branch-block, which provides the means for running
+the circuit at right angles to itself without letting the wires come
+in contact with each other where they cross. Separable current taps
+should be installed in handy places on all circuits, so that small
+heating devices may be used without removing the lamps from their
+sockets. The two wires are bared for half an inch where they run
+through these current taps, and are fastened by means of brass screws.</p>
+
+
+<p class="center padtop"><i>"Multiple" Connections</i></p>
+
+<p>All electric devices for this installation&mdash;lamps, irons, vacuum
+cleaners, motors&mdash;must be connected <i>across</i> the circuit&mdash;that is,
+bridged, from one wire to the other. This is called <i>multiple</i>, or
+shunt connection. There is only one exception to it, in wiring the
+house. That one exception is installing a wall switch, the ordinary
+snap switch. Since this wall<span class='pagenum'><a name="Page_185" id="Page_185">[Pg 185]</a></span> switch, is, in effect, merely an
+instrument, which opens or closes a circuit, it should be connected to
+only one wire, which is cut to provide two ends for the screw
+connections in the switch. When a moulding branch is run down from the
+ceiling to some convenient spot for a snap switch (with which to turn
+the lights of a room on or off), a porcelain "T" is not used. All that
+is necessary to do is to loop the bottom wire of the circuit down
+through the branch moulding, and connect it to the switch at a
+terminal block, or porcelain base.</p>
+
+<p>In wiring lamp fixtures, No. 14 rubber-covered wire will usually prove
+too large. For this purpose, No. 18 may be used, with one lamp to each
+loop. Hanging lamps may not be supported by electric lamp cord itself,
+if there is more than one lamp in the cluster, because the weight is
+apt to break the electrical connections. In such a case, the lamp
+should be supported by a chain, and the twisted cord conveying current
+to the electric bulbs, is woven in the links of the chain. For the
+pantry, kitchen, woodshed, barn, etc., a<span class='pagenum'><a name="Page_186" id="Page_186">[Pg 186]</a></span> single hanging lamp may be
+suspended from a fielding rosette, as shown in the cut, provided a
+single knot is tied inside both the rosette and the lamp socket, to
+make it secure. This makes a very cheap fixture. The rosette of
+porcelain will cost 15 cents; the lamp socket 20 cents, and the lamp
+cord suspending the lamp and carrying the current will cost 1&frac12;
+cents a foot; while a tin shade will cost another 15 cents.</p>
+
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d186.jpg" width="500" height="474" alt="" title="" />
+Detail of simple hanging lamp supported by rosette
+</div>
+
+
+
+<p><span class='pagenum'><a name="Page_187" id="Page_187">[Pg 187]</a></span></p><p class="center padtop"><i>Official Inspection</i></p>
+
+<p>In all communities, your insurance agent must inspect and pass your
+wiring before you are permitted to throw the main switch and turn on
+the electricity. Frequently they require that the moulding be left
+uncapped, until they have inspected it. If you have more than 660
+watts in lamps to a circuit; if your joints are not soldered and well
+taped; if the moulding is used in any concealed or damp place, the
+agent is liable to condemn your work and refuse permission to turn on
+the electricity. However the rules are so clearly defined that it is
+difficult to go wrong; and a farmer who does his own wiring and takes
+pride in its appearance is more apt to be right than a professional
+electrician who is careless at his task. After the work has been
+passed, tack on the moulding capping, with brads, and paint the
+moulding to match the woodwork.</p>
+
+<p>Wooden moulding wiring is perfectly satisfactory if properly
+installed. It is forbidden<span class='pagenum'><a name="Page_188" id="Page_188">[Pg 188]</a></span> in many large cities, because of the
+liability of careless workmanship. It should never be installed in
+damp places, or out of sight. If the work is well done, the system
+leaves nothing to be desired; and it has the additional advantage of
+being cheap, and easily done by any farmer who can use carpenter
+tools. Farmers with moulding machinery can make their own moulding.
+The code prescribes it shall be of straight-grained wood; that the
+raceways for the wires shall be separated by a tongue of wood one-half
+inch wide; and that the backing shall be at least 3/8 inch thick. It
+must be covered, inside and out, with at least two coats of
+moisture-repellant paint. It can be had ready-made for about 2 cents a
+foot.</p>
+
+
+<p class="center padtop"><i>Special Heating Circuits</i></p>
+
+<p>If one plans using electricity for heavy-duty stoves, such as ranges
+and radiators, it is necessary to install a separate heating circuit.
+This is the best procedure in any event, even when the devices are all
+small and suited to<span class='pagenum'><a name="Page_189" id="Page_189">[Pg 189]</a></span> lamp circuits. The wire used can be determined by
+referring to the table for carrying capacity, under the column headed
+"rubber-covered." A stove or range drawing 40 amperes, would require a
+No. 4 wire, in moulding. A good plan is to run the heating circuit
+through the basement, attaching it to the rafters by means of
+porcelain knobs. Branches can then be run up through the floor to
+places where outlets are desired. Such a branch circuit should carry
+fuses suitable to the allowed carrying capacity of the wire.</p>
+
+
+<p class="center padtop"><i>Knob and Cleat Wiring</i></p>
+
+<p>Knob and cleat wiring, such as is used extensively for barns and
+out-buildings, requires little explanation. The wires should not be
+closer than 2&frac12; inches in open places, and a wider space is better.
+The wires should be drawn taut, and supported by cleats or knobs at
+least every four feet. In case of branch circuits, one wire must be
+protected from the other it passes by means of a porcelain tube. It
+should never be used in damp<span class='pagenum'><a name="Page_190" id="Page_190">[Pg 190]</a></span> places, and should be kept clear of dust
+and litter, and protected from abrasion.</p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d190.jpg" width="500" height="451" alt="" title="" />
+Knob and cleat wiring
+</div>
+
+
+<p>Knob and tube wiring is frequently used in houses, being concealed
+between walls or flooring. In this case, the separate wires are
+stretched on adjoining beams or rafters, and porcelain tubes are used,
+in passing through cross beams. For a ceiling or wall outlet, a
+spliced branch is passed through the plaster by means of porcelain
+tubes or flexible loom.<span class='pagenum'><a name="Page_191" id="Page_191">[Pg 191]</a></span></p>
+
+<p>Wires from the house to the barn should be uniform with transmission
+wires. At the point of entry to buildings they must be at least six
+inches apart, and must take the form of the "drop loop" as shown in
+the illustration. A double-pole entrance switch must be provided,
+opening downward, with a double-pole fuse. In passing over buildings
+wires must not come closer than 7 feet to flat roofs, or one foot to a
+ridge roof. Feed-wires for electric motors should be determined from
+the table of safe carrying capacities, and should be of liberal size.</p>
+
+
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_192" id="Page_192">[Pg 192]</a></span></p>
+<h2><a name="CHAPTER_IX" id="CHAPTER_IX"></a>CHAPTER IX</h2>
+
+<p class="subhead2">THE ELECTRIC PLANT AT WORK</p>
+
+<div class="blockquot"><p>Direct-connected generating sets&mdash;Belt drive&mdash;The
+switchboard&mdash;Governors and voltage regulators&mdash;Methods of achieving
+constant pressure at all loads: Over-compounding the dynamo; A
+system of resistances; (A home-made electric radiator); Regulating
+voltage by means of the rheostat&mdash;Automatic devices&mdash;Putting the
+plant in operation.</p></div>
+
+
+<p>Dynamos may be connected to water wheels either by means of a belt, or
+the armature may spin on the same shaft as the water wheel itself. The
+latter is by far the more desirable way, as it eliminates the loss of
+power through shafting and belting, and does away altogether
+with the belts themselves as a source of trouble. An installation
+with the water wheel and armature on the same shaft is called a
+"direct-connected set" and is of almost universal use in large power
+plants.</p>
+
+<p>To be able to use such a direct-connected<span class='pagenum'><a name="Page_193" id="Page_193">[Pg 193]</a></span> set, the dynamo must be
+designed to develop its full voltage when run at a speed identical
+with that of the water wheel. That is, if the dynamo is wound to be
+run at a speed of 800 revolutions per minute, it must be driven by a
+water wheel which runs at this speed and can be governed within narrow
+limits. Small impulse wheels running under great heads attain high
+speed, and for such wheels it is possible to obtain a suitable dynamo
+at low cost. For instance, a 12-inch impulse wheel, running under a
+200-foot head will develop 6&frac34; horsepower when running at a speed of
+875 revolutions per minute. A dynamo for direct coupling to such a
+wheel should have a rated speed within 5 per cent of 875 r.p.m.; and,
+as generators of this speed are to be had from the stock of almost all
+manufacturers, there would be no extra charge.</p>
+
+<p>When it comes to the larger wheels, however, of the impulse type, or
+to turbines operating under their usual head the question becomes a
+little more difficult. In such cases, the speed of the water wheel
+will vary<span class='pagenum'><a name="Page_194" id="Page_194">[Pg 194]</a></span> from 150 revolutions per minute, to 400, which is slow
+speed for a small dynamo. As a general rule, the higher the speed of a
+dynamo, the lower the cost; because, to lower the speed for a given
+voltage, it is necessary either to increase the number of conductors
+on the armature, or to increase the number of field coils, or both.
+That means a larger machine, and a corresponding increase in cost.</p>
+
+<p>In practice, in large plants, with alternating-current machines it has
+become usual to mount the field magnets on the shaft, and build the
+armature as a stationary ring in whose air space the field coils
+revolve. This simplifies the construction of slow-speed, large-output
+dynamos. Such a machine, however, is not to be had for the modest
+isolated plant of the farmer with his small water-power.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="i194-1" id="i194-1"></a>
+<img src="images/i194-1.jpg" width="600" height="223" alt="" title="" />
+Instantaneous photograph of high-pressure water jet
+being quenched by buckets of a tangential wheel
+</div>
+
+<div class="figcenter" style="width: 500px;"><a name="i194-2" id="i194-2"></a>
+<img src="images/i194-2.jpg" width="500" height="335" alt="" title="" />
+A tangential wheel, and a dynamo keyed to the same
+shaft&mdash;the ideal method for generating electricity. The centrifugal
+governor is included on the same base
+</div>
+
+<p>Dynamos can be designed for almost any waterwheel speed, and, among
+small manufacturers especially, there is a disposition to furnish
+these special machines at little advance in price over their stock
+machines. Frequently it is merely a matter of changing the winding on
+a stock machine. The farmer himself, in many cases, can re-wind an old
+dynamo to fit the speed requirements of a direct-connected drive if
+the difference is not too<span class='pagenum'><a name="Page_195" id="Page_195">[Pg 195]</a></span> great. All that would be necessary to
+effect this change would be to get the necessary winding data from the
+manufacturer himself, and proceed with the winding. This data would
+give the gauge of wire and the number of turns required for each spool
+of the field magnets; and the gauge of wire and number of turns
+required for each slot in the armature. The average boy who has
+studied electricity (and there is something about electricity that
+makes it closer to the boy's heart than his pet dog) could do this
+work. The advantages of direct drive are so many that it should be
+used wherever possible.</p>
+
+<p>When direct drive cannot be had, a belt must be used, either from a
+main shaft, or a countershaft. The belt must be of liberal size, and
+must be of the "endless" variety&mdash;with a scarfed joint. Leather belt
+lacing, or even the better grades of wire lacing, unless <span class='pagenum'><a name="Page_196" id="Page_196">[Pg 196]</a></span>very
+carefully used, will prove unsatisfactory. The dynamo feels every
+variation in speed, and this is reflected in the lights. There is
+nothing quite so annoying as flickering lights. Usually this can be
+traced to the belt connections. Leather lacing forms a knot which
+causes the lights to flicker at each revolution of the belt. The
+endless belt does away with this trouble. Most dynamos are provided
+with sliding bases, by which the machine can be moved one way or
+another a few inches, to take up slack in the belt. To take advantage
+of this, the belt must be run in a horizontal line, or nearly so.
+Vertical belting is to be avoided.</p>
+
+<p>The dynamo is mounted on a wooden base, in a dry location where it is
+protected from the weather, or dampness from any source. It must be
+mounted firmly, to prevent vibration when running up to speed; and the
+switchboard should occupy a place within easy reach. Wires running
+from the dynamo to the switchboard should be protected from injury,
+and must be of ample size to carry<span class='pagenum'><a name="Page_197" id="Page_197">[Pg 197]</a></span> the full current of the machine
+without heating. A neat way is to carry them down through the flooring
+through porcelain tubes, thence to a point where they can be brought
+up at the back of the switchboard. If there is any danger of injury to
+these mains they may be enclosed in iron pipe. Keep the wires out of
+sight as much as possible, and make all connections on the back of the
+switchboard.</p>
+
+
+<p class="center padtop"><i>The Switchboard</i></p>
+
+<div class="figcenter" style="width: 500px;">
+<a href="images/d197-big.jpg"><img src="images/d197-small.jpg" width="500" height="156" alt="" title="" /></a>
+Connecting switchboard instruments
+</div>
+
+
+<p>The switchboard is constructed of some fireproof material, preferably
+slate or marble. When the cost of this material is an item to
+consider, build a substantial wooden frame for your switchboard. You
+can then screw asbestos shingles to this to hold the various<span class='pagenum'><a name="Page_198" id="Page_198">[Pg 198]</a></span>
+instruments and with a little care such a switchboard can be made to
+look business-like, and it is fully as serviceable as the more
+expensive kind. The switchboard instruments have already been
+described briefly. They consist of a voltmeter (to measure voltage);
+an ammeter (to measure the strength of the current drawn, in amperes),
+a rheostat (to regulate the voltage of the machine to suit the
+individual requirements); and the usual switches and fuses. The main
+switch should be so wired that when open it will throw all the current
+off the line, but still leave the field coils, the voltmeter, and the
+switchboard lamp in circuit. The main-switch fuses should have a
+capacity about 50 per cent in excess of the full load of the dynamo.
+If the machine is rated for 50 amperes, 75-ampere fuses should be
+installed. This permits throwing on an overload in an emergency; and
+at the same time guards against a short circuit. If the capacity of
+the machine is under 30 amperes, plug fuses, costing 3 cents each, can
+be used. If it is<span class='pagenum'><a name="Page_199" id="Page_199">[Pg 199]</a></span> above this capacity, cartridge fuses, costing a
+little more, are required. A supply of these fuses should be kept
+handy at all times.</p>
+
+
+<p class="center padtop"><i>Governors and Voltage Regulators</i></p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/i199.jpg" width="500" height="509" alt="" title="" />
+A centrifugal governor<br />
+
+(<i>Courtesy of the C. P. Bradway Company, West Stafford, Conn.</i>)
+</div>
+
+<p>The necessity for water wheel governors will vary with conditions. As
+a general rule, it may be said that reaction turbines working under a
+low head with a large quantity of water do not require as much
+governing as the impulse wheel, working under high heads with small
+quantities of water. When governing is necessary at all, it is because
+the prime mover varies in speed from no load to full load. Planning
+one's plant with a liberal allowance of power&mdash;two water horsepower to
+one electrical horsepower is liberal&mdash;reduces the necessity of
+governors to a<span class='pagenum'><a name="Page_200" id="Page_200">[Pg 200]</a></span> minimum. As an instance of this, the plant described
+in some detail in Chapters One and Six of this volume, runs without a
+governor.</p>
+
+<p>However, a surplus of water-power is not usual. Generally plants are
+designed within narrow limits; and then the need of a governor becomes
+immediately apparent. There are many designs of governors on the
+market, the cheapest being of the centrifugal type, in which a pair of
+whirling balls are connected to the water wheel gate by means of
+gears, and open or close the gate as the speed lowers or rises.</p>
+
+<p>Constant speed is necessary because voltage is directly dependent on
+speed. If the speed falls 25 per cent, the voltage falls likewise; and
+a plant with the voltage varying between such limits would be a
+constant source of annoyance, as well as expense for burned-out lamps.</p>
+
+<p>Since constant voltage is the result aimed at by the use of a
+governor, the same result can be attained in other ways, several of
+which will be explained here briefly.</p>
+
+
+<p><span class='pagenum'><a name="Page_201" id="Page_201">[Pg 201]</a></span></p><p class="center padtop"><i>Over-Compounding</i></p>
+
+<p>(1) Over-compounding the dynamo. This is simple and cheap, if one buys
+the right dynamo in the first instance; or if he can do the
+over-compounding himself, by the method described in the concluding
+paragraphs of Chapter Seven. If it is found that the speed of the
+water wheel drops 25 per cent between no load and full load, a dynamo
+with field coils over-compounded to this extent would give a fairly
+constant regulation. If you are buying a special dynamo for direct
+drive, your manufacturer can supply you with a machine that will
+maintain constant voltage under the normal variations in speed of your
+wheel.</p>
+
+
+<p class="center padtop"><i>A System of Resistances</i></p>
+
+<p>(2) Constant load systems. This system provides that the dynamo shall
+be delivering a fixed amount of current at all times, under which
+circumstances the water wheel would not require regulation, as the
+demands on it would not vary from minute to minute or hour to hour.</p>
+
+<p><span class='pagenum'><a name="Page_202" id="Page_202">[Pg 202]</a></span></p><p>This system is very simply arranged. It consists of having a set of
+"resistances" to throw into the circuit, in proportion to the amount
+of current used.</p>
+
+<p>Let us say, as an example, that a 50-ampere generator is used at a
+pressure of 110 volts; and that it is desirable to work this plant at
+80 per cent load, or 40 amperes current draft. When all the lights or
+appliances were in use, there would be no outside "resistance" in the
+circuit. When none of the lights or appliances were in use (as would
+be the case for many hours during the day) it would be necessary to
+consume this amount of current in some other way&mdash;to <i>waste it</i>. A
+resistance permitting 40 amperes of current to flow, would be
+necessary. Of what size should this resistance be?</p>
+
+<p>The answer is had by applying Ohm's Law, explained in Chapter Five.
+The Law in this case, would be read R = E/C. Therefore, in this case R
+= 110/40 = 2&frac34; ohms resistance, would be required, switched across
+the mains, to keep the dynamo delivering its normal load.</p>
+
+<p>The cheapest form of this resistance would<span class='pagenum'><a name="Page_203" id="Page_203">[Pg 203]</a></span> be iron wire. In place of
+iron wire, German silver wire could be used. German silver wire is to
+be had cheaply, and is manufactured in two grades, 18% and 30%, with a
+resistance respectively 18 and 30 times that of copper for the same
+gauge. Nichrome wire has a resistance 60 times that of copper; and
+manganin wire has a resistance 65 times that of copper, of the same
+gauge.</p>
+
+<p>First figure the number of feet of copper wire suitable for the
+purpose. Allowing 500 circular mills for each ampere, the gauge of the
+wire should be 40 &times; 500 = 20,000 circular mills, or approximately No.
+7 B. &amp; S. gauge. How many feet of No. 7 copper wire would give a
+resistance of 2&frac34; ohms? Referring to the copper wire table, we find
+that it requires 2006.2 of No. 7 wire to make one ohm. Then 2&frac34; ohms
+would require 5,517 feet.</p>
+
+<p>Since 30 per cent German silver wire is approximately 30 times the
+resistance of copper, a No. 7 German silver wire, for this purpose,
+would be 1/30 the length of the copper wire, or 186 feet. If nichrome
+wire<span class='pagenum'><a name="Page_204" id="Page_204">[Pg 204]</a></span> were used, it would be 1/60th the length of copper for the same
+gauge, or 93 feet. This resistance wire can be wound in spirals and
+made to occupy a very small space. As long as it is connected in
+circuit, the energy of the dynamo otherwise consumed as light would be
+wasted as heat. This heat could be utilized in the hot water boiler or
+stove when the lights were turned off.</p>
+
+<p>In actual practice, however, the resistance necessary to keep the
+dynamo up to full load permanently, would not be furnished by one set
+of resistance coils. Each lamp circuit would have a set of resistance
+coils of its own. A double-throw switch would turn off the lamps and
+turn on the resistance coils, or <i>vice versa</i>.</p>
+
+<p>Let us say a lamp circuit consisted of 6 carbon lamps, of 16
+candlepower each. It would consume 6 &times; &frac12; ampere, or 3 amperes of
+current, and interpose a resistance of 36.6 ohms&mdash;say 37 ohms. Three
+amperes would require a wire of at least 1,500 circular mills in area
+for safety. This corresponds to a No. 18<span class='pagenum'><a name="Page_205" id="Page_205">[Pg 205]</a></span> wire. A No. 18 copper wire
+interposes a resistance of one ohm, for each 156.5 feet length. For 37
+ohms, 5,790 feet would be required, for copper wire, which of course
+would be impractical. Dividing by 30 gives 193 feet for 30% German
+silver wire; and dividing by 60 gives 96 feet of nichrome wire of the
+same gauge.</p>
+
+<p>It is simple to figure each circuit in this way and to construct
+resistance units for each switch. Since the resistance units develop
+considerable heat, they must be enclosed and protected.</p>
+
+
+<p class="center padtop"><i>A Home-made Stove or Radiator</i></p>
+
+<p>While we are on the subject of resistance coils it might be well here
+to describe how to make stoves for cooking, and radiators for heating
+the house, at small expense. These stoves consist merely of
+resistances which turn hot&mdash;a dull red&mdash;when the current is turned on.
+Iron wire, German silver wire, or the various trade brands of
+resistance wire, of which nichrome, calido, and manganin are samples,<span class='pagenum'><a name="Page_206" id="Page_206">[Pg 206]</a></span>
+can be used. In buying this wire, procure the table of resistance and
+carrying capacity from the manufacturers. From this table you can make
+your own radiators to keep the house warm in winter. Iron wire has the
+disadvantage of oxidizing when heated to redness, so that it goes to
+pieces after prolonged use. It is cheap, however, and much used for
+resistance in electrical work.</p>
+
+<p>Let us say we wish to heat a bathroom, a room 6 &times; 8, and 8 feet
+high&mdash;that is a room containing 384 cubic feet of air space. Allowing
+2 watts for each cubic foot, we would require 768 watts of current, or
+practically 7 amperes at 110 volts. What resistance would be required
+to limit the current to this amount? Apply Ohm's Law, as before, and
+we have R equals E divided by C, or R equals 110 divided by 7, which
+is 15.7 ohms. Forty-two feet of No. 20 German silver wire would emit
+this amount of heat and limit the current output to 7 amperes. In the
+Far West, it is quite common, in the outlying district, to find
+electric radiators made out of iron pipe covered<span class='pagenum'><a name="Page_207" id="Page_207">[Pg 207]</a></span> with asbestos, on
+which the requisite amount of iron wire is wound and made secure. This
+pipe is mounted in a metal frame. Or the frame may consist of two
+pipes containing heating elements; and a switch, in this case, is so
+arranged that either one or two heating elements may be used at one
+time, according to the weather. An ingenious mechanic can construct
+such a radiator, experimenting with the aid of an ammeter to ascertain
+the length of wire required for any given stove.</p>
+
+
+<p class="center padtop"><i>Regulating Voltage at Switchboards</i></p>
+
+<p>The voltage of any given machine may be regulated, within wide limits,
+by means of the field rheostat on the switchboard.</p>
+
+<p>A dynamo with a rated speed of 1,500 revolutions per minute, for 110
+volts, will actually attain this voltage at as low as 1,200 r.p.m. if
+all the regulating resistance be cut out. You can test this fact with
+your own machine by cutting out the resistance from the shunt field
+entirely, and starting the<span class='pagenum'><a name="Page_208" id="Page_208">[Pg 208]</a></span> machine slowly, increasing its speed
+gradually, until the voltmeter needle registers 110 volts. Then
+measure the speed. It will be far below the rated speed of your
+machine.</p>
+
+<p>If, on the other hand, the speed of such a machine runs up to 2,500 or
+over&mdash;that is, an excess of 67%&mdash;the voltage would rise
+proportionally, unless extra resistance was cut in. By cutting in such
+resistance&mdash;by the simple expedient of turning the rheostat handle on
+the switchboard,&mdash;the field coils are so weakened that the voltage is
+kept at the desired point in spite of the excessive speed of the
+machine. Excessive speeds are to be avoided, as a rule, because of
+mechanical strain. But within a wide range, the switchboard rheostat
+can be used for voltage regulation.</p>
+
+<p>As it would be a source of continual annoyance to have to run to the
+switchboard every time the load of the machine was varied greatly this
+plan would not be practical for the isolated plant, unless the
+rheostat could be installed,&mdash;with a voltmeter&mdash;in one's<span class='pagenum'><a name="Page_209" id="Page_209">[Pg 209]</a></span> kitchen.
+This could be done simply by running a small third wire from the
+switchboard to the house. Then, when the lights became dim from
+excessive load, a turn of the handle would bring them back to the
+proper voltage; and when they flared up and burned too bright, a turn
+of the handle in the opposite direction would remedy matters. By this
+simple arrangement, any member of the family could attend to voltage
+regulation with a minimum of bother.</p>
+
+
+<p class="center padtop"><i>Automatic Devices</i></p>
+
+<p>There are several automatic devices for voltage regulation at the
+switchboard on the market. These consist usually of vibrator magnets
+or solenoids, in which the strength of the current, varying with
+different speeds, reacts in such a way as to regulate field
+resistance. Such voltage regulators can be had for $40 or less, and
+are thoroughly reliable.</p>
+
+<hr style='width: 45%;' />
+
+<p>To sum up the discussion of governors and voltage regulators: If you
+can allow a liberal<span class='pagenum'><a name="Page_210" id="Page_210">[Pg 210]</a></span> proportion of water-power, and avoid crowding
+your dynamo, the chances are you will not need a governor for the
+ordinary reaction turbine wheel. Start your plant, and let it run for
+a few days or a few weeks without a governor, or regulator. Then if
+you find the operation is unsatisfactory, decide for yourself which of
+the above systems is best adapted for your conditions. Economy as well
+as convenience will affect your decision. The plant which is most
+nearly automatic is the best; but by taking a little trouble and
+giving extra attention, a great many dollars may be saved in extras.</p>
+
+
+<p class="center padtop"><i>Starting the Dynamo</i></p>
+
+<p>You are now ready to put your plant in operation. Your dynamo has been
+mounted on a wooden foundation, and belted to the countershaft, by
+means of an endless belt.</p>
+
+<p>See that the oil cups are filled. Then throw off the main switch and
+the field switch at the switchboard; open the water gate slowly,<span class='pagenum'><a name="Page_211" id="Page_211">[Pg 211]</a></span> and
+occasionally test the speed of the dynamo. When it comes up to rated
+speed, say 1,500 per minute, let it run for a few minutes, to be sure
+everything is all right.</p>
+
+<p>Having assured yourself that the mechanical details are all right, now
+look at the voltmeter. It is probably indicating a few volts pressure,
+from 4 to 8 or 10 perhaps. This pressure is due to the residual
+magnetism in the field cores, as the field coils are not yet
+connected. If by any chance, the needle does not register, or is now
+back of 0, try changing about the connections or the voltmeter on the
+back of the switchboard.</p>
+
+<p>Now snap on the field switch. Instantly the needle will begin to move
+forward, though slowly; and it will stop. Turn the rheostat handle
+gradually; as you advance it, the voltmeter needle will advance.
+Finally you will come to a point where the needle will indicate 110
+volts.</p>
+
+<p>If you have designed your transmission line for a drop of 5 volts at
+half-load, advance the rheostat handle still further, until the<span class='pagenum'><a name="Page_212" id="Page_212">[Pg 212]</a></span>
+needle points to 115 volts. Let the machine run this way for some
+time. When assured all is right, throw on the main switch, and turn on
+the light at the switchboard. Then go to the house and gradually turn
+on lights. Come back and inspect the dynamo as the load increases. It
+should not run hot, nor even very warm, up to full load. Its brushes
+should not spark, though a little sparking will do no harm.</p>
+
+<p>Your plant is now ready to deliver current up to the capacity of its
+fuses. See that it does not lack good lubricating oil, and do not let
+its commutator get dirty. The commutator should assume a glossy
+chocolate brown color. If it becomes dirty, or the brushes spark
+badly, hold a piece of fine sandpaper against it. Never use emery
+paper! If, after years of service, it becomes roughened by wear, have
+it turned down in a lathe. Occasionally, every few weeks, say, take
+the brushes out and clean them with a cloth. They will wear out in the
+course of time and can be replaced for a few cents each. The<span class='pagenum'><a name="Page_213" id="Page_213">[Pg 213]</a></span> bearings
+may need replacing after several years' continuous use.</p>
+
+<p>Otherwise your electric plant will take care of itself. Keep it up to
+speed, and keep it clean and well oiled. Never shut it down unless you
+have to. In practice, dynamos run week after week, year after year,
+without stopping. This one, so long as you keep it running true to
+form, will deliver light, heat and power to you for nothing, which
+your city cousin pays for at the rate of 10 cents a kilowatt-hour.</p>
+
+
+<p><span class='pagenum'><a name="Page_214" id="Page_214">[Pg 214]</a></span></p>
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_215" id="Page_215">[Pg 215]</a></span></p>
+<h2><a name="PART_III" id="PART_III"></a>PART III</h2>
+
+<p class="subhead1">GASOLINE ENGINES, WINDMILLS, ETC. THE STORAGE BATTERIES</p>
+
+
+<p><span class='pagenum'><a name="Page_216" id="Page_216">[Pg 216]</a></span></p>
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_217" id="Page_217">[Pg 217]</a></span></p>
+<h2><a name="CHAPTER_X" id="CHAPTER_X"></a>CHAPTER X</h2>
+
+<p class="subhead2">GASOLINE ENGINE PLANTS</p>
+
+<div class="blockquot"><p>The standard voltage set&mdash;Two-cycle and four-cycle gasoline
+engines&mdash;Horsepower, and fuel consumption&mdash;Efficiency of small
+engines and generators&mdash;Cost of operating a one-kilowatt plant.</p></div>
+
+
+<p>Electricity is of so much value in farm operations, as well as in the
+farm house, that the farmer who is not fortunate enough to possess
+water-power of his own, or to live in a community where a co&ouml;perative
+hydro-electric plant may be established, should not deny himself its
+many conveniences. In place of the water wheel to turn the dynamo,
+there is the gasoline engine (or other forms of internal combustion
+engine using oil, gas, or alcohol as fuel); in many districts where
+steam engines are used for logging or other operations, electricity
+may be generated as a by-product; and almost any windmill capable of
+pumping water can be made to<span class='pagenum'><a name="Page_218" id="Page_218">[Pg 218]</a></span> generate enough electricity for lighting
+the farm house at small expense.</p>
+
+<p>The great advantage of water-power is that the expense of
+maintenance&mdash;once the plant is installed&mdash;is practically nothing. This
+advantage is offset in some measure by the fact that other forms of
+power, gas, steam, or windmills, are already installed, in many
+instances and that their judicious use in generating electricity does
+not impair their usefulness for the other farm operations for which
+they were originally purchased. In recent years gasoline engines have
+come into general use on farms as a cheap dependable source of power
+for all operations; and windmills date from the earliest times. They
+may be installed and maintained cheaply, solely for generating
+electricity, if desired. Steam engines, however, require so much care
+and expert attention that their use for farm electric plants is not to
+be advised, except under conditions where a small portion of their
+power can be used to make electricity as a by-product.</p>
+
+<p><span class='pagenum'><a name="Page_219" id="Page_219">[Pg 219]</a></span></p><p>There are two types of gasoline engine electric plants suitable for
+the farm, in general use:</p>
+
+<p>First: <span class="smcap">The Standard Voltage Set</span>, in which the engine and dynamo are
+mounted on one base, and the engine is kept running when current is
+required for any purpose. These sets are usually of the 110-volt type,
+and all standard appliances, such as irons, toasters, motors, etc.,
+may be used in connection with them. Since the electricity is drawn
+directly from the dynamo itself, without a storage battery, it is
+necessary that these engines be efficient and governed as to speed
+within a five per cent variation from no load to full load.</p>
+
+<p>Second: <span class="smcap">Storage Battery Sets</span>, in which the dynamo is run only a few
+hours each week, and the electricity thus generated is "stored" by
+chemical means, in storage batteries, for use when required. Since, in
+this case, the current is drawn from the battery, instead of the
+dynamo, when used for lighting or other purposes, it is not necessary
+that a<span class='pagenum'><a name="Page_220" id="Page_220">[Pg 220]</a></span> special type of engine be used to insure constant speed.</p>
+
+
+<p class="center padtop"><i>The Standard Voltage Set</i></p>
+
+<p>In response to a general demand, the first type (the direct-connected
+standard voltage set) has been developed to a high state of efficiency
+recently, and is to be had in a great variety of sizes (ranging from
+one-quarter kilowatt to 25 kilowatts and over) from many
+manufacturers.</p>
+
+<p>The principle of the gasoline engine as motive power is so familiar to
+the average farmer that it needs but a brief description here.
+Gasoline or other fuel (oil, gas, or alcohol) is transformed into
+vapor, mixed with air in correct proportions, and drawn into the
+engine cylinder and there exploded by means of a properly-timed
+electric spark.</p>
+
+<p>Internal combustion engines are of two general types&mdash;four-cycle and
+two-cycle. The former is by far the more common. In a four-cycle
+engine the piston must travel twice up and down in each cylinder, to
+deliver one<span class='pagenum'><a name="Page_221" id="Page_221">[Pg 221]</a></span> power stroke. This results in one power impulse in each
+cylinder every two revolutions of the crank shaft. On its first down
+stroke, the piston sucks in gas. On its first up stroke, it compresses
+the gas. At the height of this stroke, the gas is exploded by means of
+the electric spark and the piston is driven down, on its power stroke.
+The fourth stroke is called the scavening stroke, and expels the
+burned gas. This completes the cycle.</p>
+
+<p>A one-cylinder engine of the ordinary four-cycle type has one power
+stroke for every two revolutions of the fly wheel. A two-cylinder
+engine has one power stroke for one revolution of the fly wheel; and a
+four-cylinder engine has two power strokes to each revolution. The
+greater the number of cylinders, the more even the flow of power. In
+automobiles six cylinders are common, and in the last year or two,
+eight-cylinder engines began appearing on the market in large numbers.
+A twelve-cylinder engine is the prospect for the immediate future.</p>
+
+<p>Since the dynamo that is to supply electric<span class='pagenum'><a name="Page_222" id="Page_222">[Pg 222]</a></span> current direct to lamps
+requires a steady flow of power, the single-cylinder gas or gasoline
+engine of the four-cycle type is not satisfactory as a rule. The
+lights will flicker with every other revolution of the fly wheel. This
+would be of no importance if the current was being used to charge a
+storage battery&mdash;and right here lies the reason why a cheaper engine
+may be used in connection with a storage battery than when the dynamo
+supplies the current direct for lighting.</p>
+
+<p>A two-cylinder engine is more even in its flow of power and a
+four-cylinder engine still better. For this reason, standard voltage
+generating sets without battery are usually of two or four cylinders
+when of the four-cycle type. When a single-cylinder engine is used, it
+should be of the two-cycle type. In the two-cycle engine, there is one
+power stroke to each up-and-down journey of the piston. This effect is
+produced by having inlet and exhaust ports in the crank case, so
+arranged that, when the piston arrives at the bottom of the power
+stroke, the waste gases are pushed<span class='pagenum'><a name="Page_223" id="Page_223">[Pg 223]</a></span> out, and fresh gas drawn in before
+the up stroke begins.</p>
+
+<p>For direct lighting, the engine must be governed so as not to vary
+more than five per cent in speed between no load and full load. There
+are many makes on the market which advertise a speed variation of
+three per cent under normal loads. Governors are usually of the
+centrifugal ball type, integral with the fly wheel, regulating the
+amount of gas and air supplied to the cylinders in accordance with the
+speed. Thus, if such an engine began to slow down because of increase
+in load, the centrifugal balls would come closer together, and open
+the throttle, thus supplying more gas and air and increasing the
+speed. If the speed became excessive, due to sudden shutting off of
+lights, the centrifugal balls would fly farther apart, and the
+throttle would close until the speed was again adjusted to the load.</p>
+
+<p>These direct-connected standard voltage sets are as a rule fitted with
+the 110-volt, direct current, compound type of dynamo, the duplicate
+in every respect of the machine<span class='pagenum'><a name="Page_224" id="Page_224">[Pg 224]</a></span> described in previous chapters for
+water-power plants. They are practically automatic in operation and
+will run for hours without attention, except as to oil and gasoline
+supply. They may be installed in the woodshed or cellar without
+annoyance due to noise or vibration. It is necessary to start them, of
+course, when light or power is desired, and to stop them when no
+current is being drawn. There have appeared several makes on the
+market in which starting and stopping are automatic. Storage batteries
+are used in connection with these latter plants for starting the
+engine. When a light is turned on, or current is drawn for any
+purpose, an automatic switch turns the dynamo into a motor, and it
+starts the engine by means of the current stored in the battery.
+Instantly the engine has come up to speed, the motor becomes a dynamo
+again and begins to deliver current. When the last light is turned
+off, the engine stops automatically.</p>
+
+<p>Since the installation of a direct-connected standard voltage plant of
+this type is similar<span class='pagenum'><a name="Page_225" id="Page_225">[Pg 225]</a></span> in every respect, except as to motive power, to
+the hydro-electric plant, its cost, with this single exception, is the
+same. The same lamps, wire, and devices are used.</p>
+
+<p>With gasoline power, the cost of the engine offsets the cost of the
+water wheel. The engine is more expensive than the ordinary gasoline
+engine; but even this item of cost is offset by the cost of labor and
+materials used in installing a water wheel.</p>
+
+<p>The expense of maintenance is limited to gasoline and oil.
+Depreciation enters in both cases; and though it may be more rapid
+with a gasoline engine than a water wheel, that item will not be
+considered here. The cost of lubricating oil is inconsiderable. It
+will require, when operated at from one-half load to full load,
+approximately one pint of gasoline to each horsepower hour. When
+operated at less than half-load, its efficiency lowers. Thus, for a
+quarter-load, an average engine of this type may require three pints
+of gasoline for each horsepower hour. For this reason it is well, in
+installing such a plant, to have it of<span class='pagenum'><a name="Page_226" id="Page_226">[Pg 226]</a></span> such size that it will be
+operating on at least three-fourths load under normal draft of
+current. Norman H. Schneider, in his book "Low Voltage Electric
+Lighting," gives the following table of proportions between the engine
+and dynamo:</p>
+
+<table summary="watts and horsepower" style="width: 50%;"><tbody>
+<tr><td style="text-align: center; width: 30%;"><i>Actual watts</i></td>  <td style="text-align: center; width: 40%;"><i>Actual Horsepower</i></td>  <td style="text-align: center; width: 30%;"><i>Nearest engine size</i></td></tr>
+<tr><td class="center">150</td>  <td class="center">0.5</td>  <td class="center">&frac12;</td></tr>
+<tr><td class="center">225</td>  <td class="center">0.7</td>  <td class="center">&frac34;</td></tr>
+<tr><td class="center">300</td>  <td class="center">0.86</td>  <td class="center">1</td></tr>
+<tr><td class="center">450</td>  <td class="center">1.12</td>  <td class="center">1&frac14;</td></tr>
+<tr><td class="center">600</td>  <td class="center">1.5</td>  <td class="center">1&frac12;</td></tr>
+<tr><td class="center">750</td>  <td class="center">1.7</td>  <td class="center">1&frac34;</td></tr>
+<tr><td class="center">1000</td>  <td class="center">2.3</td>  <td class="center">2&frac12;</td></tr>
+<tr><td class="center">2000</td>  <td class="center">4.5</td>  <td class="center">5</td></tr>
+<tr><td class="center">4000</td>  <td class="center">9.0</td>  <td class="center">10</td></tr>
+</tbody></table>
+
+<p>This table is figured for an efficiency of only 40 per cent for the
+smaller generators, and 60 per cent for the larger. In machines from 5
+to 25 kilowatts, the efficiency will run considerably higher.</p>
+
+<p>To determine the expense of operating a one-kilowatt gasoline
+generator set of this type, as to gasoline consumption, we can assume
+at full load that the gasoline engine is delivering 2&frac12; horsepower,
+and consuming, let us say, 1&frac14; pint of gasoline for each horsepower
+hour<span class='pagenum'><a name="Page_227" id="Page_227">[Pg 227]</a></span> (to make allowance for lower efficiency in small engines). That
+would be 3.125 pints of gasoline per hour. Allowing a ten per cent
+loss of current in wiring, we have 900 watts of electricity to use,
+for this expenditure of gasoline. This would light 900 &divide; 25 = 36 lamps
+of 25 watts each, a liberal allowance for house and barn, and
+permitting the use of small cooking devices and other conveniences
+when part of the lights were not in use. With gasoline selling at 12
+cents a gallon, the use of this plant for an hour at full capacity
+would cost $0.047. Your city cousin pays 9 cents for the same current
+on a basis of 10 cents per kilowatt-hour; and in smaller towns where
+the rate is 15 cents, he would pay 13&frac12; cents.</p>
+
+<p>Running this plant at only half-load&mdash;that is, using only 18 lights,
+or their equivalent&mdash;would reduce the price to about 3 cents an
+hour&mdash;since the efficiency decreases with smaller load. It is
+customary to figure an average of 3&frac12; hours a day throughout the
+year, for all lights. On this basis the cost of gasoline for this
+one-kilowatt plant would be<span class='pagenum'><a name="Page_228" id="Page_228">[Pg 228]</a></span> 16&frac12; cents a day for full load, and
+approximately 10&frac12; cents a day for half-load. This is extremely
+favorable, as compared with the cost of electric current in our cities
+and towns, at the commercial rate, especially when one considers that
+light and power are to be had at any place or at any time on the farm
+simply by starting the engine. A smaller plant, operating at less cost
+for fuel, would furnish ample light for most farms; but it is well to
+remember in this connection plants smaller than one kilowatt are
+practical for light only, since electric irons, toasters, etc., draw
+from 400 to 660 watts each. Obviously a plant of 300 watts capacity
+would not permit the use of these instruments, although it would
+furnish 10 or 12 lamps of 25 watts each.</p>
+
+
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_229" id="Page_229">[Pg 229]</a></span></p>
+<h2><a name="CHAPTER_XI" id="CHAPTER_XI"></a>CHAPTER XI</h2>
+
+<p class="subhead2">THE STORAGE BATTERY</p>
+
+<div class="blockquot"><p>What a storage battery does&mdash;The lead battery and the Edison
+battery&mdash;Economy of tungsten lamps for storage batteries&mdash;The
+low-voltage battery for electric light&mdash;How to figure the capacity
+of a battery&mdash;Table of light requirements for a farm
+house&mdash;Watt-hours and lamp-hours&mdash;The cost of storage battery
+current&mdash;How to charge a storage battery&mdash;Care of storage
+batteries.</p></div>
+
+
+<p>For the man who has a small supply of water to run a water wheel a few
+hours at a time, or who wishes to store electricity while he is doing
+routine jobs with a gasoline engine or other source of power, the
+storage battery solves the problem. The storage battery may be likened
+to a tank of water which is drawn on when water is needed, and which
+must be re-filled when empty. A storage battery, or accumulator is a
+device in which a chemical action is set up when an electric current
+is passed through it. This is called <i>charging</i>.<span class='pagenum'><a name="Page_230" id="Page_230">[Pg 230]</a></span> When such a battery
+is charged, it has the property of giving off an electric current by
+means of a reversed chemical action when a circuit is provided,
+through a lamp or other connection. This reversed action is called
+<i>discharging</i>. Such a battery will discharge nearly as much current as
+is required originally to bring about the first chemical action.</p>
+
+<p>There are two common types of storage battery&mdash;the lead accumulator,
+made up of lead plates (alternately positive and negative); and the
+two-metal accumulator, of which the Edison battery is a
+representative, made up of alternate plates of iron and nickel. In the
+lead accumulator, the "positive" plate may be recognized by its brown
+color when charging, while the "negative" plate is usually light gray,
+or leaden in color. The action of the charging current is to form
+oxides of lead in the plates; the action of the discharging current is
+to reduce the oxides to metallic lead again. This process can be
+repeated over and over again during the life of the battery.</p>
+
+<p>Because of the cost of the batteries themselves, <span class='pagenum'><a name="Page_231" id="Page_231">[Pg 231]</a></span>it is possible (from
+the viewpoint of the farmer and the size of his pocketbook) to store
+only a relatively small amount of electric current. For this reason,
+the storage battery was little used for private plants, where expense
+is a considerable item, up to a few years ago. Carbon lamps require
+from 3&frac12; to 4 watts for each candlepower of light they give out; and
+a lead battery capable of storing enough electricity to supply the
+average farm house with light by means of carbon lamps for three or
+four days at a time without recharging, proved too costly for private
+use.</p>
+
+
+<p class="center padtop"><i>The Tungsten Lamp</i></p>
+
+<p>With the advent of the new tungsten lamp, however, reducing the
+current requirements for light by two-thirds, the storage battery
+immediately came into its own, and is now of general use.</p>
+
+<p>Since incandescent lamps were first invented scientists have been
+trying to find some metal of high fusion to use in place of the carbon
+filament of the ordinary lamp. The<span class='pagenum'><a name="Page_232" id="Page_232">[Pg 232]</a></span> higher the fusing point of this
+filament of wire, the more economical would be the light. Edison
+sought, thirty years ago, for just the qualities now found in tungsten
+metal. Tungsten metal was first used for incandescent lamps in the
+form of a paste, squirted into the shape of a thread. This proved too
+fragile. Later investigators devised means of drawing tungsten into
+wire; and it is tungsten wire that is now used so generally in
+lighting. A tungsten lamp has an average efficiency of 1&frac14; watts per
+candlepower, compared with 3&frac12; to 4 watts of the old-style carbon
+lamp. In larger sizes the efficiency is as low as .9 watt per
+candlepower; and only recently it has been found that if inert
+nitrogen gas is used in the glass bulb, instead of using a high vacuum
+as is the general practice, the efficiency of the lamp becomes still
+higher, approaching .5 watt for each candlepower in large lamps. This
+new nitrogen lamp is not yet being manufactured in small domestic
+sizes, though it will undoubtedly be put on the market in those sizes
+in the near future.</p>
+
+<p><span class='pagenum'><a name="Page_233" id="Page_233">[Pg 233]</a></span></p>
+
+<div class="figcenter" style="width: 500px;">
+<img src="images/d233.jpg" width="500" height="516" alt="" title="" />
+The Fairbanks Morse oil engine storage battery set
+</div>
+
+
+<p>The tungsten lamp, requiring only one-third as much electric current
+as the carbon lamp, for the same amount of light, reduces the size
+(and the cost) of the storage battery in the same degree, thus
+bringing the storage battery within the means of the farmer. Some idea
+of the power that may be put into a small storage battery is to be had
+from the fact that a storage battery of only 6 volts pressure, such as
+is used in self-starters on automobiles, will turn a motor and crank a
+heavy six-cylinder engine; or it will run the automobile, without
+gasoline, for a mile or more with its own accumulated store of
+electric current.</p>
+
+
+<p><span class='pagenum'><a name="Page_234" id="Page_234">[Pg 234]</a></span></p><p class="center padtop"><i>The Low Voltage Battery</i></p>
+
+<p>The 30-volt storage battery has become standard for small lighting
+plants, since the introduction of the tungsten lamp. Although the
+voltage of each separate cell of this battery registers 2.5 volts when
+fully charged, it falls to approximately 2 volts per cell immediately
+discharging begins. For this reason, it is customary to figure the
+working pressure of each cell at 2 volts. This means that a 30-volt
+battery should consist of at least 15 cells. Since, however, the
+voltage falls below 2 for each cell, as discharging proceeds, it is
+usual to include one additional cell for regulating purposes. Thus,
+the ordinary 30-volt storage battery consists of 16 cells, the last
+cell in the line remaining idle until the lamps begin to dim, when it
+is switched in by means of a simple arrangement of connections. This
+maintains a uniform pressure of 30 volts from the beginning to the end
+of the charge, at the lamp socket.</p>
+
+<p>We saw in earlier chapters that the 110-volt<span class='pagenum'><a name="Page_235" id="Page_235">[Pg 235]</a></span> current is the most
+satisfactory, under all conditions, where the current is to be used
+for heating and small power, as well as light. But a storage battery
+of 110 volts would require at least 55 cells, which would make it too
+expensive for ordinary farm use. As a 30-volt current is just as
+satisfactory for electric light, this type has become established, in
+connection with the battery, and it is used for electric lighting
+only, as a general rule.</p>
+
+<p>Batteries are rated first, as to voltage; second, as to their capacity
+in ampere hours&mdash;that is, the number of amperes that may be drawn from
+them in a given number of hours. Thus, a battery rated at 60 ampere
+hours would give 60 amperes, at 30 volts pressure, for one hour; 30
+amperes for 2 hours; 15 amperes for 4 hours; 7&frac12; amperes for 8
+hours; 3&frac34; amperes for 16 hours; etc., etc. In practice, a battery
+should not be discharged faster than its 8-hour rate. Thus, a
+60-ampere hour battery should not be drawn on at a greater rate than
+7&frac12; amperes per hour.</p>
+
+<p>This 8-hour rate also determines the rate<span class='pagenum'><a name="Page_236" id="Page_236">[Pg 236]</a></span> at which a battery should
+be re-charged, once it is exhausted. Thus, this battery should be
+charged at the rate of 7&frac12; amperes for 8 hours, with another hour
+added to make up for losses that are bound to occur. A battery of
+120-ampere hour capacity should be charged for 8 or 9 hours at the
+rate of 120 &divide; 8, or 15 amperes, etc.</p>
+
+<p>To determine the size of battery necessary for any particular
+instance, it is necessary first to decide on the number of lamps
+required, and their capacity. Thirty-volt lamps are to be had in the
+market in sizes of 10, 15 and 20 watts; they yield respectively 8, 12,
+and 16 candlepower each. Of these the 20-watt lamp is the most
+satisfactory for the living rooms; lamps of 10 or 15 watts may be used
+for the halls, the bathroom and the bedrooms. At 30 volts pressure
+these lamps would require a current of the following density in
+amperes:</p>
+
+<table summary="candle power and volts" style="width: 40%;"><tbody>
+<tr><td class="center" style="width: 25%;"><i>Candle Power</i></td>     <td class="center" style="width: 50%;"><i>30-volt lamp</i></td>     <td class="center" style="width: 25%;"><i>Amperes</i></td></tr>
+<tr><td class="center">8</td>  <td class="center">10 watts</td>  <td class="center">0.33</td></tr>
+<tr><td class="center">12</td>  <td class="center">15 watts</td>  <td class="center">0.50</td></tr>
+<tr><td class="center">16</td>  <td class="center">20 watts</td>  <td class="center">0.67</td></tr>
+</tbody></table>
+
+<p><span class='pagenum'><a name="Page_237" id="Page_237">[Pg 237]</a></span></p><p>Let us assume, as an example, that Farmer Brown will use 20-watt
+lamps in his kitchen, dining room, and sitting room; and 10-watt lamps
+in the halls, bathroom, and bedrooms. His requirements may be figured
+either in lamp hours or in watt-hours. Since he is using two sizes of
+lamps, it will be simpler to figure his requirements in watt-hours.
+Thus:</p>
+
+<table summary="lamps" style="width: 70%;"><tbody>
+<tr><td style="width: 4%;"></td>   <td class="left"><i>Room</i></td>  <td class="center" style="width: 10%;"><i>Number<br />of lamps</i></td>   <td class="center"><i>Size<br />of lamps</i></td>    <td class="center"><i>Hours<br />burned</i></td>     <td class="center"><i>Watt-hours</i></td></tr>
+
+<tr><td></td>                    <td class="left">Kitchen</td>      <td class="left">1</td>              <td class="center">20</td>    <td class="center">4</td>  <td class="center">80</td></tr>
+<tr><td></td>                   <td class="left">Dining room</td>   <td class="left">2</td>              <td class="center">20</td>    <td class="center">2</td>  <td class="center">80</td></tr>
+<tr><td></td>                   <td class="left">Sitting room</td>  <td class="left">3</td>                <td class="center">20</td>  <td class="center">4</td>  <td class="center">240</td></tr>
+<tr><td class="left">(3)</td>  <td class="left">Bedrooms</td>        <td class="left">1 (each)</td>  <td class="center">10</td>  <td class="center">1</td>  <td class="center">30</td></tr>
+<tr><td></td>                   <td class="left">Bathroom</td>      <td class="left">1</td>                <td class="center">10</td>  <td class="center">2</td>  <td class="center">20</td></tr>
+<tr><td class="left">(2)</td>  <td class="left">Halls</td>          <td class="left">1 (each)</td>  <td class="center">10</td>    <td class="center">4</td>  <td class="center">80</td></tr>
+<tr><td></td>                   <td class="left">Pantry</td>       <td class="left">1</td>                <td class="center">10</td>    <td class="center">1</td>  <td class="center">10</td></tr>
+<tr><td></td>                   <td class="left">Cellar</td>        <td class="left">1</td>                <td class="center">10</td>  <td class="center">1</td>  <td class="center">10</td></tr>
+<tr><td></td>                  <td></td>                           <td></td>                              <td></td>                    <td></td>                  <td class="center">&mdash;&mdash;&mdash;</td></tr>
+<tr><td></td>                   <td class="tl">Total</td>           <td></td>                             <td></td>                    <td></td>               <td class="center">550</td></tr>
+</tbody></table>
+
+<p>Since amperes equal watts divided by volts, the number of ampere hours
+required in this case each night would be 550 &divide; 30 = 18.3 ampere
+hours; or approximately 4&frac12; amperes per hour for 4 hours.</p>
+
+<p>Say it is convenient to charge this battery every fourth day. This
+would require a battery <span class='pagenum'><a name="Page_238" id="Page_238">[Pg 238]</a></span>of 4 &times; 18.3 ampere hours, or 73.2 ampere
+hours. The nearest size on the market is the 80-ampere hour battery,
+which would be the one to use for this installation.</p>
+
+<p>To charge this battery would require a dynamo capable of delivering 10
+amperes of current for 9 hours. The generator should be of 45 volts
+pressure (allowing 2&frac12; volts in the generator for each 2 volts of
+battery) and the capacity of the generator would therefore be 450
+watts. This would require a 1&frac14; horsepower gasoline engine. At 1&frac14;
+pints of gasoline for each horsepower, nine hours work of this engine
+would consume 14 pints of gasoline&mdash;or say 16 pints, or two gallons.
+At 12 cents a gallon for gasoline, lighting your house with this
+battery would cost 24 cents for four days, or 6 cents a day. Your city
+cousin, using commercial current, would pay 5&frac12; cents a day for the
+same amount of current at 10 cents a kilowatt-hour; or 8&frac14; cents at
+a 15-cent rate. If the battery is charged by the farm gasoline engine
+at the same time it is doing its other work, the cost<span class='pagenum'><a name="Page_239" id="Page_239">[Pg 239]</a></span> would be still
+less, as the extra gasoline required would be small.</p>
+
+<p>This figure does not take into account depreciation of battery and
+engine. The average farmer is too apt to overlook this factor in
+figuring the cost of machinery of all kinds, and for that reason is
+unprepared when the time comes to replace worn-out machinery. The
+dynamo and switchboard should last a lifetime with ordinary care, so
+there is no depreciation charge against them. The storage battery, a
+30-volt, 80-ampere hour installation, should not cost in excess of
+$100; and, if it is necessary to buy a gasoline engine, a 1&frac14;
+horsepower engine can be had for $50 or less according to the type.
+Storage batteries of the lead type are sold under a two-years'
+guarantee&mdash;which does not mean that their life is limited to that
+length of time. With good care they may last as long as 10 years; with
+poor care it may be necessary to throw them away at the end of a year.
+The engine should be serviceable for at least 10 years, with ordinary
+replacements; and the storage<span class='pagenum'><a name="Page_240" id="Page_240">[Pg 240]</a></span> battery may last from 6 to 10 years,
+with occasional renewal of parts. If it were necessary to duplicate
+both at the end of ten years, this would make a carrying charge of
+$1.25 a month for depreciation, which must be added to the cost of
+light.</p>
+
+
+<p class="center padtop"><i>Figuring by Lamp Hours</i></p>
+
+<p>If all the lamps are to be of the same size&mdash;either ten, fifteen, or
+twenty watts, the light requirements of a farm house can be figured
+readily by lamp hours. In that event, the foregoing table would read
+as follows:</p>
+
+<table summary="lamp hours" style="width: 40%;"><tbody>
+<tr><td></td>                                        <td class="tr"><i>Lamp hours</i></td></tr>
+<tr><td class="tl">Kitchen, 1 lamp, 4 hours</td>                      <td class="tr">4</td></tr>
+<tr><td class="tl">Sitting room, 3 lamps, 4 hours each</td>          <td class="tr">12</td></tr>
+<tr><td class="tl">Dining room, 2 lamps, 2 hours each</td>            <td class="tr">4</td></tr>
+<tr><td class="tl">Bedrooms, 3 lamps, 1 hour each</td>                <td class="tr">3</td></tr>
+<tr><td class="tl">Halls, 2 lamps, 4 hours each</td>                  <td class="tr">8</td></tr>
+<tr><td class="tl">Bathroom, 1 lamp, 2 hours</td>                    <td class="tr">2</td></tr>
+<tr><td class="tl">Pantry and cellar, 2 lamps, 1 hour each</td>       <td class="tr">2</td></tr>
+</tbody></table>
+
+<p>To determine the ampere hours from this table, multiply the total
+number of lamp hours by the current in amperes required for each lamp.
+As 10, 15, and 20-watt tungsten lamps require .33, .50 and .67
+amperes, respectively <span class='pagenum'><a name="Page_241" id="Page_241">[Pg 241]</a></span>at 30 volts pressure, the above requirements in
+ampere hours would be 12, 17&frac12;, or 24 ampere hours, according to the
+size of lamp chosen. This gives the average current consumption for
+one night. If it is desired to charge the battery twice a week on the
+average, multiply the number of lamp hours by 4, to get the size of
+battery required.</p>
+
+<p>The foregoing illustration is not intended to indicate average light
+requirements for farms, but is given merely to show how a farmer may
+figure his own requirements. In some instances, it will be necessary
+to install a battery of 120 or more ampere hours, whereas a battery of
+40 or 60 ampere hours would be quite serviceable in other instances.
+It all depends on how much light you wish to use and are willing to
+pay for, because with a storage battery the cost of electric light is
+directly in proportion to the number of lights used.</p>
+
+<p>As a general rule, a larger generator and engine are required for a
+larger battery&mdash;although it is possible to charge a large battery
+<span class='pagenum'><a name="Page_242" id="Page_242">[Pg 242]</a></span>with a small generator and engine by taking more time for the
+operation.</p>
+
+
+<p class="center padtop"><i>How to Charge a Storage Battery</i></p>
+
+<p>Direct current only can be used for charging storage batteries. In the
+rare instance of alternating current only being available, it must be
+converted into direct current by any one of the many mechanical,
+chemical, or electrical devices on the market&mdash;that is, the
+alternating current must be straightened out, to flow always in one
+direction.</p>
+
+<p>A shunt-wound dynamo must be used; else, when the voltage of the
+battery rises too high, it may "back up" and turn the dynamo as a
+motor, causing considerable damage. If a compound dynamo is already
+installed, or if it is desired to use such a machine for charging
+storage batteries, it can be done simply by disconnecting the series
+windings on the field coils, thus turning the machine into a shunt
+dynamo.</p>
+
+<p>The voltage of the dynamo should be approximately 50 per cent above
+the working<span class='pagenum'><a name="Page_243" id="Page_243">[Pg 243]</a></span> pressure of the battery. For this reason 45-volt machines
+are usually used for 30 or 32-volt batteries. Higher voltages may be
+used, if convenient. Thus a 110-volt dynamo may be used to charge a
+single 2-volt cell if necessary, although it is not advisable.</p>
+
+
+<p class="center padtop"><i>Direction of Current</i></p>
+
+<p>Electricity flows from the positive to the negative terminal. A
+charging current must be so connected that the negative wire of the
+dynamo is always connected to the negative terminal of the battery,
+and the positive wire to the positive terminal. As the polarity is
+always marked on the battery, there is little danger of making a
+mistake in this particular.</p>
+
+<p>When the storage battery is charged, and one begins to use its
+accumulation of energy, the current comes out in the opposite
+direction from which it entered in charging. In this respect, a
+storage battery is like a clock spring, which is wound up in one
+direction, and unwinds itself in the other. With all storage battery
+outfits, an ammeter (or current measure) <span class='pagenum'><a name="Page_244" id="Page_244">[Pg 244]</a></span>is supplied with zero at the
+center. When the battery is being charged, the indicating needle
+points in one direction in proportion to the strength of the current
+flowing in; and when the battery is being discharged, the needle
+points in the opposite direction, in proportion to the strength of the
+current flowing out.</p>
+
+<p>Sometimes one is at loss, in setting about to connect a battery and
+generator, to know which is the positive and which the negative wire
+of the generator. A very simple test is as follows:</p>
+
+<p>Start the generator and bring it up to speed. Connect some form of
+resistance in "series" with the mains. A lamp in an ordinary lamp
+socket will do very well for this resistance. Dip the two ends of the
+wire (one coming from the generator, the other through the lamp) into
+a cup of water, in which a pinch of salt is dissolved. Bring them
+almost together and hold them there. Almost instantly, one wire will
+begin to turn bright, and give off bubbles. The wire which turns
+bright and gives off bubbles is the <i>negative</i> wire. The other is the
+positive.</p>
+
+
+<div class="figcenter" style="width: 500px;"><a name="i244" id="i244"></a>
+<img src="images/i244.jpg" width="500" height="390" alt="" title="" />
+A rough-and-ready farm electric plant, supplying two
+farms with light, heat and power; and a Ward Leonard-type
+circuit-breaker for charging storage batteries
+</div>
+
+<p><span class='pagenum'><a name="Page_245" id="Page_245">[Pg 245]</a></span></p>
+
+<p class="center padtop"><i>Care of Battery</i></p>
+
+<p>Since specific directions are furnished with all storage batteries, it
+is not necessary to go into the details of their care here. Storage
+battery plants are usually shipped with all connections made, or
+plainly indicated. All that is necessary is to fill the batteries with
+the acid solution, according to directions, and start the engine. If
+the engine is fitted with a governor, and the switchboard is of the
+automatic type, all the care necessary in charging is to start the
+engine. In fact, many makes utilize the dynamo as a "self-starter" for
+the engine, so that all that is necessary to start charging is to
+throw a switch which starts the engine. When the battery is fully
+charged, the engine is stopped automatically.</p>
+
+<p>The "electrolyte" or solution in which the plates of the lead battery
+are immersed, is sulphuric acid, diluted with water in the<span class='pagenum'><a name="Page_246" id="Page_246">[Pg 246]</a></span> proportion
+of one part of acid to five of water, by volume.</p>
+
+<p>The specific gravity of ordinary commercial sulphuric acid is 1.835.
+Since its strength is apt to vary, however, it is best to mix the
+electrolyte with the aid of the hydrometer furnished with the battery.
+The hydrometer is a sealed glass tube, with a graduated scale somewhat
+resembling a thermometer. The height at which it floats in any given
+solution depends on the density of the solution. It should indicate
+approximately 1.15 for a storage battery electrolyte before charging.
+It should not be over 1.15&mdash;or 1,150 if your hydrometer reads in
+thousandths.</p>
+
+<p>Only pure water should be used. Distilled water is the best, but fresh
+clean rain water is permissible. Never under any circumstances use
+hydrant water, as it contains impurities which will injure the
+battery, probably put it out of commission before its first charge.</p>
+
+<p><i>Pour the acid into the water.</i> Never under any circumstances pour the
+water into the acid, else an explosion may occur from the<span class='pagenum'><a name="Page_247" id="Page_247">[Pg 247]</a></span> heat
+developed. Mix the electrolyte in a stone crock, or glass container,
+stirring with a glass rod, and testing from time to time with a
+hydrometer. Let it stand until cool and then pour it into the battery
+jars, filling them to &frac12; inch above the top of the plates.</p>
+
+<p>Then begin charging. The first charge will probably take a longer time
+than subsequent charges. If the installation is of the automatic type,
+all that is necessary is to start the engine. If it is not of the
+automatic type, proceed as follows:</p>
+
+<p>First be sure all connections are right. Then start the engine and
+bring the dynamo up to its rated speed. Adjust the voltage to the
+pressure specified. Then throw the switch connecting generator to
+battery. Watch the ammeter. It should register in amperes, one-eighth
+of the ampere-hour capacity of the battery, as already explained. If
+it registers too high, reduce the voltage of the generator slightly,
+by means of the field rheostat connected to the generator. This will
+also reduce the amperes flowing. If too low, raise the<span class='pagenum'><a name="Page_248" id="Page_248">[Pg 248]</a></span> voltage until
+the amperes register correctly. Continue the charging operation until
+the cells begin to give off gas freely; or until the specific gravity
+of the electrolyte, measured by the hydrometer, stands at 1.24. Your
+battery is now fully charged. Throw the switch over to the service
+line, and your accumulator is ready to furnish light if you turn on
+your lamps.</p>
+
+<p>Occasionally add distilled water to the cells, to make up for
+evaporation. It is seldom necessary to add acid, as this does not
+evaporate. If the battery is kept fully charged, it will not freeze
+even when the thermometer is well below zero.</p>
+
+<p>A storage battery should be installed as near the house as
+possible&mdash;in the house, if possible. Since its current capacity is
+small, transmission losses must be reduced to a minimum.</p>
+
+<p>In wiring the house for storage battery service, the same rules apply
+as with standard voltage. Not more than 6 amperes should be used on
+any single branch circuit. With low voltage batteries (from 12 volts
+to 32 volts) it<span class='pagenum'><a name="Page_249" id="Page_249">[Pg 249]</a></span> is well to use No. 10 or No. 12 B. &amp; S. gauge
+rubber-covered wire, instead of the usual No. 14 used with standard
+voltage. The extra expense will be only a few cents for each circuit,
+and precious volts will be saved in distribution of the current.</p>
+
+
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_250" id="Page_250">[Pg 250]</a></span></p>
+<h2><a name="CHAPTER_XII" id="CHAPTER_XII"></a>CHAPTER XII</h2>
+
+<p class="subhead2">BATTERY CHARGING DEVICES</p>
+
+<div class="blockquot"><p>The automatic plant most desirable&mdash;How an automobile lighting and
+starting system works&mdash;How the same results can be achieved in
+house lighting, by means of automatic devices&mdash;Plants without
+automatic regulation&mdash;Care necessary&mdash;The use of heating devices on
+storage battery current&mdash;Portable batteries&mdash;An electricity
+"route"&mdash;Automobile power for lighting a few lamps.</p></div>
+
+
+<p>The water-power electric plants described in preceding chapters are
+practically automatic in operation. This is very desirable, as such
+plants require the minimum of care. It is possible to attain this same
+end with a storage battery plant.</p>
+
+<p>Automatic maintenance approaches a high degree of perfection in the
+electric starting and lighting device on a modern automobile. In this
+case, a small dynamo geared to the main shaft is running whenever the
+engine is running. It is always ready to "pump"<span class='pagenum'><a name="Page_251" id="Page_251">[Pg 251]</a></span> electricity into the
+storage battery when needed. An electric magnet, wound in a peculiar
+manner, automatically cuts off the charging current from the dynamo,
+when the battery is "full;" and the same magnet, or "regulator,"
+permits the current to flow into the battery when needed. The
+principle is the same as in the familiar plumbing trap, which
+constantly maintains a given level of water in a tank, no matter how
+much water may be drawn from the tank. The result, in the case of the
+automobile battery, is that the battery is always kept fully charged;
+for no sooner does the "level" of electricity begin to drop (when used
+for starting or lighting) than the generator begins to charge. This is
+very desirable in more ways than one. In the first place, the energy
+of the battery is always the same; and in the second place, the mere
+fact that the battery is always kept fully charged gives it a long
+life.</p>
+
+<p>The same result can be achieved in storage battery plants for house
+lighting, where the source of power is a gasoline or other engine<span class='pagenum'><a name="Page_252" id="Page_252">[Pg 252]</a></span>
+engaged normally in other work. Then your electric current becomes
+merely a by-product of some other operation.</p>
+
+<p>Take a typical instance where such a plant would be feasible: Farmer
+Brown has a five horsepower gasoline engine&mdash;an ordinary farm engine
+for which he paid probably $75 or $100. Electric light furnished
+direct from such an engine would be intolerable because of its
+constant flickering. This five horsepower engine is installed in the
+milk room of the dairy, and is belted to a countershaft. This
+countershaft is belted to the vacuum pump for the milking machine, and
+to the separator, and to a water pump, any one of which may be thrown
+into service by means of a tight-and-loose pulley. This countershaft
+is also belted to a small dynamo, which runs whenever the engine is
+running. The milking machine, the separator, and the water pump
+require that the gasoline engine be run on the average three hours
+each day.</p>
+
+<p>The dynamo is connected by wires to the house storage battery through
+a properly<span class='pagenum'><a name="Page_253" id="Page_253">[Pg 253]</a></span> designed switchboard. The "brains" of this switchboard is
+a little automatic device (called a regulator or a circuit breaker),
+which opens and shuts according to the amount of current stored in the
+battery and the strength of the current from the generator. When the
+battery is "full," this regulator is "open" and permits no current to
+flow. Then the dynamo is running idle, and the amount of power it
+absorbs from the gasoline engine is negligible. When the "level" of
+electricity in the battery falls, due to drawing current for light,
+the regulator is "shut," that is, the dynamo and battery are
+connected, and current flows into the battery.</p>
+
+<p>These automatic instruments go still farther in their brainy work.
+They do not permit the dynamo to charge the battery when the voltage
+falls below a fixed point, due to the engine slowing down; neither do
+they permit the dynamo current to flow when the voltage gets too high
+due to sudden speeding up of the engine.</p>
+
+<p>Necessarily, an instrument which will take<span class='pagenum'><a name="Page_254" id="Page_254">[Pg 254]</a></span> care of a battery in this
+way, is intricate in construction. That is not an argument against it
+however. A watch is intricate, but so long as we continue to wind it
+at stated intervals, it keeps time. So with this storage battery
+plant: so long as Farmer Brown starts his engine to do his farm chores
+every day, his by-product of electricity is stored automatically.</p>
+
+<p>Such installations are not expensive. A storage battery capable of
+lighting 8 tungsten lamps, of 16 candlepower each, continuously for 8
+hours (or fewer lamps for a longer time); a switchboard containing all
+the required regulating instruments; and a dynamo of suitable size,
+can be had for from $250 to $300. All that is necessary to put such a
+plant in operation, is to belt the dynamo to the gasoline engine so
+that it will run at proper speed; and to connect the wires from dynamo
+to switchboard, and thence to the house service. The dynamo required
+for the above plant delivers 10 amperes at 45 volts pressure, or 10 &times;
+45 = 450 watts. A gasoline, gas, or oil<span class='pagenum'><a name="Page_255" id="Page_255">[Pg 255]</a></span> engine, or a windmill of
+1&frac12; horsepower furnishes all the power needed. If the farmer uses
+his engine daily, or every other day, for other purposes, the cost of
+power will be practically negligible. With this system electric lights
+are available at any time day or night; and when the gasoline engine
+is in service daily for routine farm chores, the battery will never
+run low.</p>
+
+<p>This system is especially desirable where one uses a windmill for
+power. The speed of the windmill is constantly fluctuating, so much so
+in fact that it could not be used for electric light without a storage
+battery. But when equipped with a regulator on the switchboard which
+permits the current to flow only when the battery needs it, and then
+only when the speed of the windmill is correct, the problem of turning
+wind power into electric light is solved.</p>
+
+<hr style='width: 45%;' />
+
+<p>If the farmer does not desire to go to the additional expense of
+automatic regulation, there are cheaper plants, requiring attention<span class='pagenum'><a name="Page_256" id="Page_256">[Pg 256]</a></span>
+for charging. These plants are identical with those described above,
+except they have no regulators. With these plants, when the battery
+runs low (as is indicated by dimming of the lights) it is necessary to
+start the engine, bring it up to speed, adjust the dynamo voltage to
+the proper pressure, and throw a switch to charge the battery. For
+such plants it is customary to run the engine to charge the battery
+twice a week. It is necessary to run the engine from 8 to 10 hours to
+fully charge the discharged battery. When the battery approaches full
+charge, the fact is evidenced by so-called "gassing" or giving off of
+bubbles. Another way to determine if the battery is fully charged is
+by means of the voltmeter, as the volts slowly rise to the proper
+point during the process of charging. A third way, and probably the
+most reliable is by the use of the hydrometer. The voltage of each
+cell when fully charged should be 2.5; it should never be discharged
+below 1.75 volts. Many storage battery electric light plants on the
+market are provided with<span class='pagenum'><a name="Page_257" id="Page_257">[Pg 257]</a></span> a simple and inexpensive circuit breaker,
+which automatically cuts off the current and stops the engine when the
+battery is charged. The current is then thrown from the dynamo to the
+house service by an automatic switch. If such a circuit breaker is not
+included, it is necessary to throw the switch by hand when charging is
+begun or ended.</p>
+
+<p>Since the principal item of first cost, as well as depreciation, in a
+storage battery electric light plant is the storage battery itself,
+the smallest battery commensurate with needs is selected. Since the
+amount of current stored by these batteries is relatively small,
+electric irons and heating devices such as may be used freely on a
+direct-connected plant without a battery, are rather expensive
+luxuries. For instance, an electric iron drawing 400 watts an hour
+while in use, requires as much energy as 20 tungsten lamps of 16
+candlepower each burning for the same length of time. Its rate of
+current consumption would be over 13 amperes, at 30 volts; which would
+require a larger battery than<span class='pagenum'><a name="Page_258" id="Page_258">[Pg 258]</a></span> needed for light in the average farm
+home.</p>
+
+<p>The use to which electricity from a storage battery is put, however,
+is wholly a matter of expense involved; and if one is willing to pay
+for these rather expensive luxuries, there is no reason why he should
+not have them. Heating, in any form, by electricity, requires a large
+amount of current proportionally. As a matter of fact, there is less
+heat to be had in thermal units from a horsepower-hour of electricity
+than from three ounces of coal. When one is generating current from
+water-power, or even direct from gasoline or oil, this is not an
+argument against electric heating devices. But it becomes a very
+serious consideration when one is installing a storage battery as the
+source of current, because of the high initial cost, and depreciation
+of such a battery.</p>
+
+<p>Farmers who limit the use of their storage battery plants to lighting
+will get the best service.</p>
+
+
+<p><span class='pagenum'><a name="Page_259" id="Page_259">[Pg 259]</a></span></p><p class="center padtop"><i>Portable Batteries</i></p>
+
+<p>Abroad it is becoming quite common for power companies to deliver
+storage batteries fully charged, and call for them when discharged.
+Without a stretch of the imagination, we can imagine an ingenious
+farmer possessing a water-power electric plant building up a thriving
+business among his less fortunate neighbors, with an "electricity"
+route. It could be made quite as paying as a milk route.</p>
+
+<div class="figleft" style="width: 500px;">
+<img src="images/d259.jpg" width="500" height="630" alt="" title="" />
+Connections for charging storage batteries on 110-volt
+mains
+</div>
+
+
+<p>Many communities have water or steam power at a distance too great to
+transmit 110-volt current by wire economically; and because of lack of
+expert supervision, they do not care to risk using current at a
+pressure of 500 volts or higher, because of its danger to human life.</p>
+
+<p>In such a case it would be quite feasible for families to wire their
+houses, and carry their<span class='pagenum'><a name="Page_260" id="Page_260">[Pg 260]</a></span> batteries to the generating plant two or
+three times a week to be charged. There are a number of portable
+batteries on the market suitable for such service, at voltages ranging
+from 6 to 32 volts. The best results would be obtained by having two
+batteries, leaving one to be charged while the other was in use; and
+if the generating station was located at the creamery or feed mill,
+where the farmer calls regularly, the trouble would be reduced to a
+minimum.</p>
+
+<p>Such a battery would necessarily be small, and of the sealed type,
+similar to those used in automobiles. It could be used merely for
+reading lamps&mdash;or it could be used for general lighting, according to
+the expense the farmer is willing to incur for batteries.</p>
+
+<p>An ordinary storage battery used in automobile ignition and lighting
+systems is of the 6-volt, 60-ampere type, called in trade a "6-60."
+Lamps can be had for these batteries ranging in sizes from 2
+candlepower to 25 candlepower. A lamp of 15 candlepower, drawing 2&frac12;
+amperes, is used for automobile<span class='pagenum'><a name="Page_261" id="Page_261">[Pg 261]</a></span> headlights, and, as any one knows
+after an experience of meeting a headlight on a dark road, they give a
+great deal of light. A "6-60" battery keeps one of these lamps running
+for 24 hours, or two lamps running 12 hours. A minimum of wiring would
+be required to install such a battery for the reading lights in the
+sitting room, and for a hanging light in the dining room. The
+customary gates for charging these batteries in a large city is 10
+cents; but in a country plant it could be made less.</p>
+
+<p>To charge such a battery on a 110-volt direct current, it is necessary
+to install some means of limiting the amount of current, or in other
+words, the charging rate. This charging rate, for 8 hours should be,
+as we have seen, one-eighth of the ampere-hour capacity of the
+battery. Thus a "6-60" battery would require a 7&frac12; ampere current.</p>
+
+<p>Connecting two such batteries in "series" (that is, the negative pole
+of one battery to the positive pole of the second) would make a
+12-volt battery. Ten or twelve such batteries<span class='pagenum'><a name="Page_262" id="Page_262">[Pg 262]</a></span> could be connected in
+"series," and a 110-volt direct current generator would charge them in
+8 hours at a 7&frac12; ampere rate.</p>
+
+<p>The diagram on page 259 shows the connections for charging on a
+110-volt circuit.</p>
+
+<p>An ordinary 16-candlepower carbon lamp is of 220 ohms resistance, and
+(by Ohm's Law, C equals E divided by R) permits &frac12; ampere of current
+to flow. By connecting 15 such lamps across the mains, in parallel,
+the required 7&frac12; amperes of current would be flowing from the
+generator through the lamps, and back again. Connect the battery in
+"series" at any point on either of the two mains, between the lamps
+and the generator, being careful to connect the positive end to the
+positive pole of the battery, and <i>vice versa</i>.</p>
+
+<p>Lamps are the cheapest form of resistance; but in case they are not
+available, any other form of resistance can be used. Iron wire wound
+in spirals can be used, or any of the many makes of special resistance
+wire on the market. First it is necessary to determine the amount of
+resistance required.</p>
+
+<p><span class='pagenum'><a name="Page_263" id="Page_263">[Pg 263]</a></span></p><p>We have just seen that the charging rate of a 60-ampere hour battery
+is 7&frac12; amperes. Applying Ohm's Law here, we find that ohms
+resistance equals volts divided by amperes, or R = 110/7.5 = 14.67
+ohms. With a 220-volt current, the ohms resistance required in series
+with the storage battery of this size would be 29.33 ohms.</p>
+
+
+<p class="center padtop"><i>Automobile Power for Lighting</i></p>
+
+<p>There are many ingenious ways by which an automobile may be utilized
+to furnish electric light for the home. The simplest is to run wires
+direct from the storage battery of the self-starting system, to the
+house or barn, in such a way that the current may be used for reading
+lamps in the sitting room. By a judicious use of the current in this
+way, the normal operation of the automobile in the daytime will keep
+the battery charged for use of the night lamps, and if care is used,
+such a plan should not affect the life of the battery. Care should be
+used also, in this regard, not to discharge the battery too low<span class='pagenum'><a name="Page_264" id="Page_264">[Pg 264]</a></span> to
+prevent its utilizing its function of starting the car when it was
+desired to use the car. However, if the battery were discharged below
+its starting capacity, by any peradventure, the car could be started
+by the old-fashioned cranking method.</p>
+
+<p>Using an automobile lighting system for house lighting implies that
+the car be stored in a garage near the house or barn; as this battery
+is too low in voltage to permit transmitting the current any distance.
+One hundred feet, with liberal sized transmission wires is probably
+the limit.</p>
+
+<p>That such a system is feasible is amply proved by an occurrence
+recently reported in the daily papers. A doctor summoned to a remote
+farm house found that an immediate operation was necessary to save the
+patient's life. There was no light available, except a small kerosene
+lamp which was worse than nothing. The surgeon took a headlight off
+his car, strung a pair of wires through a window, and instantly had at
+his command a light of the necessary intensity.</p>
+
+<p><span class='pagenum'><a name="Page_265" id="Page_265">[Pg 265]</a></span></p><p>Another manner in which an automobile engine may be used for house
+lighting is to let it serve as the charging power of a separate
+storage battery. The engine can be belted to the generator, in such a
+case, by means of the fly wheel. Or a form of friction drive can be
+devised, by means of which the rear wheels (jacked up off the floor)
+may supply the necessary motive power. In such a case it would be
+necessary to make allowance for the differential in the rear axle, so
+that the power developed by the engine would be delivered to the
+friction drive.</p>
+
+
+
+<hr style="width: 65%;" />
+
+<p><span class='pagenum'><a name="Page_266" id="Page_266">[Pg 266]</a></span></p>
+
+<p class="subhead3">The following pages contain advertisements of Macmillan books by the
+same author or on related subjects.</p>
+
+<hr style="width: 65%;" />
+
+
+<p><span class='pagenum'><a name="Page_267" id="Page_267">[Pg 267]</a></span></p>
+
+<p class="subhead1">WATER POWER ENGINEERS</p>
+
+<p class="subhead2">DESIGNERS AND MANUFACTURERS</p>
+
+<p class="subhead1" style="margin-bottom: 0;">HUNT</p>
+
+<p class="subhead3" style="margin-top: 0;">SUPERIOR QUALITY</p>
+
+<p>Complete equipments for developing water powers including:&mdash;Water
+Wheels, Flumes, Governors, Supply Pipes, Gates, Hoists, Valves,
+Screens, Gears, Pulleys, Clutches, Bearings, Shafting, etc.</p>
+
+<p>Three types of water power developing wheels, ranged to meet every
+condition.</p>
+
+<div class="figleft" style="width: 175px;">
+<img src="images/ad.jpg" width="175" height="281" alt="drawing of turbine" title="" />
+</div>
+
+<div class="blockquot padtop"><p>Div. No. 1&mdash;<span class="smcap">Turbine Water Wheels</span> for large powers and large
+quantities of water.</p>
+
+<p>Div. No. 2&mdash;<span class="smcap">Rim Leverage Wheels</span> for small powers and very limited
+quantities of water.</p>
+
+<p>Div. No. 3&mdash;<span class="smcap">Small Water Motors</span> for minimum water supplies under
+high heads.</p>
+
+<p>Send for special catalogues and Water Power Blanks to fill in for
+estimates on suitable type of Water Wheel for developing your water
+power to best advantage.</p>
+</div>
+<p>
+RODNEY HUNT MACHINE COMPANY<br />
+60 MILL STREET<br />
+ORANGE, MASSACHUSETTS, U.S.A.<br />
+</p>
+
+
+<p><span class='pagenum'><a name="Page_268" id="Page_268">[Pg 268]</a></span></p>
+
+
+<div class="blockquot">
+<p style="clear: left; font-size: 110%;"><b>The Farmer of Tomorrow</b></p>
+
+<p style="text-align: right;"><i>Cloth, 12mo, $1.50</i></p>
+
+<p>"A crisp, entertaining, and instructive discussion of the
+conditions which have brought about the present agricultural
+problem in America."&mdash;<i>Countryside Magazine.</i></p>
+
+<p>"The book is interestingly written and full of many vital
+discussions."&mdash;<i>Annals of the American Academy of Political and
+Social Science.</i></p>
+
+<p>"A popular consideration of the fundamental factors affecting the
+business of farming."&mdash;<i>Pacific Rural Press.</i></p>
+
+<p>"The growing, popular question of farming analyzed from all angles,
+with many helpful suggestions."&mdash;<i>Leslie's Weekly.</i></p>
+
+<p>"Any person of intelligence, alive to the present and future
+welfare of his country will find 'The Farmer of Tomorrow,' a book
+of absorbing character."&mdash;<i>Times-Star.</i></p>
+
+
+<p>
+THE MACMILLAN COMPANY<br />
+Publishers<br />
+64-66 Fifth Avenue<br />
+New York<br />
+</p>
+</div>
+
+<p><span class='pagenum'><a name="Page_269" id="Page_269">[Pg 269]</a></span></p>
+
+<div class="blockquot">
+<p style="font-size: 110%;"><b>Co&ouml;peration in Agriculture</b></p>
+
+<p><span class="smcap">By</span> G. HAROLD POWELL</p>
+
+<p style="text-align: right;"><i>Cloth, 12mo, $1.50</i></p>
+
+<p>"The author has a broad outlook and never fails to suggest that the
+economic advantages of co&ouml;peration may frequently be quite
+subordinate to the general social and community interests which are
+fostered through a common undertaking. He writes with the genuine
+interest of a man having experience and faith in that of which he
+speaks."&mdash;<i>Political Science Quarterly.</i></p>
+
+<p>"A volume which explains in a lucid way the features of the
+existing system and the measures taken by farmers to protect their
+interests."&mdash;<i>Journal of the Royal Statistical Society.</i></p>
+
+<p>"Mr. Powell has not attempted to cover the entire field of
+agricultural co&ouml;peration, but has confined himself to its more
+important phases. His work shows a grasp of the issues involved and
+a ripeness of conclusion that comes only from actual contact with
+the practical side of co&ouml;peration."&mdash;<i>American Economic Review.</i></p>
+
+<p>"The book is decidedly worth while."&mdash;<i>Farm Life and Agriculture.</i></p>
+
+<p>
+THE MACMILLAN COMPANY<br />
+Publishers<br />
+64-66 Fifth Avenue<br />
+New York<br />
+</p></div>
+
+<hr style="width: 65%;" />
+
+
+<p><span class='pagenum'><a name="Page_270" id="Page_270">[Pg 270]</a></span></p>
+
+
+<p class="subhead2">RURAL SCIENCE SERIES<br />
+Edited by L. H. BAILEY<br />
+<i>Each volume illustrated. Cloth, 12mo.</i><br />
+</p>
+
+<p>A series of practical books for farmers and gardeners, sold as a set
+or separately. Each one is the work of a competent specialist, and is
+suitable for consultation alike by the amateur or professional tiller
+of the soil, the scientist or the student. Illustrations of marked
+beauty are freely used, and the books are clearly printed and well
+bound.</p>
+
+<table summary="rural science series books" style="width: 60%;"><tbody>
+<tr><td class="tl" style="font-size: 110%;" colspan="2"><b>ON SELECTION OF LAND, ETC.</b></td></tr>
+
+<tr><td class="tl">Isaac P. Roberts' The Farmstead</td>                             <td class="tr">$1 50</td></tr>
+<tr><td class="tl">T. F. Hunt's How to Choose a Farm</td>   <td class="tr">1 75</td></tr>
+<tr><td class="tl">E. S. Cheyney and J. P. Wentling's The Farm Woodlot</td>   <td class="tr">1 50</td></tr>
+<tr><td class="tl">Glenn W. Herrick's Insects Injurious to the Household</td>   <td class="tr">1 75</td></tr>
+
+<tr><td class="tl" style="font-size: 110%;" colspan="2"><b>ON TILLAGE, ETC.</b></td></tr>
+
+<tr><td class="tl">F. H. King's The Soil</td>   <td class="tr">1 50</td></tr>
+<tr><td class="tl">Isaac P. Roberts' The Fertility of the Land</td>   <td class="tr">1 50</td></tr>
+<tr><td class="tl">F. H. King's Irrigation and Drainage</td>   <td class="tr">1 50</td></tr>
+<tr><td class="tl">Edward B. Voorhees' Fertilizers</td>   <td class="tr">1 25</td></tr>
+<tr><td class="tl">Edward B. Voorhees' Forage Crops</td>   <td class="tr">1 50</td></tr>
+<tr><td class="tl">J. A. Widtsoe's Dry Farming</td>   <td class="tr">1 50</td></tr>
+<tr><td class="tl">L. H. Bailey's Principles of Agriculture</td>   <td class="tr">1 25</td></tr>
+<tr><td class="tl">S. M. Tracy's Forage Crops for the South</td>   <td class="tr">1 50</td></tr>
+
+<tr><td class="tl" style="font-size: 110%;" colspan="2"><b>ON PLANT DISEASES, ETC.</b></td></tr>
+
+<tr><td class="tl">E. C. Lodeman's The Spraying of Plants</td>   <td class="tr">1 25</td></tr>
+
+<tr><td class="tl" style="font-size: 110%;" colspan="2"><b>ON GARDEN-MAKING</b></td></tr>
+
+<tr><td class="tl">L. H. Bailey's Garden-Making</td>   <td class="tr">1 50</td></tr>
+<tr><td class="tl">L. H. Bailey's Vegetable-Gardening</td>   <td class="tr">1 50</td></tr>
+<tr><td class="tl">L. H. Bailey's Forcing Book</td>   <td class="tr">1 25</td></tr>
+<tr><td class="tl">L. H. Bailey's Plant Breeding</td>   <td class="tr">2 00</td></tr>
+
+<tr><td class="tl" style="font-size: 110%;" colspan="2"><b>ON FRUIT-GROWING, ETC.</b></td></tr>
+
+<tr><td class="tl">L. H. Bailey's Nursery Book</td>   <td class="tr">1 50</td></tr>
+<tr><td class="tl">L. H. Bailey's Fruit-Growing (New Edition)</td>                   <td class="tr">1 75</td></tr>
+<tr><td class="tl">L. H. Bailey's The Pruning Book</td>   <td class="tr">1 50</td></tr>
+<tr><td class="tl">F. W. Card's Bush Fruits</td>   <td class="tr">1 50</td></tr>
+<tr><td class="tl">W. Paddock &amp; O. B. Whipple's Fruit-Growing in Arid Regions</td>   <td class="tr">1 50</td></tr>
+<tr><td class="tl">J. E. Coit's Citrus Fruits</td>                                 <td class="tr"> <i>Prepar</i></td></tr>
+
+<tr><td class="tl" style="font-size: 110%;" colspan="2"><b>ON THE CARE OF LIVE-STOCK</b></td></tr>
+
+<tr><td class="tl">Nelson S. Mayo's The Diseases of Animals</td>   <td class="tr">1 50</td></tr>
+<tr><td class="tl">W. H. Jordan's The Feeding of Animals</td>   <td class="tr">1 50</td></tr>
+<tr><td class="tl">I. P. Roberts' The Horse</td>   <td class="tr">1 25</td></tr>
+<tr><td class="tl">M. W. Harper's Breaking and Training of Horses</td>   <td class="tr">1 75</td></tr>
+<tr><td class="tl">George C. Watson's Farm Poultry. New edition</td>   <td class="tr">1 50</td></tr>
+<tr><td class="tl">John A. Craig's Sheep Farming</td>   <td class="tr">1 50</td></tr>
+
+<tr><td class="tl" style="font-size: 110%;" colspan="2"><b>ON DAIRY WORK, FARM CHEMISTRY, ETC.</b></td></tr>
+
+<tr><td class="tl">Henry H. Wing's Milk and Its Products. New edition</td>   <td class="tr">1 50</td></tr>
+<tr><td class="tl">J. G. Lipman's Bacteria and Country Life</td>   <td class="tr">1 50</td></tr>
+
+<tr><td class="tl" style="font-size: 110%;" colspan="2"><b>ON ECONOMICS AND ORGANIZATION</b></td></tr>
+
+<tr><td class="tl">William A. McKeever's Farm Boys and Girls</td>   <td class="tr">1 50</td></tr>
+<tr><td class="tl">I. P. Roberts' The Farmer's Business Handbook</td>   <td class="tr">1 25</td></tr>
+<tr><td class="tl">George T. Fairchild's Rural Wealth and Welfare</td>   <td class="tr">1 25</td></tr>
+<tr><td class="tl">H. N. Ogden's Rural Hygiene</td>   <td class="tr">1 50</td></tr>
+<tr><td class="tl">J. Green's Law for the American Farmer</td>   <td class="tr">1 50</td></tr>
+<tr><td class="tl">G. H. Powell's Co&ouml;peration in Agriculture</td>                    <td class="tr">1 50</td></tr>
+</tbody></table>
+
+<div class="blockquot">
+<p>
+THE MACMILLAN COMPANY<br />
+PUBLISHERS<br />
+64-66 Fifth Avenue<br />
+NEW YORK<br />
+</p></div>
+
+<hr style="width: 65%;" />
+
+<p><span class='pagenum'><a name="Page_271" id="Page_271">[Pg 271]</a></span></p>
+
+<p class="subhead2">RURAL TEXT-BOOK SERIES<br />
+Edited by L. H. BAILEY<br />
+<i>Each volume illustrated. Cloth, 12mo.</i></p>
+
+
+<p>While the RURAL SCIENCE SERIES is designed primarily for popular
+reading and for general use, this related new series is designed for
+classroom work and for special use in consultation and reference. The
+RURAL TEXT-BOOK SERIES is planned to cover eventually the entire range
+of public school and college texts.</p>
+
+<table summary="rural text-book series" style="width: 60%;"><tbody>
+<tr><td class="tl" colspan="2"><b>Duggar, B. M.</b></td></tr>
+<tr><td class="tl">Physiology of Plant Production</td>                     <td class="tr">$1 60</td></tr>
+
+<tr><td class="tl" colspan="2"><b>Duggar, John Frederick</b></td></tr>
+<tr><td class="tl">Southern Field Crops</td>  <td class="tr">1 75</td></tr>
+
+<tr><td class="tl" colspan="2"><b>Gay, C. Warren</b></td></tr>
+<tr><td class="tl">Principles and Practice of Judging Live-Stock</td>  <td class="tr">1 50</td></tr>
+
+<tr><td class="tl" colspan="2"><b>Harper, M. W.</b></td></tr>
+<tr><td class="tl">Animal Husbandry for Schools</td>  <td class="tr">1 40</td></tr>
+
+<tr><td class="tl" colspan="2"><b>Hitchcock, A. S.</b></td></tr>
+<tr><td class="tl">Grasses</td>  <td class="tr">1 50</td></tr>
+
+<tr><td class="tl" colspan="2"><b>Livingston, George</b></td></tr>
+<tr><td class="tl">Field Crop Production</td>  <td class="tr">1 40</td></tr>
+
+<tr><td class="tl" colspan="2"><b>Lyon, T. L. and Fippin, E. O.</b></td></tr>
+<tr><td class="tl">Principles of Soil Management</td>  <td class="tr">1 75</td></tr>
+
+<tr><td class="tl" colspan="2"><b>Mann, A. R.</b></td></tr>
+<tr><td class="tl">Beginnings in Agriculture</td>                             <td class="tr">75</td></tr>
+
+<tr><td class="tl" colspan="2"><b>Montgomery, G. F.</b></td></tr>
+<tr><td class="tl">Corn Crops</td>  <td class="tr">1 60</td></tr>
+
+<tr><td class="tl" colspan="2"><b>Piper, Charles V.</b></td></tr>
+<tr><td class="tl">Forage Plants and Their Culture</td>  <td class="tr">1 75</td></tr>
+
+<tr><td class="tl" colspan="2"><b>Warren, G. F.</b></td></tr>
+<tr><td class="tl">Elements of Agriculture</td>  <td class="tr">1 10</td></tr>
+
+<tr><td class="tl" colspan="2"><b>Warren, G. F.</b></td></tr>
+<tr><td class="tl">Farm Management</td>  <td class="tr">1 75</td></tr>
+
+<tr><td class="tl" colspan="2"><b>Wheeler, H. J.</b></td></tr>
+<tr><td class="tl">Manures and Fertilizers</td>  <td class="tr">1 60</td></tr>
+
+<tr><td class="tl" colspan="2"><b>Widtsoe, John A.</b></td></tr>
+<tr><td class="tl">Principles of Irrigation Practice</td>  <td class="tr">1 75</td></tr>
+</tbody></table>
+
+<div class="blockquot">
+<p>
+THE MACMILLAN COMPANY<br />
+PUBLISHERS<br />
+64-66 Fifth Avenue<br />
+NEW YORK<br />
+</p></div>
+
+<hr style="width: 65%;" />
+
+
+<p><span class='pagenum'><a name="Page_272" id="Page_272">[Pg 272]</a></span></p>
+
+<p class="subhead2">The Rural Outlook Set<br />
+By L. H. BAILEY</p>
+
+<p><i>Four Volumes. Each, cloth, 12mo. Uniform binding, attractively boxed.
+$5.00 per set; carriage extra. Each volume also sold separately.</i></p>
+
+<p>In this set are included three of Professor Bailey's most popular
+books as well as a hitherto unpublished one,&mdash;"The Country-Life
+Movement." The long and persistent demand for a uniform edition of
+these little classics is answered with the publication of this
+attractive series.</p>
+
+<p><b>The Country Life Movement</b></p>
+
+<p><i>Cloth, 12mo, 220 pages, $1.25 postage extra</i></p>
+
+<p>This hitherto unpublished volume deals with the present movement for
+the redirection of rural civilization, discussing the real
+country-life problem as distinguished from the city problem, known as
+the back-to-the-land movement.</p>
+
+<p><b>The Outlook to Nature</b> (New and Revised Edition)</p>
+
+<p><i>Cloth, 12mo, 195 pages, $1.25 postage extra</i></p>
+
+<p>In this alive and bracing book, full of suggestions and encouragement,
+Professor Bailey argues the importance of contact with nature, a
+sympathetic attitude toward which "means greater efficiency,
+hopefulness, and repose."</p>
+
+<p><b>The State and the Farmer</b> (New Edition)</p>
+
+<p><i>Cloth, 12mo, $1.25 postage extra</i></p>
+
+<p>It is the relation of the farmer to the government that Professor
+Bailey here discusses in its varying aspects. He deals specifically
+with the change in agricultural methods, in the shifting of the
+geographical centers of farming in the United States, and in the
+growth of agricultural institutions.</p>
+
+<p><b>The Nature Study Idea</b> (New Edition)</p>
+
+<p><i>Cloth, 12mo, $1.25 postage extra</i></p>
+
+<p>"It would be well," the critic of <i>The Tribune Farmer</i> once wrote, "if
+'The Nature Study Idea' were in the hands of every person who favors
+nature study in the public schools, of every one who is opposed to it,
+and most important, of every one who teaches it or thinks he does." It
+has been Professor Bailey's purpose to interpret the new school
+movement to put the young into relation and sympathy with nature,&mdash;a
+purpose which he has admirably accomplished.</p>
+
+
+
+<p>
+THE MACMILLAN COMPANY<br />
+PUBLISHERS<br />
+64-66 Fifth Avenue<br />
+NEW YORK<br />
+</p>
+
+
+
+
+
+
+
+
+<pre>
+
+
+
+
+
+End of the Project Gutenberg EBook of Electricity for the farm, by 
+Frederick Irving Anderson
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+</pre>
+
+</body>
+</html>
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+Project Gutenberg's Electricity for the farm, by Frederick Irving Anderson
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Electricity for the farm
+       Light, heat and power by inexpensive methods from the water
+       wheel or farm engine
+
+Author: Frederick Irving Anderson
+
+Release Date: November 14, 2008 [EBook #27257]
+
+Language: English
+
+Character set encoding: ASCII
+
+*** START OF THIS PROJECT GUTENBERG EBOOK ELECTRICITY FOR THE FARM ***
+
+
+
+
+Produced by Stacy Brown, Marcia Brooks, Steven Giacomelli
+and the Online Distributed Proofreading Team at
+https://www.pgdp.net (This file was produced from images
+produced by Core Historical Literature in Agriculture
+(CHLA), Cornell University)
+
+
+
+
+
+
+
+
+
+ELECTRICITY FOR THE FARM
+
+
+THE MACMILLAN COMPANY
+
+NEW YORK . BOSTON . CHICAGO . DALLAS
+ATLANTA . SAN FRANCISCO
+
+MACMILLAN & CO., Limited
+LONDON . BOMBAY . CALCUTTA . MELBOURNE
+
+THE MACMILLAN CO. OF CANADA, Ltd.
+TORONTO
+
+
+
+
+[Illustration: Even the tiny trout brook becomes a thing of utility
+as well as of joy
+
+(_Courtesy of the Fitz Water Wheel Company, Hanover, Pa._)]
+
+
+
+
+ELECTRICITY FOR
+THE FARM
+
+
+LIGHT, HEAT AND POWER BY INEXPENSIVE
+METHODS FROM THE WATER
+WHEEL OR FARM ENGINE
+
+
+BY
+FREDERICK IRVING ANDERSON
+
+AUTHOR OF "THE FARMER OF TO-MORROW," ETC., ETC.
+
+
+  New York
+  THE MACMILLAN COMPANY
+  1915
+
+_All rights reserved_
+
+
+
+
+  Copyright, 1915
+  By THE CURTIS PUBLISHING COMPANY
+  The Country Gentleman
+
+
+  Copyright, 1915
+  By THE MACMILLAN COMPANY
+  Set up and electrotyped. Published April, 1915.
+
+
+
+
+PREFACE
+
+
+This book is designed primarily to give the farmer a practical working
+knowledge of electricity for use as light, heat, and power on the
+farm. The electric generator, the dynamo, is explained in detail; and
+there are chapters on electric transmission and house-wiring, by which
+the farm mechanic is enabled to install his own plant without the aid
+and expense of an expert.
+
+With modern appliances, within the means of the average farmer, the
+generation of electricity, with its unique conveniences, becomes
+automatic, provided some dependable source of power is to be had--such
+as a water wheel, gasoline (or other form of internal combustion)
+engine, or the ordinary windmill. The water wheel is the ideal prime
+mover for the dynamo in isolated plants. Since water-power is running
+to waste on tens of thousands of our farms throughout the country,
+several chapters are devoted to this phase of the subject: these
+include descriptions and working diagrams of weirs and other simple
+devices for measuring the flow of streams; there are tables and
+formulas by which any one, with a knowledge of simple arithmetic, may
+determine the power to be had from falling water under given
+conditions; and in addition, there are diagrams showing in general the
+method of construction of dams, bulkheads, races, flumes, etc., from
+materials usually to be found on a farm. The tiny unconsidered brook
+that waters the farm pasture frequently possesses power enough to
+supply the farmstead with clean, cool, safe light in place of the
+dangerous, inconvenient oil lamp; a small stream capable of developing
+from twenty-five to fifty horsepower will supply a farmer (at
+practically no expense beyond the original cost of installation) not
+only with light, but with power for even the heavier farm operations,
+as threshing; and in addition will do the washing, ironing, and
+cooking, and at the same time keep the house warm in the coldest
+weather. Less than one horsepower of energy will light the farmstead;
+less than five horsepower of energy will provide light and small
+power, and take the drudgery out of the kitchen.
+
+For those not fortunate enough to possess water-power which can be
+developed, there are chapters on the use of the farm gasoline engine
+and windmill, in connection with the modern storage battery, as
+sources of electric current.
+
+It is desired to make acknowledgment for illustrations and assistance
+in gathering material for the book, to the editors of _The Country
+Gentleman_, Philadelphia, Pa.; The Crocker-Wheeler Company, Ampere, N.
+J.; The General Electric Company, Schenectady, N. Y.; the Weston
+Electrical Instrument Company, of Newark, N. J.; The Chase Turbine
+Manufacturing Company, Orange, Mass.; the C. P. Bradway Machine Works,
+West Stafford, Conn.; The Pelton Water Wheel Company, San Francisco
+and New York; the Ward Leonard Manufacturing Company, Bronxville, N.
+Y.; The Fairbanks, Morse Company, Chicago; and the Fitz Water Wheel
+Company, Hanover, Pa.
+
+
+
+
+TABLE OF CONTENTS
+
+
+                                                             PAGE
+
+  INTRODUCTION                                               xvii
+
+
+  PART I
+
+  WATER-POWER
+
+
+  CHAPTER I
+
+  A WORKING PLANT
+
+  The "agriculturist"--An old chair factory--A neighbor's
+  home-coming--The idle wheel in commission again--Light,
+  heat and power for nothing--Advantages
+  of electricity                                                3
+
+
+  CHAPTER II
+
+  A LITTLE PROSPECTING
+
+  Small amount of water required for an electric
+  plant--Exploring, on a dull day--A rough and ready
+  weir--What a little water will do--The water wheel
+  and the dynamo--Electricity consumed the instant
+  it is produced--The price of the average small
+  plant, not counting labor                                    22
+
+
+  CHAPTER III
+
+  HOW TO MEASURE WATER-POWER
+
+  What is a horsepower?--How the Carthaginians
+  manufactured horsepower--All that goes up must come
+  down--How the sun lifts water up for us to
+  use--Water the ideal power for generating
+  electricity--The weir--Table for estimating
+  flow of streams with a weir--Another method of
+  measuring--Figuring water horsepower--The size
+  of the wheel--What head is required--Quantity of
+  water necessary                                              32
+
+
+  CHAPTER IV
+
+  THE WATER WHEEL AND HOW TO INSTALL IT
+
+  Different types of water wheels--The impulse and the
+  reaction wheels--The impulse wheel adapted to
+  high heads and small amount of water--Pipe lines--Table
+  of resistance in pipes--Advantages and disadvantages
+  of the impulse wheel--Other forms
+  of impulse wheels--The reaction turbine, suited to
+  low heads and large quantity of water--Its advantages
+  and limitations--Developing a water-power
+  project: the dam; the race; the flume; the penstock;
+  and the tailrace--Water rights for the farmer                56
+
+
+  PART II
+
+  ELECTRICITY
+
+
+  CHAPTER V
+
+  THE DYNAMO; WHAT IT DOES, AND HOW
+
+  Electricity compared to the heat and light of the
+  Sun--The simple dynamo--The amount of electric energy
+  a dynamo will generate--The modern dynamo--Measuring
+  power in terms of electricity--The volt--The
+  ampere--The ohm--The watt and the kilowatt--Ohm's
+  Law of the electric circuit, and some
+  examples of its application--Direct current, and
+  alternating current--Three types of direct-current
+  dynamos: series, shunt, and compound                         89
+
+
+  CHAPTER VI
+
+  WHAT SIZE PLANT TO INSTALL
+
+  The farmer's wife his partner--Little and big
+  plants--Limiting factors--Fluctuations in water
+  supply--The average plant--The actual plant--Amount
+  of current required for various operations--Standard
+  voltage--A specimen allowance for electric
+  light--Heating and cooking by electricity--Electric
+  power: the electric motor                                   121
+
+
+  CHAPTER VII
+
+  TRANSMISSION LINES
+
+  Copper wire--Setting of poles--Loss of power in
+  transmission--Ohm's Law and examples of how it is
+  used in figuring size of wire--Copper-wire
+  tables--Examples of transmission lines--When to
+  use high voltages--Over-compounding a dynamo to
+  overcome transmission loss                                  153
+
+
+  CHAPTER VIII
+
+  WIRING THE HOUSE
+
+  The insurance code--Different kinds of wiring
+  described--Wooden moulding cheap and effective--The
+  distributing panel--Branch circuits--Protecting the
+  circuits--The use of porcelain tubes and other
+  insulating devices--Putting up chandeliers and
+  wall-brackets--"Multiple" connections--How to connect
+  a wall switch--Special wiring required for heat and
+  power circuits--Knob and cleat wiring, its advantages
+  and disadvantages                                           172
+
+
+  CHAPTER IX
+
+  THE ELECTRIC PLANT AT WORK
+
+  Direct-connected generating sets--Belt drive--The
+  switchboard--Governors and voltage regulators--Methods
+  of achieving constant pressure at all loads:
+  Over-compounding the dynamo; A system of resistances
+  (a home-made electric radiator); Regulating
+  voltage by means of the rheostat--Automatic
+  devices--Putting the plant in operation                     192
+
+
+  PART III
+
+  GASOLINE ENGINES, WINDMILLS, ETC.
+  THE STORAGE BATTERIES
+
+
+  CHAPTER X
+
+  GASOLINE ENGINE PLANTS
+
+  The standard voltage set--Two-cycle and four-cycle
+  gasoline engines--Horsepower, and fuel
+  consumption--Efficiency of small engines and
+  generators--Cost of operating a one-kilowatt plant          217
+
+
+  CHAPTER XI
+
+  THE STORAGE BATTERY
+
+  What a storage battery does--The lead battery and the
+  Edison battery--Economy of tungsten lamps for
+  storage batteries--The low-voltage battery for
+  electric light--How to figure the capacity of a
+  battery--Table of light requirements for a farm
+  house--Watt-hours and lamp-hours--The cost of storage
+  battery current--How to charge a storage
+  battery--Care of storage batteries                          229
+
+
+  CHAPTER XII
+
+  BATTERY CHARGING DEVICES
+
+  The automatic plant most desirable--How an automobile
+  lighting and starting system works--How the same
+  results can be achieved in house lighting, by means
+  of automatic devices--Plants without automatic
+  regulation--Care necessary--The use of heating devices
+  on storage battery current--Portable batteries--An
+  electricity "route"--Automobile power for
+  lighting a few lamps                                        250
+
+
+
+
+ILLUSTRATIONS
+
+
+  Even the tiny trout brook becomes a thing of utility as
+  well as of joy                                   _Frontispiece_
+
+  Farm labor and materials built this crib and stone dam       17
+
+  Measuring a small stream with a weir                         23
+
+  Efficient modern adaptations of the archaic undershot
+  and overshot water wheels                                    59
+
+  A direct-current dynamo or motor, showing details of
+  construction                                                 92
+
+  Details of voltmeter or ammeter                             128
+
+  Instantaneous photograph of high-pressure water jet being
+  quenched by buckets of a tangential wheel                   194
+
+  A tangential wheel, and a dynamo keyed to the same
+  shaft--the ideal method for generating electricity          194
+
+  A rough-and-ready farm electric plant, supplying two
+  farms with light, heat and power; and a Ward
+  Leonard-type circuit breaker for charging storage
+  batteries                                                   244
+
+
+
+
+INTRODUCTION
+
+
+The sight of a dozen or so fat young horses and mares feeding and
+frolicking on the wild range of the Southwest would probably inspire
+the average farmer as an awful example of horsepower running to waste.
+If, by some miracle, he came on such a sight in his own pastures, he
+would probably consume much time practising the impossible art of
+"creasing" the wild creatures with a rifle bullet--after the style of
+Kit Carson and other free rovers of the old prairies when they were in
+need of a new mount. He would probably spend uncounted hours behind
+the barn learning to throw a lariat; and one fine day he would sally
+forth to capture a horsepower or two--and, once captured, he would use
+strength and strategy breaking the wild beast to harness. A single
+horsepower--animal--will do the work of lifting 23,000 pounds one foot
+in one minute, providing the animal is young, and sound, and is fed
+12 quarts of oats and 10 or 15 pounds of hay a day, and is given a
+chance to rest 16 hours out of 24--providing also it has a dentist to
+take care of its teeth occasionally, and a blacksmith chiropodist to
+keep it in shoes. On the hoof, this horsepower is worth about
+$200--unless the farmer is looking for something fancy in the way of
+drafters, when he will have to go as high as $400 for a big fellow.
+And after 10 or 15 years, the farmer would look around for another
+horse, because an animal grows old.
+
+This animal horsepower isn't a very efficient horsepower. In fact, it
+is less than three-fourths of an actual horsepower, as engineers use
+the term. A real horsepower will do the work of lifting 33,000 pounds
+one foot in one minute--or 550 pounds one foot in one second. Burn a
+pint of gasoline, with 14 pounds of air, in a gasoline engine, and the
+engine will supply one 33,000-pound horsepower for an hour. The
+gasoline will cost about 2 cents, and the air is supplied free. If it
+was the air that cost two cents a pound, instead of the gasoline, the
+automobile industry would undoubtedly stop where it began some fifteen
+years ago. It is human nature, however, to grumble over this two
+cents.
+
+Yet the average farmer who would get excited if sound young chunks and
+drafters were running wild across his pastures, is not inspired by any
+similar desire of possession and mastery by the sight of a brook, or a
+rivulet that waters his meadows. This brook or river is flowing down
+hill to the sea. Every 4,000 gallons that falls one foot in one
+minute; every 400 gallons that falls 10 feet in one minute; or every
+40 gallons that falls 100 feet in one minute, means the power of one
+horse going to waste--not the $200 flesh-and-blood kind that can lift
+only 23,000 pounds a foot a minute--but the 33,000 foot-pound kind.
+Thousands of farms have small streams in their very dooryard, capable
+of developing five, ten, twenty, fifty horsepower twenty-four hours a
+day, for the greater part of the year. Within a quarter of a mile of
+the great majority of farms (outside of the dry lands themselves)
+there are such streams. Only a small fraction of one per cent of them
+have been put to work, made to pay their passage from the hills to the
+sea.
+
+The United States government geological survey engineers recently made
+an estimate of the waterfalls capable of developing 1,000 horsepower
+and over, that are running to waste, unused, in this country. They
+estimated that there is available, every second of the day and night,
+some 30,000,000 horsepower, in dry weather--and twice this during the
+eight wet months of the year. The waterfall capable of giving up 1,000
+horsepower in energy is not the subject of these chapters. It is the
+small streams--the brooks, the creeks, the rivulets--which feed the
+1,000 horsepower torrents, make them possible, that are of interest to
+the farmer. These small streams thread every township, every county,
+seeking the easiest way to the main valleys where they come together
+in great rivers.
+
+What profitable crop on your farm removes the least plant food? A
+bee-farmer enters his honey for the prize in this contest. Another
+farmer maintains that his ice-crop is the winner. But electricity
+generated from falling water of a brook meandering across one's acres,
+comes nearer to the correct answer of how to make something out of
+nothing. It merely utilizes the wasted energy of water rolling down
+hill--the weight of water, the pulling power of gravity. Water is
+still water, after it has run through a turbine wheel to turn an
+electric generator. It is still wet; it is there for watering the
+stock; and a few rods further down stream, where it drops five or ten
+feet again, it can be made to do the same work over again--and over
+and over again as long as it continues to fall, on its journey to the
+sea. The city of Los Angeles has a municipal water plant, generating
+200,000 horsepower of electricity, in which the water is used three
+times in its fall of 6,000 feet; and in the end, where it runs out of
+the race in the valley, it is sold for irrigation.
+
+One water-horsepower will furnish light for the average farm; five
+water-horsepower will furnish light and power, and do the ironing and
+baking. The cost of installing a plant of five water-horsepower should
+not exceed the cost of one sound young horse, the $200 kind--under
+conditions which are to be found on thousands of farms and farm
+communities in the East, the Central West, and the Pacific States.
+This electrical horsepower will work 24 hours a day, winter and
+summer, and the farmer would not have to grow oats and hay for it on
+land that might better be used in growing food for human beings. It
+would not become "aged" at the end of ten or fifteen years, and the
+expense of maintenance would be practically nothing after the first
+cost of installation. It would require only water as food--waste
+water. Two hundred and fifty cubic feet of water a minute, falling ten
+feet, will supply the average farm with all the conveniences of
+electricity. This is a very modest creek--the kind of brook or creek
+that is ignored by the man who would think time well spent in putting
+in a week capturing a wild horse, if a miracle should send such a
+beast within reach. And the task of harnessing and breaking this
+water-horsepower is much more simple and less dangerous than the task
+of breaking a colt to harness.
+
+
+
+
+PART I
+
+WATER-POWER
+
+
+
+
+ELECTRICITY FOR THE FARM
+
+CHAPTER I
+
+A WORKING PLANT
+
+     The "agriculturist"--An old chair factory--A neighbor's
+     home-coming--The idle wheel in commission again--Light, heat and
+     power for nothing--Advantages of electricity.
+
+
+Let us take an actual instance of one man who did go ahead and find
+out by experience just how intricate and just how simple a thing
+electricity from farm water-power is. This man's name was Perkins, or,
+we will call him that, in relating this story.
+
+Perkins was what some people call, not a farmer, but an
+"agriculturist,"--that is, he was a back-to-the-land man. He had been
+born and raised on a farm. He knew that you must harness a horse on
+the left side, milk a cow on the right, that wagon nuts tighten the
+way the wheel rims, and that a fresh egg will not float.
+
+He had a farm that would grow enough clover to fill the average dairy
+if he fed it lime; he had a boy coming to school age; and both he and
+his wife wanted to get back to the country. They had their little
+savings, and they wanted, first of all, to take a vacation, getting
+acquainted with their farm. They hadn't taken a vacation in fifteen
+years.
+
+He moved in, late in the summer, and started out to get acquainted
+with his neighbors, as well as his land. This was in the New England
+hills. Water courses cut through everywhere. In regard to its
+bountiful water supply, the neighborhood had much in common with all
+the states east of the Mississippi, along the Atlantic seaboard, in
+the lake region of the central west, and in the Pacific States. With
+this difference; the water courses in his neighborhood had once been
+of economic importance.
+
+A mountain river flowed down his valley. Up and down the valley one
+met ramshackle mills, fallen into decay. Many years ago before
+railroads came, before it was easy to haul coal from place to place
+to make steam, these little mills were centers of thriving industries,
+which depended on the power of falling water to make turned articles,
+spin cotton, and so forth. Then the railroads came, and it was easy to
+haul coal to make steam. And the same railroads that hauled the coal
+to make steam, were there to haul away the articles manufactured by
+steam power. So in time the little manufacturing plants on the river
+back in the hills quit business and moved to railroad stations. Then
+New England, from being a manufacturing community made up of many
+small isolated water plants, came to be a community made up of huge
+arteries and laterals of smoke stacks that fringed the railroads.
+Where the railroad happened to follow a river course--as the
+Connecticut River--the water-power plants remained; but the little
+plants back in the hills were wiped off the map--because steam power
+with railroads at the front door proved cheaper than water-power with
+railroads ten miles away.
+
+One night Perkins came in late from a long drive with his next-door
+neighbor. He had learned the first rule of courtesy in the country,
+which is to unhitch his own side of the horse and help back the buggy
+into the shed. They stumbled around in the barn putting up the horse,
+and getting down hay and grain for it, by the light of an oil lantern,
+which was set on the floor in a place convenient to be kicked over. He
+went inside and took supper by the light of a smoky smelly oil lamp,
+that filled the room full of dark corners; and when supper was over,
+the farmwife groped about in the cellar putting things away by the
+light of a candle.
+
+The next day his neighbor was grinding cider at his ramshackle water
+mill--one of the operations for which a week must be set aside every
+fall. Perkins sat on a log and listened to the crunch-crunch of the
+apples in the chute, and the drip of the frothy yellow liquid that
+fell into waiting buckets.
+
+"How much power have you got here?" he asked.
+
+"Thirty or forty horsepower, I guess."
+
+"What do you do with it, besides grinding cider to pickle your
+neighbors' digestion with?"
+
+"Nothing much. I've got a planer and a moulding machine in there, to
+work up jags of lumber occasionally. That's all. This mill was a
+chair-factory in my grandfather's day, back in 1830."
+
+"Do you use it thirty days in a year?"
+
+"No; not half that."
+
+"What are you going to do with it this winter?"
+
+"Nothing; I keep the gate open and the wheel turning, so it won't
+freeze, but nothing else. I am going to take the family to Texas to
+visit my wife's folks for three months. We've worked hard enough to
+take a vacation."
+
+"Will you rent me the mill while you are gone?"
+
+"Go ahead; you can have it for nothing, if you will watch the ice."
+
+"All right; let me know when you come back and I'll drive to town and
+bring you home."
+
+       *       *       *       *       *
+
+Three months went by, and one day in February the city man, in
+response to a letter, hitched up and drove to town to bring his
+neighbor back home. It was four o'clock in the afternoon when they
+started out, and it was six--dark--when they turned the bend in the
+road to the farm house. They helped the wife and children out, with
+their baggage, and as Perkins opened the door of the house, he reached
+up on the wall and turned something that clicked sharply.
+
+Instantly light sprang from everywhere. In the barn-yard a street lamp
+with an 18-inch reflector illuminated all under it for a space of 100
+feet with bright white rays of light. Another street lamp hung over
+the watering trough. The barn doors and windows burst forth in light.
+There was not a dark corner to be found anywhere. In the house it was
+the same. Perkins led the amazed procession from room to room of the
+house they had shut up for the winter. On the wall in the hall
+outside of every room was a button which he pushed, and the room
+became as light as day before they entered. The cellar door, in
+opening, automatically lighted a lamp illuminating that cavern as it
+had never been lighted before since the day a house was built over it.
+
+Needless to say, the farmer and his family were reduced to a state of
+speechlessness.
+
+"How the deuce did you do it?" finally articulated the farmer.
+
+"I put your idle water wheel to work," said Perkins; and then,
+satisfied with this exhibition, he put them back in the sleigh and
+drove to his home, where his wife had supper waiting.
+
+While the men were putting up the team in the electric lighted barn,
+the farmwife went into the kitchen. Her hostess was cooking supper on
+an electric stove. It looked like a city gas range and it cooked all
+their meals, and did the baking besides. A hot-water tank stood
+against the wall, not connected to anything hot, apparently. But it
+was scalding hot, by virtue of a little electric water heater the size
+of a quart tin can, connected at the bottom. Twenty-four hours a day
+the water wheel pumped electricity into that "can," so that hot water
+was to be had at any hour simply by turning a faucet. In the laundry
+there was an electric pump that kept the tank in the attic filled
+automatically. When the level of water in this tank fell to a certain
+point, a float operated a switch that started the pump; and when the
+water level reached a certain height, the same float stopped the pump.
+A small motor, the size of a medium Hubbard squash operated a washing
+machine and wringer on wash days. This same motor was a
+man-of-all-work for this house, for, when called on, it turned the
+separator, ground and polished knives and silverware, spun the sewing
+machine, and worked the vacuum cleaner.
+
+Over the dining room table hung the same hanging shade of old days,
+but the oil lamp itself was gone. In its place was a 100-watt
+tungsten lamp whose rays made the white table cloth fairly glisten.
+The wires carrying electricity to this lamp were threaded through the
+chains reaching to the ceiling, and one had to look twice to see where
+the current came from. In the sitting room, a cluster of electric
+bulbs glowed from a fancy wicker work basket that hung from the
+ceiling. The housewife had made use of what she had throughout the
+house. Old-fashioned candle-shades sat like cocked hats astride
+electric bulbs. There is little heat to an electric bulb for the
+reason that the white-hot wire that gives the light is made to burn in
+high vacuum, which transmits heat very slowly. The housewife had taken
+advantage of this fact and from every corner gleamed lights dressed in
+fancy designs of tissue paper and silk.
+
+"Now we will talk business," said Perkins when supper was over and
+they had lighted their pipes.
+
+The returned native looked dubious. His New England training had
+warned him long ago that one cannot expect to get something for
+nothing, and he felt sure there was a joker in this affair.
+
+"How much do I owe you?" he asked.
+
+"Nothing," said Perkins. "You furnish the water-power with your idle
+wheel, and I furnish the electric installation. This is only a small
+plant I have put in, but it gives us enough electricity to go around,
+with a margin for emergencies. I have taken the liberty of wiring your
+house and your horse-barn and cow-barn and your barn-yard. Altogether,
+I suppose you have 30 lights about the place, and during these long
+winter days you will keep most of them going from 3 to 5 hours a night
+and 2 or 3 hours in the early morning. If you were in town, those
+lights would cost you about 12 cents an hour, at the commercial rate
+of electricity. Say 60 cents a day--eighteen dollars a month. That
+isn't a very big electric light bill for some people I know in
+town--and they consider themselves lucky to have the privilege of
+buying electricity at that rate. Your wheel is running all winter to
+prevent ice from forming and smashing it. It might just as well be
+spinning the dynamo.
+
+"If you think it worth while," continued Perkins,--"this $18 worth of
+light you have on tap night and morning, or any hour of the day,--we
+will say the account is settled. That is, of course, if you will give
+me the use of half the electricity that your idle wheel is grinding
+out with my second-hand dynamo. We have about eight electrical
+horsepower on our wires, without overloading the machine. Next spring
+I am going to stock up this place; and I think about the first thing I
+do, when my dairy is running, will be to put in a milking machine and
+let electricity do the milking for me. It will also fill my silo,
+grind my mowing-machine knives, saw my wood, and keep water running in
+my barn. You will probably want to do the same.
+
+"But what it does for us men in the barn and barn-yard, isn't to be
+compared to what it does for the women in the house. When my wife
+wants a hot oven she presses a button. When she wants to put the
+'fire' out, she presses another. That's all there is to it. No heat,
+no smoke, no ashes. The same with ironing--and washing. No oil lamps
+to fill, no wicks to trim, no chimneys to wash, no kerosene to kick
+over and start a fire."
+
+"You say the current you have put in my house would cost me about $18
+a month, in town."
+
+"Yes, about that. Making electricity from coal costs money."
+
+"What does it cost here?"
+
+"Practically nothing. Your river, that has been running to waste ever
+since your grandfather gave up making chairs, does the work. There is
+nothing about a dynamo to wear out, except the bearings, and these can
+be replaced once every five or ten years for a trifle. The machine
+needs to be oiled and cared for--fill the oil cups about once in three
+days. Your water wheel needs the same attention. That's all there is
+to it. You can figure the cost of your current yourself--just about
+the cost of the lubricating oil you use--and the cost of the time you
+give it--about the same time you give to any piece of good machinery,
+from a sulky plow to a cream separator."
+
+This is a true story. This electric plant, where Perkins furnishes the
+electric end, and his neighbor the water-power, has been running now
+for two years, grinding out electricity for the two places twenty-four
+hours a day. Perkins was not an electrical engineer. He was just a
+plain intelligent American citizen who found sufficient knowledge in
+books to enable him to install and operate this plant. Frequently he
+is away for long periods, but his neighbor (who has lost his original
+terror of electricity) takes care of the plant. In fact, this farmer
+has given a lot of study to the thing, through curiosity, until he
+knows fully as much about it now as his city neighbor.
+
+He had the usual idea, at the start, that a current strong enough to
+light a 100 candlepower lamp would kick like a mule if a man happened
+to get behind it. He watched the city man handle bare wires and
+finally he plucked up courage to do it himself.
+
+It was a 110-volt current, the pressure used in our cities for
+domestic lighting. The funny part about it was, the farmer could not
+feel it at all at first. His fingers were calloused and no current
+could pass through them. Finally he sandpapered his fingers and tried
+it again. Then he was able to get the "tickle" of 110 volts. It wasn't
+so deadly after all--about the strength of a weak medical battery,
+with which every one is familiar. A current of 110 volts cannot do any
+harm to the human body unless contact is made over a very large
+surface, which is impossible unless a man goes to a lot of trouble to
+make such a contact. A current of 220 volts pressure--the pressure
+used in cities for motors--has a little more "kick" to it, but still
+is not uncomfortable. When the pressure rises to 500 volts (the
+pressure used in trolley wires for street cars), it begins to be
+dangerous. But there is no reason why a farm plant should be over 110
+volts, under usual conditions; engineers have decided on this pressure
+as the best adapted to domestic use, and manufacturers who turn out
+the numerous electrical devices, such as irons, toasters, massage
+machines, etc., fit their standard instruments to this voltage.
+
+[Illustration: Farm labor and materials built this crib and stone
+dam]
+
+As to the cost of this co-operative plant--it was in the neighborhood
+of $200. As we have said, it provided eight electrical horsepower on
+tap at any hour of the day or night--enough for the two farms, and a
+surplus for neighbors, if they wished to string lines and make use of
+it.
+
+The dynamo, a direct-current machine, 110 volts pressure, and what is
+known in the trade as "compound,"--that is, a machine that maintains a
+constant pressure automatically and does not require an attendant--was
+picked up second-hand, through a newspaper "ad" and cost $90. The
+switchboard, a make-shift affair, not very handsome, but just as
+serviceable as if it were made of marble, cost less than $25 all told.
+The transmission wire cost $19 a hundred pounds; it is of copper, and
+covered with weatherproofed tape. Perkins bought a 50-cent book on
+house-wiring, and did the wiring himself, the way the book told him
+to, a simple operation. For fixtures, as we have said, his wife
+devised fancy shades out of Mexican baskets, tissue paper, and silk,
+in which are hidden electric globes that glow like fire-flies at the
+pressing of a button. The lamps themselves are mostly old-style carbon
+lamps, which can be bought at 16 cents each retail. In his living room
+and dining room he used the new-style tungsten lamps instead of
+old-style carbon. These cost 30 cents each. Incandescent lamps are
+rated for 1,000 hours useful life. The advantage of tungsten lights is
+that they give three times as much light for the same expenditure of
+current as carbon lights. This is a big advantage in the city, where
+current is costly; but it is not so much of an advantage in the
+country where a farmer has plenty of water-power--because his current
+costs him practically nothing, and he can afford to be wasteful of it
+to save money in lamps. Another advantage he has over his city cousin:
+In town, an incandescent lamp is thrown away after it has been used
+1,000 hours because after that it gives only 80% of the light it did
+when new--quite an item when one is paying for current. The experience
+of Perkins and his neighbor in their cooperative plant has been that
+they have excess light anyway, and if a few bulbs fall off a fifth in
+efficiency, it is not noticeable. As a matter of fact most of their
+bulbs have been in use without replacing for the two years the plant
+has been in operation. The lamps are on the wall or the ceiling, out
+of the way, not liable to be broken; so the actual expense in
+replacing lamps is less than for lamp chimneys in the old days.
+
+Insurance companies recognize that a large percentage of farm fires
+comes from the use of kerosene; for this reason, they are willing to
+make special rates for farm homes lighted by electricity. They
+prescribe certain rules for wiring a house, and they insist that their
+agent inspect and pass such wiring before current is turned on. Once
+the wiring is passed, the advantage is all in favor of the farmer
+with electricity over the farmer with kerosene. The National Board of
+Fire Underwriters is sufficiently logical in its demands, and powerful
+enough, so that manufacturers who turn out the necessary fittings find
+no sale for devices that do not conform to insurance standards.
+Therefore it is difficult to go wrong in wiring a house.
+
+Finally, as to the added value a water-power electric plant adds to
+the selling price of a farm. Let the farmer answer this question for
+himself. If he can advertise his farm for sale, with a paragraph
+running: "Hydroelectric plant on the premises, furnishing electricity
+for light, heat, and power"--what do you suppose a wide-awake
+purchaser would be willing to pay for that? Perkins and his neighbor
+believe that $1,000 is a very modest estimate added by their electric
+plant to both places. And they talk of doing still more. They use only
+a quarter of the power of the water that is running to waste through
+the wheel. They are figuring on installing a larger dynamo, of say 30
+electrical horse-power, which will provide clean, dry, safe heat for
+their houses even on the coldest days in winter. When they have done
+this, they will consider that they are really putting their small
+river to work.
+
+
+
+
+CHAPTER II
+
+A LITTLE PROSPECTING
+
+     Small amount of water required for an electric plant--Exploring, on
+     a dull day--A rough and ready weir--What a little water will
+     do--The water wheel and the dynamo--Electricity consumed the
+     instant it is produced--The price of the average small plant, not
+     counting labor.
+
+
+The average farmer makes the mistake of considering that one must have
+a river of some size to develop power of any practical use. On your
+next free day do a little prospecting. We have already said that 250
+cubic feet of water falling 10 feet a minute will provide light, heat
+and small motor power for the average farm. A single water horsepower
+will generate enough electricity to provide light for the house and
+barn. But let us take five horsepower as a desirable minimum in this
+instance.
+
+[Illustration: Measuring a small stream with a weir]
+
+In your neighborhood there is a creek three or four feet wide,
+toiling along day by day, at its task of watering your fields. Find a
+wide board a little longer than the width of this creek you have
+scorned. Set it upright across the stream between the banks, so that
+no water flows around the ends or under it. It should be high enough
+to set the water back to a dead level for a few feet upstream, before
+it overflows. Cut a gate in this board, say three feet wide and ten
+inches deep, or according to the size of a stream. Cut this gate from
+the top, so that all the water of the stream will flow through the
+opening, and still maintain a level for several feet back of the
+board.
+
+This is what engineers call a weir, a handy contrivance for measuring
+the flow of small streams. Experts have figured out an elaborate
+system of tables as to weirs. All we need to do now, in this rough
+survey, is to figure out the number of square inches of water flowing
+through this opening and falling on the other side. With a rule,
+measure the depth of the overflowing water, from the bottom of the
+opening to the top of the dead level of the water behind the board.
+Multiply this depth by the width of the opening, which will give the
+square inches of water escaping. For every square inch of this water
+escaping, engineers tell us that stream is capable of delivering,
+roughly, one cubic foot of water a minute.
+
+Thus, if the water is 8 inches deep in an opening 32 inches wide, then
+the number of cubic feet this stream is delivering each minute is 8
+times 32, or 256 cubic feet a minute. So, a stream 32 inches wide,
+with a uniform depth of 8 inches running through our weir is capable
+of supplying the demands of the average farm in terms of electricity.
+Providing, of course, that the lay of the land is such that this water
+can be made to fall 10 feet into a water wheel.
+
+Go upstream and make a rough survey of the fall. In the majority of
+instances (unless this is some sluggish stream in a flat prairie) it
+will be found feasible to divert the stream from its main channel by
+means of a race--an artificial channel--and to convey it to a not
+far-distant spot where the necessary fall can be had at an angle of
+about 30 degrees from horizontal.
+
+If you find there is _twice_ as much water as you need for the amount
+of power you require, a five-foot fall will give the same result. Or,
+if there is only _one-half_ as much water as the 250 cubic feet
+specified, you can still obtain your theoretical five horsepower if
+the means are at hand for providing a fall of twenty feet instead of
+ten. Do not make the very common mistake of figuring that a stream is
+delivering a cubic foot a minute to each square inch of weir opening,
+simply because it _fills_ a certain opening. It is the excess water,
+falling _over_ the opening, after the stream has set back to a
+permanent dead level, that is to be measured.
+
+This farmer who spends an idle day measuring the flow of his brook
+with a notched board, may say here: "This is all very well. This is
+the spring of the year, when my brook is flowing at high-water mark.
+What am I going to do in the dry months of summer, when there are not
+250 cubic feet of water escaping every minute?"
+
+There are several answers to this question, which will be taken up in
+detail in subsequent chapters. Here, let us say, even if this brook
+does flow in sufficient volume only 8 months in a year--the dark
+months, by the way,--is not electricity and the many benefits it
+provides worth having eight months in the year? My garden provides
+fresh vegetables four months a year. Because it withers and dies and
+lies covered with snow during the winter, is that any reason why I
+should not plow and manure and plant my garden when spring comes
+again?
+
+A water wheel, the modern turbine, is a circular fan with curved iron
+blades, revolving in an iron case. Water, forced through the blades of
+this fan by its own weight, causes the wheel to revolve on its axis;
+and the fan, in turn causes a shaft fitted with pulleys to revolve.
+
+The water, by giving the iron-bladed fan a turning movement as it
+rushes through, imparts to it mechanical power. The shaft set in
+motion by means of this mechanical power is, in turn, belted to the
+pulley of a dynamo. This dynamo consists, first, of a shaft on which
+is placed a spool, wound in a curious way, with many turns of
+insulated copper wire. This spool revolves freely in an air space
+surrounded by electric magnets. The spool does not touch these
+magnets. It is so nicely balanced that the weight of a finger will
+turn it. Yet, when it is revolved by water-power at a predetermined
+speed--say 1,500 revolutions a minute--it generates electricity,
+transforms the mechanical power of the water wheel into another form
+of energy--a form of energy which can be carried for long distances on
+copper wires, which can, by touching a button, be itself converted
+into light, or heat, or back into mechanical energy again.
+
+If two wires be led from opposite sides of this revolving spool, and
+an electric lamp be connected from one to the other wire, the lamp
+will be lighted--will grow white hot,--hence _incandescent light_.
+The instant this lamp is turned on, the revolving spool feels a
+stress, the magnets by which it is surrounded begin to pull back on
+it. The power of the water wheel, however, overcomes this pull. If one
+hundred lights be turned on, the backward pull of the magnets
+surrounding the spool will be one hundred times as strong as for one
+light. For every ounce of electrical energy used in light or heat or
+power, the dynamo will require a like ounce of mechanical power from
+the water wheel which drives it.
+
+The story is told of a canny Scotch engineer, who, in the first days
+of dynamos, not so very long ago, scoffed at the suggestion that such
+a spool, spinning in free air, in well lubricated bearings, could
+bring his big Corliss steam engine to a stop. Yet he saw it done
+simply by belting this "spool," a dynamo, to his engine and asking the
+dynamo for more power in terms of light than his steam could deliver
+in terms of mechanical power to overcome the pull of the magnets.
+
+Electricity must be consumed the instant it is generated (except in
+rare instances where small amounts are accumulated in storage
+batteries by a chemical process). The pressure of a button, or the
+throw of a switch causes the dynamo instantly to respond with just
+enough energy to do the work asked of it, always in proportion to the
+amount required. Having this in mind, it is rather curious to think of
+electricity as being an article of export, an item in international
+trade. Yet in 1913 hydro-electric companies in Canada "exported" by
+means of wires, to this country over 772,000,000 kilowatt-hours (over
+one billion horsepower hours) of electricity for use in factories near
+the boundary line.
+
+This 250 cubic feet of water per minute then, which the farmer has
+measured by means of his notched board, will transform by means of its
+falling weight mechanical power into a like amount of electrical
+power--less friction losses, which may amount to as much as 60% in
+very small machines, and 15% in larger plants. That is, the brook
+which has been draining your pastures for uncounted ages contains the
+potential power of 3 and 4 young horses--with this difference: that it
+works 24 hours a day, runs on forever, and requires no oats or hay.
+And the cost of such an electric plant, which is ample for the needs
+of the average farm, _is in most cases less than the price of a good
+farm horse_--the $200 kind--not counting labor of installation.
+
+It is the purpose of these chapters to awaken the farmer to the
+possibilities of such small water-power as he or his community may
+possess; to show that the generating of electricity is a very simple
+operation, and that the maintenance and care of such a plant is within
+the mechanical ability of any American farmer or farm boy; and to show
+that electricity itself is far from being the dangerous death-dealing
+"fluid" of popular imagination. Electricity must be studied; and then
+it becomes an obedient, tireless servant. During the past decade or
+two, mathematical wizards have studied electricity, explored its
+atoms, reduced it to simple arithmetic--and although they cannot yet
+tell us _why_ it is generated, they tell us _how_. It is with this
+simple arithmetic, and the necessary manual operations that we have to
+do here.
+
+
+
+
+CHAPTER III
+
+HOW TO MEASURE WATER-POWER
+
+     What is a horsepower?--How the Carthaginians manufactured
+     horsepower--All that goes up must come down--How the sun lifts
+     water up for us to use--Water the ideal power for generating
+     electricity--The weir--Table for estimating flow of streams, with a
+     weir--Another method of measuring--Figuring water horsepower--The
+     size of the wheel--What head is required--Quantity of water
+     necessary.
+
+
+If a man were off in the woods and needed a horsepower of energy to
+work for him, he could generate it by lifting 550 pounds of stone or
+wood, or whatnot, one foot off the ground, and letting it fall back in
+the space of one second. As a man possesses capacity for work equal to
+one-fifth horsepower, it would take him five seconds to do the work of
+lifting the weight up that the weight itself accomplished in falling
+down. All that goes up must come down; and by a nice balance of
+physical laws, a falling body hits the ground with precisely the same
+force as is required to lift it to the height from which it falls.
+
+The Carthaginians, and other ancients (who were deep in the woods as
+regards mechanical knowledge) had their slaves carry huge stones to
+the top of the city wall; and the stones were placed in convenient
+positions to be tipped over on the heads of any besieging army that
+happened along. Thus by concentrating the energy of many slaves in one
+batch of stones, the warriors of that day were enabled to deliver
+"horsepower" in one mass where it would do the most good. The farmer
+who makes use of the energy of falling water to generate electricity
+for light, heat, and power does the same thing--he makes use of the
+capacity for work stored in water in being lifted to a certain height.
+As in the case of the gasoline engine, which burns 14 pounds of air
+for every pound of gasoline, the engineer of the water-power plant
+does not have to concern himself with the question of how this
+natural source of energy happened to be in a handy place for him to
+make use of it.
+
+The sun, shining on the ocean, and turning water into vapor by its
+heat has already lifted it up for him. This vapor floating in the air
+and blown about by winds, becomes chilled from one cause or another,
+gives up its heat, turns back into water, and falls as rain. This
+rain, falling on land five, ten, a hundred, a thousand, or ten
+thousand feet above the sea level, begins to run back to the sea,
+picking out the easiest road and cutting a channel that we call a
+brook, a stream, or a river. Our farm lands are covered to an average
+depth of about three feet a year with water, every gallon of which has
+stored in it the energy expended by the heat of the sun in lifting it
+to the height where it is found.
+
+The farmer, prospecting on his land for water-power, locates a spot on
+a stream which he calls Supply; and another spot a few feet down hill
+near the same stream, which he calls Power. Every gallon of water that
+falls between these two points, and is made to escape through the
+revolving blades of a water wheel is capable of work in terms of
+foot-pounds--an amount of work that is directly proportional to the
+_quantity_ of water, and to the _distance_ in feet which it falls to
+reach the wheel--_pounds_ and _feet_.
+
+
+_The Efficient Water Wheel_
+
+And it is a very efficient form of work, too. In fact it is one of the
+most efficient forms of mechanical energy known--and one of the
+easiest controlled. A modern water wheel uses 85 per cent of the total
+capacity for work imparted to falling water by gravity, and delivers
+it as rotary motion. Compare this water wheel efficiency with other
+forms of mechanical power in common use: Whereas a water wheel uses 85
+per cent of the energy of its water supply, and wastes only 15 per
+cent, a gasoline engine reverses the table, and delivers only 15 per
+cent of the energy in gasoline and wastes 85 per cent--and it is
+rather a high-class gasoline engine that can deliver even 15 per cent;
+a steam engine, on the other hand, uses about 17 per cent of the
+energy in the coal under its boilers and passes the rest up the
+chimney as waste heat and smoke.
+
+There is still another advantage possessed by water-power over its two
+rivals, steam and gas: It gives the most even flow of power. A gas
+engine "kicks" a wheel round in a circle, by means of successive
+explosions in its cylinders. A reciprocating steam engine "kicks" a
+wheel round in a circle by means of steam expanding first in one
+direction, then in another. A water wheel, on the other hand, is made
+to revolve by means of the pressure of water--by the constant force of
+gravity, itself--weight. Weight is something that does not vary from
+minute to minute, or from one fraction of a second to another. It is
+always the same. A square inch of water pressing on the blades of a
+water wheel weights ten, twenty, a hundred pounds, according to the
+height of the pipe conveying that water from the source of supply, to
+the wheel. So long as this column of water is maintained at a fixed
+height, the power it delivers to the wheel does not vary by so much as
+the weight of a feather.
+
+This property of falling water makes it the ideal power for generating
+electricity. Electricity generated from mechanical power depends on
+constant speed for steady pressure--since the electric current, when
+analyzed, is merely a succession of pulsations through a wire, like
+waves beating against a sea wall. Water-power delivers these waves at
+a constant speed, so that electric lights made from water-power do not
+flicker and jump like the flame of a lantern in a gusty wind. On the
+other hand, to accomplish the same thing with steam or gasoline
+requires an especially constructed engine.
+
+
+_The Simple Weir_
+
+Since a steady flow of water, and a constant head, bring about this
+ideal condition in the water wheel, the first problem that faces the
+farmer prospector is to determine the amount of water which his stream
+is capable of delivering. This is always measured, for convenience,
+in _cubic feet per minute_. (A cubic foot of water weighs 62.5 pounds,
+and contains 7-1/2 gallons.) This measurement is obtained in several
+ways, among which probably the use of a weir is the simplest and most
+accurate, for small streams.
+
+A weir is, in effect, merely a temporary dam set across the stream in
+such a manner as to form a small pond; and to enable one to measure
+the water escaping from this pond.
+
+It may be likened to the overflow pipe of a horse trough which is
+being fed from a spring. To measure the flow of water from such a
+spring, all that is necessary is to measure the water escaping through
+the overflow when the water in the trough has attained a permanent
+level.
+
+[Illustration: Detail of home-made weir]
+
+[Illustration: Cross-section of weir]
+
+The diagrams show the cross-section and detail of a typical weir,
+which can be put together in a few minutes with the aid of a saw and
+hammer. The cross-section shows that the lower edge of the slot
+through which the water of the temporary pond is made to escape, is
+cut on a bevel, with its sharp edge upstream. The wing on each side of
+the opening is for the purpose of preventing the stream from narrowing
+as it flows through the opening, and thus upsetting the calculations.
+This weir should be set directly across the flow of the stream,
+perfectly level, and upright. It should be so imbedded in the banks,
+and in the bottom of the stream, that no water can escape, except
+through the opening cut for that purpose. It will require a little
+experimenting with a rough model to determine just how wide and how
+deep this opening should be. It should be large enough to prevent
+water flowing over the top of the board; and it should be small
+enough to cause a still-water pond to form for several feet behind the
+weir. Keep in mind the idea of the overflowing water trough when
+building your weir. The stream, running down from a higher level
+behind, should be emptying into a still-water pond, which in turn
+should be emptying itself through the aperture in the board at the
+same rate as the stream is keeping the pond full.
+
+Your weir should be fashioned with the idea of some permanency so that
+a number of measurements may be taken, extending over a period of
+time--thus enabling the prospector to make a reliable estimate not
+only of the amount of water flowing at any one time, but of its
+fluctuations.
+
+Under expert supervision, this simple weir is an exact
+contrivance--exact enough, in fact, for the finest calculations
+required in engineering work. To find out how many cubic feet of water
+the stream is delivering at any moment, all that is necessary is to
+measure its depth where it flows through the opening. There are
+instruments, like the hook-gauge, which are designed to measure this
+depth with accuracy up to one-thousandth of an inch. An ordinary foot
+rule, or a folding rule, will give results sufficiently accurate for
+the water prospector in this instance. The depth should be measured
+not at the opening itself, but a short distance back of the opening,
+where the water is setting at a dead level and is moving very slowly.
+
+With this weir, every square inch of water flowing through the opening
+indicates roughly one cubic foot of water a minute. Thus if the
+opening is 10 inches wide and the water flowing through it is 5 inches
+deep, the number of cubic feet a minute the stream is delivering is 10
+x 5 = 50 square inches = 50 cubic feet a minute. This is a very small
+stream; yet, if it could be made to fall through a water wheel 10 feet
+below a pond or reservoir, it would exert a continuous pressure of
+30,000 pounds per minute on the blades of the wheel--nearly one
+theoretical horsepower.
+
+This estimate of one cubic foot to each square inch is a very rough
+approximation. Engineers have developed many complicated formulas for
+determining the flow of water through weirs, taking into account fine
+variations that the farm prospector need not heed. The so-called
+Francis formula, developed by a long series of actual experiments at
+Lowell, Mass., in 1852 by Mr. James B. Francis, with weirs 10 feet
+long and 5 feet 2 inches high, is standard for these calculations and
+is expressed (for those who desire to use it for special purposes) as
+follows:
+
+  Q = 3.33 L H^(3/2) or, Q = 3.33 L H sqrt(H),
+
+in which Q means _quantity_ of water in cubic feet per second, L is
+length of opening, in feet; and H is height of opening in feet.
+
+The following table is figured according to the Francis formula, and
+gives the discharge in cubic feet per minute, for openings one inch
+wide:
+
+TABLE OF WEIRS
+
+    Inches        0         1/4        1/2        3/4
+       1        0.403      0.563      0.740      0.966
+       2        1.141      1.360      1.593      1.838
+       3        2.094      2.361      2.639      2.927
+       4        3.225      3.531      3.848      4.173
+       5        4.506      4.849      5.200      5.558
+       6        5.925      6.298      6.681      7.071
+       7        7.465      7.869      8.280      8.697
+       8        9.121      9.552      9.990     10.427
+       9       10.884     11.340     11.804     12.272
+      10       12.747     13.228     13.716     14.208
+      11       14.707     15.211     15.721     16.236
+      12       16.757     17.283     17.816     18.352
+      13       18.895     19.445     19.996     20.558
+      14       21.116     21.684     22.258     22.835
+      15       23.418     24.007     24.600     25.195
+      16       25.800     26.406     27.019     27.634
+      17       28.256     28.881     29.512     30.145
+      18       30.785     31.429     32.075     32.733
+
+Thus, let us say, our weir has an opening 30 inches wide, and the
+water overflows through the opening at a uniform depth of 6-1/4
+inches, when measured a few inches behind the board at a point before
+the overflow curve begins. Run down the first column on the left to
+"6", and cross over to the second column to the right, headed "1/4".
+This gives the number of cubic feet per minute for this depth one inch
+wide, as 6.298. Since the weir is 30 inches wide, multiply 6.298 x 30
+= 188.94--or, say, 189 cubic feet per minute.
+
+Once the weir is set, it is the work of but a moment to find out the
+quantity of water a stream is delivering, simply by referring to the
+above table.
+
+
+_Another Method of Measuring a Stream_
+
+Weirs are for use in small streams. For larger streams, where the
+construction of a weir would be difficult, the U. S. Geological Survey
+engineers recommend the following simple method:
+
+Choose a place where the channel is straight for 100 or 200 feet, and
+has a nearly constant depth and width; lay off on the bank a line 50
+or 100 feet in length. Throw small chips into the stream, and measure
+the time in seconds they take to travel the distance laid off on the
+bank. This gives the surface velocity of the water. Multiply the
+average of several such tests by 0.80, which will give very nearly the
+mean velocity. Then it is necessary to find the cross-section of the
+flowing water (its average depth multiplied by width), and this
+number, in square feet, multiplied by the velocity in feet per second,
+will give the number of cubic feet the stream is delivering each
+second. Multiplied by 60 gives cubic feet a minute.
+
+
+_Figuring a Stream's Horsepower_
+
+By one of the above simple methods, the problem of _Quantity_ can
+easily be determined. The next problem is to determine what _Head_ can
+be obtained. _Head_ is the distance in feet the water may be made to
+fall, from the Source of Supply, to the water wheel itself. The power
+of water is directly proportional to _head_, just as it is directly
+proportional to _quantity_. Thus the typical weir measured above was
+30 inches wide and 6-1/4 deep, giving 189 cubic feet of water a
+minute--_Quantity._ Since such a stream is of common occurrence on
+thousands of farms, let us analyze briefly its possibilities for
+power: One hundred and eighty-nine cubic feet of water weighs 189 x
+62.5 pounds = 11,812.5 pounds. Drop this weight one foot, and we have
+11,812.5 foot-pounds. Drop it 3 feet and we have 11,812 x 3 =
+35,437.5 foot-pounds. Since 33,000 foot-pounds exerted in one minute
+is one horsepower, we have here a little more than one horsepower. For
+simplicity let us call it a horsepower.
+
+[Illustration: Detail of a water-power plant, showing setting of
+wheel, and dynamo connection]
+
+Now, since the work to be had from this water varies directly with
+_quantity_ and _head_, it is obvious that a stream _one-half_ as big
+falling _twice_ as far, would still give one horsepower at the wheel;
+or, a stream of 189 cubic feet a minute falling _ten times_ as far, 30
+feet, would give _ten times_ the power, or _ten_ horsepower; a stream
+falling _one hundred times_ as far would give _one hundred_
+horsepower. Thus small quantities of water falling great distances, or
+large quantities of water falling small distances may accomplish the
+same results. From this it will be seen, that the simple formula for
+determining the theoretical horsepower of any stream, in which
+Quantity and Head are known, is as follows:
+
+                               Cu. Ft.
+                               per       Feet
+                               minute  x head x 62.5
+  (A) Theoretical Horsepower = ----------------------
+                                       33,000
+
+_As an example, let us say that we have a stream whose weir
+measurement shows it capable of delivering 376 cubic feet a minute,
+with a head (determined by survey) of 13 feet 6 inches. What is the
+horsepower of this stream?_
+
+  Answer:
+
+         Cu. ft. p. m.   head   pounds
+            376        x 13.5 x  62.5
+  H.P. = ----------------------------- = 9.614 horsepower
+                     33,000
+
+This is _theoretical horsepower_. To determine the _actual_ horsepower
+that can be counted on, in practice, it is customary, with small water
+wheels, to figure 25 per cent loss through friction, etc. In this
+instance, the actual horsepower would then be 7.2.
+
+
+_The Size of the Wheel_
+
+Water wheels are not rated by horsepower by manufacturers, because the
+same wheel might develop one horsepower or one hundred horsepower, or
+even a thousand horsepower, according to the conditions under which
+it is used. With a given supply of water, the head, in feet,
+determines the size of wheel necessary. The farther a stream of water
+falls, the smaller the pipe necessary to carry a given number of
+gallons past a given point in a given time.
+
+A small wheel, under 10 x 13.5 ft. head, would give the same power
+with the above 376 cubic feet of water a minute, as a large wheel
+would with 10 x 376 cubic feet, under a 13.5 foot head.
+
+This is due to the _acceleration of gravity_ on falling bodies. A
+rifle bullet shot into the air with a muzzle velocity of 3,000 feet a
+second begins to diminish its speed instantly on leaving the muzzle,
+and continues to diminish in speed at the fixed rate of 32.16 feet a
+second, until it finally comes to a stop, and starts to descend. Then,
+again, its speed accelerates at the rate of 32.16 feet a second, until
+on striking the earth it has attained the velocity at which it left
+the muzzle of the rifle, less loss due to friction.
+
+The acceleration of gravity affects falling water in the same manner
+as it affects a falling bullet. At any one second, during its course
+of fall, it is traveling at a rate 32.16 feet a second in excess of
+its speed the previous second.
+
+In figuring the size wheel necessary under given conditions or to
+determine the power of water with a given nozzle opening, it is
+necessary to take this into account. The table on page 51 gives
+velocity per second of falling water, ignoring the friction of the
+pipe, in heads from 5 to 1000 feet.
+
+The scientific formula from which the table is computed is expressed
+as follows, for those of a mathematical turn of mind:
+
+Velocity (ft. per sec.) = sqrt(2gh); or, velocity is equal to the
+square root of the product (g = 32.16,--times head in feet, multiplied
+by 2).
+
+
+    SPOUTING VELOCITY OF WATER, IN FEET PER SECOND, IN HEADS
+    OF FROM 5 TO 1,000 FEET
+
+      Head   Velocity
+
+       5       17.9
+       6       19.7
+       7       21.2
+       8       22.7
+       9       24.1
+      10       25.4
+      11       26.6
+      11.5     27.2
+      12       27.8
+      12.5     28.4
+      13       28.9
+      13.5     29.5
+      14       30.0
+      14.5     30.5
+      15       31.3
+      15.5     31.6
+      16       32.1
+      16.5     32.6
+      17       33.1
+      17.5     33.6
+      18       34.0
+      18.5     34.5
+      19       35.0
+      19.5     35.4
+      20       35.9
+      20.5     36.3
+      21       36.8
+      21.5     37.2
+      22       37.6
+      22.5     38.1
+      23       38.5
+      23.5     38.9
+      24       39.3
+      24.5     39.7
+      25       40.1
+      26       40.9
+      27       41.7
+      28       42.5
+      29       43.2
+      30       43.9
+      31       44.7
+      32       45.4
+      33       46.1
+      34       46.7
+      35       47.4
+      36       48.1
+      37       48.8
+      38       49.5
+      39       50.1
+      40       50.7
+      41       51.3
+      42       52.0
+      43       52.6
+      44       53.2
+      45       53.8
+      46       54.4
+      47       55.0
+      48       55.6
+      49       56.2
+      50       56.7
+      55       59.5
+      60       62.1
+      65       64.7
+      70       67.1
+      75       69.5
+      80       71.8
+      85       74.0
+      90       76.1
+      95       78.2
+     100       80.3
+     200      114.0
+     300      139.0
+     400      160.0
+     500      179.0
+    1000      254.0
+
+
+_In the above example, we found that 376 cubic feet of water a minute,
+under 13.5 feet head, would deliver 7.2 actual horsepower. Question:
+What size wheel would it be necessary to install under such
+conditions?_
+
+By referring to the table of velocity above, (or by using the
+formula), we find that water under a head of 13.5 feet, has a spouting
+velocity of 29.5 feet a second. This means that a solid stream of
+water 29.5 feet long would pass through the wheel in one second. _What
+should be the diameter of such a stream, to make its cubical contents
+376 cubic feet a minute or 376/60 = 6.27 cubic feet a second?_ The
+following formula should be used to determine this:
+
+                             144 x cu. ft. per second
+  (B) Sq. Inches of wheel = --------------------------
+                             Velocity in ft. per sec.
+
+Substituting values, in the above instance, we have:
+
+  Answer: Sq. Inches of wheel =
+
+       144 x 6.27 (Cu. Ft. Sec.)
+      --------------------------- = 30.6 sq. in.
+          29.5 (Vel. in feet.)
+
+That is, a wheel capable of using 30.6 square inches of water would
+meet these conditions.
+
+
+_What Head is Required_
+
+Let us attack the problem of water-power in another way. _A farmer
+wishes to install a water wheel that will deliver 10 horsepower on the
+shaft, and he finds his stream delivers 400 cubic feet of water a
+minute. How many feet fall is required?_ Formula:
+
+                      33,000 x horsepower required
+  (C) Head in feet = ------------------------------
+                       Cu. Ft. per minute x 62.5
+
+Since a theoretical horsepower is only 75 per cent efficient, he would
+require 10 x 4/3 = 13.33 theoretical horsepower of water, in this
+instance. Substituting the values of the problem in the formula, we
+have:
+
+                  33,000 x 13.33
+  Answer: Head = ---------------- = 17.6 feet fall required.
+                    400 x 62.5
+
+_What capacity of wheel would this prospect (400 cubic feet of water a
+minute falling 17.6 feet, and developing 13.33 horsepower) require?_
+
+By referring to the table of velocities, we find that the velocity for
+17.5 feet head (nearly) is 33.6 feet a second. Four hundred feet of
+water a minute is 400/60 = 6.67 cu. ft. a second. Substituting these
+values, in formula (B) then, we have:
+
+  Answer: Capacity of wheel =
+
+      144 x 6.67
+      ---------- = 28.6 square inches of water.
+         33.6
+
+
+_Quantity of Water_
+
+Let us take still another problem which the prospector may be called
+on to solve: _A man finds that he can conveniently get a fall of 27
+feet. He desires 20 actual horsepower. What quantity of water will be
+necessary, and what capacity wheel?_
+
+Twenty actual horsepower will be 20 x 4/3 = 26.67 theoretical
+horsepower. Formula:
+
+                              33,000 x Hp. required
+  (D) Cubic feet per minute = ---------------------
+                              (Head in feet x 62.5)
+
+Substituting values, then, we have:
+
+  Cu. ft. per minute =
+
+  33,000 x 26.67
+  -------------- = 521.5 cubic feet a minute.
+    27 x 62.5
+
+A head of 27 feet would give this stream a velocity of 41.7 feet a
+second, and, from formula (B) we find that the capacity of the wheel
+should be 30 square inches.
+
+It is well to remember that the square inches of wheel capacity does
+not refer to the size of pipe conveying water from the head to the
+wheel, but merely to the actual nozzle capacity provided by the wheel
+itself. In small installations of low head, such as above a penstock
+at least six times the nozzle capacity should be used, to avoid losing
+effective head from friction. Thus, with a nozzle of 30 square inches,
+the penstock or pipe should be 180 square inches, or nearly 14 inches
+square inside measurement. A larger penstock would be still better.
+
+
+
+
+CHAPTER IV
+
+THE WATER WHEEL AND HOW TO INSTALL IT
+
+     Different types of water wheels--The impulse and reaction
+     wheels--The impulse wheel adapted to high heads and small amount of
+     water--Pipe lines--Table of resistance in pipes--Advantages and
+     disadvantages of the impulse wheel--Other forms of impulse
+     wheels--The reaction turbine, suited to low heads and large
+     quantity of water--Its advantages and limitations--Developing a
+     water-power project: the dam; the race; the flume; the penstock;
+     and the tailrace--Water rights for the farmer.
+
+
+In general, there are two types of water wheels, the _impulse_ wheel
+and the _reaction_ wheel. Both are called turbines, although the name
+belongs, more properly, to the reaction wheel alone.
+
+Impulse wheels derive their power from the _momentum_ of falling
+water. Reaction wheels derive their power from the _momentum and
+pressure_ of falling water. The old-fashioned _undershot_, _overshot_,
+and _breast_ wheels are familiar to all as examples of impulse
+wheels. Water wheels of this class revolve in the air, with the energy
+of the water exerted on one face of their buckets. On the other hand,
+reaction wheels are enclosed in water-tight cases, either of metal or
+of wood, and the buckets are entirely surrounded by water.
+
+The old-fashioned undershot, overshot, and breast wheels were not very
+efficient; they wasted about 75 per cent of the power applied to them.
+A modern impulse wheel, on the other hand, operates at an efficiency
+of 80 per cent and over. The loss is mainly through friction and
+leakage, and cannot be eliminated altogether. The modern reaction
+wheel, called the _turbine_, attains an equal efficiency. Individual
+conditions govern the type of wheel to be selected.
+
+
+_The Impulse, or Tangential Water Wheel_
+
+The modern impulse, or tangential wheel (so called because the driving
+stream of water strikes the wheel at a tangent) is best adapted to
+situations where the amount of water is limited, and the head is
+large. Thus, a mountain brook supplying only seven cubic feet of water
+a minute--a stream less than two-and-a-half inches deep flowing over a
+weir with an opening three inches wide--would develop two actual
+horsepower, under a head of 200 feet--not an unusual head to be found
+in the hill country. Under a head of one thousand feet, a stream
+furnishing 352.6 cubic feet of water a minute would develop 534.01
+horsepower at the nozzle.
+
+Ordinarily these wheels are not used under heads of less than 20 feet.
+A wheel of this type, six feet in diameter, would develop six
+horsepower, with 188 cubic feet of water a minute and 20-foot head.
+The great majority of impulse wheels are used under heads of 100 feet
+and over. In this country the greatest head in use is slightly over
+2,100 feet, although in Switzerland there is one plant utilizing a
+head of over 5,000 feet.
+
+[Illustration: Runner of Pelton wheel, showing peculiar shape of the
+buckets]
+
+[Illustration: The Fitz overshoot wheel
+
+Efficient Modern Adaptations of the Archaic Undershot and Overshot
+Water Wheels]
+
+The old-fashioned impulse wheels were inefficient because of the fact
+that their buckets were not constructed scientifically, and much of
+the force of the water was lost at the moment of impact. The impulse
+wheel of to-day, however, has buckets which so completely absorb the
+momentum of water issuing from a nozzle, that the water falls into the
+tailrace with practically no velocity. When it is remembered that the
+nozzle pressure under a 2,250-foot head is nearly 1,000 pounds to the
+square inch, and that water issues from this nozzle with a velocity of
+23,000 feet a minute, the scientific precision of this type of bucket
+can be appreciated.
+
+A typical bucket for such a wheel is shaped like an open clam shell,
+the central line which cuts the stream of water into halves being
+ground to a sharp edge. The curves which absorb the momentum of the
+water are figured mathematically and in practice become polished like
+mirrors. So great is the eroding action of water, under great
+heads--especially when it contains sand or silt--that it is
+occasionally necessary to replace these buckets. For this reason the
+larger wheels consist merely of a spider of iron or steel, with each
+bucket bolted separately to its circumference, so that it can be
+removed and replaced easily. Usually only one nozzle is provided; but
+in order to use this wheel under low heads--down to 10 feet--a number
+of nozzles are used, sometimes five, where the water supply is
+plentiful.
+
+The wheel is keyed to a horizontal shaft running in babbited bearings,
+and this same shaft is used for driving the generator, either by
+direct connection, or by means of pulleys and a belt. The wheel may be
+mounted on a home-made timber base, or on an iron frame. It takes up
+very little room, especially when it is so set that the nozzle can be
+mounted under the flooring. The wheel itself is enclosed, above the
+floor, in a wooden box, or a casing made of cast or sheet iron, which
+should be water-tight.
+
+Since these wheels are usually operated under great heads, the problem
+of regulating their water supply requires special consideration. A
+gate is always provided at the upper, or intake end, where the water
+pipe leaves the flume. Since the pressure reaches 1,000 pounds the
+square inch and more, there would be danger of bursting the pipe if
+the water were suddenly shut off at the nozzle itself. For this reason
+it is necessary to use a needle valve, similar to that in an ordinary
+garden hose nozzle; and by such a valve the amount of water may be
+regulated to a nicety. Where the head is so great that even such a
+valve could not be used safely, provision is made to deflect the
+nozzle. These wheels have a speed variation amounting to as much as 25
+per cent from no-load to full load, in generating electricity, and
+since the speed of the prime mover--the water wheel--is reflected
+directly in the voltage or pressure of electricity delivered, the
+wheel must be provided with some form of automatic governor. This
+consists usually of two centrifugal balls, similar to those used in
+governing steam engines; these are connected by means of gears to the
+needle valve or the deflector.
+
+As the demand for farm water-powers in our hill sections becomes more
+general, the tangential type of water wheel will come into common use
+for small plants. At present it is most familiar in the great
+commercial installations of the Far West, working under enormous
+heads. These wheels are to be had in the market ranging in size from
+six inches to six feet and over. Wheels ranging in size from six
+inches to twenty-four inches are called water motors, and are to be
+had in the market, new, for $30 for the smallest size, and $275 for
+the largest. Above three feet in diameter, the list prices will run
+from $200 for a 3-foot wheel to $800 for a 6-foot wheel. Where one has
+a surplus of water, it is possible to install a multiple nozzle wheel,
+under heads of from 10 to 100 feet, the cost for 18-inch wheels of
+this pattern running from $150 to $180 list, and for 24-inch wheels
+from $200 to $250. A 24-inch wheel, with a 10-foot head would give
+1.19 horsepower, enough for lighting the home, and using an electric
+iron. Under a 100-foot head this same wheel would provide 25.9
+horsepower, to meet the requirements of a bigger-than-average farm
+plant.
+
+
+_The Pipe Line_
+
+The principal items of cost in installing an impulse wheel are in
+connection with the pipe line, and the governor. In small heads, that
+is, under 100 feet, the expense of pipe line is low. Frequently,
+however, the governor will cost more than the water motor itself,
+although cheaper, yet efficient, makes are now being put on the market
+to meet this objection. In a later chapter, we will take up in detail
+the question of governing the water wheel, and voltage regulation, and
+will attempt to show how this expense may be practically eliminated by
+the farmer.
+
+To secure large heads, it is usually necessary to run a pipe line many
+hundreds (and in many cases, many thousands) of feet from the flume to
+the water wheel. Water flowing through pipes is subject to loss of
+head, by friction, and for this reason the larger the pipe the less
+the friction loss. Under no circumstances is it recommended to use a
+pipe of less than two inches in diameter, even for the smallest water
+motors; and with a two-inch pipe, the run should not exceed 200 feet.
+Where heavy-pressure mains, such as those of municipal or commercial
+water systems, are available, the problem of both water supply and
+head becomes very simple. Merely ascertain the pressure of the water
+in the mains _when flowing_, determine the amount of power required
+(as illustrated in a succeeding chapter of this book), and install the
+proper water motor with a suitably sized pipe.
+
+Where one has his own water supply, however, and it is necessary to
+lay pipe to secure the requisite fall, the problem is more difficult.
+Friction in pipes acts in the same way as cutting down the head a
+proportional amount; and by cutting down the head, your water motor
+loses power in direct proportion to the number of feet head lost. This
+head, obtained by subtracting friction and other losses from the
+surveyed head, is called the _effective head_, and determines the
+amount of power delivered at the nozzle.
+
+The tables on pages 66-67 show the friction loss in pipes up to 12
+inches in diameter, according to the amount of water, and the length
+of pipe.
+
+In this example it is seen that a 240-foot static head is reduced by
+friction to 230.1 feet effective head. By referring to the table we
+find the wheel fitting these conditions has a nozzle so small that it
+cuts down the rate of flow of water in the big pipe to 4.4 feet a
+second, and permits the flow of only 207 cubic feet of water a minute.
+The actual horsepower of this tube and nozzle, then, can be figured by
+applying formula (A), Chapter III, allowing 80 per cent for the
+efficiency of the wheel. Thus:
+
+  Actual horsepower =
+
+      207 x 230.1 x 62.5
+      ------------------ = 90.21 x .80 = 72.168 Hp.
+            33,000
+
+To calculate what the horsepower of this tube 12 inches in diameter
+and 900 feet long, would be without a nozzle, under a head of 240
+feet, introduces a new element of friction losses, which is too
+complicated to figure here. Such a condition would not be met with in
+actual practice, in any event. The largest nozzles used, even in the
+jumbo plants of the Far West, rarely exceed 10 inches in diameter; and
+the pipe conveying water to such a nozzle is upwards of eight feet in
+diameter.
+
+
+    PIPE FRICTION TABLES
+
+    INDICATING THE CALCULATED LOSS OF HEAD DUE TO FRICTION IN RIVETED
+    STEEL PIPE WITH VARIOUS WATER QUANTITIES AND VELOCITIES
+
+    [Courtesy of the Pelton Water Wheel Company]
+
+    Heavy-faced figures = Loss of head in feet for each one thousand
+    feet of pipe. Light-faced figures = Water quantity in cubic feet per
+    minute.
+
+--------+-------------------------------------------------------------------------------------------+
+Pipe    |                      Velocity in Feet per Second                                          |
+Diameter+------+------+------+------+------+------+------+------+------+------+------+------+-------+
+        |  2.0 |  2.2 |  2.4 |  2.6 |  2.8 |  3.0 |  3.2 |  3.4 |  3.6 |  3.8 |  4.0 |  4.2 |  4.4  |
+--------+------+------+------+------+------+------+------+------+------+------+------+------+-------+
+        |=17.1=|=20.0=|=25.6=|=28.3=|=32.0=|=37.3=|=40.9=|=45.8=|=50.4=|=56.0=|=62.3=|=68.1=|=74.9= |
+    3"  |  5.9 |  6.5 |  7.1 |  7.7 |  8.3 |  8.9 |  9.4 | 10.0 | 10.6 | 11.2 | 11.8 | 12.4 | 13.0  |
+        |=11.0=|=13.0=|=15.0=|=17.3=|=20.2=|=23.2=|=26.2=|=29.6=|=33.0=|=36.5=|=41.0=|=45.4=|=49.2= |
+    4"  | 10.5 | 11.5 | 12.6 | 13.6 | 14.7 | 15.7 | 16.8 | 17.8 | 18.8 | 19.9 | 21.0 | 22.0 | 23.0  |
+        | =7.7=| =9.4=|=11.0=|=12.9=|=14.9=|=16.9=|=19.5=|=21.6=|=24.0=|=27.0=|=29.8=|=32.9=|=36.0= |
+    5"  | 16.4 | 18.0 | 19.6 | 21.2 | 22.9 | 24.5 | 26.1 | 27.8 | 29.5 | 31.0 | 32.7 | 34.3 | 36.0  |
+        | =6.0=| =7.2=| =8.6=| =9.9=|=11.7=|=13.0=|=14.6=|=16.6=|=19.0=|=21.5=|=23.4=|=25.5=|=27.8= |
+    6"  | 23.5 | 25.9 | 28.2 | 30.6 | 32.9 | 35.3 | 37.7 | 40.0 | 42.4 | 44.7 | 47.1 | 49.5 | 51.8  |
+        | =4.9 | =6.9=| =7.0=| =8.1=| =9.3=|=10.6=|=12.0=|=13.6=|=15.2=|=17.0=|=19.0=|=21.0=|=23.0= |
+    7"  | 32.0 | 35.3 | 38.5 | 41.7 | 44.9 | 48.1 | 51.3 | 54.5 | 57.7 | 60.9 | 64.1 | 67.3 | 70.5  |
+        | =4.0=| =4.9=| =6.0=| =6.9=| =7.8=| =9.1=|=10.0=|=10.2=|=13.0=|=14.4=|=15.9=|=17.2=|=19.2= |
+    8"  | 41.9 | 46.1 | 50.2 | 54.4 | 58.6 | 62.8 | 67.0 | 71.2 | 75.4 | 79.6 | 83.7 | 87.9 | 92.1  |
+        | =3.4=| =4.2=| =5.1=| =5.9=| =6.7=| =7.7=| =8.9=| =9.8=|=11.0=|=12.2=|=13.8=|=15.0=|=16.0= |
+    9"  | 53.0 | 58.3 | 63.6 | 68.9 | 74.2 | 79.5 | 84.8 | 90.1 | 95.4 |101   |106   |111   |116    |
+        | =2.9=| =3.7=| =4.4=| =5.1=| =5.9=| =6.7=| =7.5=| =8.6=| =9.5=|=10.6=|=12.1=|=13.1=|=14.1= |
+   10"  | 65.4 | 72.0 | 78.5 | 85.1 | 91.6 | 98.2 |105   |111   |118   |124   |131   |137   |144    |
+        | =2.6=| =3.2=| =3.8=| =4.4=| =5.1=| =5.9=| =6.6=| =7.5=| =8.4=| =9.5=|=10.3=|=10.1=|=12.5= |
+   11"  | 79   | 87   | 95   |103   |111   |119   |127   |134   |142   |150   |158   |166   |174    |
+        |=2.36=| =2.9=| =3.4=| =3.9=| =4.5=| =5.2=| =5.9=| =6.7=| =7.5=| =8.5=| =9.4=|=10.0=|=11.0= |
+   12"  |94    |103   |113   |122   |132   |141   |151   |160   |169   |179   |188   |198   |207    |
+--------+------+------+------+------+------+------+------+------+------+------+------+------+-------+
+
+
+--------+------+------+------+------+-------+-------+-------+-------+-------+-------+-------+-------+
+        | 4.6  |  4.8 |  5.0 | 5.2  |   5.4 |   5.6 |   5.8 |   6.0 |   7.0 |   8.0 |  9.0  |  10.0 |
+--------+------+------+------+------+-------+-------+-------+-------+-------+-------+-------+-------+
+        |=78.1=|=82.0=|=89.5=|=98.9=|=105.0=|=113.2=|=120.8=|=130.0=|=162.8=|=216.0=|=270.= |=323.= |
+    3"  | 13.6 | 14.2 | 14.8 | 15.3 |  15.9 |  16.5 |  17.1 |  17.7 |  20.6 |  23.5 |  26.5 |  29.5 |
+        |=52.3=|=57.0=|=61.5=|=68.0=| =72.5=| =78.2=| =83.1=| =89.5=|=121.= |=155.= |=198.= |=242.= |
+    4"  | 24.1 | 25.1 | 26.2 | 27.2 |  28.3 |  29.3 |  30.4 |  31.5 |  36.6 |  41.9 |  47.2 |  52.4 |
+        |=39.2=|=42.3=|=46.0=|=49.8=| =53.5=| =58.0=| =62.0=| =67.0=| =89.= |=118.= |=148.= |=182.= |
+    5"  | 37.6 | 39.2 | 40.9 | 42.5 |  44.1 |  45.8 |  47.5 |  49.1 |  57.1 |  65.4 |  73.7 |  82.0 |
+        |=30.6=|=33.1=|=35.6=|=39.0=| =41.6=| =44.6=| =48.0=| =51.6=| =69.0=| =89.0=|=114.= |=140.= |
+    6"  | 54.1 | 56.5 | 58.9 | 61.2 |  63.6 |  65.9 |  68.3 |  70.7 |  82.4 |  94.3 | 106   | 118   |
+        |=25.1=|=27.3=|=29.5=|=32.0=| =34.5=| =37.1=| =40.0=| =43.0=| =58.0=| =75.0=| =95.0=|=116.= |
+    7"  | 73.7 | 76.9 | 80.2 | 83.3 |  86.6 |  89.8 |  93.0 |  96.2 | 112   | 128   | 145   | 161   |
+        |=20.0=|=22.5=|=24.9=|=27.0=| =28.8=| =30.6=| =32.8=| =35.5=| =47.5=| =61.2=| =78.6=| =95.1=|
+    8"  | 96.3 |101   |105   |109   | 113   | 117   | 121   | 125   | 146   | 168   | 189   | 210   |
+        |=17.1=|=19.2=|=21.0=|=22.9=| =24.6=| =26.2=| =28.0=| =30.1=| =40.1=| =52.1=| =66.6=| =82.0=|
+    9"  |122   |127   |132   |138   | 143   | 148   | 154   | 159   | 185   | 212   | 238   | 265   |
+        |=14.8=|=16.7=|=17.9=|=19.9=| =21.0=| =22.7=| =24.3=| =25.9=| =34.8=| =45.9=| =58.0=| =70.1=|
+   10"  |150   |157   |163   |170   | 177   | 183   | 190   | 196   | 229   | 261   | 295   | 327   |
+        |=13.0=|=14.7=|=15.9=|=17.1=| =18.2=| =20.1=| =21.3=| =22.6=| =30.7=| =40.0=| =50.8=| =62.0=|
+   11"  |182   |190   |198   |206   | 214   | 222   | 229   | 237   | 277   | 316   | 356   | 396   |
+        |=11.6=|=13.0=|=14.0=|=15.1=| =16.1=| =17.8=| =19.1=| =20.2=| =27.1=| =35.9=| =45.4=| =55.9=|
+   12"  |217   |226   |235   |245   | 254   | 264   | 273   | 283   | 330   | 377   | 425   | 472   |
+--------+---------+----------+------+-------+-------+-------+-------+-------+-------+-------+-------+
+
+    EXAMPLE
+
+    Assume the surveyed head as 240 feet, the water quantity as 207
+    cubic feet per minute and a pipe line 12 inches in diameter 900 feet
+    long. To ascertain the friction loss, refer to column of pipe
+    diameter and follow across the column for 12 inches diameter to the
+    quantity, 207 cubic feet per minute. The heavy-faced figures above
+    207 indicate that the loss per 1000 feet of pipe length is 11 feet.
+    Therefore, since the pipe in the example is 900 feet long, the loss
+    will be
+
+    11.' x 900/1000 or 9.9 feet, and the effective head will be
+    240' - 9.9' = 230.1'
+
+
+Steel tubing for supply pipes, from 3 to 12 inches in diameter is
+listed at from 20 cents to $1.50 a foot, according to the diameter and
+thickness of the material. Discounts on these prices will vary from 25
+to 50 per cent. The farmer can cut down the cost of this pipe by
+conveying his supply water from its natural source to a pond, by means
+of an open race, or a wooden flume. An ingenious mechanic can even
+construct his own pipe out of wood, though figuring labor and
+materials, it is doubtful if anything would be saved over a riveted
+steel pipe, purchased at the regular price. This pipe, leading from
+the pond, or forebay, to the water wheel, should be kept as short as
+possible; at the same time, the fall should not be too sharp. An angle
+of 30 deg. will be found very satisfactory, although pipe is frequently
+laid at angles up to 50 deg.
+
+
+_Other Types of Impulse Wheels_
+
+In recent years more efficient forms of the old-fashioned overshoot,
+pitch-back breast, and undershoot wheels have been developed, by
+substituting steel or other metal for wood, and altering the shape of
+the buckets to make better use of the power of falling water.
+
+In some forms of overshoot wheels, an efficiency of over 90 per cent
+is claimed by manufacturers; and this type offers the additional
+advantage of utilizing small quantities of water, as well as being
+efficient under varying quantities of water. They utilize the falling
+weight of water, although by giving the water momentum at the point of
+delivery, by means of the proper fall, impulse too is utilized in some
+measure. The modern steel overshoot wheel receives water in its
+buckets from a spout set a few degrees back of dead center; and its
+buckets are so shaped that the water is retained a full
+half-revolution of the wheel. The old-style overshoot wheel was
+inefficient principally because the buckets began emptying themselves
+at the end of a quarter-revolution. Another advantage claimed for
+these wheels over the old style is that, being made of thin metal,
+their buckets attain the temperature of the water itself, thus
+reducing the danger of freezing to a minimum. They are manufactured in
+sizes from 6 feet in diameter to upwards of fifty feet; and with
+buckets of from 6 inches to 10 feet in width. In practice it is usual
+to deliver water to the buckets by means of a trough or pipe, through
+a suitable spout and gate, at a point two feet above the crown of the
+wheel. For this reason, the diameter of the wheel corresponds very
+closely to the head in feet.
+
+
+_The Reaction Turbine_
+
+The reaction turbine is best adapted to low heads, with a large supply
+of water. It is not advisable, under ordinary circumstances, to use it
+under heads exceeding 100 feet, as its speed is then excessive. It
+may be used under falls as low as two feet. Five thousand cubic feet
+of water a minute would give approximately 14 actual horsepower under
+such a head. A sluggish creek that flows in large volume could thus be
+utilized for power with the reaction turbine, whereas it would be
+useless with an impulse wheel. Falls of from five to fifteen feet are
+to be found on thousands of farm streams, and the reaction turbine is
+admirably adapted to them.
+
+Reaction turbines consist of an iron "runner" which is in effect a
+rotary fan, the pressure and momentum of the column of water pressing
+on the slanted blades giving it motion and power. These wheels are
+manufactured in a great variety of forms and sizes; and are to be
+purchased either as the runner (set in bearings) alone, or as a runner
+enclosed in an iron case. In case the runner alone is purchased, the
+owner must enclose it, either with iron or wood. They vary in price
+according to size, and the means by which the flow of water is
+controlled. A simple 12-inch reaction turbine wheel, such as would be
+suitable for many power plants can be had for $75. A twelve-inch
+wheel, using 18 or 20 square inches of water, would generate about
+7-1/2 horsepower under a 20-foot head, with 268 cubic feet of water a
+minute. Under a 30-foot head, and with 330 cubic feet of water such a
+wheel will give 14 horsepower. A 36-inch wheel, under a 5-foot head,
+would use 2,000 cubic feet of water, and give 14 horsepower. Under a
+30-foot head, this same wheel, using 4,900 cubic feet of water a
+minute, would develop over 200 horsepower. If the farmer is confronted
+by the situation of a great deal of water and small head, a large
+wheel would be necessary. Thus he could secure 35 horsepower with only
+a 3-foot head, providing his water supply is equal to the draft of
+8,300 cubic feet a minute.
+
+From these sample figures, it will be seen that the reaction turbine
+will meet the requirements of widely varying conditions up to, say a
+head of 100 feet. The farmer prospector should measure first the
+quantity of water to be depended on, and then the number of feet fall
+to be had. The higher the fall, with certain limits, the smaller the
+expense of installation, and the less water required. When he has
+determined _quantity_ and _head_, the catalogue of a reputable
+manufacturer will supply him with what information is necessary to
+decide on the style and size wheel he should install. In the older
+settled communities, especially in New England, a farmer should be
+able to pick up a second-hand turbine, at half the price asked for a
+new one; and since these wheels do not depreciate rapidly, it would
+serve his purpose as well, in most cases, as a new one.
+
+[Illustration: A typical vertical turbine]
+
+Reaction turbines may be either horizontal or vertical. If they are
+vertical, it is necessary to connect them to the main shaft by means
+of a set of bevel gears. These gears should be substantially large,
+and if the teeth are of hard wood (set in such a manner that they can
+be replaced when worn) they will be found more satisfactory than if of
+cast or cut metal.
+
+[Illustration: Two wheels on a horizontal shaft
+
+(Courtesy of the C. P. Bradway Company, West Stafford, Conn.)]
+
+The horizontal turbine is keyed to its shaft, like the impulse wheel,
+so that the wheel shaft itself is used for driving, without gears or a
+quarter-turn belt. (The latter is to be avoided, wherever possible.)
+There are many forms of horizontal turbines; they are to be had of the
+duplex type, that is, two wheels on one shaft. These are arranged so
+that either wheel may be run separately, or both together, thus
+permitting one to take advantage of the seasonal fluctuation in water
+supply. A convenient form of these wheels includes draft tubes, by
+which the wheel may be set several feet above the tailrace, and the
+advantage of this additional fall still be preserved. In this case the
+draft tube must be airtight so as to form suction, when filled with
+escaping water, and should be proportioned to the size of the wheel.
+Theoretically these draft tubes might be 34 feet long, but in practice
+it has been found that they should not exceed 10 or 12 feet under
+ordinary circumstances. They permit the wheel to be installed on the
+main floor of the power station, with the escape below, instead of
+being set just above the tailrace level itself, as is the case when
+draft tubes are not used.
+
+Reaction turbines when working under a variable load require water
+governors (like impulse wheels) although where the supply of water is
+large, and the proportion of power between water wheel and dynamo is
+liberal--say two to one, or more--this necessity is greatly reduced.
+Reaction wheels as a rule govern themselves better than impulse
+wheels, due both to the fact that they use more water, and that they
+operate in a small airtight case. The centrifugal ball governor is the
+type usually used with reaction wheels as well as with impulse wheels.
+This subject will be discussed more fully later.
+
+
+_Installing a Power Plant_
+
+In developing a power prospect, the dam itself is usually not the site
+of the power plant. In fact, because of danger from flood water and
+ice, it is better to locate it in a more protected spot, leading the
+water to the wheel by means of a race and flume.
+
+[Illustration: Bird's-eye view of a developed water-power plant]
+
+A typical crib dam, filled with stone, is shown in section in the
+diagram, and the half-tone illustration shows such a dam in course of
+construction. The first bed of timbers should be laid on hard-pan or
+solid rock in the bed of the stream parallel to its flow. The second
+course, across the stream, is then begun, being spiked home by means
+of rods cut to length and sharpened by the local blacksmith, from
+3/4-inch Norway iron. Hemlock logs are suitable for building the crib;
+and as the timbers are finally laid, it should be filled in and made
+solid with boulders. This filling in should proceed section by
+section, as the planking goes forward, otherwise there will be no
+escape for the water of the stream, until it rises and spills over
+the top timbers. The planking should be of two-inch chestnut, spiked
+home with 60 penny wire spikes. When the last section of the crib is
+filled with boulders and the water rises, the remaining planks may be
+spiked home with the aid of an iron pipe in which to drive the spike
+by means of a plunger of iron long enough to reach above the level of
+the water. When the planking is completed, the dam should be well
+gravelled, to within a foot or two of its crest. Such dams are
+substantial, easily made with the aid of unskilled labor, and the
+materials are to be had on the average farm with the exception of the
+hardware.
+
+[Illustration: Cross-section of a rock and timber dam]
+
+This dam forms a pond from which the race draws its supply of water
+for the wheel. It also serves as a spillway over which the surplus
+water escapes. The race should enter the pond at some convenient
+point, and should be protected at or near its point of entrance by a
+bulkhead containing a gate, so that the supply of water may be cut off
+from the race and wheel readily. The lay of the land will determine
+the length and course of the race. The object of the race is to secure
+the required head by carrying a portion of the available water to a
+point where it can escape, by a fall of say 30 deg. to the tailrace. It
+may be feasible to carry the race in a line almost at right angles to
+the stream itself, or, again, it may be necessary to parallel the
+stream. If the lay of the land is favorable, the race may be dug to a
+distance of a rod or so inshore, and then be permitted to cut its own
+course along the bank, preventing the water escaping back to the river
+or brook before the site of the power plant is reached, by building
+suitable retaining embankments. The race should be of ample size for
+conveying the water required without too much friction. It should end
+in a flume constructed stoutly of timbers. It is from this flume that
+the penstock draws water for the wheel. When the wheel gate is closed
+the water in the mill pond behind the dam, and in the flume itself
+should maintain an approximate level. Any surplus flow is permitted to
+escape over flushboards in the flume; these same flushboards maintain
+a constant head when the wheel is in operation by carrying off what
+little surplus water the race delivers from the pond.
+
+[Illustration: Detail of bulkhead gate]
+
+At some point in the race or flume, the flow should be protected from
+leaves and other trash by means of a rack. This rack is best made of
+1/4 or 1/2-inch battens from 1-1/2 to 3 inches in width, bolted
+together on their flat faces and separated a distance equal to the
+thickness of the battens by means of iron washers. This rack will
+accumulate leaves and trash, varying with the time of year and should
+be kept clean, so as not to cut down the supply of water needed by the
+wheel.
+
+The penstock, or pipe conveying water from the flume to the wheel,
+should be constructed of liberal size, and substantially, of two-inch
+chestnut planking, with joints caulked with oakum, and the whole well
+bound together to resist the pressure of the water. Means should be
+provided near the bottom for an opening through which to remove any
+obstructions that may by accident pass by the rack. Many wheels have
+plates provided in their cases for this purpose.
+
+The tailrace should be provided with enough fall to carry the escaping
+water back to the main stream, without backing up on the wheel itself
+and thus cutting down the head.
+
+It is impossible to make any estimates of the cost of such a
+water-power plant. The labor required will in most instances be
+supplied by the farmer himself, his sons, and his help, during times
+when farm operations are slack.
+
+
+_Water Rights of the Farmer_
+
+The farmer owns the bed of every stream not navigable, lying within
+the boundary lines of the farm; and his right to divert and make use
+of the water of such streams is determined in most states by common
+law. In the dry-land states where water is scarce and is valuable for
+irrigation, a special set of statutes has sprung up with the
+development of irrigation in this country.
+
+A stream on the farm is either public or private; its being navigable
+or "floatable" (suitable for floating logs) determining which. Water
+rights are termed in law "riparian" rights, and land is riparian only
+when water flows over it or along its borders.
+
+Green (Law for the American Farmer) says:
+
+"Water is the common and equal property of every one through whose
+land it flows, and the right of each land-owner to use and consume it
+without destroying, or unreasonably impairing the rights of others, is
+the same. An owner of land bordering on a running stream has the right
+to have its waters flow naturally, and none can lawfully divert them
+without his consent. Each riparian proprietor has an equal right with
+all the others to have the stream flow in its natural way without
+substantial reduction in volume, or deterioration in quality, subject
+to a proper and reasonable use of its waters for domestic,
+agricultural and manufacturing purposes, and he is entitled to use it
+himself for such purposes, but in doing so must not substantially
+injure others. In addition to the right of drawing water for the
+purposes just mentioned, a riparian proprietor, if he duly regards the
+rights of others, and does not unreasonably deplete the supply, has
+also the right to take the water for some other proper uses."
+
+Thus, the farmer who seeks to develop water-power from a stream
+flowing across his own land, has the right to divert such a stream
+from its natural channel--providing it is not a navigable or floatable
+stream--but in so doing, he must return it to its own channel for
+lower riparian owners. The generation of water-power does not pollute
+the water, nor does it diminish the water in quantity, therefore the
+farmer is infringing on no other owner's rights in using the water for
+such a purpose.
+
+When a stream is a dividing line between two farms, as is frequently
+the case, each proprietor owns to the middle of the stream and
+controls its banks. Therefore to erect a dam across such a private
+stream and divert all or a part of the water for power purposes,
+requires the consent of the neighboring owner. The owner of the dam is
+responsible for damage due to flooding, to upstream riparian owners.
+
+
+
+
+PART II
+
+ELECTRICITY
+
+
+
+
+CHAPTER V
+
+THE DYNAMO; WHAT IT DOES, AND HOW
+
+     Electricity compared to the heat and light of the Sun--The simple
+     dynamo--The amount of electric energy a dynamo will generate--The
+     modern dynamo--Measuring power in terms of electricity--The
+     volt--The ampere--The ohm--The watt and the kilowatt--Ohm's Law of
+     the electric circuit, and some examples of its application--Direct
+     current, and alternating current--Three types of direct-current
+     dynamos: series, shunt, and compound.
+
+
+What a farmer really does in generating electricity from water that
+would otherwise run to waste in his brook, is to install a private Sun
+of his own--which is on duty not merely in daylight, but twenty-four
+hours a day; a private Sun which is under such simple control that it
+shines or provides heat and power, when and where wanted, simply by
+touching a button.
+
+This is not a mere fanciful statement. When you come to look into it
+you find that electricity actually is the life-giving power of the
+Sun's rays, so transformed that it can be handily conveyed from place
+to place by means of wires, and controlled by mechanical devices as
+simple as the spigot that drains a cask.
+
+Nature has the habit of traveling in circles. Sometimes these circles
+are so big that the part of them we see looks like a straight line,
+but it is not. Even parallel lines, according to the mathematicians,
+"meet in infinity." Take the instance of the water wheel which the
+farmer has installed under the fall of his brook. The power which
+turns the wheel has the strength of many horses. It is there in a
+handy place for use, because the Sun brought it there. The Sun, by its
+heat, lifted the water from sea-level, to the pond where we find
+it--and we cannot get any more power out of this water by means of a
+turbine using its pressure and momentum in falling, than the Sun
+itself expended in raising the water against the force of gravity.
+
+Once we have installed the wheel to change the energy of falling water
+into mechanical power, the task of the dynamo is to turn this
+mechanical power into another mode of motion--electricity. And the
+task of electricity is to change this mode of motion back into the
+original heat and light of the Sun--which started the circle in the
+beginning.
+
+Astronomers refer to the Sun as "he" and "him" and they spell his name
+with a capital letter, to show that he occupies the center of our
+small neighborhood of the universe at all times.
+
+
+_Magnets and Magnetism_
+
+The dynamo is a mechanical engine, like the steam engine, the water
+turbine or the gas engine; and it converts the mechanical motion of
+the driven wheel into electrical motion, with the aid of a magnet.
+Many scientists say that the full circle of energy that keeps the
+world spinning, grows crops, and paints the sky with the Aurora
+Borealis, begins and ends with magnetism--that the sun's rays are
+magnetic rays. Magnetism is the force that keeps the compass needle
+pointing north and south. Take a steel rod and hold it along the
+north and south line, slightly inclined towards the earth, and strike
+it a sharp blow with a hammer, and it becomes a magnet--feeble, it is
+true, but still a magnet.
+
+Take a wire connected with a common dry battery and hold a compass
+needle under it and the needle will immediately turn around and point
+directly across the wire, showing that the wire possesses magnetism
+encircling it in invisible lines, stronger than the magnetism of the
+earth.
+
+[Illustration: (_Courtesy of the Crocker-Wheeler Company_)
+
+A direct-current dynamo or motor, showing details of construction]
+
+Insulate this wire by covering it with cotton thread, and wind it
+closely on a spool. Connect the two loose ends to a dry battery, and
+you will find that you have multiplied the magnetic strength of a
+single loop of wire by the number of turns on the spool--concentrated
+all the magnetism of the length of that wire into a small space. Put
+an iron core in the middle of this spool and the magnet seems still
+more powerful. Lines of force which otherwise would escape in great
+circles into space, are now concentrated in the iron. The iron core
+is a magnet. Shut off the current from the battery and the iron is
+still a magnet--weak, true, but it will always retain a small portion
+of its magnetism. Soft iron retains very little of its magnetism. Hard
+steel retains a great deal, and for this reason steel is used for
+permanent magnets, of the horseshoe type so familiar.
+
+
+_A Simple Dynamo_
+
+A dynamo consists, first, of a number of such magnets, wound with
+insulated wire. Their iron cores point towards the center of a circle
+like the spokes of a wheel; and their curved inner faces form a circle
+in which a spool, wound with wire in another way, may be spun by the
+water wheel.
+
+Now take a piece of copper wire and make a loop of it. Pass one side
+of this loop in front of an electric magnet.
+
+As the wire you hold in your hands passes the iron face of the magnet,
+a wave of energy that is called electricity flows around this loop at
+the rate of 186,000 miles a second--the same speed as light comes to
+us from the sun. As you move the wire away from the magnet, a second
+wave starts through the wire, flowing in the opposite direction. You
+can prove this by holding a compass needle under the wire and see it
+wag first in one direction, then in another.
+
+[Illustration: A wire "cutting" the lines of force of an
+electro-magnet]
+
+This is a simple dynamo. A wire "cutting" the invisible lines of
+force, that a magnet is spraying out into the air, becomes
+"electrified." Why this is true, no one has ever been able to explain.
+
+The amount of electricity--its capacity for work--which you have
+generated with the magnet and wire, does not depend alone on the
+pulling power of that simple magnet. Let us say the magnet is very
+weak--has not enough power to lift one ounce of iron. Nevertheless,
+if you possessed the strength of Hercules, and could pass that wire
+through the field of force of the magnet many thousands of times a
+second, you would generate enough electricity in the wire to cause the
+wire to melt in your hands from heat.
+
+[Illustration: Cross-section of an armature revolving in its field]
+
+[Illustration: Forms of annealed steel discs used in armature
+construction]
+
+This experiment gives the theory of the dynamo. Instead of passing
+only one wire through the field of force of a magnet, we have hundreds
+bound lengthwise on a revolving drum called an armature. Instead of
+one magnetic pole in a dynamo we have two, or four, or twenty
+according to the work the machine is designed for--always in pairs, a
+North pole next to a South pole, so that the lines of force may flow
+out of one and into another, instead of escaping in the surrounding
+air. If you could see these lines of force, they would appear in
+countless numbers issuing from each pole face of the field magnets,
+pressing against the revolving drum like hair brush bristles--trying
+to hold it back. This drum, in practice, is built up of discs of
+annealed steel, and the wires extending lengthwise on its face are
+held in place by slots to prevent them from flying off when the drum
+is whirled at high speed. The drum does not touch the face of the
+magnets, but revolves in an air space. If we give the electric
+impulses generated in these wires a chance to flow in a circuit--flow
+out of one end of the wires, and in at the other, the drum will
+require more and more power to turn it, in proportion to the amount of
+electricity we permit to flow. Thus, if one electric light is turned
+on, the drum will press back with a certain strength on the water
+wheel; if one hundred lights are turned on it will press back one
+hundred times as much. Providing there is enough power in the water
+wheel to continue turning the drum at its predetermined speed, the
+dynamo will keep on giving more and more electricity if asked to,
+until it finally destroys itself by fire. You cannot take more power,
+in terms of electricity, out of a dynamo that you put into it, in
+terms of mechanical motion. In fact, to insure flexibility and
+constant speed at all loads, it is customary to provide twice as much
+water wheel, or engine, power as the electrical rating of the dynamo.
+
+[Illustration: An armature partly wound, showing slots and commutator]
+
+We have seen that a water wheel is 85 per cent efficient under ideal
+conditions. A dynamo's efficiency in translating mechanical motion
+into electricity, varies with the type of machine and its size. The
+largest machines attain as high as 90 per cent efficiency; the
+smallest ones run as low as 40 per cent.
+
+
+_Measuring Electric Power_
+
+The amount of electricity any given dynamo can generate depends,
+generally speaking, on two factors, i. e., (1) the power of the water
+wheel, or other mechanical engine that turns the armature; and (2) the
+size (carrying capacity) of the wires on this drum.
+
+Strength, of electricity, is measured in _amperes_. An ampere of
+electricity is the unit of the rate of flow and may be likened to a
+gallon of water per minute.
+
+In surveying for water-power, in Chapter III, we found that the
+number of gallons or cubic feet of water alone did not determine the
+amount of power. We found that the number of gallons or cubic feet
+multiplied by the distance in feet it falls in a given time, was the
+determining factor--pounds (quantity) multiplied by feet per
+second--(velocity).
+
+[Illustration: Showing the analogy of water to volts and amperes of
+electricity]
+
+The same is true in figuring the power of electricity. We multiply the
+_amperes_ by the number of electric impulses that are created in the
+wire in the course of one second. The unit of velocity, or pressure of
+the electric current is called a _volt_. Voltage is the pressure which
+causes electricity to flow. A volt may be likened to the velocity in
+feet per second of water in falling past a certain point. If you
+think a moment you will see that this has nothing to do with quantity.
+A pin-hole stream of water under 40 pounds pressure has the same
+velocity as water coming from a nozzle as big as a barrel, under the
+same pressure. So with electricity under the pressure of one volt or
+one hundred volts.
+
+One volt is said to consist of a succession of impulses caused by _one
+wire cutting 100,000,000 lines of magnetic force in one second_. Thus,
+if the strength of a magnet consisted of one line of force, to create
+the pressure of one volt we would have to "cut" that line of force
+100,000,000 times a second, with one wire; or 100,000 times a second
+with one thousand wires. Or, if a magnet could be made with
+100,000,000 lines of force, a single wire cutting those lines once in
+a second would create one volt pressure. In actual practice, field
+magnets of dynamos are worked at densities up to and over 100,000
+lines of force to the square inch, and armatures contain several
+hundred conductors to "cut" these magnetic lines. The voltage then
+depends on the speed at which the armature is driven. In machines for
+isolated plants, it will be found that the speed varies from 400
+revolutions per minute, to 1,800, according to the design of dynamo
+used.
+
+[Illustration: Pressure determines volume of flow in a given time]
+
+Multiplying amperes (strength) by volts (pressure), gives us _watts_
+(power). Seven hundred and forty-six watts of electrical energy is
+equal to one horsepower of mechanical energy--will do the same work.
+Thus an electric current under a pressure of 100 volts, and a density
+of 7.46 amperes, is one horsepower; as is 74.6 amperes, at 10 volts
+pressure; or 746 amperes at one volt pressure. For convenience (as a
+watt is a small quantity) electricity is measured in _kilowatts_, or
+1,000 watts. Since 746 watts is one horsepower, 1,000 watts or one
+kilowatt is 1.34 horsepower. The work of such a current for one hour
+is called a _kilowatt-hour_, and in our cities, where electricity is
+generated from steam, the retail price of a kilowatt-hour varies from
+10 to 15 cents.
+
+Now as to how electricity may be controlled, so that a dynamo will not
+burn itself up when it begins to generate.
+
+Again we come back to the analogy of water. The amount of water that
+passes through a pipe in any given time, depends on the size of the
+pipe, if the pressure is maintained uniform. In other words the
+_resistance_ of the pipe to the flow of water determines the amount.
+If the pipe be the size of a pin-hole, a very small amount of water
+will escape. If the pipe is as big around as a barrel, a large amount
+will force its way through. So with electricity. Resistance,
+introduced in the electric circuit, controls the amount of current
+that flows. A wire as fine as a hair will permit only a small quantity
+to pass, under a given pressure. A wire as big as one's thumb will
+permit a correspondingly greater quantity to pass, the pressure
+remaining the same. The unit of electrical resistance is called the
+_ohm_--named after a man, as are all electrical units.
+
+
+_Ohm's Law_
+
+The _ohm_ is that amount of _resistance_ that will permit the passage
+of _one ampere_, under the pressure of _one volt_. It would take two
+volts to force two amperes through one ohm; or 100 volts to force 100
+amperes through the resistance of one ohm. From this we have Ohm's
+Law, a simple formula which is the beginning and end of all electric
+computations the farmer will have to make in installing his
+water-power electric plant. Ohm's Law tells us that the density of
+current (amperes) that can pass through a given resistance in ohms (a
+wire, a lamp, or an electric stove) equals _volts_ divided by
+_ohms_--or _pressure_ divided by _resistance_. This formula may be
+written in three ways, thus:
+
+C = E/R, or R = E/C or, E = C x R. Or to express the same thing in
+words, _current_ equals _volts_ divided by _ohms_; _ohms_ equals
+_volts_ divided by _current_; or _volts_ equals _current_ multiplied
+by _ohms_. So, with any two of these three determining factors known,
+we can find the third. As we have said, this simple law is the
+beginning and end of ordinary calculations as to electric current, and
+it should be thoroughly understood by any farmer who essays to be his
+own electrical engineer. Once understood and applied, the problem of
+the control of the electric current becomes simple a b c.
+
+
+_Examples of Ohm's Law_
+
+Let us illustrate its application by an example. The water wheel is
+started and is spinning the dynamo at its rated speed, say 1,500
+r.p.m. Two heavy wires, leading from brushes which collect electricity
+from the revolving armature, are led, by suitable insulated supports
+to the switchboard, and fastened there. They do not touch each other.
+Dynamo mains must not be permitted to touch each other _under any
+conditions_. They are separated by say four inches of air. Dry air is
+a very poor conductor of electricity. Let us say, for the example,
+that dry air has a resistance to the flow of an electric current, of
+1,000,000 ohms to the inch--that would be 4,000,000 ohms. How much
+electricity is being permitted to escape from the armature of this
+110-volt dynamo, when the mains are separated by four inches of dry
+air? Apply Ohm's law, C equals E divided by R. E, in this case is 110;
+R is 4,000,000; therefore C (amperes) equals 110/4,000,000--an
+infinitesimal amount--about .0000277 ampere.
+
+Let us say that instead of separating these two mains by air we
+separated them by the human body--that a man took hold of the bare
+wires, one in each hand. The resistance of the human body varies from
+5,000 to 10,000 ohms. In that case C (amperes) equals 110/5,000, or
+110/10,000--about 1/50th, or 1/100th of an ampere. This illustrates
+why an electric current of 110 volts pressure is not fatal to human
+beings, under ordinary circumstances. The body offers too much
+resistance. But, if the volts were 1,100 instead of the usual 110 used
+in commercial and private plants for domestic use, the value of C, by
+this formula at 5,000 ohms, would be nearly 1/5th ampere. To drive
+1/5th ampere of electricity through the human body would be fatal in
+many instances. The higher the voltage, the more dangerous the
+current. In large water-power installations in the Far West, where the
+current must be transmitted over long distances to the spot where it
+is to be used, it is occasionally generated at a pressure of 150,000
+volts. Needless to say, contact with such wires means instant death.
+Before being used for commercial or domestic purposes, in such cases,
+the voltage is "stepped down" to safe pressures--to 110, or to 220, or
+to 550 volts--always depending on the use made of it.
+
+Now, if instead of interposing four inches of air, or the human body,
+between the mains of our 110-volt dynamo, we connected an incandescent
+lamp across the mains, how much electricity would flow from the
+generator? An incandescent lamp consists of a vacuum bulb of glass, in
+which is mounted a slender thread of carbonized fibre, or fine
+tungsten wire. To complete a circuit, the current must flow through
+this wire or filament. In flowing through it, the electric current
+turns the wire or filament white hot--incandescent--and thus turns
+electricity back into light, with a small loss in heat. In an ordinary
+16 candlepower carbon lamp, the resistance of this filament is 220
+ohms. Therefore the amount of current that a 110-volt generator can
+force through that filament is 110/220, or 1/2 ampere.
+
+[Illustration: Armature and field coils of a direct current dynamo]
+
+One hundred lamps would provide 100 paths of 220 ohms resistance each
+to carry current, and the amount required to light 100 such lamps
+would be 100 x 1/2 or 50 amperes. Every electrical device--a lamp, a
+stove, an iron, a motor, etc.,--must, by regulations of the Fire
+Underwriters' Board be plainly marked with the voltage of the current
+for which it is designed and the amount of current it will consume.
+This is usually done by indicating its capacity in watts, which as we
+have seen, means volts times amperes, and from this one can figure
+ohms, by the above formulas.
+
+
+_A Short Circuit_
+
+We said a few paragraphs back that under no conditions must two bare
+wires leading from electric mains be permitted to touch each other,
+without some form of resistance being interposed in the form of lamps,
+or other devices. Let us see what would happen if two such bare wires
+did touch each other. Our dynamo as we discover by reading its plate,
+is rated to deliver 50 amperes, let us say, at 110 volts pressure.
+Modern dynamos are rated liberally, and can stand 100% overload for
+short periods of time, without dangerous overheating. Let us say that
+the mains conveying current from the armature to the switchboard are
+five feet long, and of No. 2 B. & S. gauge copper wire, a size which
+will carry 50 amperes without heating appreciably. The resistance of
+this 10 feet of No. 2 copper wire, is, as we find by consulting a wire
+table, .001560 ohms. If we touch the ends of these two five-foot wires
+together, we instantly open a clear path for the flow of electric
+current, limited only by the carrying capacity of the wire and the
+back pressure of .001560 ohms resistance. Using Ohm's Law, C equals E
+divided by R, we find that C (amperes) equals 110/.001560 or _70,515
+amperes_!
+
+[Illustration: A direct current dynamo]
+
+Unless this dynamo were properly protected, the effect of such a
+catastrophe would be immediate and probably irreparable. In effect, it
+would be suddenly exerting a force of nearly 10,000 horsepower against
+the little 10 horsepower water wheel that is driving this dynamo. The
+mildest thing that could happen would be to melt the feed-wire or to
+snap the driving belt, in which latter case the dynamo would come to a
+stop. If by any chance the little water wheel was given a chance to
+maintain itself against the blow for an instant, the dynamo, rated at
+50 amperes, would do its best to deliver the 70,515 amperes you called
+for--and the result would be a puff of smoke, and a ruined dynamo.
+This is called a "short circuit"--one of the first "don'ts" in
+handling electricity.
+
+As a matter of fact every dynamo is protected against such a calamity
+by means of safety devices, which will be described in a later
+chapter--because no matter how careful a person may be, a partial
+short circuit is apt to occur. Happily, guarding against its
+disastrous effects is one of the simplest problems in connection with
+the electric plant.
+
+
+_Direct Current and Alternating Current_
+
+When one has mastered the simple Ohm's Law of the electric circuit,
+the next step is to determine what type of electrical generator is
+best suited to the requirements of a farm plant.
+
+In the first place, electric current is divided into two classes of
+interest here--_alternating_, and _direct_.
+
+We have seen that when a wire is moved through the field of a magnet,
+there is induced in it two pulsations--first in one direction, then in
+another. This is an _alternating_ current, so called because it
+changes its direction. If, with our armature containing hundreds of
+wires to "cut" the lines of force of a group of magnets, we connected
+the beginning of each wire with one copper ring, and the end of each
+wire with another copper ring, we would have what is called an
+_alternating-current_ dynamo. Simply by pressing a strap of flexible
+copper against each revolving copper ring, we would gather the sum of
+the current of these conductors. Its course would be represented by
+the curved line in the diagram, one loop on each side of the middle
+line (which represents time) would be a _cycle_. The number of
+_cycles_ to the second depends on the speed of the armature; in
+ordinary practice it is usually twenty-five or sixty. Alternating
+current has many advantages, which however, do not concern us here.
+Except under very rare conditions, a farmer installing his own plant
+should not use this type of machine.
+
+[Illustration: Diagram of alternating and direct current]
+
+If, however, instead of gathering all the current with brushes bearing
+on two copper rings, we collected all the current traveling in one
+direction, on one set of brushes--and all the current traveling in the
+other direction on another set of brushes,--we would straighten out
+this current, make it all travel in one direction. Then we would have
+a _direct current_. A direct current dynamo, the type generally used
+in private plants, does this. Instead of having two copper rings for
+collecting the current, it has a single ring, made up of segments of
+copper bound together, but insulated from each other, one segment for
+each set of conductors on the armature. This ring of many segments, is
+called a _commutator_, because it commutates, or changes, the
+direction of the electric impulses, and delivers them all in one
+direction. In effect, it is like the connecting rod of a steam engine
+that straightens out the back-and-forth motion of the piston in the
+steam cylinder and delivers the motion to a wheel running in one
+direction.
+
+Such a current, flowing through a coil of wire would make a magnet,
+one end of which would always be the north end, and the other end the
+south end. An alternating current, on the other hand, flowing through
+a coil of wire, would make a magnet that changed its poles with each
+half-cycle. It would no sooner begin to pull another magnet to it,
+than it would change about and push the other magnet away from it, and
+so on, as long as it continued to flow. This is one reason why a
+direct current dynamo is used for small plants. Alternating current
+will light the same lamps and heat the same irons as a direct current;
+but for electric power it requires a different type of motor.
+
+
+_Types of Direct Current Dynamos_
+
+Just as electrical generators are divided into two classes,
+alternating and direct, so direct current machines are divided into
+three classes, according to the manner in which their output, in
+amperes and volts, is regulated. They differ as to the manner in which
+their field magnets (in whose field of force the armature spins) are
+excited, or made magnetic. They are called _series_, _shunt_, and
+_compound_ machines.
+
+
+_The Series Dynamo_
+
+By referring to the diagram, it will be seen that the current of a
+_series_ dynamo issues from the armature mains, and passes through the
+coils of the field magnets before passing into the external circuit to
+do its work. The residual magnetism, or the magnetism left in the
+iron cores of the field magnets from its last charge, provides the
+initial excitation, when the machine is started. As the resistance of
+the external circuit is lowered, by turning on more and more lights,
+more and more current flows from the armature, through the field
+magnets. Each time the resistance is lowered, therefore, the current
+passing through the field magnets becomes more dense in amperes, and
+makes the field magnets correspondingly stronger.
+
+We have seen that the voltage depends on the number of lines of
+magnetic force cut by the armature conductors in a given time. If the
+speed remains constant then, and the magnets grow stronger and
+stronger, the voltage will rise in a straight line. When no current is
+drawn, it is 0; at full load, it may be 100 volts, or 500, or 1,000
+according to the machine. This type of machine is used only in street
+lighting, in cities, with the lights connected in "series," or one
+after another on the same wire, the last lamp finally returning the
+wire to the machine to complete the circuit. This type of dynamo has
+gained the name for itself of "mankiller," as its voltage becomes
+enormous at full load. It is unsuitable, in every respect, for the
+farm plant. Its field coils consist of a few turns of very heavy wire,
+enough to carry all the current of the external circuit, without
+heating.
+
+[Illustration: Connections of a series dynamo]
+
+
+_The Shunt Dynamo_
+
+The shunt dynamo, on the other hand, has field coils connected
+directly _across_ the circuit, from one wire to another, instead of in
+"series." These coils consist of a great many turns of very fine wire,
+thus introducing _resistance_ into the circuit, which limits the
+amount of current (amperes) that can be forced through them at any
+given voltage. As a shunt dynamo is brought up to its rated speed, its
+voltage gradually rises until a condition of balance occurs between
+the field coils and the armature. There it remains constant. When
+resistance on the external circuit is lowered, by means of turning on
+lamps or other devices, the current from the armature increases in
+working power, by increasing its amperes. Its voltage remains
+stationary; and, since the resistance of its field coils never
+changes, the magnets do not vary in strength.
+
+[Illustration: Connections of a shunt dynamo]
+
+The objection to this type of machine for a farm plant is that, in
+practice, the armature begins to exercise a de-magnetizing effect on
+the field magnets after a certain point is reached--weakens them;
+consequently the voltage begins to fall. The voltage of a shunt dynamo
+begins to fall after half-load is reached; and at full load, it has
+fallen possibly 20 per cent. A rheostat, or resistance box on the
+switchboard, makes it possible to cut out or switch in additional
+resistance in the field coils, thus varying the strength of the field
+coils, within a limit of say 15 per cent, to keep the voltage
+constant. This, however, requires a constant attendance on the
+machine. If the voltage were set right for 10 lights, the lights would
+grow dim when 50 lights were turned on; and if it were adjusted for 50
+lights, the voltage would be too high for only ten lights--would cause
+them to "burn out."
+
+Shunt dynamos are used for charging storage batteries, and are
+satisfactory for direct service only when an attendant is constantly
+at hand to regulate them.
+
+
+_The Compound Dynamo_
+
+The ideal between these two conditions would be a compromise, which
+included the characteristics of both _series_ and _shunt_ effects.
+That is exactly what the _compound_ dynamo effects.
+
+A compound dynamo is a shunt dynamo with just enough series turns on
+its field coils, to counteract the de-magnetizing effect of the
+armature at full load. A machine can be designed to make the voltage
+rise gradually, or swiftly, by combining the two systems. For country
+homes, the best combination is a machine that will keep the voltage
+constant from no load to full load. A so-called _flat-compounded_
+machine does this. In actual practice, this voltage rises slightly at
+the half-load line--only two or three volts, which will not damage the
+lamps in a 110-volt circuit.
+
+The compound dynamo is therefore self-regulating, and requires no
+attention, except as to lubrication, and the incidental care given to
+any piece of machinery. Any shunt dynamo can be made into a compound
+dynamo, by winding a few turns of heavy insulated wire around the
+shunt coils, and connecting them in "series" with the external
+circuit. How many turns are necessary depends on conditions. Three or
+four turns to each coil usually are sufficient for "flat compounding."
+If the generating plant is a long distance from the farm house where
+the light, heat, and power are to be used, the voltage drops at full
+load, due to resistance of the transmission wires. To overcome this,
+enough turns can be wound on top of the shunt coils to cause the
+voltage to rise at the switchboard, but remain stationary at the spot
+where the current is used. The usual so-called flat-compounded dynamo,
+turned out by manufacturers, provides for constant voltage at the
+switchboard. Such a dynamo is eminently fitted for the farm electric
+plant. Any other type of machine is bound to cause constant trouble
+and annoyance.
+
+[Illustration: Connections of a compound dynamo]
+
+
+
+
+CHAPTER VI
+
+WHAT SIZE PLANT TO INSTALL
+
+     The farmer's wife his partner--Little and big plants--Limiting
+     factors--Fluctuations in water supply--The average plant--The
+     actual plant--Amount of current required for various
+     operations--Standard voltage--A specimen allowance for electric
+     light--Heating and cooking by electricity--Electric power: the
+     electric motor.
+
+
+The farmer's wife becomes his partner when he has concluded the
+preliminary measurements and surveys for building his water-power
+electric plant. Now the question is, how big a plant is necessary, or
+how small a plant can he get along with. Electricity may be used for a
+multitude of purposes on the farm, in its sphere of furnishing
+portable light, heat and power; but when this multitude of uses has
+been enumerated, it will be found that the wife shares in the benefits
+no less than the farmer himself. The greatest dividend of all,
+whether dividends are counted in dollars or happiness, is that
+electricity takes the drudgery out of housework. Here, the work of the
+farmer himself ends when he has brought electricity to the house, just
+as his share in housework ends when he has brought in the kerosene,
+and filled the woodbox. Of the light and heat, she will use the lion's
+share; and for the power, she will discover heretofore undreamed-of
+uses. So she must be a full partner when it comes to deciding how much
+electricity they need.
+
+How much electricity, in terms of light, heat, and power, will the
+farmer and his wife have use for? How big a plant should be installed
+to meet the needs of keeping house and running the farm?
+
+The answer hangs mainly on how much water-power there is available,
+through all the seasons of the year, with which to generate
+electricity. Beyond that, it is merely a question of the farmer's
+pocketbook. How much money does he care to spend? Electricity is a
+cumulative "poison." The more one uses it, the more he wants to use
+it. After a plant has been in operation a year, the family have
+discovered uses for electricity which they did not think of in the
+beginning. For this reason, it is well to put in a plant larger than
+the needs of the moment seem to require. An electrical horsepower or
+two one way or another will not greatly change the first cost, and you
+will always find use for any excess.
+
+Once for all, to settle the question of water-power, the water wheel
+should be twice the normal capacity of the dynamo it drives, in terms
+of power. This allows for overload, which is bound to occur
+occasionally; and it also insures smooth running, easy governing, and
+the highest efficiency. Since the electric current, once the plant is
+installed, will cost practically nothing, the farmer can afford to
+ignore the power going to waste, and consider only how to get the best
+service.
+
+
+_The Two Extremes_
+
+The amount of water to be had to be turned into electricity, will vary
+with location, and with the season. It may be only enough, the
+greater part of the year, for a "toy" plant--a very practical toy, by
+the way--one that will keep half a dozen lights burning in the house
+and barn at one time; under some conditions water may be so scarce
+that it must be stored for three or four days to get enough power to
+charge a storage battery for these six or eight lights. A one-quarter,
+or a one-half kilowatt electrical generator, with a one horsepower (or
+smaller) wheel, will light a farmstead very satisfactorily--much
+better than kerosene lamps.
+
+On the other hand, the driving power of your wheel may be sufficient
+to furnish 50 or 100 lights for the house, barn, and out-buildings,
+and barn-yard and drives; to provide ample current for irons,
+toasters, vacuum cleaners, electric fans, etc.; to do all the cooking
+and baking and keep the kitchen boiler hot; and to heat the house in
+the coldest weather with a dry clean heat that does not vitiate the
+air, with no ashes, smoke or dust or woodchopping--nothing but an
+electric switch to turn on and off; and to provide power for motors
+ranging from tiny ones to run the sewing machine, to one of 15
+horsepower to do the threshing. A plant capable of developing from 30
+to 50 kilowatts of electricity, and requiring from 50 to 100
+horsepower at the water wheel, would do all this, depending on the
+size of the farmstead. One hundred horsepower is a very small water
+project, in a commercial way; and there are thousands of farms
+possessing streams of this capacity.
+
+
+_Fluctuations in Water Supply_
+
+It would be only during the winter months that such a plant would be
+driven to its full capacity; and since water is normally plentiful
+during these months, the problem of power would be greatly simplified.
+The heaviest draft on such a plant in summer would be during
+harvesting; otherwise it would be confined to light, small power for
+routine work, and cooking. Thus, a plant capable of meeting all the
+ordinary requirements of the four dry months of summer, when water is
+apt to be scarce, doubles or quadruples its capacity during the
+winter months, to meet the necessities of heat for the house.
+
+A dynamo requires only as much power to drive it, at any given time,
+as is being used in terms of electricity. There is some small loss
+through friction, of course, but aside from this the power required of
+the prime mover (the water wheel) is always in proportion to the
+amount of current flowing. When water is scarce, and the demands for
+current for heating are low, it is good practice to close a portion of
+the buckets of the turbine wheel with wooden blocks provided for this
+purpose. It is necessary to keep the speed of the dynamo uniform under
+all water conditions; and where there is a great fluctuation between
+high and low water periods, it is frequently necessary to have a
+separate set of pulleys for full gate and for half-gate. The head must
+remain the same, under all conditions. Changing the gate is in effect
+choking or opening the nozzle supplying the wheel, to cut down or
+increase its consumption of water.
+
+
+_The Average Plant_
+
+It will be the exceptional plant, however, among the hundreds of
+thousands to be had on our farms, which will banish not only the oil
+lamp and kitchen stove, but all coal or wood burning stoves as
+well--which will heat the house in below-zero weather, and provide
+power for the heavier operations of the farm. Also, on the other hand,
+it will be the exceptional plant whose capacity is limited to
+furnishing a half-dozen lights and no more.
+
+A happy medium between these two conditions is the plant large enough
+to supply between five and ten electrical horsepower, in all seasons.
+Such a plant will meet the needs of the average farm, outside of
+winter heating and large power operations, and will provide an excess
+on which to draw in emergencies, or to pass round to one's neighbors.
+It is such a plant that we refer to when we say that (not counting
+labor) its cost, under ordinary conditions should not greatly exceed
+the price of one sound young horse for farm work.
+
+Since the plant we described briefly in the first chapter, meets the
+requirements of this "average plant" let us inquire a little more
+fully into its installation, maintenance, and cost.
+
+
+_An Actual Plant_
+
+In this instance, the water-power was already installed, running to
+waste, in fact. The wheel consists of the so-called thirty-six inch
+vertical turbine, using 185 square inches of water, under a 14-foot
+head. Water is supplied to this wheel by a wooden penstock 33 inches
+square, inside measurements, and sloping at an angle of 30 deg. from
+the flume to the wheel.
+
+[Illustration: Details of voltmeter or ammeter]
+
+This wheel, under a 14-foot head, takes 2,312 cubic feet of water a
+minute; and it develops 46.98 actual horsepower (as may be figured by
+using the formulas of Chapter III). The water supply is provided by a
+small mountain river. The dam is 10 feet high, and the race, which
+feeds the flume from the mill pond is 75 yards long. The race has two
+spillways, one near the dam, and the second at the flume itself, to
+maintain an even head of water at all times.
+
+
+_Half-Gate_
+
+Since the water supply varies with the seasons, it has been found
+practical to run the wheel at half-gate--that is, with the gate only
+half-open. A set of bevel gears work the main shaft, which runs at
+approximately 200 revolutions per minute; and the dynamo is worked up
+to its required speed of 1,500 revolutions per minute through a
+countershaft.
+
+The dynamo is a modern four-pole machine, compound-wound, with a rated
+output of 46 amperes, at 125 volts--in other words a dynamo of 5.75
+kilowatts capacity, or 7.7 electrical horsepower. At full load this
+dynamo would require a driving power of 10 horsepower, counting it as
+75 per cent efficient; and, to conform to our rule of two water
+horsepower to one electrical horsepower, the wheel should be capable
+of developing 20 horsepower. As a matter of fact, in this particular
+instance, shutting down the wheel to half-gate more than halves the
+rated power of the wheel, and little more than 15 horsepower is
+available. This allowance has proved ample, under all conditions met
+with, in this plant.
+
+The dynamo is mounted on a firm floor foundation; and it is belted
+from the countershaft by an endless belt running diagonally. A
+horizontal belt drive is the best. Vertical drive should be avoided
+wherever possible.
+
+
+_The Switchboard_
+
+The switchboard originally consisted of a wooden frame on which were
+screwed ordinary asbestos shingles, and the instruments were mounted
+on these. Later, a sheet of electric insulating fibre was substituted,
+for look's sake. The main requisite is something substantial--and
+fireproof. The switchboard instruments consist of a voltmeter, with a
+range of from 0 to 150 volts; an ammeter, with a range, 0 to 75
+amperes; a field regulating rheostat (which came with the dynamo); a
+main switch, with cartridge fuses protecting the machine against a
+draft of current over 60 amperes; and two line switches for the two
+owners, one fuse at 20 amperes, and the other at 40 amperes. Electric
+fuses are either cartridges or plugs, enclosing lead wire of a size
+corresponding to their rating. All the current of the line they
+protect passes through this lead wire. If the current drawn exceeds
+the capacity of the lead wire, it melts from the heat, and thus opens
+the circuit, and cuts off the current.
+
+[Illustration: A switchboard and its connections: _G._ Dynamo; _A._
+Shunt field coils; _B._ Series coils; _DD._ Fuses; _FF._ Main switch;
+_F._ Field switch; _C._ Ammeter; _V._ Voltmeter; _E._ Lamp; _R._
+Rheostat. Dotted lines show connections on back of board]
+
+
+_Items of Cost_
+
+This water wheel would cost $250 new. There is a duplicate in the
+neighborhood bought at second-hand, for $125. The dynamo cost $90,
+and was picked up second-hand in New York City. New it would cost
+$150. The voltmeter cost $7, and the ammeter $10; and the switches and
+fuses could be had for $5. A wheel one-half the size, using one-half
+the amount of water at full gate, would do the work required, and the
+cost would be correspondingly less.
+
+
+_Capacity_
+
+This plant supplies two farms with electric light. One farm (that of
+the owner of the wheel) has 30 lamps, of 16 candlepower each, and two
+barn-yard lamps of 92 candlepower each. His wife has an electric iron
+and an electric water heater. Needless to say, all these lamps, and
+the iron and water heater are not in use at one time.
+
+[Illustration: Carbon Lamps Gem Type (1/4 scale)]
+
+The partner who owns the electric part of the plant has 30 lamps in
+his house and barn, many of them being 25 watt tungsten, which give
+more light for less power, but cost more to buy. They are not all in
+use at one time, though (since the current costs nothing) the
+inclination is to turn them on at night and let them burn. In his
+kitchen he has an electric range, and a water heater for the 40 gallon
+boiler. In addition to this he has all sorts of appliances,--irons,
+toasters, grills, a vacuum cleaner, a vibrator, etc. Naturally all
+these appliances are not in use at one time, else the draft on the
+plant would be such as to "blow" the fuses. For instance, all the
+baking is done in daylight; and when the oven is used after dark, they
+are careful to turn off all lights not needed. An ideal plant, of
+course, would be a plant big enough to take care of the sum of lamps
+and handy devices used at one time.
+
+To make this plant ideal, (for, being an actual affair, it has
+developed some short-comings, with the extension of the use of
+electricity) it would require a dynamo whose capacity can be figured,
+from the following:
+
+                                                        Watts
+    15 carbon lamps, 16 candlepower, @60 watts each      900
+    10 tungsten lamps, 20 candlepower, @25 watts each    250
+    2 tungsten lamps, 92 candlepower, @100 watts each    200
+    Water heater, continuous service                     800
+    Toaster, occasional service                          600
+    Iron, occasional service                             400
+    Oven-baking, roasting, etc                         2,000
+    2 stove plates @1,000 watts each                   2,000
+    1 stove plate                                        400
+    Vacuum cleaner, occasional service                   200
+    Vibrator, occasional service                         100
+    Small water heater, quart capacity                   400
+    Small motor, 1/4 horsepower, occasional              250
+    Motor, 1/2 hp, pumping water, etc                    500
+    Electric fan, occasional service                     100
+                                                     -------
+             Total current, one house                  9,100
+
+
+    30 carbon lamps, 16 candlepower, @60               1,800
+    2 lamps, 100 watt tungsten                           200
+    Electric iron                                        400
+    Small water or milk heater                           600
+                                                     -------
+             Total current, 2nd house                  3,000
+                            1st house                  9,100
+                                                     -------
+                                                      12,100
+
+Thus, in this plant, if every electrical device were turned on at
+once, the demand on the dynamo would be for 12.1 kilowatts, or an
+overload of over 100 per cent. The main-switch fuse, being for 60
+amperes, would "blow" or melt, and cut off all current for the
+moment. To repair the damage would be merely the work of a second--and
+at a cost of a few cents--simply insert a new fuse, of which there
+must be a supply on hand at all times. Or, if either owner exceeded
+his capacity, the line fuses (one for 20 amperes, and the other for 40
+amperes) would instantly cut off all current from the greedy one.
+
+[Illustration: 25 and 40 watt Mazda tungsten lamps (1/4 scale)]
+
+
+_Lessons From This Plant_
+
+The story of this plant illustrates two things which the farmer and
+his wife must take into account when they are figuring how much
+electricity they require. First, it illustrates how one uses more and
+more current, as he finds it so serviceable and labor-saving, and at
+the same time free. The electric range and the water boiler, in the
+above instance, were later acquisitions not counted on in figuring the
+original installation. Second, it illustrates, that while the normal
+load of this generator is _5.75_ kilowatts, one does not have to limit
+the electrical conveniences in the home to this amount. True, he
+cannot use more electricity than his plant will produce _at any one
+time_,--but it is only by a stretch of the imagination that one may
+conceive the necessity of using them all at once. Ironing, baking, and
+the use of small power are usually limited to daylight hours when no
+lights are burning.
+
+As a matter of fact, this plant has proved satisfactory in every way;
+and only on one or two occasions have fuses been "blown", and then it
+was due to carelessness. A modern dynamo is rated liberally. It will
+stand an overload of as much as 100 per cent for a short time--half an
+hour or so. The danger from overloading is from heating. When the
+machine grows too hot for the hand, it is beginning to char its
+insulation, to continue which, of course would ruin it. The best plant
+is that which works under one-half or three-quarters load, under
+normal demands.
+
+
+_Standard Voltage_
+
+We are assuming the farmer's plant to be, in 99 cases out of 100, the
+standard 110-volt, direct current type. Such a plant allows for at
+least a 10 per cent regulation, in voltage, up or down the scale;
+supplies for this voltage are to be had without delay in even the more
+remote parts of the country, and (being sold in greater volume) they
+are cheaper than those for other voltages.
+
+There are two general exceptions to this rule as to 110-volt plants:
+(1) If the plant is located at a distance greater than a quarter of a
+mile from the house, it will be found cheaper (in cost of transmission
+line, as will be shown later) to adopt the 220-volt plant; (2), If the
+water supply is so meagre that it must be stored for many hours at a
+time, and then used for charging storage batteries, it will be found
+most economical to use a 30-volt plant. A storage battery is made up
+of cells of approximately 2 volts each; and, since more than 55 such
+cells would be required for a 110-volt installation, its cost would
+be prohibitive, with many farmers.
+
+So we will assume that this plant is a 110-volt plant, to be run
+without storage battery. It will be well to make a chart, dividing the
+farm requirements into three heads--light, heat, and power.
+
+
+_Light_
+
+[Illustration: 60 and 100 watt Mazda tungsten lamp. These lamps may be
+had in sizes from 10 to 500 watts (1/4 scale)]
+
+[Illustration: The lamp of the future. A 1000 watt Mazda nitrogen
+lamp, giving 2000 candlepower (1/4 scale)]
+
+Light is obtained by means of incandescent lamps. There are two styles
+in common use, the carbon and the tungsten lamp. It requires 3.5 to 4
+watts of electricity to produce one candlepower in a carbon lamp. It
+requires from 1 to 1.25 watt to produce one candlepower in the
+tungsten lamp. The new nitrogen lamp, not yet in general use, requires
+only 1/2 watt to the candlepower. Since tungsten lamps give three
+times the light of the carbon lamp, they are the most economical to
+use in the city or town where one is paying for commercial current.
+But, in the country where water-power furnishes current for nothing,
+it will be found most economical to use the carbon lamp, since its
+cost at retail is 16 cents, as compared with 30 cents for a
+corresponding size in tungsten. A 60 watt carbon lamp, of 16
+candlepower; or a 25 watt tungsten lamp, of 20 candlepower, are the
+sizes to use. In hanging lamps, as over the dining room table, a 100
+watt tungsten lamp, costing 70 cents, and giving 92 candlepower light
+is very desirable; and for lighting the barn-yard, these 100 watt
+tungsten lamps should be used. For reading lamps, the tungsten style,
+of 40 or 60 watt capacity, will be found best. Otherwise, in all
+locations use the cheaper carbon lamp. Both styles have a rated life
+of 1,000 hours, after which they begin to fall off in efficiency. Here
+again, the farmer need not worry over lack of highest efficiency, as a
+lamp giving only 80 per cent of its rated candlepower is still
+serviceable when he is not paying for the current. With care not to
+use them at voltages beyond their ratings, lamps will last for years.
+
+
+_A Specimen Light Allowance_
+
+Below is a typical table of lights for a large farm house, the barns
+and barn-yard. It is given merely as a guide, to be varied for each
+individual case:
+
+                                                        Watts
+    Kitchen, 2 lights @60 watts                          120
+    Dining room, 1 light, tungsten                       100
+    Living room, table lamp with 3 tungstens @40         120
+    Living room, 2 wall fixtures, 4 lamps @60 watts      240
+    Parlor, same as living room                          360
+    Pantry, 1 hanging lamp                                60
+    Cellar, one portable lamp                             60
+    Woodshed, 1 hanging lamp                              60
+    2 bedrooms, 2 lights each @ 60                       240
+    2 bed rooms, 1 light each @60                        120
+    Bathroom, 1 "turn-down" light, @60                    60
+    Hall, downstairs, 2 lights @60                       120
+    Hall, upstairs, 1 light                               60
+    Attic, 1 light                                        60
+    Porch, 1 light                                        60
+    Barn and barn-yard:
+    Barn-yard entrance, 1 tungsten                       100
+    Watering trough,    1    "                           100
+    Front gate,         1    "                           100
+    Horse barn, 4 lights @60                             240
+    Cow barn, 4 lights @60                               240
+    Pig house, 1 light                                    60
+    Hay barn, 2 lights, @60                              120
+                                                     -------
+    Total for farmstead                                2,800
+
+This provides for 44 lights, an extremely liberal allowance. How many
+of these lights will be burning at any one time? Probably not one-half
+of them; yet the ideal plant is that which permits all fixtures to be
+in service at one time on the rare occasions when necessary. Thus, for
+lighting only, 2,800 watts maximum service would require a 4 kilowatt
+generator, and 10 water horsepower, on the liberal rating of two to
+one. A 3 kilowatt generator would take care of these lights, with a 30
+per cent overload (which is not excessive) for maximum service. The
+above liberal allowance of lights may be cut in two, or four--or even
+eight--and still throw a kerosene lamp in shadow. It all depends on
+the number of lights one wants burning at one time; and the power of
+the water wheel.
+
+If the 36 carbon lights in the above table were replaced by 25 watt
+tungsten lights, the saving in power would be 35 watts each, or 1,260
+watts, nearly two electrical horsepower; while the added first cost
+would be 14 cents a light, or $5.04. A generator of 2 kilowatt
+capacity would take care of all these lights then, with 460 watts to
+spare.
+
+
+_Heating_
+
+Electric heating and cooking is in its infancy, due to the prohibitive
+cost of commercial current in our cities. Here the farmer has the
+advantage again, with his cheap current.
+
+For heating the house, it is calculated that 2 watts is required for
+each cubic foot of air space in a room, during ordinary winter
+weather. Thus, a room 10 x 12, and 8 feet high, would contain 960
+cubic feet, and would require 1,820 watts energy to heat it in cold
+weather. Five such rooms would require 9.1 kilowatts; and 10 such
+rooms, or their equivalent, would require 18.2 kilowatts.
+
+Electric heating devices are divided into two classes: (1) those which
+can be used on lamp circuits, _and do not draw more than 660 watts
+each_; and (2) those which draw more than 660, therefore _require
+special wiring_. The capacity of these devices is approximately as
+follows:
+
+    Lamp circuit devices:              Watts
+        Electric iron                400 to 660
+        Toaster                      350 to 660
+        Vacuum cleaner               200 to 400
+        Grill                        400 to 660
+        Small water heater           400 to 660
+        Hot plates                   400 to 660
+
+    Lamp circuit devices:
+        Coffee percolator            400 to 660
+        Chafing dish                 400 to 660
+        Electric fan                 100 to 250
+
+    Special circuit devices:
+        Hot water boiler heater      800 to 1,200
+        Small ovens                  660 to 1,200
+        Range ovens                1,200 to 3,000
+        Range, hot plates            400 to 1,300
+        Radiators (small)            750 to 1,500
+        Radiators (large)          1,500 to 6,000
+
+The only device in the above list which is connected continuously, is
+the hot water boiler, and this can be credited with at least one
+electrical horsepower 24 hours a day. It is a small contrivance, not
+much bigger than a quart can, attached to the back of the kitchen
+boiler, and it keeps the water hot throughout the house at all hours.
+Its cost will vary with the make, ranging from $8 to $15; and since it
+is one of the real blessings of the farm kitchen and bathroom, it
+should be included in all installations where power permits. Electric
+radiators will be used 24 hours a day in winter, and not at all in
+summer. They are portable, and can be moved from room to room, and
+only such rooms as are in actual use need be heated. The other devices
+are for intermittent service, many of them (like the iron) for only a
+few hours each week.
+
+The grill, chafing dish, coffee percolator, etc., which are used on
+the dining room table while the family is at meals, each draw an
+equivalent of from 6 to 10 carbon lights. By keeping this in view and
+turning off spare lights, one can have the use of them, with even a
+small plant. Thus, a one kilowatt plant permits the use of any one of
+these lamp circuit devices at a time, with a few lights in addition.
+
+
+_Power_
+
+Electric power is to be had through motors. A direct current dynamo
+and a direct current motor are identical in construction. That is, a
+motor becomes a generator if belted to power; and a generator becomes
+a motor, if connected to electric mains. This is best illustrated by
+citing the instance of a trans-continental railroad which crosses the
+Bitter Root Mountains by means of electric power. Running 200 miles up
+a 2 per cent grade, it is drawn by its motors. Coasting 200 miles
+down the 2 per cent grade on the other side of the mountains, its
+motors become generators. They act as brakes, and at the same time
+they pump the power of the coasting weight of this train back into the
+wires to help a train coming up the other side of the mountains.
+
+[Illustration: Connections of shunt motor and starting rheostat]
+
+Just as there are three types of direct current generators, so there
+are three types of direct current motors: _series_, _shunt_, and
+_compound_, with features already explained in the case of generators.
+Motors are rated by horsepower, and generators are rated by kilowatts.
+Thus a one kilowatt generator has a capacity of 1,000 watts; as a
+motor, it would be rated as 1000/746 horsepower, or 1.34 horsepower.
+Their efficiency varies with their size, ranging from 40 to 60 per
+cent in very small motors, and up to 95 per cent in very large ones.
+The following table may be taken as a guide in calculating the power
+required by motors, on 110-volt circuits:
+
+     1/4 Horsepower     2-1/2 amperes, or 275 watts
+     1/2 hp             4-1/2 amperes, or 500 watts
+      1  hp             9     amperes, or 990 watts
+      2  hp            17     amperes, or 1.97 kilowatts
+      3  hp            26     amperes, or 2.86 kilowatts
+      5  hp            40     amperes, or 4.40 kilowatts
+    7-1/2 hp           60     amperes, or 6.60 kilowatts
+     10  hp            76     amperes, or 8.36 kilowatts
+     15  hp           112     amperes, or 12.32 kilowatts
+
+An electric motor, in operation, actually generates electricity, which
+it pushes back into the line as a counter-electromotive-force. The
+strength of this counter force, in volts, depends on the motor's
+speed, the same as if it were running as a dynamo. For this reason,
+when a motor is started, and before it comes up to speed, there would
+be a rush of current from the line, with nothing to hold it back, and
+the motor would be burned out unless some means were provided to
+protect it for the moment. This is done by means of a starting
+rheostat, similar to the regulating rheostat on the dynamo
+switchboard. This resistance box is connected in "series" with the
+armature, in the case of shunt and compound motors; and with the
+entire motor circuit in the case of a series machine.
+
+A _series_ motor has a powerful starting torque, and adjusts its speed
+to the load. It is used almost altogether in street cars. It can be
+used in stump pulling, or derrick work, such as using a hay fork. It
+must always be operated under load, otherwise, it would increase in
+speed until it tore itself to pieces through mechanical strain. The
+ingenious farmer who puts together an electric plow, with the mains
+following behind on a reel, will use a series motor.
+
+A _shunt_ motor should be used in all situations where a fairly
+uniform speed under load is required, such as separating, in milking
+machines, running a lathe, an ensilage cutter, vacuum cleaners,
+grinders, etc.
+
+The _compound_ motor has the characteristics of the series and shunt
+motors, giving an increased starting torque, and a more nearly
+constant speed under varying loads than the shunt motor, since the
+latter drops off slightly in speed with increasing load.
+
+
+_Flexible Power_
+
+An electric motor is an extremely satisfactory form of power because
+it is so flexible. Thus, one may use a five horsepower motor for a one
+horsepower task, and the motor will use only one electrical horsepower
+in current--just enough to overcome the task imposed on it. For this
+reason, a large-sized motor may be used for any operation, from one
+requiring small power, up to its full capacity. It will take an
+overload, the same as a dynamo. In other words it is "eager" for any
+task imposed on it; therefore it must be protected by fuses, or it
+will consume itself, if too big an overload is imposed on it.
+
+A one horsepower shunt or compound motor is very serviceable for
+routine farm operations, such as operating the separator, the churn,
+the milking machine, grinder, pump, and other small power jobs. Motors
+of 1/4 horsepower are handy in the kitchen, for grinding knives,
+polishing silver, etc., and can be used also for vacuum cleaners, and
+running the sewing machine. For the larger operations, motors will
+vary from three horsepower for cutting ensilage, to fifteen horsepower
+for threshing. They can be mounted on trucks and conveyed from one
+point to another, being fed current from the mains by means of
+suitable wires wound on reels.
+
+Remember, in estimating the size of your plant for light, heat, and
+power, that it does not have to be big enough to use all the devices
+at one time. Also remember, that two water horsepower to one
+electrical horsepower is a very liberal allowance; and that a
+generator working under one-half or two-thirds capacity at normal
+loads will require less attention than a machine constantly being
+worked above its capacity. Therefore, let your generator be of liberal
+size, because the difference in cost between a 5 and 10 kilowatt
+machine is not in proportion to their capacity. In fact (especially
+among second-hand machines), the difference in cost is very small. The
+mere fact that the generator is of 110 electrical horsepower capacity
+does not require a turbine of 20 horsepower. The chances are that
+(unless you wish to heat your house and do large power jobs) you will
+not use more than 3 to 5 electrical horsepower normally; therefore an
+allowance of 10 water horsepower, in this case, would be ample. A
+plant used simply for lighting the house and barn, for irons, and
+toasters, and one horsepower motors, need not exceed 2 or 2-1/2
+kilowatts for the generator, and 5 or 6 horsepower for the turbine
+wheel. Normally it would not use one-half this capacity.
+
+
+
+
+CHAPTER VII
+
+TRANSMISSION LINES
+
+     Copper wire--Setting of poles--Loss of power in transmission--Ohm's
+     Law and examples of how it is used in figuring size of
+     wire--Copper-wire tables--Examples of transmission lines--When to
+     use high voltages--Over-compounding a dynamo to overcome
+     transmission loss.
+
+
+Having determined on the location of the farm water-power electric
+plant, and its capacity, in terms of electricity, there remains the
+wiring, for the transmission line, and the house and barn.
+
+For transmission lines, copper wire covered with waterproof braid--the
+so-called weatherproof wire of the trade--is used. Under no
+circumstances should a wire smaller than No. 8, B. & S. gauge be used
+for this purpose, as it would not be strong enough mechanically. The
+poles should be of chestnut or cedar, 25 feet long, and set four feet
+in the ground. Where it is necessary to follow highways, they should
+be set on the fence line; and in crossing public highways, the
+ordinance of your own town must guide you. Some towns prescribe a
+height of 19 feet above the road, others 27 feet, some 30. Direct
+current, such as is advised for farm installations, under ordinary
+circumstances, does not affect telephone wires, and therefore
+transmission lines may be strung on telephone poles. Poles are set at
+an average distance of 8 rods; they are set inclined outward on
+corners. Sometimes it is necessary to brace them with guy wires or
+wooden braces. Glass insulators are used to fasten the wires to the
+cross-arms of the poles, and the tie-wires used for this purpose must
+be the same size as the main wire and carry the same insulation.
+
+
+_Size of Wire for Transmission_
+
+To determine the size of the transmission wires will require knowledge
+of the strength of current (in amperes) to be carried, and the
+distance in feet. In transmission, the electric current is again
+analogous to water flowing in pipes. It is subject to resistance,
+which cuts down the amount of current (in watts) delivered.
+
+[Illustration: Bringing wires into the house or barn]
+
+The loss in transmission is primarily measured in volts; and since the
+capacity of an electric current for work equals the _volts_ multiplied
+by _amperes_, which gives _watts_, every volt lost reduces the working
+capacity of the current by so much. This loss is referred to by
+electrical engineers as the "C^2R loss," which is another way of
+saying that the loss is equal to the _square of the current in
+amperes_, multiplied by _ohms_ resistance. Thus, if the amperes
+carried is 10, and the ohms resistance of the line is 5, then the loss
+in watts to convey that current would be (10 x 10) x 5, or 500 watts,
+nearly a horsepower.
+
+The pressure of _one volt_ (as we have seen in another chapter) is
+sufficient to force _one ampere_, through a resistance of _one ohm_.
+Such a current would have no capacity for work, since its pressure
+would be consumed in the mere act of transmission.
+
+If, however, the pressure were _110 volts_, and the current _one
+ampere_, and the resistance _one ohm_, the effective pressure after
+transmission would be 110-1, or 109 volts.
+
+To force a 110-volt current of _50 amperes_ through the resistance of
+_one ohm_, would require the expenditure of _50 volts_ pressure. Its
+capacity for work, after transmission, would be 110-50, or _60 volts,
+x 50 amperes_, or 3,000 watts. As this current consisted of _110 x
+50_, or 5,500 watts at the point of starting, the loss would be 2,500
+watts, or about 45 per cent. It is bad engineering to allow more than
+10 per cent loss in transmission.
+
+There are two ways of keeping this loss down. One is by increasing
+the size of the transmission wires, thus cutting down the resistance
+in ohms; the other way is by raising the voltage, thus cutting down
+the per cent loss. For instance, suppose the pressure was 1,100 volts,
+instead of 110 volts. Five amperes at 1,100 volts pressure, gives the
+same number of watts, power, as 50 amperes, at 110 volts pressure.
+Therefore it would be necessary to carry only 5 amperes, at this rate.
+The loss would be 5 volts, or less than 1/2 of 1 per cent, as compared
+with 45 per cent with 110 volts.
+
+[Illustration: Splicing transmission wire]
+
+In large generating stations, where individual dynamos frequently
+generate as much as 20,000 horsepower, and the current must be
+transmitted over several hundred miles of territory, the voltage is
+frequently as high as 150,000, with the amperes reduced in proportion.
+Then the voltage is lowered to a suitable rate, and the amperage
+raised in proportion, by special machinery, at the point of use.
+
+It is the principle of the C^2R loss, which the farmer must apply in
+determining the size of wire he is to use in transmitting his current
+from the generator switchboard to his house or barn. The wire table on
+page 159, together with the formula to be used in connection with it,
+reduce the calculations necessary to simple arithmetic. In this table
+the resistance of the various sizes of wire is computed from the fact
+that a wire of pure copper 1 foot long, and 1/1000 inch in diameter
+(equal to one circular mill) offers a resistance of 10.6 ohms to the
+foot. The principle of the C^2R loss is founded on Ohm's Law, which is
+explained in Chapter V.
+
+The formula by which the size of transmission wire is determined, for
+any given distance, and a given number of amperes, is as follows:
+
+  Distance ft. one way x 22 x No. of amperes   circular
+  ------------------------------------------ =  mills.
+             Number of volts lost
+
+In other words, multiply the _distance in feet_ from mill to house by
+22, and multiply this product by the _number of amperes_ to be
+carried. Then divide the product by the _number of volts_ to be lost;
+and the result will be the diameter of the wire required _in circular
+mills_. By referring to the table above, the B. & S. gauge of the wire
+necessary for transmission, can be found from the nearest
+corresponding number under the second column, entitled "circular mills
+area."
+
+
+     COPPER WIRE TABLE
+
+  --------+----------+-----------+-----------+-----------+------------
+          |          | _Area in  | _(R) Ohms |           |
+  _B.& S. | _Feet    | circular  | per 1,000 | _Feet     | _(R) Ohms
+  Gauge_  | per Lb._ | mills_    | feet_     | per Ohm_  | per pound_
+  --------+----------+-----------+-----------+-----------+------------
+   0000   |   1.561  | 211,600   |   .04904  | 20,392.90 |  .00007653
+   000    |   1.969  | 167,805   |   .06184  | 16,172.10 |  .00012169
+   00     |   2.482  | 133,079   |   .07797  | 12,825.40 |  .00019438
+   0      |   3.130  | 105,534   |   .09829  | 10,176.40 |  .00030734
+     1    |   3.947  |  83,694   |   .12398  |  8,066.00 |  .00048920
+     2    |   4.977  |  66,373   |   .15633  |  6,396.70 |  .00077784
+     3    |   6.276  |  52,634   |   .19714  |  5,072.50 |  .00123700
+     4    |   7.914  |  41,742   |   .24858  |  4,022.90 |  .00196660
+     5    |   9.980  |  33,102   |   .31346  |  3,190.20 |  .00312730
+     6    |  12.58   |  26,250   |   .39528  |  2,529.90 |  .00497280
+     7    |  15.87   |  20,816   |   .49845  |  2,006.20 |  .00790780
+     8    |  20.01   |  16,509   |   .62840  |  1,591.10 |  .01257190
+     9    |  25.23   |  13,094   |   .79242  |  1,262.00 |  .01998530
+    10    |  31.82   |  10,381   |   .99948  |  1,000.50 |  .03178460
+    11    |  40.12   |   8,234.0 |  1.26020  |    793.56 |  .05054130
+    12    |  50.59   |   6,529.9 |  1.58900  |    629.32 |  .08036410
+    13    |  63.79   |   5,178.4 |  2.00370  |    499.06 |  .12778800
+    14    |  80.44   |   4,106.8 |  2.52660  |    395.79 |  .20318000
+    15    | 101.4    |   3,256.7 |  3.18600  |    313.87 |  .32307900
+    16    | 127.9    |   2,582.9 |  4.01760  |    248.90 |  .51373700
+    17    | 161.3    |   2,048.2 |  5.06600  |    197.39 |  .81683900
+    18    | 203.4    |   1,624.3 |  6.38800  |    156.54 | 1.29876400
+  --------+----------+-----------+-----------+-----------+------------
+
+
+     CARRYING CAPACITY OF WIRES AND WEIGHT
+
+  -----------+-------------------+--------------------+--------------------
+             | _Weight 1,000 ft. | _Carrying capacity | _Carrying capacity
+  _B. & S.   |  Weatherproof     | Weatherproof       | rubber cov.
+  Gauge No._ |  (Pounds)_        | (Amperes)_         | (Amperes)_
+  -----------+-------------------+--------------------+--------------------
+    0000     |        800        |        312         |        175
+     000     |        666        |        262         |        145
+      00     |        500        |        220         |        120
+       0     |        363        |        185         |        100
+       1     |        313        |        156         |         95
+       2     |        250        |        131         |         70
+       3     |        200        |        110         |         60
+       4     |        144        |         92         |         50
+       5     |        125        |         77         |         45
+       6     |        105        |         65         |         35
+       7     |         87        |         55         |         30
+       8     |         69        |         46         |         25
+      10     |         50        |         32         |         20
+      12     |         31        |         23         |         15
+      14     |         22        |         16         |         10
+      16     |         14        |          8         |          5
+      18     |         11        |          5         |          3
+  -----------+-------------------+--------------------+--------------------
+
+Since two wires are required for electrical transmission, the above
+formula is made simple by counting the distance only one way, in feet,
+and doubling the resistance constant, 10.6, which, for convenience is
+taken as 22, instead of 21.2.
+
+
+_Examples of Transmission Lines_
+
+As an example, let us say that Farmer Jones has installed a
+water-power electric plant on his brook, _200 yards distant_ from his
+house. The generator is a 5 kilowatt machine, capable of producing _45
+amperes_ at _110 volts pressure_. He has a 3 horsepower motor, drawing
+26 amperes at full load; he has 20 lights of varying capacities,
+requiring 1,200 watts, or 10 amperes when all on; and his wife uses
+irons, toasters, etc., which amount to another 9 or 10 amperes--say 45
+altogether. The chances are that he will never use all of the
+apparatus at one time; but for flexibility, and his own satisfaction
+in not having to stop to think if he is overloading his wires, he
+would like to be able to draw the full _45 amperes_ if he wishes to.
+He is willing to allow _5 per cent loss_ in transmission. _What size
+wires will be necessary, and what will they cost?_ Substituting these
+values in the above formula, the result is:
+
+  Answer: 600 x 22 x 45
+          ------------- = 108,000 circular mills.
+               5.5
+
+[Illustration: Transmission wire on glass insulator]
+
+Referring to the table, No. 0 wire is 105,534 circular mills, and is
+near enough; so this wire would be used. It would require 1,200 feet,
+which would weigh, by the second table, 435.6 pounds. At 19 cents a
+pound, it would cost $82.76.
+
+Farmer Jones says this is more money than he cares to spend for
+transmission. As a matter of fact, he says, he never uses his motor
+except in the daytime, when his lights are not burning; so the maximum
+load on his line at any one time would be _26 amperes_, not 45. _What
+size wire would he use in this instance?_
+
+Substituting 26 for 45 in the equation, the result is 61,300 circular
+mills, which corresponds to No. 2 wire. It would cost $57.00.
+
+Now, if Farmer Jones, in an emergency, wished to use his motor at the
+same time he was using all his lights and his wife was ironing and
+making toast--in other words, if he wanted to use the _45 amperes_
+capacity of his dynamo, _how many volts would he lose?_ To get this
+answer, we change the formula about, until it reads as follows:
+
+   Distance in feet x 22 x amperes
+  --------------------------------- = Number of volts lost
+           circular mills
+
+Substituting values, we have, in this case, 600 x 22 x 45/66,373 (No.
+2) = 9 volts, nearly, less than 10 per cent. This is a very efficient
+line, under the circumstances. Now if he is willing to lose 10 per
+cent on _half-load_, instead of full load, he can save still more
+money in line wire. In that case (as you can find by applying the
+formula again), he could use No. 5 wire, at a cost of $28.50. He would
+lose 11 volts pressure drawing 26 amperes; and he would lose 18 volts
+pressure drawing 45 amperes, if by any chance he wished to use full
+load.
+
+In actual practice, this dynamo would be regulated, by means of the
+field resistance, to register 110 plus 11 volts, or 121 volts at the
+switchboard to make up for the loss at half-load. At full load, his
+voltage at the end of the line would be 121 minus 18, or 103 volts;
+his motor would run a shade slower, at this voltage, and his lights
+would be slightly dimmer. He would probably not notice the difference.
+If he did, he could walk over to his generating station, and raise
+the voltage a further 7 volts by turning the rheostat handle another
+notch.
+
+[Illustration: A barn-yard light]
+
+Thousands of plants can be located within 100 feet of the house. If
+Farmer Jones could do this, he could use No. 8 wire, costing $2.62.
+The drop in pressure would be 5.99 volts at full load--so small it
+could be ignored entirely. In this case the voltmeter should be made
+to read 116 volts at the switchboard, by means of the rheostat.
+
+If, on the other hand, this plant were 1,000 feet away from the house
+and the loss 10 volts the size wire would be
+
+  1,000 x 22 x 45
+  ---------------  = 99,000 circular mills;
+        10
+
+a No. 0 wire comes nearest to this figure, and its cost, for 2,000
+feet, at 19 cents a pound, would be $137.94. A No. 0000 wire, costing
+$294.00, would give a 5 per cent drop at full load. In this case, the
+cost of transmission can be reduced to a much lower figure, by
+allowing a bigger drop at half-load, with regulation at the
+switchboard. Thus, a No. 2 wire here, costing but $95, would be
+satisfactory in every way. The loss at half-load would be about 9
+volts, and the rheostat would be set permanently for 119 or 120 volts.
+A modern dynamo can be regulated in voltage by over 25 per cent in
+either direction, without harm, if care is taken not to overload it.
+
+
+_Benefit of Higher Voltages_
+
+If Farmer Jones' plant is a half of a mile away from the house, he
+faces a more serious proposition in the way of transmission. Say he
+wishes to transmit 26 amperes with a loss of 10 volts. What size wire
+will be necessary?
+
+        2640 x 22 x 26
+  Thus: -------------- = 151,000 circular mills.
+              10
+
+A No. 000 wire is nearest this size, and 5,280 feet of it would cost
+over $650.00. This cost would be prohibitive. If, however, he
+installed a 220-volt dynamo--at no increase in cost--then he would
+have to transmit only a half of 26 amperes, or 13 amperes, and he
+could allow 22 volts loss, counting 10 per cent. In this case, the
+problem would work out as follows:
+
+  2640 x 22 x 13
+  -------------- = 34,320 circular mills,
+        22
+
+or approximately a No. 5 wire which, at 19 cents a pound, would cost
+$120.65.
+
+Install a 550-volt generator, instead of a 220-volt machine and the
+amperes necessary would be cut to 5.2, and the volts lost would be
+raised to 55. In this case a No. 12 wire would carry the current; but
+since it would not be strong enough for stringing on poles, a No. 8
+wire would be used, costing about $63.
+
+It will be readily seen from these examples how voltage influences the
+efficiency of transmission. Current generated at a pressure in excess
+of 550 volts is not to be recommended for farm plants unless an expert
+is in charge. A safer rule is not to exceed 220 volts, for while 550
+volts is not necessarily deadly, it is dangerous. When one goes into
+higher voltages, it is necessary to change the type of dynamo to
+_alternating current_, so that the current can be transformed to safe
+voltages at the point where it is used. Since only the occasional farm
+plant requires a high-tension system, the details of such a plant will
+not be gone into here.
+
+In transmitting the electric current over miles of territory,
+engineers are accustomed to figure 1,000 volts for each mile. Since
+this is a deadly pressure, it should not be handled by any one not an
+expert, which, in this case, the farmer is not.
+
+
+_Over-Compounding the Generator_
+
+One can absorb the loss in transmission frequently, by
+over-compounding the machine. In describing the compound machine, in
+Chapter Five, it is shown that the usual compound dynamo on the market
+is the so-called flat-compounded type. In such a dynamo, the voltage
+remains constant at the switchboard, from no load to full load,
+allowing for a slight curve which need not be taken into account.
+
+Now, by adding a few more turns to the series wires on the field coils
+of such a dynamo, a machine is to be had which gradually raises its
+voltage as the load comes on in increasing volume. Thus, one could
+secure such a machine, which would begin generating at 110 volts, and
+would gradually rise to 150 at full load. Yet the voltage would remain
+constant at the point of use, the excess being absorbed in
+transmission. A machine of this type can be made to respond to any
+required rise in voltage.
+
+As an example of how to take advantage of this very valuable fact, let
+us take an instance:
+
+Say that Farmer Jones has a transmission line 1,000 feet long strung
+with No. 7 copper wire. This 2,000 feet of wire would introduce a
+resistance of one ohm in the circuit. That is, every ampere of current
+drawn at his house would cause the working voltage there to fall one
+volt. If he drew 26 amperes, the voltage would fall, at the house, 26
+volts. If his switchboard voltage was set at say 120, the voltage at
+his house, at 26 amperes of load, would fall to 94 volts, which would
+cause his lights to dim considerably. It would be a very
+unsatisfactory transmission line, with a flat-compounded dynamo.
+
+On the other hand, if his dynamo was over-compounded 25 per cent--that
+is, if it gained 28 volts from no load to full load, the system would
+be perfect. In this case, the dynamo would be operated at 110 volts
+pressure at the switchboard with no load. At full load the voltmeter
+would indicate 110 plus 26, or 136 volts. The one or two lights burned
+at the power plant would be subject to a severe strain; but the 50 or
+100 lights burned at the house and barn would burn at constant
+voltage, which is very economical for lamps.
+
+The task of over-compounding a dynamo can be done by any trained
+electrician. The farmer himself, if he progresses far enough in his
+study of electricity, can do it. It is necessary to remove the top or
+"series" winding from the field coils. Count the number of turns of
+this wire to each spool. Then procure some identical wire in town and
+begin experimenting. Say you found four turns of field wire to each
+spool. Now wind on five, or six, being careful to wind it in the same
+direction as the coils you removed and connect it in the same way. If
+this additional number of turns does not raise the voltage enough, in
+actual practice, when the dynamo is running from no load to full load,
+add another turn or two. With patience, the task can be done by any
+careful mechanic. The danger is in not winding the coils the same way
+as before, and getting the connections wrong. To prevent this mistake,
+make a chart of the "series" coils as you take them off.
+
+To make the task of over-compounding your own dynamo even more simple,
+write to the manufacturers, giving style and factory number of your
+machine. Tell them how much voltage rise you wish to secure, and ask
+them how many turns of "series" wire should be wound on each spool in
+place of the old "series" coil. They could tell you exactly, since
+they have mathematical diagrams of each machine they make.
+
+Avoid overloading an over-compounded machine. Since its voltage is
+raised automatically, its output in watts is increased a similar
+amount at the switchboard, and, for a given resistance, its output in
+amperes would be increased the same amount, as can be ascertained by
+applying Ohm's Law. Your ammeter is the best guide. Your machine is
+built to stand a certain number of amperes, and this should not be
+exceeded in general practice.
+
+
+
+
+CHAPTER VIII
+
+WIRING THE HOUSE
+
+     The insurance code--Different kinds of wiring described--Wooden
+     moulding cheap and effective--The distributing panel--Branch
+     circuits--Protecting the circuits--The use of porcelain tubes and
+     other insulating devices--Putting up chandeliers and wall
+     brackets--"Multiple" connections--How to connect a wall
+     switch--Special wiring required for heat and power circuits--Knob
+     and cleat wiring, its advantages and drawbacks.
+
+
+The task of wiring your house is a simple one, with well-defined rules
+prescribed by your insurance company. Electricity, properly installed,
+is much safer than oil lamps--so much so indeed that insurance
+companies are ready to quote especial rates. But they require that the
+wiring be done in accordance with rules laid down by their experts,
+who form a powerful organization known as the National Board of Fire
+Underwriters. Ask your insurance agent for a copy of the code rules.
+
+Danger of fire from an electric current comes from the "short
+circuit," partial or complete; and it is against this danger that the
+rules guard one. The amount of electricity flowing through a short
+circuit is limited only by the fuse protecting that line; and since
+there is no substance known that can withstand the heat of the
+electric arc, short circuits must be guarded against. Happily the
+current is so easily controlled that the fire hazard is eliminated
+entirely--something which cannot be done with oil lamps.
+
+In house-wiring for farm plants, the wire should be rubber-covered,
+and not smaller than No. 14 B. & S. gauge. This is the wire to use on
+all lamp circuits. It costs about $0.85 cents per 100 feet. There are
+four kinds of wiring permitted, under the insurance code:
+
+(1) _Flexible armoured cable_: This consists of two-wire cable,
+protected with a covering of flexible steel. It is installed out of
+sight between the walls, and provides suitable outlets for lamps,
+etc., by means of metal boxes set flush with the plaster. It is
+easily installed in a house being built, but requires much tearing
+down of plaster for an old house. Since its expense prohibits it in
+the average farm house, this system will not be described in detail
+here.
+
+(2) _Rigid and flexible conduit_: As the name implies this system
+consists of iron pipe, in connection with flexible conduit, run
+between the walls. It differs from the above system, in that the pipes
+with their fittings and outlet boxes are installed first, and the
+wires are then "fished" through them. Duplex wires--the two wires of
+the circuit woven in one braid--are used; and a liberal amount of
+soapstone, and occasionally kerosene, are used to make the wires slip
+easily into place. This is the most expensive system, and the best;
+but it is difficult to install it in an old house without tearing down
+a good deal of plaster. It has the advantage of being absolutely
+waterproof and fireproof.
+
+(3) _Wooden moulding_: This is simply moulding, providing two
+raceways for the insulated wires to run in, and covered with a
+capping. It is nailed or screwed firmly to the wall, on top of the
+plaster; and when the wires have been installed in their respective
+slots and the capping tacked on, the moulding is given a coat of paint
+to make it in harmony with the other moulding in the room. This system
+is cheap, safe, and easily installed, and will be described in detail
+here.
+
+[Illustration: Detail of wooden moulding]
+
+(4) _Open wiring_: In open wiring, the wires are stretched from one
+support to another (such as beams) and held by means of porcelain
+cleats, or knobs. It is the simplest to install; but it has the
+objection of leaving the wires unprotected, and is ugly. It is very
+satisfactory in barns or out-buildings however.
+
+
+_The Distributing Panel_
+
+The first point to consider in wiring a house with wooden moulding is
+the distribution board. It should be located centrally, on the wall
+near the ceiling, so as to be out of ordinary reach. It consists of a
+panel of wood--though fireproof material is better--firmly screwed to
+the wall, and containing in a row, the porcelain cut-outs, as shown in
+the cut, from which the various branch circuits are to be led. Each
+cut-out provides for two branch circuits; and each branch contains
+receptacles for two plug fuses. These fuses should be of 6 amperes
+each. The Insurance Code limits the amount of electricity that may be
+drawn on any branch lamp circuit to 660 watts; and these fuses protect
+the circuit from drafts beyond this amount.
+
+[Illustration: Porcelain cut-out and plug fuse]
+
+The mains, leading from the entrance switch, as shown in the diagram,
+to the panel board, should be of the same size as the transmission
+wire itself, and rubber-covered. These mains terminate at the
+distributing board. They are connected to the terminals of the
+cut-outs by means of heavy brass screws.
+
+
+_Wire Joints_
+
+[Illustration: Examples of cleat and knob wiring, 1, 2, 3; wire
+joints, 4; flexible armoured conductor, 5]
+
+The branch circuits are, as has been said, of No. 14 rubber-covered
+wire, running concealed in wooden moulding. All joints or splices in
+this wire are made, as shown in the illustration, by first scraping
+the wires bright, and fastening them stoutly together. This joint is
+then soldered, to make the connection electrically perfect. Soft
+solder is used, with ordinary soldering salts. There are several
+compounds on the market, consisting of soft solder in powder form,
+ready-mixed with flux. Coat the wire joint with this paste and apply
+the flame of an alcohol lamp. The soldered joint is then covered with
+rubber tape, and over this ordinary friction tape is wound on. A neat
+joint should not be larger than the diameter of the wire before
+insulation is removed.
+
+
+_Branch Circuits_
+
+First, make a diagram of your rooms and indicate where you wish lamps,
+or outlets for other purposes. Since wooden moulding can be run across
+ceilings, and up or down walls, lamps may be located in places where
+they are out of the way. In planning the circuit, remember that you
+will want many outlets in handy places on the walls, from which
+portable cords will convey current to table lamps, to electric irons
+and toasters and other handy devices which can be used on the lamp
+circuit. These outlets are made of porcelain, in two pieces. One
+piece is merely a continuation of the moulding itself; and the other
+is a cap to connect permanently to the end of the lamp or iron cord,
+which may be snapped into place in a second. Since there are a great
+many designs of separable current taps on the market, it is well to
+select one design and stick to it throughout the house, so that any
+device can be connected to any outlet.
+
+The code permits 660 watts on each circuit. This would allow 12 lamps
+of 55 watts each. It is well to limit any one circuit to 6 lamps; this
+will give leeway for the use of small stoves, irons, toasters, etc.
+without overloading the circuit and causing a fuse to blow.
+
+Having installed your distributing board, with its cut-outs, figure
+out the course of your first branch circuit. Let us say it will
+provide lights and outlets for the dining room and living room. It
+will be necessary to run the wires through the partitions or floors in
+several places. For this purpose porcelain tubes should be used,
+costing one to three cents each. Knock holes in the plaster at the
+determined point, insert the tubes so they project 3/4 inch on each
+side, and fill up the ragged edge of the hole neatly with plaster.
+
+[Illustration: The distributing panel]
+
+When all the tubes have been set in place, begin laying the moulding.
+Run it in a straight line, on the wall against the ceiling wherever
+possible, mitering the joints neatly. Whenever it is necessary to
+change the run from the ceiling to the wall and a miter cannot be
+made, the wires should be protected in passing from one slot to the
+other by being enclosed in non-metallic flexible conduit, called
+circular loom.
+
+In running wooden moulding, avoid brick walls liable to sweat or draw
+dampness; keep away from places where the heat of a stove might
+destroy the rubber insulation of the wires; do not pass nearer than
+six inches to water pipes when possible--and when it is necessary to
+pass nearer than this, the wooden moulding should pass above the pipe,
+not below it, with at least an inch of air space intervening, thus
+avoiding dampness from sweating of pipes.
+
+[Illustration: Snap switch connections]
+
+Places where chandeliers or wall bracket lamps are to be installed
+permanently are fitted with wooden terminal blocks, which fit over
+the moulding and flush with the plaster. These, after holes have been
+bored in them for the wires, and the wires drawn through, should be
+screwed firmly to the wall or ceiling, always choosing a joist or beam
+for support. Then a crow's-foot, or tripod of iron, tapped and
+threaded for iron pipe, is screwed to the terminal block. The iron
+pipe of the chandelier or wall bracket is then screwed home in this
+crow's-foot.
+
+Do not begin stringing wires until all the moulding of the circuit has
+been laid. Then thread the wires through the wall or floor tubes and
+lay them in their respective slots. If trouble be found making them
+stay in place before the capping is put on, small tacks may be driven
+into the moulding beside them to hold them. When a terminal block is
+reached, a loop is made of each wire, through the hole cut in the
+block, if the circuit is to continue in the same direction. If it is
+to end there, the two wires are drawn through taut, and cut off at a
+length of 5 or 6 inches. These end wires, or loops, are then scraped
+bare and spliced to the two wires coming out of the chandelier or
+wall bracket. This joint is then soldered and covered with tape, and
+the shell of the chandelier is screwed into place, covering the joint.
+
+[Illustration: Detail of wooden moulding]
+
+If the moulding is run along the walls flush with the ceiling, as is
+usual, a branch is made for a wall light, or wall tap, by means of a
+porcelain "T," or branch-block, which provides the means for running
+the circuit at right angles to itself without letting the wires come
+in contact with each other where they cross. Separable current taps
+should be installed in handy places on all circuits, so that small
+heating devices may be used without removing the lamps from their
+sockets. The two wires are bared for half an inch where they run
+through these current taps, and are fastened by means of brass screws.
+
+
+_"Multiple" Connections_
+
+All electric devices for this installation--lamps, irons, vacuum
+cleaners, motors--must be connected _across_ the circuit--that is,
+bridged, from one wire to the other. This is called _multiple_, or
+shunt connection. There is only one exception to it, in wiring the
+house. That one exception is installing a wall switch, the ordinary
+snap switch. Since this wall switch, is, in effect, merely an
+instrument, which opens or closes a circuit, it should be connected to
+only one wire, which is cut to provide two ends for the screw
+connections in the switch. When a moulding branch is run down from the
+ceiling to some convenient spot for a snap switch (with which to turn
+the lights of a room on or off), a porcelain "T" is not used. All that
+is necessary to do is to loop the bottom wire of the circuit down
+through the branch moulding, and connect it to the switch at a
+terminal block, or porcelain base.
+
+In wiring lamp fixtures, No. 14 rubber-covered wire will usually prove
+too large. For this purpose, No. 18 may be used, with one lamp to each
+loop. Hanging lamps may not be supported by electric lamp cord itself,
+if there is more than one lamp in the cluster, because the weight is
+apt to break the electrical connections. In such a case, the lamp
+should be supported by a chain, and the twisted cord conveying current
+to the electric bulbs, is woven in the links of the chain. For the
+pantry, kitchen, woodshed, barn, etc., a single hanging lamp may be
+suspended from a fielding rosette, as shown in the cut, provided a
+single knot is tied inside both the rosette and the lamp socket, to
+make it secure. This makes a very cheap fixture. The rosette of
+porcelain will cost 15 cents; the lamp socket 20 cents, and the lamp
+cord suspending the lamp and carrying the current will cost 1-1/2
+cents a foot; while a tin shade will cost another 15 cents.
+
+[Illustration: Detail of simple hanging lamp supported by rosette]
+
+
+_Official Inspection_
+
+In all communities, your insurance agent must inspect and pass your
+wiring before you are permitted to throw the main switch and turn on
+the electricity. Frequently they require that the moulding be left
+uncapped, until they have inspected it. If you have more than 660
+watts in lamps to a circuit; if your joints are not soldered and well
+taped; if the moulding is used in any concealed or damp place, the
+agent is liable to condemn your work and refuse permission to turn on
+the electricity. However the rules are so clearly defined that it is
+difficult to go wrong; and a farmer who does his own wiring and takes
+pride in its appearance is more apt to be right than a professional
+electrician who is careless at his task. After the work has been
+passed, tack on the moulding capping, with brads, and paint the
+moulding to match the woodwork.
+
+Wooden moulding wiring is perfectly satisfactory if properly
+installed. It is forbidden in many large cities, because of the
+liability of careless workmanship. It should never be installed in
+damp places, or out of sight. If the work is well done, the system
+leaves nothing to be desired; and it has the additional advantage of
+being cheap, and easily done by any farmer who can use carpenter
+tools. Farmers with moulding machinery can make their own moulding.
+The code prescribes it shall be of straight-grained wood; that the
+raceways for the wires shall be separated by a tongue of wood one-half
+inch wide; and that the backing shall be at least 3/8 inch thick. It
+must be covered, inside and out, with at least two coats of
+moisture-repellant paint. It can be had ready-made for about 2 cents a
+foot.
+
+
+_Special Heating Circuits_
+
+If one plans using electricity for heavy-duty stoves, such as ranges
+and radiators, it is necessary to install a separate heating circuit.
+This is the best procedure in any event, even when the devices are all
+small and suited to lamp circuits. The wire used can be determined by
+referring to the table for carrying capacity, under the column headed
+"rubber-covered." A stove or range drawing 40 amperes, would require a
+No. 4 wire, in moulding. A good plan is to run the heating circuit
+through the basement, attaching it to the rafters by means of
+porcelain knobs. Branches can then be run up through the floor to
+places where outlets are desired. Such a branch circuit should carry
+fuses suitable to the allowed carrying capacity of the wire.
+
+
+_Knob and Cleat Wiring_
+
+Knob and cleat wiring, such as is used extensively for barns and
+out-buildings, requires little explanation. The wires should not be
+closer than 2-1/2 inches in open places, and a wider space is better.
+The wires should be drawn taut, and supported by cleats or knobs at
+least every four feet. In case of branch circuits, one wire must be
+protected from the other it passes by means of a porcelain tube. It
+should never be used in damp places, and should be kept clear of dust
+and litter, and protected from abrasion.
+
+[Illustration: Knob and cleat wiring]
+
+Knob and tube wiring is frequently used in houses, being concealed
+between walls or flooring. In this case, the separate wires are
+stretched on adjoining beams or rafters, and porcelain tubes are used,
+in passing through cross beams. For a ceiling or wall outlet, a
+spliced branch is passed through the plaster by means of porcelain
+tubes or flexible loom.
+
+Wires from the house to the barn should be uniform with transmission
+wires. At the point of entry to buildings they must be at least six
+inches apart, and must take the form of the "drop loop" as shown in
+the illustration. A double-pole entrance switch must be provided,
+opening downward, with a double-pole fuse. In passing over buildings
+wires must not come closer than 7 feet to flat roofs, or one foot to a
+ridge roof. Feed-wires for electric motors should be determined from
+the table of safe carrying capacities, and should be of liberal size.
+
+
+
+
+CHAPTER IX
+
+THE ELECTRIC PLANT AT WORK
+
+     Direct-connected generating sets--Belt drive--The
+     switchboard--Governors and voltage regulators--Methods of achieving
+     constant pressure at all loads: Over-compounding the dynamo; A
+     system of resistances; (A home-made electric radiator); Regulating
+     voltage by means of the rheostat--Automatic devices--Putting the
+     plant in operation.
+
+
+Dynamos may be connected to water wheels either by means of a belt, or
+the armature may spin on the same shaft as the water wheel itself. The
+latter is by far the more desirable way, as it eliminates the loss of
+power through shafting and belting, and does away altogether
+with the belts themselves as a source of trouble. An installation
+with the water wheel and armature on the same shaft is called a
+"direct-connected set" and is of almost universal use in large power
+plants.
+
+To be able to use such a direct-connected set, the dynamo must be
+designed to develop its full voltage when run at a speed identical
+with that of the water wheel. That is, if the dynamo is wound to be
+run at a speed of 800 revolutions per minute, it must be driven by a
+water wheel which runs at this speed and can be governed within narrow
+limits. Small impulse wheels running under great heads attain high
+speed, and for such wheels it is possible to obtain a suitable dynamo
+at low cost. For instance, a 12-inch impulse wheel, running under a
+200-foot head will develop 6-3/4 horsepower when running at a speed of
+875 revolutions per minute. A dynamo for direct coupling to such a
+wheel should have a rated speed within 5 per cent of 875 r.p.m.; and,
+as generators of this speed are to be had from the stock of almost all
+manufacturers, there would be no extra charge.
+
+When it comes to the larger wheels, however, of the impulse type, or
+to turbines operating under their usual head the question becomes a
+little more difficult. In such cases, the speed of the water wheel
+will vary from 150 revolutions per minute, to 400, which is slow
+speed for a small dynamo. As a general rule, the higher the speed of a
+dynamo, the lower the cost; because, to lower the speed for a given
+voltage, it is necessary either to increase the number of conductors
+on the armature, or to increase the number of field coils, or both.
+That means a larger machine, and a corresponding increase in cost.
+
+In practice, in large plants, with alternating-current machines it has
+become usual to mount the field magnets on the shaft, and build the
+armature as a stationary ring in whose air space the field coils
+revolve. This simplifies the construction of slow-speed, large-output
+dynamos. Such a machine, however, is not to be had for the modest
+isolated plant of the farmer with his small water-power.
+
+[Illustration: Instantaneous photograph of high-pressure water jet
+being quenched by buckets of a tangential wheel]
+
+[Illustration: A tangential wheel, and a dynamo keyed to the same
+shaft--the ideal method for generating electricity. The centrifugal
+governor is included on the same base]
+
+Dynamos can be designed for almost any waterwheel speed, and, among
+small manufacturers especially, there is a disposition to furnish
+these special machines at little advance in price over their stock
+machines. Frequently it is merely a matter of changing the winding on
+a stock machine. The farmer himself, in many cases, can re-wind an old
+dynamo to fit the speed requirements of a direct-connected drive if
+the difference is not too great. All that would be necessary to
+effect this change would be to get the necessary winding data from the
+manufacturer himself, and proceed with the winding. This data would
+give the gauge of wire and the number of turns required for each spool
+of the field magnets; and the gauge of wire and number of turns
+required for each slot in the armature. The average boy who has
+studied electricity (and there is something about electricity that
+makes it closer to the boy's heart than his pet dog) could do this
+work. The advantages of direct drive are so many that it should be
+used wherever possible.
+
+When direct drive cannot be had, a belt must be used, either from a
+main shaft, or a countershaft. The belt must be of liberal size, and
+must be of the "endless" variety--with a scarfed joint. Leather belt
+lacing, or even the better grades of wire lacing, unless very
+carefully used, will prove unsatisfactory. The dynamo feels every
+variation in speed, and this is reflected in the lights. There is
+nothing quite so annoying as flickering lights. Usually this can be
+traced to the belt connections. Leather lacing forms a knot which
+causes the lights to flicker at each revolution of the belt. The
+endless belt does away with this trouble. Most dynamos are provided
+with sliding bases, by which the machine can be moved one way or
+another a few inches, to take up slack in the belt. To take advantage
+of this, the belt must be run in a horizontal line, or nearly so.
+Vertical belting is to be avoided.
+
+The dynamo is mounted on a wooden base, in a dry location where it is
+protected from the weather, or dampness from any source. It must be
+mounted firmly, to prevent vibration when running up to speed; and the
+switchboard should occupy a place within easy reach. Wires running
+from the dynamo to the switchboard should be protected from injury,
+and must be of ample size to carry the full current of the machine
+without heating. A neat way is to carry them down through the flooring
+through porcelain tubes, thence to a point where they can be brought
+up at the back of the switchboard. If there is any danger of injury to
+these mains they may be enclosed in iron pipe. Keep the wires out of
+sight as much as possible, and make all connections on the back of the
+switchboard.
+
+
+_The Switchboard_
+
+[Illustration: Connecting switchboard instruments]
+
+The switchboard is constructed of some fireproof material, preferably
+slate or marble. When the cost of this material is an item to
+consider, build a substantial wooden frame for your switchboard. You
+can then screw asbestos shingles to this to hold the various
+instruments and with a little care such a switchboard can be made to
+look business-like, and it is fully as serviceable as the more
+expensive kind. The switchboard instruments have already been
+described briefly. They consist of a voltmeter (to measure voltage);
+an ammeter (to measure the strength of the current drawn, in amperes),
+a rheostat (to regulate the voltage of the machine to suit the
+individual requirements); and the usual switches and fuses. The main
+switch should be so wired that when open it will throw all the current
+off the line, but still leave the field coils, the voltmeter, and the
+switchboard lamp in circuit. The main-switch fuses should have a
+capacity about 50 per cent in excess of the full load of the dynamo.
+If the machine is rated for 50 amperes, 75-ampere fuses should be
+installed. This permits throwing on an overload in an emergency; and
+at the same time guards against a short circuit. If the capacity of
+the machine is under 30 amperes, plug fuses, costing 3 cents each, can
+be used. If it is above this capacity, cartridge fuses, costing a
+little more, are required. A supply of these fuses should be kept
+handy at all times.
+
+
+_Governors and Voltage Regulators_
+
+[Illustration: A centrifugal governor (Courtesy of the C. P. Bradway
+Company, West Stafford, Conn.)]
+
+The necessity for water wheel governors will vary with conditions. As
+a general rule, it may be said that reaction turbines working under a
+low head with a large quantity of water do not require as much
+governing as the impulse wheel, working under high heads with small
+quantities of water. When governing is necessary at all, it is because
+the prime mover varies in speed from no load to full load. Planning
+one's plant with a liberal allowance of power--two water horsepower to
+one electrical horsepower is liberal--reduces the necessity of
+governors to a minimum. As an instance of this, the plant described
+in some detail in Chapters One and Six of this volume, runs without a
+governor.
+
+However, a surplus of water-power is not usual. Generally plants are
+designed within narrow limits; and then the need of a governor becomes
+immediately apparent. There are many designs of governors on the
+market, the cheapest being of the centrifugal type, in which a pair of
+whirling balls are connected to the water wheel gate by means of
+gears, and open or close the gate as the speed lowers or rises.
+
+Constant speed is necessary because voltage is directly dependent on
+speed. If the speed falls 25 per cent, the voltage falls likewise; and
+a plant with the voltage varying between such limits would be a
+constant source of annoyance, as well as expense for burned-out lamps.
+
+Since constant voltage is the result aimed at by the use of a
+governor, the same result can be attained in other ways, several of
+which will be explained here briefly.
+
+
+_Over-Compounding_
+
+(1) Over-compounding the dynamo. This is simple and cheap, if one buys
+the right dynamo in the first instance; or if he can do the
+over-compounding himself, by the method described in the concluding
+paragraphs of Chapter Seven. If it is found that the speed of the
+water wheel drops 25 per cent between no load and full load, a dynamo
+with field coils over-compounded to this extent would give a fairly
+constant regulation. If you are buying a special dynamo for direct
+drive, your manufacturer can supply you with a machine that will
+maintain constant voltage under the normal variations in speed of your
+wheel.
+
+
+_A System of Resistances_
+
+(2) Constant load systems. This system provides that the dynamo shall
+be delivering a fixed amount of current at all times, under which
+circumstances the water wheel would not require regulation, as the
+demands on it would not vary from minute to minute or hour to hour.
+
+This system is very simply arranged. It consists of having a set of
+"resistances" to throw into the circuit, in proportion to the amount
+of current used.
+
+Let us say, as an example, that a 50-ampere generator is used at a
+pressure of 110 volts; and that it is desirable to work this plant at
+80 per cent load, or 40 amperes current draft. When all the lights or
+appliances were in use, there would be no outside "resistance" in the
+circuit. When none of the lights or appliances were in use (as would
+be the case for many hours during the day) it would be necessary to
+consume this amount of current in some other way--to _waste it_. A
+resistance permitting 40 amperes of current to flow, would be
+necessary. Of what size should this resistance be?
+
+The answer is had by applying Ohm's Law, explained in Chapter Five.
+The Law in this case, would be read R = E/C. Therefore, in this case R
+= 110/40 = 2-3/4 ohms resistance, would be required, switched across
+the mains, to keep the dynamo delivering its normal load.
+
+The cheapest form of this resistance would be iron wire. In place of
+iron wire, German silver wire could be used. German silver wire is to
+be had cheaply, and is manufactured in two grades, 18% and 30%, with a
+resistance respectively 18 and 30 times that of copper for the same
+gauge. Nichrome wire has a resistance 60 times that of copper; and
+manganin wire has a resistance 65 times that of copper, of the same
+gauge.
+
+First figure the number of feet of copper wire suitable for the
+purpose. Allowing 500 circular mills for each ampere, the gauge of the
+wire should be 40 x 500 = 20,000 circular mills, or approximately No.
+7 B. & S. gauge. How many feet of No. 7 copper wire would give a
+resistance of 2-3/4 ohms? Referring to the copper wire table, we find
+that it requires 2006.2 of No. 7 wire to make one ohm. Then 2-3/4 ohms
+would require 5,517 feet.
+
+Since 30 per cent German silver wire is approximately 30 times the
+resistance of copper, a No. 7 German silver wire, for this purpose,
+would be 1/30 the length of the copper wire, or 186 feet. If nichrome
+wire were used, it would be 1/60th the length of copper for the same
+gauge, or 93 feet. This resistance wire can be wound in spirals and
+made to occupy a very small space. As long as it is connected in
+circuit, the energy of the dynamo otherwise consumed as light would be
+wasted as heat. This heat could be utilized in the hot water boiler or
+stove when the lights were turned off.
+
+In actual practice, however, the resistance necessary to keep the
+dynamo up to full load permanently, would not be furnished by one set
+of resistance coils. Each lamp circuit would have a set of resistance
+coils of its own. A double-throw switch would turn off the lamps and
+turn on the resistance coils, or _vice versa_.
+
+Let us say a lamp circuit consisted of 6 carbon lamps, of 16
+candlepower each. It would consume 6 x 1/2 ampere, or 3 amperes of
+current, and interpose a resistance of 36.6 ohms--say 37 ohms. Three
+amperes would require a wire of at least 1,500 circular mills in area
+for safety. This corresponds to a No. 18 wire. A No. 18 copper wire
+interposes a resistance of one ohm, for each 156.5 feet length. For 37
+ohms, 5,790 feet would be required, for copper wire, which of course
+would be impractical. Dividing by 30 gives 193 feet for 30% German
+silver wire; and dividing by 60 gives 96 feet of nichrome wire of the
+same gauge.
+
+It is simple to figure each circuit in this way and to construct
+resistance units for each switch. Since the resistance units develop
+considerable heat, they must be enclosed and protected.
+
+
+_A Home-made Stove or Radiator_
+
+While we are on the subject of resistance coils it might be well here
+to describe how to make stoves for cooking, and radiators for heating
+the house, at small expense. These stoves consist merely of
+resistances which turn hot--a dull red--when the current is turned on.
+Iron wire, German silver wire, or the various trade brands of
+resistance wire, of which nichrome, calido, and manganin are samples,
+can be used. In buying this wire, procure the table of resistance and
+carrying capacity from the manufacturers. From this table you can make
+your own radiators to keep the house warm in winter. Iron wire has the
+disadvantage of oxidizing when heated to redness, so that it goes to
+pieces after prolonged use. It is cheap, however, and much used for
+resistance in electrical work.
+
+Let us say we wish to heat a bathroom, a room 6 x 8, and 8 feet
+high--that is a room containing 384 cubic feet of air space. Allowing
+2 watts for each cubic foot, we would require 768 watts of current, or
+practically 7 amperes at 110 volts. What resistance would be required
+to limit the current to this amount? Apply Ohm's Law, as before, and
+we have R equals E divided by C, or R equals 110 divided by 7, which
+is 15.7 ohms. Forty-two feet of No. 20 German silver wire would emit
+this amount of heat and limit the current output to 7 amperes. In the
+Far West, it is quite common, in the outlying district, to find
+electric radiators made out of iron pipe covered with asbestos, on
+which the requisite amount of iron wire is wound and made secure. This
+pipe is mounted in a metal frame. Or the frame may consist of two
+pipes containing heating elements; and a switch, in this case, is so
+arranged that either one or two heating elements may be used at one
+time, according to the weather. An ingenious mechanic can construct
+such a radiator, experimenting with the aid of an ammeter to ascertain
+the length of wire required for any given stove.
+
+
+_Regulating Voltage at Switchboards_
+
+The voltage of any given machine may be regulated, within wide limits,
+by means of the field rheostat on the switchboard.
+
+A dynamo with a rated speed of 1,500 revolutions per minute, for 110
+volts, will actually attain this voltage at as low as 1,200 r.p.m. if
+all the regulating resistance be cut out. You can test this fact with
+your own machine by cutting out the resistance from the shunt field
+entirely, and starting the machine slowly, increasing its speed
+gradually, until the voltmeter needle registers 110 volts. Then
+measure the speed. It will be far below the rated speed of your
+machine.
+
+If, on the other hand, the speed of such a machine runs up to 2,500 or
+over--that is, an excess of 67%--the voltage would rise
+proportionally, unless extra resistance was cut in. By cutting in such
+resistance--by the simple expedient of turning the rheostat handle on
+the switchboard,--the field coils are so weakened that the voltage is
+kept at the desired point in spite of the excessive speed of the
+machine. Excessive speeds are to be avoided, as a rule, because of
+mechanical strain. But within a wide range, the switchboard rheostat
+can be used for voltage regulation.
+
+As it would be a source of continual annoyance to have to run to the
+switchboard every time the load of the machine was varied greatly this
+plan would not be practical for the isolated plant, unless the
+rheostat could be installed,--with a voltmeter--in one's kitchen.
+This could be done simply by running a small third wire from the
+switchboard to the house. Then, when the lights became dim from
+excessive load, a turn of the handle would bring them back to the
+proper voltage; and when they flared up and burned too bright, a turn
+of the handle in the opposite direction would remedy matters. By this
+simple arrangement, any member of the family could attend to voltage
+regulation with a minimum of bother.
+
+
+_Automatic Devices_
+
+There are several automatic devices for voltage regulation at the
+switchboard on the market. These consist usually of vibrator magnets
+or solenoids, in which the strength of the current, varying with
+different speeds, reacts in such a way as to regulate field
+resistance. Such voltage regulators can be had for $40 or less, and
+are thoroughly reliable.
+
+       *       *       *       *       *
+
+To sum up the discussion of governors and voltage regulators: If you
+can allow a liberal proportion of water-power, and avoid crowding
+your dynamo, the chances are you will not need a governor for the
+ordinary reaction turbine wheel. Start your plant, and let it run for
+a few days or a few weeks without a governor, or regulator. Then if
+you find the operation is unsatisfactory, decide for yourself which of
+the above systems is best adapted for your conditions. Economy as well
+as convenience will affect your decision. The plant which is most
+nearly automatic is the best; but by taking a little trouble and
+giving extra attention, a great many dollars may be saved in extras.
+
+
+_Starting the Dynamo_
+
+You are now ready to put your plant in operation. Your dynamo has been
+mounted on a wooden foundation, and belted to the countershaft, by
+means of an endless belt.
+
+See that the oil cups are filled. Then throw off the main switch and
+the field switch at the switchboard; open the water gate slowly, and
+occasionally test the speed of the dynamo. When it comes up to rated
+speed, say 1,500 per minute, let it run for a few minutes, to be sure
+everything is all right.
+
+Having assured yourself that the mechanical details are all right, now
+look at the voltmeter. It is probably indicating a few volts pressure,
+from 4 to 8 or 10 perhaps. This pressure is due to the residual
+magnetism in the field cores, as the field coils are not yet
+connected. If by any chance, the needle does not register, or is now
+back of 0, try changing about the connections or the voltmeter on the
+back of the switchboard.
+
+Now snap on the field switch. Instantly the needle will begin to move
+forward, though slowly; and it will stop. Turn the rheostat handle
+gradually; as you advance it, the voltmeter needle will advance.
+Finally you will come to a point where the needle will indicate 110
+volts.
+
+If you have designed your transmission line for a drop of 5 volts at
+half-load, advance the rheostat handle still further, until the
+needle points to 115 volts. Let the machine run this way for some
+time. When assured all is right, throw on the main switch, and turn on
+the light at the switchboard. Then go to the house and gradually turn
+on lights. Come back and inspect the dynamo as the load increases. It
+should not run hot, nor even very warm, up to full load. Its brushes
+should not spark, though a little sparking will do no harm.
+
+Your plant is now ready to deliver current up to the capacity of its
+fuses. See that it does not lack good lubricating oil, and do not let
+its commutator get dirty. The commutator should assume a glossy
+chocolate brown color. If it becomes dirty, or the brushes spark
+badly, hold a piece of fine sandpaper against it. Never use emery
+paper! If, after years of service, it becomes roughened by wear, have
+it turned down in a lathe. Occasionally, every few weeks, say, take
+the brushes out and clean them with a cloth. They will wear out in the
+course of time and can be replaced for a few cents each. The bearings
+may need replacing after several years' continuous use.
+
+Otherwise your electric plant will take care of itself. Keep it up to
+speed, and keep it clean and well oiled. Never shut it down unless you
+have to. In practice, dynamos run week after week, year after year,
+without stopping. This one, so long as you keep it running true to
+form, will deliver light, heat and power to you for nothing, which
+your city cousin pays for at the rate of 10 cents a kilowatt-hour.
+
+
+
+
+PART III
+
+GASOLINE ENGINES, WINDMILLS, ETC. THE STORAGE BATTERIES
+
+
+
+
+CHAPTER X
+
+GASOLINE ENGINE PLANTS
+
+     The standard voltage set--Two-cycle and four-cycle gasoline
+     engines--Horsepower, and fuel consumption--Efficiency of small
+     engines and generators--Cost of operating a one-kilowatt plant.
+
+
+Electricity is of so much value in farm operations, as well as in the
+farm house, that the farmer who is not fortunate enough to possess
+water-power of his own, or to live in a community where a cooperative
+hydro-electric plant may be established, should not deny himself its
+many conveniences. In place of the water wheel to turn the dynamo,
+there is the gasoline engine (or other forms of internal combustion
+engine using oil, gas, or alcohol as fuel); in many districts where
+steam engines are used for logging or other operations, electricity
+may be generated as a by-product; and almost any windmill capable of
+pumping water can be made to generate enough electricity for lighting
+the farm house at small expense.
+
+The great advantage of water-power is that the expense of
+maintenance--once the plant is installed--is practically nothing. This
+advantage is offset in some measure by the fact that other forms of
+power, gas, steam, or windmills, are already installed, in many
+instances and that their judicious use in generating electricity does
+not impair their usefulness for the other farm operations for which
+they were originally purchased. In recent years gasoline engines have
+come into general use on farms as a cheap dependable source of power
+for all operations; and windmills date from the earliest times. They
+may be installed and maintained cheaply, solely for generating
+electricity, if desired. Steam engines, however, require so much care
+and expert attention that their use for farm electric plants is not to
+be advised, except under conditions where a small portion of their
+power can be used to make electricity as a by-product.
+
+There are two types of gasoline engine electric plants suitable for
+the farm, in general use:
+
+First: The Standard Voltage Set, in which the engine and dynamo are
+mounted on one base, and the engine is kept running when current is
+required for any purpose. These sets are usually of the 110-volt type,
+and all standard appliances, such as irons, toasters, motors, etc.,
+may be used in connection with them. Since the electricity is drawn
+directly from the dynamo itself, without a storage battery, it is
+necessary that these engines be efficient and governed as to speed
+within a five per cent variation from no load to full load.
+
+Second: Storage Battery Sets, in which the dynamo is run only a few
+hours each week, and the electricity thus generated is "stored" by
+chemical means, in storage batteries, for use when required. Since, in
+this case, the current is drawn from the battery, instead of the
+dynamo, when used for lighting or other purposes, it is not necessary
+that a special type of engine be used to insure constant speed.
+
+
+_The Standard Voltage Set_
+
+In response to a general demand, the first type (the direct-connected
+standard voltage set) has been developed to a high state of efficiency
+recently, and is to be had in a great variety of sizes (ranging from
+one-quarter kilowatt to 25 kilowatts and over) from many
+manufacturers.
+
+The principle of the gasoline engine as motive power is so familiar to
+the average farmer that it needs but a brief description here.
+Gasoline or other fuel (oil, gas, or alcohol) is transformed into
+vapor, mixed with air in correct proportions, and drawn into the
+engine cylinder and there exploded by means of a properly-timed
+electric spark.
+
+Internal combustion engines are of two general types--four-cycle and
+two-cycle. The former is by far the more common. In a four-cycle
+engine the piston must travel twice up and down in each cylinder, to
+deliver one power stroke. This results in one power impulse in each
+cylinder every two revolutions of the crank shaft. On its first down
+stroke, the piston sucks in gas. On its first up stroke, it compresses
+the gas. At the height of this stroke, the gas is exploded by means of
+the electric spark and the piston is driven down, on its power stroke.
+The fourth stroke is called the scavening stroke, and expels the
+burned gas. This completes the cycle.
+
+A one-cylinder engine of the ordinary four-cycle type has one power
+stroke for every two revolutions of the fly wheel. A two-cylinder
+engine has one power stroke for one revolution of the fly wheel; and a
+four-cylinder engine has two power strokes to each revolution. The
+greater the number of cylinders, the more even the flow of power. In
+automobiles six cylinders are common, and in the last year or two,
+eight-cylinder engines began appearing on the market in large numbers.
+A twelve-cylinder engine is the prospect for the immediate future.
+
+Since the dynamo that is to supply electric current direct to lamps
+requires a steady flow of power, the single-cylinder gas or gasoline
+engine of the four-cycle type is not satisfactory as a rule. The
+lights will flicker with every other revolution of the fly wheel. This
+would be of no importance if the current was being used to charge a
+storage battery--and right here lies the reason why a cheaper engine
+may be used in connection with a storage battery than when the dynamo
+supplies the current direct for lighting.
+
+A two-cylinder engine is more even in its flow of power and a
+four-cylinder engine still better. For this reason, standard voltage
+generating sets without battery are usually of two or four cylinders
+when of the four-cycle type. When a single-cylinder engine is used, it
+should be of the two-cycle type. In the two-cycle engine, there is one
+power stroke to each up-and-down journey of the piston. This effect is
+produced by having inlet and exhaust ports in the crank case, so
+arranged that, when the piston arrives at the bottom of the power
+stroke, the waste gases are pushed out, and fresh gas drawn in before
+the up stroke begins.
+
+For direct lighting, the engine must be governed so as not to vary
+more than five per cent in speed between no load and full load. There
+are many makes on the market which advertise a speed variation of
+three per cent under normal loads. Governors are usually of the
+centrifugal ball type, integral with the fly wheel, regulating the
+amount of gas and air supplied to the cylinders in accordance with the
+speed. Thus, if such an engine began to slow down because of increase
+in load, the centrifugal balls would come closer together, and open
+the throttle, thus supplying more gas and air and increasing the
+speed. If the speed became excessive, due to sudden shutting off of
+lights, the centrifugal balls would fly farther apart, and the
+throttle would close until the speed was again adjusted to the load.
+
+These direct-connected standard voltage sets are as a rule fitted with
+the 110-volt, direct current, compound type of dynamo, the duplicate
+in every respect of the machine described in previous chapters for
+water-power plants. They are practically automatic in operation and
+will run for hours without attention, except as to oil and gasoline
+supply. They may be installed in the woodshed or cellar without
+annoyance due to noise or vibration. It is necessary to start them, of
+course, when light or power is desired, and to stop them when no
+current is being drawn. There have appeared several makes on the
+market in which starting and stopping are automatic. Storage batteries
+are used in connection with these latter plants for starting the
+engine. When a light is turned on, or current is drawn for any
+purpose, an automatic switch turns the dynamo into a motor, and it
+starts the engine by means of the current stored in the battery.
+Instantly the engine has come up to speed, the motor becomes a dynamo
+again and begins to deliver current. When the last light is turned
+off, the engine stops automatically.
+
+Since the installation of a direct-connected standard voltage plant of
+this type is similar in every respect, except as to motive power, to
+the hydro-electric plant, its cost, with this single exception, is the
+same. The same lamps, wire, and devices are used.
+
+With gasoline power, the cost of the engine offsets the cost of the
+water wheel. The engine is more expensive than the ordinary gasoline
+engine; but even this item of cost is offset by the cost of labor and
+materials used in installing a water wheel.
+
+The expense of maintenance is limited to gasoline and oil.
+Depreciation enters in both cases; and though it may be more rapid
+with a gasoline engine than a water wheel, that item will not be
+considered here. The cost of lubricating oil is inconsiderable. It
+will require, when operated at from one-half load to full load,
+approximately one pint of gasoline to each horsepower hour. When
+operated at less than half-load, its efficiency lowers. Thus, for a
+quarter-load, an average engine of this type may require three pints
+of gasoline for each horsepower hour. For this reason it is well, in
+installing such a plant, to have it of such size that it will be
+operating on at least three-fourths load under normal draft of
+current. Norman H. Schneider, in his book "Low Voltage Electric
+Lighting," gives the following table of proportions between the engine
+and dynamo:
+
+     Actual watts    Actual Horsepower    Nearest engine size
+       150                   .5                 1/2
+       225                   .7                 3/4
+       300                   .86              1
+       450                  1.12              1-1/4
+       600                  1.5               1-1/2
+       750                  1.7               1-3/4
+      1000                  2.3               2-1/2
+      2000                  4.5               5
+      4000                  9.0              10
+
+This table is figured for an efficiency of only 40 per cent for the
+smaller generators, and 60 per cent for the larger. In machines from 5
+to 25 kilowatts, the efficiency will run considerably higher.
+
+To determine the expense of operating a one-kilowatt gasoline
+generator set of this type, as to gasoline consumption, we can assume
+at full load that the gasoline engine is delivering 2-1/2 horsepower,
+and consuming, let us say, 1-1/4 pint of gasoline for each horsepower
+hour (to make allowance for lower efficiency in small engines). That
+would be 3.125 pints of gasoline per hour. Allowing a ten per cent
+loss of current in wiring, we have 900 watts of electricity to use,
+for this expenditure of gasoline. This would light 900 / 25 = 36 lamps
+of 25 watts each, a liberal allowance for house and barn, and
+permitting the use of small cooking devices and other conveniences
+when part of the lights were not in use. With gasoline selling at 12
+cents a gallon, the use of this plant for an hour at full capacity
+would cost $0.047. Your city cousin pays 9 cents for the same current
+on a basis of 10 cents per kilowatt-hour; and in smaller towns where
+the rate is 15 cents, he would pay 13-1/2 cents.
+
+Running this plant at only half-load--that is, using only 18 lights,
+or their equivalent--would reduce the price to about 3 cents an
+hour--since the efficiency decreases with smaller load. It is
+customary to figure an average of 3-1/2 hours a day throughout the
+year, for all lights. On this basis the cost of gasoline for this
+one-kilowatt plant would be 16-1/2 cents a day for full load, and
+approximately 10-1/2 cents a day for half-load. This is extremely
+favorable, as compared with the cost of electric current in our cities
+and towns, at the commercial rate, especially when one considers that
+light and power are to be had at any place or at any time on the farm
+simply by starting the engine. A smaller plant, operating at less cost
+for fuel, would furnish ample light for most farms; but it is well to
+remember in this connection plants smaller than one kilowatt are
+practical for light only, since electric irons, toasters, etc., draw
+from 400 to 660 watts each. Obviously a plant of 300 watts capacity
+would not permit the use of these instruments, although it would
+furnish 10 or 12 lamps of 25 watts each.
+
+
+
+
+CHAPTER XI
+
+THE STORAGE BATTERY
+
+     What a storage battery does--The lead battery and the Edison
+     battery--Economy of tungsten lamps for storage batteries--The
+     low-voltage battery for electric light--How to figure the capacity
+     of a battery--Table of light requirements for a farm
+     house--Watt-hours and lamp-hours--The cost of storage battery
+     current--How to charge a storage battery--Care of storage
+     batteries.
+
+
+For the man who has a small supply of water to run a water wheel a few
+hours at a time, or who wishes to store electricity while he is doing
+routine jobs with a gasoline engine or other source of power, the
+storage battery solves the problem. The storage battery may be likened
+to a tank of water which is drawn on when water is needed, and which
+must be re-filled when empty. A storage battery, or accumulator is a
+device in which a chemical action is set up when an electric current
+is passed through it. This is called _charging_. When such a battery
+is charged, it has the property of giving off an electric current by
+means of a reversed chemical action when a circuit is provided,
+through a lamp or other connection. This reversed action is called
+_discharging_. Such a battery will discharge nearly as much current as
+is required originally to bring about the first chemical action.
+
+There are two common types of storage battery--the lead accumulator,
+made up of lead plates (alternately positive and negative); and the
+two-metal accumulator, of which the Edison battery is a
+representative, made up of alternate plates of iron and nickel. In the
+lead accumulator, the "positive" plate may be recognized by its brown
+color when charging, while the "negative" plate is usually light gray,
+or leaden in color. The action of the charging current is to form
+oxides of lead in the plates; the action of the discharging current is
+to reduce the oxides to metallic lead again. This process can be
+repeated over and over again during the life of the battery.
+
+Because of the cost of the batteries themselves, it is possible (from
+the viewpoint of the farmer and the size of his pocketbook) to store
+only a relatively small amount of electric current. For this reason,
+the storage battery was little used for private plants, where expense
+is a considerable item, up to a few years ago. Carbon lamps require
+from 3-1/2 to 4 watts for each candlepower of light they give out; and
+a lead battery capable of storing enough electricity to supply the
+average farm house with light by means of carbon lamps for three or
+four days at a time without recharging, proved too costly for private
+use.
+
+
+_The Tungsten Lamp_
+
+With the advent of the new tungsten lamp, however, reducing the
+current requirements for light by two-thirds, the storage battery
+immediately came into its own, and is now of general use.
+
+Since incandescent lamps were first invented scientists have been
+trying to find some metal of high fusion to use in place of the carbon
+filament of the ordinary lamp. The higher the fusing point of this
+filament of wire, the more economical would be the light. Edison
+sought, thirty years ago, for just the qualities now found in tungsten
+metal. Tungsten metal was first used for incandescent lamps in the
+form of a paste, squirted into the shape of a thread. This proved too
+fragile. Later investigators devised means of drawing tungsten into
+wire; and it is tungsten wire that is now used so generally in
+lighting. A tungsten lamp has an average efficiency of 1-1/4 watts per
+candlepower, compared with 3-1/2 to 4 watts of the old-style carbon
+lamp. In larger sizes the efficiency is as low as .9 watt per
+candlepower; and only recently it has been found that if inert
+nitrogen gas is used in the glass bulb, instead of using a high vacuum
+as is the general practice, the efficiency of the lamp becomes still
+higher, approaching .5 watt for each candlepower in large lamps. This
+new nitrogen lamp is not yet being manufactured in small domestic
+sizes, though it will undoubtedly be put on the market in those sizes
+in the near future.
+
+[Illustration: The Fairbanks Morse oil engine storage battery set]
+
+The tungsten lamp, requiring only one-third as much electric current
+as the carbon lamp, for the same amount of light, reduces the size
+(and the cost) of the storage battery in the same degree, thus
+bringing the storage battery within the means of the farmer. Some idea
+of the power that may be put into a small storage battery is to be had
+from the fact that a storage battery of only 6 volts pressure, such as
+is used in self-starters on automobiles, will turn a motor and crank a
+heavy six-cylinder engine; or it will run the automobile, without
+gasoline, for a mile or more with its own accumulated store of
+electric current.
+
+
+_The Low Voltage Battery_
+
+The 30-volt storage battery has become standard for small lighting
+plants, since the introduction of the tungsten lamp. Although the
+voltage of each separate cell of this battery registers 2.5 volts when
+fully charged, it falls to approximately 2 volts per cell immediately
+discharging begins. For this reason, it is customary to figure the
+working pressure of each cell at 2 volts. This means that a 30-volt
+battery should consist of at least 15 cells. Since, however, the
+voltage falls below 2 for each cell, as discharging proceeds, it is
+usual to include one additional cell for regulating purposes. Thus,
+the ordinary 30-volt storage battery consists of 16 cells, the last
+cell in the line remaining idle until the lamps begin to dim, when it
+is switched in by means of a simple arrangement of connections. This
+maintains a uniform pressure of 30 volts from the beginning to the end
+of the charge, at the lamp socket.
+
+We saw in earlier chapters that the 110-volt current is the most
+satisfactory, under all conditions, where the current is to be used
+for heating and small power, as well as light. But a storage battery
+of 110 volts would require at least 55 cells, which would make it too
+expensive for ordinary farm use. As a 30-volt current is just as
+satisfactory for electric light, this type has become established, in
+connection with the battery, and it is used for electric lighting
+only, as a general rule.
+
+Batteries are rated first, as to voltage; second, as to their capacity
+in ampere hours--that is, the number of amperes that may be drawn from
+them in a given number of hours. Thus, a battery rated at 60 ampere
+hours would give 60 amperes, at 30 volts pressure, for one hour; 30
+amperes for 2 hours; 15 amperes for 4 hours; 7-1/2 amperes for 8
+hours; 3-3/4 amperes for 16 hours; etc., etc. In practice, a battery
+should not be discharged faster than its 8-hour rate. Thus, a
+60-ampere hour battery should not be drawn on at a greater rate than
+7-1/2 amperes per hour.
+
+This 8-hour rate also determines the rate at which a battery should
+be re-charged, once it is exhausted. Thus, this battery should be
+charged at the rate of 7-1/2 amperes for 8 hours, with another hour
+added to make up for losses that are bound to occur. A battery of
+120-ampere hour capacity should be charged for 8 or 9 hours at the
+rate of 120 / 8, or 15 amperes, etc.
+
+To determine the size of battery necessary for any particular
+instance, it is necessary first to decide on the number of lamps
+required, and their capacity. Thirty-volt lamps are to be had in the
+market in sizes of 10, 15 and 20 watts; they yield respectively 8, 12,
+and 16 candlepower each. Of these the 20-watt lamp is the most
+satisfactory for the living rooms; lamps of 10 or 15 watts may be used
+for the halls, the bathroom and the bedrooms. At 30 volts pressure
+these lamps would require a current of the following density in
+amperes:
+
+     Candle
+     Power     30-volt lamp    Amperes
+       8         10 watts        0.33
+      12         15 watts        0.50
+      16         20 watts        0.67
+
+Let us assume, as an example, that Farmer Brown will use 20-watt
+lamps in his kitchen, dining room, and sitting room; and 10-watt lamps
+in the halls, bathroom, and bedrooms. His requirements may be figured
+either in lamp hours or in watt-hours. Since he is using two sizes of
+lamps, it will be simpler to figure his requirements in watt-hours.
+Thus:
+
+                          Number     Size of   Hours    Watt-
+          Room          of lamps     lamps     burned   hours
+
+         Kitchen           1           20        4       80
+         Dining room       2           20        2       80
+         Sitting room      3           20        4      240
+    (3)  Bedrooms          1 (each)    10        1       30
+         Bathroom          1           10        2       20
+    (2)  Halls             1 (each)    10        4       80
+         Pantry            1           10        1       10
+         Cellar            1           10        1       10
+                                                       ----
+           Total                                        550
+
+Since amperes equal watts divided by volts, the number of ampere hours
+required in this case each night would be 550 / 30 = 18.3 ampere
+hours; or approximately 4-1/2 amperes per hour for 4 hours.
+
+Say it is convenient to charge this battery every fourth day. This
+would require a battery of 4 x 18.3 ampere hours, or 73.2 ampere
+hours. The nearest size on the market is the 80-ampere hour battery,
+which would be the one to use for this installation.
+
+To charge this battery would require a dynamo capable of delivering 10
+amperes of current for 9 hours. The generator should be of 45 volts
+pressure (allowing 2-1/2 volts in the generator for each 2 volts of
+battery) and the capacity of the generator would therefore be 450
+watts. This would require a 1-1/4 horsepower gasoline engine. At 1-1/4
+pints of gasoline for each horsepower, nine hours work of this engine
+would consume 14 pints of gasoline--or say 16 pints, or two gallons.
+At 12 cents a gallon for gasoline, lighting your house with this
+battery would cost 24 cents for four days, or 6 cents a day. Your city
+cousin, using commercial current, would pay 5-1/2 cents a day for the
+same amount of current at 10 cents a kilowatt-hour; or 8-1/4 cents at
+a 15-cent rate. If the battery is charged by the farm gasoline engine
+at the same time it is doing its other work, the cost would be still
+less, as the extra gasoline required would be small.
+
+This figure does not take into account depreciation of battery and
+engine. The average farmer is too apt to overlook this factor in
+figuring the cost of machinery of all kinds, and for that reason is
+unprepared when the time comes to replace worn-out machinery. The
+dynamo and switchboard should last a lifetime with ordinary care, so
+there is no depreciation charge against them. The storage battery, a
+30-volt, 80-ampere hour installation, should not cost in excess of
+$100; and, if it is necessary to buy a gasoline engine, a 1-1/4
+horsepower engine can be had for $50 or less according to the type.
+Storage batteries of the lead type are sold under a two-years'
+guarantee--which does not mean that their life is limited to that
+length of time. With good care they may last as long as 10 years; with
+poor care it may be necessary to throw them away at the end of a year.
+The engine should be serviceable for at least 10 years, with ordinary
+replacements; and the storage battery may last from 6 to 10 years,
+with occasional renewal of parts. If it were necessary to duplicate
+both at the end of ten years, this would make a carrying charge of
+$1.25 a month for depreciation, which must be added to the cost of
+light.
+
+
+_Figuring by Lamp Hours_
+
+If all the lamps are to be of the same size--either ten, fifteen, or
+twenty watts, the light requirements of a farm house can be figured
+readily by lamp hours. In that event, the foregoing table would read
+as follows:
+
+                                             Lamp hours
+    Kitchen, 1 lamp, 4 hours                      4
+    Sitting room, 3 lamps, 4 hours each          12
+    Dining room, 2 lamps, 2 hours each            4
+    Bedrooms, 3 lamps, 1 hour each                3
+    Halls, 2 lamps, 4 hours each                  8
+    Bathroom, 1 lamp, 2 hours                     2
+    Pantry and cellar, 2 lamps, 1 hour each       2
+
+To determine the ampere hours from this table, multiply the total
+number of lamp hours by the current in amperes required for each lamp.
+As 10, 15, and 20-watt tungsten lamps require .33, .50 and .67
+amperes, respectively at 30 volts pressure, the above requirements in
+ampere hours would be 12, 17-1/2, or 24 ampere hours, according to the
+size of lamp chosen. This gives the average current consumption for
+one night. If it is desired to charge the battery twice a week on the
+average, multiply the number of lamp hours by 4, to get the size of
+battery required.
+
+The foregoing illustration is not intended to indicate average light
+requirements for farms, but is given merely to show how a farmer may
+figure his own requirements. In some instances, it will be necessary
+to install a battery of 120 or more ampere hours, whereas a battery of
+40 or 60 ampere hours would be quite serviceable in other instances.
+It all depends on how much light you wish to use and are willing to
+pay for, because with a storage battery the cost of electric light is
+directly in proportion to the number of lights used.
+
+As a general rule, a larger generator and engine are required for a
+larger battery--although it is possible to charge a large battery
+with a small generator and engine by taking more time for the
+operation.
+
+
+_How to Charge a Storage Battery_
+
+Direct current only can be used for charging storage batteries. In the
+rare instance of alternating current only being available, it must be
+converted into direct current by any one of the many mechanical,
+chemical, or electrical devices on the market--that is, the
+alternating current must be straightened out, to flow always in one
+direction.
+
+A shunt-wound dynamo must be used; else, when the voltage of the
+battery rises too high, it may "back up" and turn the dynamo as a
+motor, causing considerable damage. If a compound dynamo is already
+installed, or if it is desired to use such a machine for charging
+storage batteries, it can be done simply by disconnecting the series
+windings on the field coils, thus turning the machine into a shunt
+dynamo.
+
+The voltage of the dynamo should be approximately 50 per cent above
+the working pressure of the battery. For this reason 45-volt machines
+are usually used for 30 or 32-volt batteries. Higher voltages may be
+used, if convenient. Thus a 110-volt dynamo may be used to charge a
+single 2-volt cell if necessary, although it is not advisable.
+
+
+_Direction of Current_
+
+Electricity flows from the positive to the negative terminal. A
+charging current must be so connected that the negative wire of the
+dynamo is always connected to the negative terminal of the battery,
+and the positive wire to the positive terminal. As the polarity is
+always marked on the battery, there is little danger of making a
+mistake in this particular.
+
+When the storage battery is charged, and one begins to use its
+accumulation of energy, the current comes out in the opposite
+direction from which it entered in charging. In this respect, a
+storage battery is like a clock spring, which is wound up in one
+direction, and unwinds itself in the other. With all storage battery
+outfits, an ammeter (or current measure) is supplied with zero at the
+center. When the battery is being charged, the indicating needle
+points in one direction in proportion to the strength of the current
+flowing in; and when the battery is being discharged, the needle
+points in the opposite direction, in proportion to the strength of the
+current flowing out.
+
+Sometimes one is at loss, in setting about to connect a battery and
+generator, to know which is the positive and which the negative wire
+of the generator. A very simple test is as follows:
+
+Start the generator and bring it up to speed. Connect some form of
+resistance in "series" with the mains. A lamp in an ordinary lamp
+socket will do very well for this resistance. Dip the two ends of the
+wire (one coming from the generator, the other through the lamp) into
+a cup of water, in which a pinch of salt is dissolved. Bring them
+almost together and hold them there. Almost instantly, one wire will
+begin to turn bright, and give off bubbles. The wire which turns
+bright and gives off bubbles is the _negative_ wire. The other is the
+positive.
+
+[Illustration: A rough-and-ready farm electric plant, supplying two
+farms with light, heat and power; and a Ward Leonard-type
+circuit-breaker for charging storage batteries]
+
+
+_Care of Battery_
+
+Since specific directions are furnished with all storage batteries, it
+is not necessary to go into the details of their care here. Storage
+battery plants are usually shipped with all connections made, or
+plainly indicated. All that is necessary is to fill the batteries with
+the acid solution, according to directions, and start the engine. If
+the engine is fitted with a governor, and the switchboard is of the
+automatic type, all the care necessary in charging is to start the
+engine. In fact, many makes utilize the dynamo as a "self-starter" for
+the engine, so that all that is necessary to start charging is to
+throw a switch which starts the engine. When the battery is fully
+charged, the engine is stopped automatically.
+
+The "electrolyte" or solution in which the plates of the lead battery
+are immersed, is sulphuric acid, diluted with water in the proportion
+of one part of acid to five of water, by volume.
+
+The specific gravity of ordinary commercial sulphuric acid is 1.835.
+Since its strength is apt to vary, however, it is best to mix the
+electrolyte with the aid of the hydrometer furnished with the battery.
+The hydrometer is a sealed glass tube, with a graduated scale somewhat
+resembling a thermometer. The height at which it floats in any given
+solution depends on the density of the solution. It should indicate
+approximately 1.15 for a storage battery electrolyte before charging.
+It should not be over 1.15--or 1,150 if your hydrometer reads in
+thousandths.
+
+Only pure water should be used. Distilled water is the best, but fresh
+clean rain water is permissible. Never under any circumstances use
+hydrant water, as it contains impurities which will injure the
+battery, probably put it out of commission before its first charge.
+
+_Pour the acid into the water._ Never under any circumstances pour the
+water into the acid, else an explosion may occur from the heat
+developed. Mix the electrolyte in a stone crock, or glass container,
+stirring with a glass rod, and testing from time to time with a
+hydrometer. Let it stand until cool and then pour it into the battery
+jars, filling them to 1/2 inch above the top of the plates.
+
+Then begin charging. The first charge will probably take a longer time
+than subsequent charges. If the installation is of the automatic type,
+all that is necessary is to start the engine. If it is not of the
+automatic type, proceed as follows:
+
+First be sure all connections are right. Then start the engine and
+bring the dynamo up to its rated speed. Adjust the voltage to the
+pressure specified. Then throw the switch connecting generator to
+battery. Watch the ammeter. It should register in amperes, one-eighth
+of the ampere-hour capacity of the battery, as already explained. If
+it registers too high, reduce the voltage of the generator slightly,
+by means of the field rheostat connected to the generator. This will
+also reduce the amperes flowing. If too low, raise the voltage until
+the amperes register correctly. Continue the charging operation until
+the cells begin to give off gas freely; or until the specific gravity
+of the electrolyte, measured by the hydrometer, stands at 1.24. Your
+battery is now fully charged. Throw the switch over to the service
+line, and your accumulator is ready to furnish light if you turn on
+your lamps.
+
+Occasionally add distilled water to the cells, to make up for
+evaporation. It is seldom necessary to add acid, as this does not
+evaporate. If the battery is kept fully charged, it will not freeze
+even when the thermometer is well below zero.
+
+A storage battery should be installed as near the house as
+possible--in the house, if possible. Since its current capacity is
+small, transmission losses must be reduced to a minimum.
+
+In wiring the house for storage battery service, the same rules apply
+as with standard voltage. Not more than 6 amperes should be used on
+any single branch circuit. With low voltage batteries (from 12 volts
+to 32 volts) it is well to use No. 10 or No. 12 B. & S. gauge
+rubber-covered wire, instead of the usual No. 14 used with standard
+voltage. The extra expense will be only a few cents for each circuit,
+and precious volts will be saved in distribution of the current.
+
+
+
+
+CHAPTER XII
+
+BATTERY CHARGING DEVICES
+
+     The automatic plant most desirable--How an automobile lighting and
+     starting system works--How the same results can be achieved in
+     house lighting, by means of automatic devices--Plants without
+     automatic regulation--Care necessary--The use of heating devices on
+     storage battery current--Portable batteries--An electricity
+     "route"--Automobile power for lighting a few lamps.
+
+
+The water-power electric plants described in preceding chapters are
+practically automatic in operation. This is very desirable, as such
+plants require the minimum of care. It is possible to attain this same
+end with a storage battery plant.
+
+Automatic maintenance approaches a high degree of perfection in the
+electric starting and lighting device on a modern automobile. In this
+case, a small dynamo geared to the main shaft is running whenever the
+engine is running. It is always ready to "pump" electricity into the
+storage battery when needed. An electric magnet, wound in a peculiar
+manner, automatically cuts off the charging current from the dynamo,
+when the battery is "full;" and the same magnet, or "regulator,"
+permits the current to flow into the battery when needed. The
+principle is the same as in the familiar plumbing trap, which
+constantly maintains a given level of water in a tank, no matter how
+much water may be drawn from the tank. The result, in the case of the
+automobile battery, is that the battery is always kept fully charged;
+for no sooner does the "level" of electricity begin to drop (when used
+for starting or lighting) than the generator begins to charge. This is
+very desirable in more ways than one. In the first place, the energy
+of the battery is always the same; and in the second place, the mere
+fact that the battery is always kept fully charged gives it a long
+life.
+
+The same result can be achieved in storage battery plants for house
+lighting, where the source of power is a gasoline or other engine
+engaged normally in other work. Then your electric current becomes
+merely a by-product of some other operation.
+
+Take a typical instance where such a plant would be feasible: Farmer
+Brown has a five horsepower gasoline engine--an ordinary farm engine
+for which he paid probably $75 or $100. Electric light furnished
+direct from such an engine would be intolerable because of its
+constant flickering. This five horsepower engine is installed in the
+milk room of the dairy, and is belted to a countershaft. This
+countershaft is belted to the vacuum pump for the milking machine, and
+to the separator, and to a water pump, any one of which may be thrown
+into service by means of a tight-and-loose pulley. This countershaft
+is also belted to a small dynamo, which runs whenever the engine is
+running. The milking machine, the separator, and the water pump
+require that the gasoline engine be run on the average three hours
+each day.
+
+The dynamo is connected by wires to the house storage battery through
+a properly designed switchboard. The "brains" of this switchboard is
+a little automatic device (called a regulator or a circuit breaker),
+which opens and shuts according to the amount of current stored in the
+battery and the strength of the current from the generator. When the
+battery is "full," this regulator is "open" and permits no current to
+flow. Then the dynamo is running idle, and the amount of power it
+absorbs from the gasoline engine is negligible. When the "level" of
+electricity in the battery falls, due to drawing current for light,
+the regulator is "shut," that is, the dynamo and battery are
+connected, and current flows into the battery.
+
+These automatic instruments go still farther in their brainy work.
+They do not permit the dynamo to charge the battery when the voltage
+falls below a fixed point, due to the engine slowing down; neither do
+they permit the dynamo current to flow when the voltage gets too high
+due to sudden speeding up of the engine.
+
+Necessarily, an instrument which will take care of a battery in this
+way, is intricate in construction. That is not an argument against it
+however. A watch is intricate, but so long as we continue to wind it
+at stated intervals, it keeps time. So with this storage battery
+plant: so long as Farmer Brown starts his engine to do his farm chores
+every day, his by-product of electricity is stored automatically.
+
+Such installations are not expensive. A storage battery capable of
+lighting 8 tungsten lamps, of 16 candlepower each, continuously for 8
+hours (or fewer lamps for a longer time); a switchboard containing all
+the required regulating instruments; and a dynamo of suitable size,
+can be had for from $250 to $300. All that is necessary to put such a
+plant in operation, is to belt the dynamo to the gasoline engine so
+that it will run at proper speed; and to connect the wires from dynamo
+to switchboard, and thence to the house service. The dynamo required
+for the above plant delivers 10 amperes at 45 volts pressure, or 10 x
+45 = 450 watts. A gasoline, gas, or oil engine, or a windmill of
+1-1/2 horsepower furnishes all the power needed. If the farmer uses
+his engine daily, or every other day, for other purposes, the cost of
+power will be practically negligible. With this system electric lights
+are available at any time day or night; and when the gasoline engine
+is in service daily for routine farm chores, the battery will never
+run low.
+
+This system is especially desirable where one uses a windmill for
+power. The speed of the windmill is constantly fluctuating, so much so
+in fact that it could not be used for electric light without a storage
+battery. But when equipped with a regulator on the switchboard which
+permits the current to flow only when the battery needs it, and then
+only when the speed of the windmill is correct, the problem of turning
+wind power into electric light is solved.
+
+       *       *       *       *       *
+
+If the farmer does not desire to go to the additional expense of
+automatic regulation, there are cheaper plants, requiring attention
+for charging. These plants are identical with those described above,
+except they have no regulators. With these plants, when the battery
+runs low (as is indicated by dimming of the lights) it is necessary to
+start the engine, bring it up to speed, adjust the dynamo voltage to
+the proper pressure, and throw a switch to charge the battery. For
+such plants it is customary to run the engine to charge the battery
+twice a week. It is necessary to run the engine from 8 to 10 hours to
+fully charge the discharged battery. When the battery approaches full
+charge, the fact is evidenced by so-called "gassing" or giving off of
+bubbles. Another way to determine if the battery is fully charged is
+by means of the voltmeter, as the volts slowly rise to the proper
+point during the process of charging. A third way, and probably the
+most reliable is by the use of the hydrometer. The voltage of each
+cell when fully charged should be 2.5; it should never be discharged
+below 1.75 volts. Many storage battery electric light plants on the
+market are provided with a simple and inexpensive circuit breaker,
+which automatically cuts off the current and stops the engine when the
+battery is charged. The current is then thrown from the dynamo to the
+house service by an automatic switch. If such a circuit breaker is not
+included, it is necessary to throw the switch by hand when charging is
+begun or ended.
+
+Since the principal item of first cost, as well as depreciation, in a
+storage battery electric light plant is the storage battery itself,
+the smallest battery commensurate with needs is selected. Since the
+amount of current stored by these batteries is relatively small,
+electric irons and heating devices such as may be used freely on a
+direct-connected plant without a battery, are rather expensive
+luxuries. For instance, an electric iron drawing 400 watts an hour
+while in use, requires as much energy as 20 tungsten lamps of 16
+candlepower each burning for the same length of time. Its rate of
+current consumption would be over 13 amperes, at 30 volts; which would
+require a larger battery than needed for light in the average farm
+home.
+
+The use to which electricity from a storage battery is put, however,
+is wholly a matter of expense involved; and if one is willing to pay
+for these rather expensive luxuries, there is no reason why he should
+not have them. Heating, in any form, by electricity, requires a large
+amount of current proportionally. As a matter of fact, there is less
+heat to be had in thermal units from a horsepower-hour of electricity
+than from three ounces of coal. When one is generating current from
+water-power, or even direct from gasoline or oil, this is not an
+argument against electric heating devices. But it becomes a very
+serious consideration when one is installing a storage battery as the
+source of current, because of the high initial cost, and depreciation
+of such a battery.
+
+Farmers who limit the use of their storage battery plants to lighting
+will get the best service.
+
+
+_Portable Batteries_
+
+Abroad it is becoming quite common for power companies to deliver
+storage batteries fully charged, and call for them when discharged.
+Without a stretch of the imagination, we can imagine an ingenious
+farmer possessing a water-power electric plant building up a thriving
+business among his less fortunate neighbors, with an "electricity"
+route. It could be made quite as paying as a milk route.
+
+[Illustration: Connections for charging storage batteries on 110-volt
+mains]
+
+Many communities have water or steam power at a distance too great to
+transmit 110-volt current by wire economically; and because of lack of
+expert supervision, they do not care to risk using current at a
+pressure of 500 volts or higher, because of its danger to human life.
+
+In such a case it would be quite feasible for families to wire their
+houses, and carry their batteries to the generating plant two or
+three times a week to be charged. There are a number of portable
+batteries on the market suitable for such service, at voltages ranging
+from 6 to 32 volts. The best results would be obtained by having two
+batteries, leaving one to be charged while the other was in use; and
+if the generating station was located at the creamery or feed mill,
+where the farmer calls regularly, the trouble would be reduced to a
+minimum.
+
+Such a battery would necessarily be small, and of the sealed type,
+similar to those used in automobiles. It could be used merely for
+reading lamps--or it could be used for general lighting, according to
+the expense the farmer is willing to incur for batteries.
+
+An ordinary storage battery used in automobile ignition and lighting
+systems is of the 6-volt, 60-ampere type, called in trade a "6-60."
+Lamps can be had for these batteries ranging in sizes from 2
+candlepower to 25 candlepower. A lamp of 15 candlepower, drawing 2-1/2
+amperes, is used for automobile headlights, and, as any one knows
+after an experience of meeting a headlight on a dark road, they give a
+great deal of light. A "6-60" battery keeps one of these lamps running
+for 24 hours, or two lamps running 12 hours. A minimum of wiring would
+be required to install such a battery for the reading lights in the
+sitting room, and for a hanging light in the dining room. The
+customary gates for charging these batteries in a large city is 10
+cents; but in a country plant it could be made less.
+
+To charge such a battery on a 110-volt direct current, it is necessary
+to install some means of limiting the amount of current, or in other
+words, the charging rate. This charging rate, for 8 hours should be,
+as we have seen, one-eighth of the ampere-hour capacity of the
+battery. Thus a "6-60" battery would require a 7-1/2 ampere current.
+
+Connecting two such batteries in "series" (that is, the negative pole
+of one battery to the positive pole of the second) would make a
+12-volt battery. Ten or twelve such batteries could be connected in
+"series," and a 110-volt direct current generator would charge them in
+8 hours at a 7-1/2 ampere rate.
+
+The diagram on page 259 shows the connections for charging on a
+110-volt circuit.
+
+An ordinary 16-candlepower carbon lamp is of 220 ohms resistance, and
+(by Ohm's Law, C equals E divided by R) permits 1/2 ampere of current
+to flow. By connecting 15 such lamps across the mains, in parallel,
+the required 7-1/2 amperes of current would be flowing from the
+generator through the lamps, and back again. Connect the battery in
+"series" at any point on either of the two mains, between the lamps
+and the generator, being careful to connect the positive end to the
+positive pole of the battery, and _vice versa_.
+
+Lamps are the cheapest form of resistance; but in case they are not
+available, any other form of resistance can be used. Iron wire wound
+in spirals can be used, or any of the many makes of special resistance
+wire on the market. First it is necessary to determine the amount of
+resistance required.
+
+We have just seen that the charging rate of a 60-ampere hour battery
+is 7-1/2 amperes. Applying Ohm's Law here, we find that ohms
+resistance equals volts divided by amperes, or R = 110/7.5 = 14.67
+ohms. With a 220-volt current, the ohms resistance required in series
+with the storage battery of this size would be 29.33 ohms.
+
+
+_Automobile Power for Lighting_
+
+There are many ingenious ways by which an automobile may be utilized
+to furnish electric light for the home. The simplest is to run wires
+direct from the storage battery of the self-starting system, to the
+house or barn, in such a way that the current may be used for reading
+lamps in the sitting room. By a judicious use of the current in this
+way, the normal operation of the automobile in the daytime will keep
+the battery charged for use of the night lamps, and if care is used,
+such a plan should not affect the life of the battery. Care should be
+used also, in this regard, not to discharge the battery too low to
+prevent its utilizing its function of starting the car when it was
+desired to use the car. However, if the battery were discharged below
+its starting capacity, by any peradventure, the car could be started
+by the old-fashioned cranking method.
+
+Using an automobile lighting system for house lighting implies that
+the car be stored in a garage near the house or barn; as this battery
+is too low in voltage to permit transmitting the current any distance.
+One hundred feet, with liberal sized transmission wires is probably
+the limit.
+
+That such a system is feasible is amply proved by an occurrence
+recently reported in the daily papers. A doctor summoned to a remote
+farm house found that an immediate operation was necessary to save the
+patient's life. There was no light available, except a small kerosene
+lamp which was worse than nothing. The surgeon took a headlight off
+his car, strung a pair of wires through a window, and instantly had at
+his command a light of the necessary intensity.
+
+Another manner in which an automobile engine may be used for house
+lighting is to let it serve as the charging power of a separate
+storage battery. The engine can be belted to the generator, in such a
+case, by means of the fly wheel. Or a form of friction drive can be
+devised, by means of which the rear wheels (jacked up off the floor)
+may supply the necessary motive power. In such a case it would be
+necessary to make allowance for the differential in the rear axle, so
+that the power developed by the engine would be delivered to the
+friction drive.
+
+
+
+
+The following pages contain advertisements of Macmillan books by the
+same author or on related subjects.
+
+
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+
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+condition.
+
+[Illustration]
+
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+     quantities of water.
+
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+     high heads.
+
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+estimates on suitable type of Water Wheel for developing your water
+power to best advantage.
+
+  RODNEY HUNT MACHINE COMPANY
+  60 MILL STREET
+  ORANGE, MASSACHUSETTS, U.S.A.
+
+
+THE FARMER OF TOMORROW
+
+_Cloth, 12mo, $1.50_
+
+     "A crisp, entertaining, and instructive discussion of the
+     conditions which have brought about the present agricultural
+     problem in America."--_Countryside Magazine._
+
+     "The book is interestingly written and full of many vital
+     discussions."--_Annals of the American Academy of Political and
+     Social Science._
+
+     "A popular consideration of the fundamental factors affecting the
+     business of farming."--_Pacific Rural Press._
+
+     "The growing, popular question of farming analyzed from all angles,
+     with many helpful suggestions."--_Leslie's Weekly._
+
+     "Any person of intelligence, alive to the present and future
+     welfare of his country will find 'The Farmer of Tomorrow,' a book
+     of absorbing character."--_Times-Star._
+
+
+  THE MACMILLAN COMPANY
+  Publishers
+  64-66 Fifth Avenue
+  New York
+
+
+Cooperation in Agriculture
+
+By G. HAROLD POWELL
+
+_Cloth, 12mo, $1.50_
+
+     "The author has a broad outlook and never fails to suggest that the
+     economic advantages of cooperation may frequently be quite
+     subordinate to the general social and community interests which are
+     fostered through a common undertaking. He writes with the genuine
+     interest of a man having experience and faith in that of which he
+     speaks."--_Political Science Quarterly._
+
+     "A volume which explains in a lucid way the features of the
+     existing system and the measures taken by farmers to protect their
+     interests."--_Journal of the Royal Statistical Society._
+
+     "Mr. Powell has not attempted to cover the entire field of
+     agricultural cooperation, but has confined himself to its more
+     important phases. His work shows a grasp of the issues involved and
+     a ripeness of conclusion that comes only from actual contact with
+     the practical side of cooperation."--_American Economic Review._
+
+     "The book is decidedly worth while."--_Farm Life and Agriculture._
+
+  THE MACMILLAN COMPANY
+  Publishers
+  64-66 Fifth Avenue
+  New York
+
+
+RURAL SCIENCE SERIES
+
+Edited by L. H. BAILEY
+
+_Each volume illustrated. Cloth, 12mo._
+
+A series of practical books for farmers and gardeners, sold as a set
+or separately. Each one is the work of a competent specialist, and is
+suitable for consultation alike by the amateur or professional tiller
+of the soil, the scientist or the student. Illustrations of marked
+beauty are freely used, and the books are clearly printed and well
+bound.
+
+ON SELECTION OF LAND, ETC.
+
+  Isaac P. Roberts' The Farmstead                             $1 50
+  T. F. Hunt's How to Choose a Farm                            1 75
+  E. S. Cheyney and J. P. Wentling's The Farm Woodlot          1 50
+  Glenn W. Herrick's Insects Injurious to the Household        1 75
+
+ON TILLAGE, ETC.
+
+  F. H. King's The Soil                                        1 50
+  Isaac P. Roberts' The Fertility of the Land                  1 50
+  F. H. King's Irrigation and Drainage                         1 50
+  Edward B. Voorhees' Fertilizers                              1 25
+  Edward B. Voorhees' Forage Crops                             1 50
+  J. A. Widtsoe's Dry Farming                                  1 50
+  L. H. Bailey's Principles of Agriculture                     1 25
+  S. M. Tracy's Forage Crops for the South                     1 50
+
+ON PLANT DISEASES, ETC.
+
+  E. C. Lodeman's The Spraying of Plants                       1 25
+
+ON GARDEN-MAKING
+
+  L. H. Bailey's Garden-Making                                 1 50
+  L. H. Bailey's Vegetable-Gardening                           1 50
+  L. H. Bailey's Forcing Book                                  1 25
+  L. H. Bailey's Plant Breeding                                2 00
+
+ON FRUIT-GROWING, ETC.
+
+  L. H. Bailey's Nursery Book                                  1 50
+  L. H. Bailey's Fruit-Growing (New Edition)                   1 75
+  L. H. Bailey's The Pruning Book                              1 50
+  F. W. Card's Bush Fruits                                     1 50
+  W. Paddock & O. B. Whipple's Fruit-Growing in Arid Regions   1 50
+  J. E. Coit's Citrus Fruits                                  _Prepar_
+
+ON THE CARE OF LIVE-STOCK
+
+  Nelson S. Mayo's The Diseases of Animals                     1 50
+  W. H. Jordan's The Feeding of Animals                        1 50
+  I. P. Roberts' The Horse                                     1 25
+  M. W. Harper's Breaking and Training of Horses               1 75
+  George C. Watson's Farm Poultry. New edition                 1 50
+  John A. Craig's Sheep Farming                                1 50
+
+ON DAIRY WORK, FARM CHEMISTRY, ETC.
+
+  Henry H. Wing's Milk and Its Products. New edition           1 50
+  J. G. Lipman's Bacteria and Country Life                     1 50
+
+ON ECONOMICS AND ORGANIZATION
+
+  William A. McKeever's Farm Boys and Girls                    1 50
+  I. P. Roberts' The Farmer's Business Handbook                1 25
+  George T. Fairchild's Rural Wealth and Welfare               1 25
+  H. N. Ogden's Rural Hygiene                                  1 50
+  J. Green's Law for the American Farmer                       1 50
+  G. H. Powell's Cooperation in Agriculture                    1 50
+
+  THE MACMILLAN COMPANY
+  PUBLISHERS
+  64-66 Fifth Avenue
+  NEW YORK
+
+
+RURAL TEXT-BOOK SERIES
+
+Edited by L. H. BAILEY
+
+_Each volume illustrated. Cloth, 12mo._
+
+While the RURAL SCIENCE SERIES is designed primarily for popular
+reading and for general use, this related new series is designed for
+classroom work and for special use in consultation and reference. The
+RURAL TEXT-BOOK SERIES is planned to cover eventually the entire range
+of public school and college texts.
+
+  Duggar, B. M.
+    Physiology of Plant Production                     $1 60
+
+  Duggar, John Frederick
+    Southern Field Crops                                1 75
+
+  Gay, C. Warren
+    Principles and Practice of Judging Live-Stock       1 50
+
+  Harper, M. W.
+    Animal Husbandry for Schools                        1 40
+
+  Hitchcock, A. S.
+    Grasses                                             1 50
+
+  Livingston, George
+    Field Crop Production                               1 40
+
+  Lyon, T. L. and Fippin, E. O.
+    Principles of Soil Management                       1 75
+
+  Mann, A. R.
+    Beginnings in Agriculture                             75
+
+  Montgomery, G. F.
+    Corn Crops                                          1 60
+
+  Piper, Charles V.
+    Forage Plants and Their Culture                     1 75
+
+  Warren, G. F.
+    Elements of Agriculture                             1 10
+
+  Warren, G. F.
+    Farm Management                                     1 75
+
+  Wheeler, H. J.
+    Manures and Fertilizers                             1 60
+
+  Widtsoe, John A.
+    Principles of Irrigation Practice                   1 75
+
+  THE MACMILLAN COMPANY
+  Publishers
+  64-66 Fifth Avenue
+  New York
+
+
+The Rural Outlook Set
+
+By L. H. BAILEY
+
+_Four Volumes. Each, cloth, 12mo. Uniform binding, attractively boxed.
+$5.00 per set; carriage extra. Each volume also sold separately._
+
+In this set are included three of Professor Bailey's most popular
+books as well as a hitherto unpublished one,--"The Country-Life
+Movement." The long and persistent demand for a uniform edition of
+these little classics is answered with the publication of this
+attractive series.
+
+THE COUNTRY LIFE MOVEMENT
+
+_Cloth, 12mo, 220 pages, $1.25 postage extra_
+
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+country-life problem as distinguished from the city problem, known as
+the back-to-the-land movement.
+
+THE OUTLOOK TO NATURE (New and Revised Edition)
+
+_Cloth, 12mo, 195 pages, $1.25 postage extra_
+
+In this alive and bracing book, full of suggestions and encouragement,
+Professor Bailey argues the importance of contact with nature, a
+sympathetic attitude toward which "means greater efficiency,
+hopefulness, and repose."
+
+THE STATE AND THE FARMER (New Edition)
+
+_Cloth, 12mo, $1.25 postage extra_
+
+It is the relation of the farmer to the government that Professor
+Bailey here discusses in its varying aspects. He deals specifically
+with the change in agricultural methods, in the shifting of the
+geographical centers of farming in the United States, and in the
+growth of agricultural institutions.
+
+THE NATURE STUDY IDEA (New Edition)
+
+_Cloth, 12mo, $1.25 postage extra_
+
+"It would be well," the critic of _The Tribune Farmer_ once wrote, "if
+'The Nature Study Idea' were in the hands of every person who favors
+nature study in the public schools, of every one who is opposed to it,
+and most important, of every one who teaches it or thinks he does." It
+has been Professor Bailey's purpose to interpret the new school
+movement to put the young into relation and sympathy with nature,--a
+purpose which he has admirably accomplished.
+
+  THE MACMILLAN COMPANY
+  PUBLISHERS
+  64-66 Fifth Avenue
+  NEW YORK
+
+
+       *       *       *       *       *
+
+
+Transcriber's Notes:
+
+The square root symbol is indicated by sqrt(..)
+
+Exponents are indicated by ^
+
+Bold in a table is indicated by =..=
+
+
+
+
+
+End of the Project Gutenberg EBook of Electricity for the farm, by
+Frederick Irving Anderson
+
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