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+This eBook, including all associated images, markup, improvements,
+metadata, and any other content or labor, has been confirmed to be
+in the PUBLIC DOMAIN IN THE UNITED STATES.
+
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+Project Gutenberg (https://www.gutenberg.org) public repository for
+eBook #53893 (https://www.gutenberg.org/ebooks/53893)
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-The Project Gutenberg EBook of The Thompson-Houston System of Electric
-Lighting, by H. T. Cory
-
-This eBook is for the use of anyone anywhere in the United States and most
-other parts of the world 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. If you are not located in the United States, you'll have
-to check the laws of the country where you are located before using this ebook.
-
-Title: The Thompson-Houston System of Electric Lighting
-
-Author: H. T. Cory
-
-Release Date: January 5, 2017 [EBook #53893]
-
-Language: English
-
-Character set encoding: UTF-8
-
-*** START OF THIS PROJECT GUTENBERG EBOOK THOMPSON-HOUSTON SYSTEM--ELECTRIC LIGHTING ***
-
-
-
-
-Produced by The Online Distributed Proofreading Team at
-http://www.pgdp.net (This file was produced from images
-generously made available by The Internet Archive)
-
-
-
-
-
-
-
-
-
- The Thompson-Houston
- System of Electric
- Lighting.
-
- Thesis submitted for the degree of
- Bachelor of Science in Mechanical Engineering,
-
- to the Faculty of Purdue University
-
-
- June 1887
-
-------------------------------------------------------------------------
-
-
-
-
-“In its power to assume always that form of energy which happens to be
-the most useful lies the great importance of electricity.” This
-importance has been brought to the notice of the public by means of the
-many recent exhibitions. Public interest has been roused and there is
-everywhere a desire for information and a guide through this far
-reaching field for discovery and invention. And, although there are many
-works treating on electricity and electric light, people specially want
-a short and concise though thorough description of the various schemes
-by which electric light is produced. In this thesis the object is to
-give a brief treatise on one of the many schemes of producing light by
-electric currents viz—The Thomson-Houston System.
-
-In pursuing the subject of electricity, the first thing noticed is the
-analogy and difference between the dynamo and its older and more
-powerful rival the steam engine. The resemblances are, First as in the
-development of the steam engine, but few of the improvements and
-inventions in electrical machines were made by mathematical leaders.
-Watt ran across the idea of the seperate condenser while repairing the
-Newcomen model and applied the expansion of steam to the steam engine by
-a mechanical accident rather than by his own ingenuity, and so we find
-the first designers of the dynamo were mechanics rather than
-philosophers. Secondly the tendency to disregard old methods and
-instruments because of new discoveries and inventions has, as in the
-steam engine, hindered the advancement in electrical science. As an
-example it has become customary to regard frictional and statical
-electric machines, for practical purposes, as obsolete, but recent
-discoveries seem to hint that they may yet be utilized. Lately Prof.
-Dodge has shown that dust and vapor whirling in the air may be settled
-by a discharge of electricity consisting of a continuous series of
-electric sparks. This has been utilized to clear the atmosphere in lead
-smelting works from the fumes of volatized lead and with its application
-comes the invention of Wimhurst which produces with a minimum of
-mechanical labor a continuous series of electric sparks and works
-admirably.
-
-The differences between the engine’s and dynamo’s developement are:
-_First_ the marvelously rapid developement of the dynamo as compared
-with that of the steam engine. Since 1867 when the term “dynamo electric
-machinery” even to scientific men had but little signification, the
-dynamo has been brought to a very high degree of perfection. _Secondly_,
-the development of the dynamo has reached a much higher degree of
-perfection than that of the steam engine. Among the best steam engines
-twenty per cent effeciency is considered as very good while a good
-dynamo gives out in the form of electricity, ninety per cent of the
-mechanical energy put in it. But the class of people who improved and
-made the steam engine what it is were as well educated in one sense as
-were the men who brought out the dynamo. While it is true that in Watt’s
-time the knowledge concerning steam was very meagre, yet the practical
-men who _made_ the dynamo, did it by themselves as nearly all the
-teachers of electricity knew nothing except what may be called
-electrical tricks. As has been said[1] “The teachers and writers of
-textbooks, practically did not know that there was anything in common
-between the electricity from a rubbed glass machine and voltaic
-electricity, or to be brief, that there was a science of electricity as
-distinguished from mere natural history.” In fact as late as 1870 there
-were really no textbooks on electricity. Even now electrical knowledge
-is so meagre as to warrant the same writer’s expression, “We can not
-imagine a mechanical engineer mistaking a few inches for a few miles or
-a grocer compounding an ounce of sugar with a carload, but this gives
-too truthful an idea of the vagueness that still exists.”
-
-In the distant future, electricity will be used for electric lighting
-only as subordinate to other uses to which it may be applied such as
-heating houses, taking place of stoves for cooking, being used as a
-substitute for the steam engine. In fact the motor is rapidly becoming
-of as much practical use as the electric light. The principle of the
-motor is just this; a certain amount of mechanical energy say thirty
-four horsepower per minute into the form of electric currents, which by
-the way gives enough current to run 45, 2000 candle power lamps, send
-the current and distance through suitable conductors and attach them to
-similar dynamo or dynamos but in such a manner that the current in the
-second set of dynamos flows in the reverse direction to that of the
-first; when, the armature of the second dynamo or dynamos will revolve
-and at the pulley or pulleys of the dynamos, aside from friction, will
-be given out 95% of the thirty-four horsepower, the loss being due to
-the resistance of the conductors. Now in practice a motor is placed on
-the arc light circuit the same as a lamp, for energy less than twelve
-horsepower. It does not affect the lights and is a clean, neat way of
-obtaining energy.
-
-But however true the foregoing may be, the greatest present use of
-electricity is to start and maintain light. There are several so-called
-systems, embracing dynamos, lamps, regulators, etc, from which I select
-the Thomson-Houston as the one for the purpose of describing for several
-reasons, _first_, it is at least as good as the average system of which
-there is a mushroom growth; _second_, valuble information was kindly
-offered by the parent Company; _third_, a good plant is near to which
-free acess was given, and _fourth_, we have at the Mechanical Hall of
-this University, a dynamo, loaned by the parent Company, which affords
-information without any inconvenience. As each part of the system comes
-up to be described a little of its history will be given. As the first
-part of a system necessary to be produced is the current generator we
-will first describe
-
-
-
-
- _The Thomson-Houston Dynamo._
-
-
-In considering the current generator the first thing to be decided upon
-is the definition of the term dynamo. The following is thought to be a
-correct definition,—A dynamo or dynamo electric machine is a machine
-which is used to convert energy in the form of mechanical motion into
-energy of electric currents, or _vica-versa_. Those used to generate
-currents of electricity are called dynamos, those used to generate
-mechanical motion are known as motors.
-
-In attempting to make clear the theory of the dynamo, we will recall
-some simple experiments. In Fig. 1, send a current around B from right
-to left. Now A being free to move vertically either up or down, connect
-its binding posts to a _galvanometer_ (that is, an instrument used to
-tell the direction of a current and also used to test the _relative_
-strength of two or more currents) and move A up suddenly when a current
-will be generated in A whose direction will be the same as that of the
-current in B. Now this current is not created energy, because in
-lifting[2] the coil A, work is expending against the attraction between
-the coils, as between two currents flowing in the same direction there
-is an attraction. If we pursue this experiment in its various forms we
-will find the following statement known as Lentz law is true, viz: “If
-the relative positions of two conductors A and B be changed of which B
-is traversed by a current, a current is induced in A in such a direction
-that by its electro dynamic action on the current in B it would have
-imparted to the conductor a motion of the contrary kind to that by which
-the inducing action was produced.”
-
-The theory of this law is that around every wire carrying a current
-there is a magnetic whirl (Fig. 3). Now if the conducting wire be passed
-through a hole in a horizontal plate of glass and iron filings be sifted
-upon the latter they will arrange themselves, as shown in Fig. 2., along
-lines, radial in this case, known as lines of force, which arranging is
-due to the magnetic attraction of the current in the wire upon the iron
-filings. Now in B. Fig. 1, every portion of the wire has just such a
-whirl and just such lines of force, or magnetic field, and when A is
-moved each part of the wire of A cuts one or more lines of force of the
-many magnetic fields making up the magnetic field of the entire coil B.
-Now when the wire of coil A cuts magnetic field of B a current is
-generated in A acording to the following statement known as Faraday’s
-Law; “When a conductor in a field of force moves in any way so as to cut
-the lines of force there is an electromotive force produced in the
-conductor in such a direction that supposing a figure swimming in the
-conductor to turn to look along the positive direction of the lines of
-force (in Fig. 1, toward axis of B), and the conductor be moved to his
-right, he will be swimming with the current so induced.” Hence in Fig.
-1, the current generated in it will be from left to right.
-
-Practically Faraday’s principle means just this: by moving a wire across
-a space where there are magnetic lines, the motion of the wire as it
-cuts the magnetic lines sets up around the cutting wire a magnetic whirl
-or in other words sets up a current in that wire.
-
-The foregoing laws are the “principles of the dynamo,” yet after their
-deduction, the progress of the evolution of the dynamo was slow and
-attended by many dificulties. Between 1860 and 1870 however, a working
-knowledge of these laws became the property of thousands of mechanics,
-and by comparing the number of inventions before and after that date
-(1860) the present generous growth of systems, dynamos and lamps, prove
-that inventions were almost in proportion to the number of people who
-had any electrical knowledge. In 1866 Wilde produced a toy
-magneto-electric machine for giving shocks, in which he used excited
-electromagnets. In the same years Varley and others produced a machine
-which excited its own field magnets the type of all machines used in
-practice. With this principle of Varley’s and Pacinnotti’s ring, Gramme
-produced in 1871 his since famous continuous current generator, one of
-which the second dynamo electric machine ever brought to this country
-can now be seen at the engine house at Purdue University. In 1877 Silas
-Brush brought out his famous dynamo and it may be interesting to know
-that he designed and had one made without experimenting in the least. In
-the following year a patent was issued to Messrs. Elihu Thomson and
-Edwin J. Houston, Professors of electricity in Philadelphia on the
-present though much improved _Thomson Houston Dynamo._
-
-[Illustration:
-
- _Fig. 1._
-
- _Fig. 2._
-
- _Fig. 3._
-
- _Fig. 4._
-
- _Fig. 5._
-
- _Fig. 6._
-
- _Fig. 7._]
-
-To go back to Lentz and Faraday’s laws and carefully consider them we
-can but assent to S. P. Thompson’s “fifteen propositions on the dynamo”
-which are:—1. A part of the energy of an electric current exists in the
-form of a magnetic whirl surrounding the wire.
-
-2. Currents may be generated in a wire by setting up these whirls.
-
-3. We can set up these whirls by increasing or decreasing the relative
-distance between magnets and wires.
-
-4. To set up and maintain these whirls consumes power.
-
-5. To induce currents in a conductor there must be motion between them
-so as to alter the number of lines of force (Fig. 4 to 7).
-
-6. Increase in the number of lines of force in the circuit produces a
-current of the opposite sense to decrease (Fig. 7).
-
-7. Approach induces electromotive force in the opposite direction to
-that induced by retreat.
-
-8. The stronger the magnetic field the stronger the current.
-
-9. The more rapid the motion the stronger the current.
-
-10. The greater the length of the conductor which cuts lines of force
-the stronger the current.
-
-11. The shorter the conductor not so employed the stronger the current.
-
-12. Approach being a finite process the approaching and receeding must
-give alternating directions to the current.
-
-13. By the use of a commutator all the currents can be turned in the
-same direction.
-
-14. In a steady circuit it makes no difference what kind of magnets are
-used to procure the requisite magnetic field whether permanent or
-electromagnets.
-
-15. Hence the current of the generator may be used to excite the
-magnetism of field magnets.
-
-Now the Thomson-Houston dynamo comes under that class of dynamos in
-which there is a rotation of coils in a uniform field of force, such
-rotation (Fig. 6.) being affected round an axis in the plane of the
-coil. Of course this dynamo is made like all others of its class to have
-_first_, as powerful field-magnets as possible, _second_, the armature
-or rotating coil has as great a lenght of wire in it as possible the
-wire being thick to offer little resistance and _third_, built to stand
-high rotative speed.
-
-The simple theoretical dynamo is shown at Fig. 8, consisting of a single
-rectangular loop of wire rotating in the magnetic field formed by large
-magnets, and in order to take the current so generated from the loop so
-as to give a continuous current, we use a two part commutator (Fig. 9)
-consisting of a metal tube split in two and mounted on wood, each half
-connected to one end of the loop. The current is taken off by brushes
-which lead to the main circuit. But manifestly this dynamo would give no
-appreciable current becase it has a very small length of wire on the
-armature, so a great number of loops were used which at present
-constitute the so-called _drum armature_.
-
-We may rotate the loops of wire in Fig. 8, on one of its sides as an
-axis or even push it farther from the center of revolution than that. To
-do this, wrap the wire around a ring and connect both ends to a two part
-commutator (Fig. 10). If instead of the ring in Fig. 10, being solid it
-be a number of coils of wire and if instead of there being one coil
-around the ring there be thirty we will have Pacinnotti’s ring before
-spoken of. If we used four to ten coils or “bobbins” of large size which
-is shown diagramatically at Fig. 11, we would have the Brush dynamo.
-
-So with exceptions we may say that there are practically two types of
-dynamos as regards armatures, the _ring_ type as Brush, Pacinnotti’s
-Gramme, and the _drum_ armature (page 20).
-
-The Thomson-Houston dynamo is like the rest of that dynamo, unique. To
-quote S. P. Thompson; “The Thomson-Houston spherical armature is unique
-among armatures, its cup shaped field magnets are unique among field
-magnets, its three part commutator is unique commutators.”
-
-[Illustration:
-
- _Fig. 8._
- Simple Dynamo.
-
- _Fig. 9._
-
- _Fig. 10._
-
- _Fig. 11._
-
- _Fig. 12._
-
- _Fig. 13._]
-
-An armature of a dynamo is the rotating coil or coils which generates
-currents of electricity by moving in a magnetic field of force. It is
-the most important part of a dynamo as it is literally the current
-generator. So we first consider the Thomson-Houston
-
-
-
-
- _Armature_
-
-
-It is spheroidal in shape as is noted for the fact of its very seldom
-_burning out_, i. e., the electricity heating the wires of the armature
-to such an extent as to destroy the insulation or fuse the wires, either
-rendering the armature useless. It is made by keying two dish-shaped
-iron disks _SS_ Fig. 12, to the shaft x and putting ribs _dd_ about ten
-in number in the twenty-five light machine, and over the whole putting
-varnished paper. Then at stated intervals, pegs JJJ are driven into
-suitable holes in the disks and ribs to help in winding wire on the
-shell. Next three insulated wires of equal length are joined together at
-_h_ Fig. 13, and the three wires are then wound over the shell in the
-following peculiar manner: one half of No. 1 is wound so as to form a
-zone of a sphere of which the shaft is in the same plane as the center
-circumference of the zone. The armature is then turned on the shaft as
-an axis 120° and one half of No. 2 is wound in the same manner as the
-first half of No. 1. The armature is moved 120° more and all of No. 3 is
-wound. The armature is then turned back, 120° on the shaft as an axis
-and the remainder of No. 2 is wound. Lastly the armature is turned back
-120° more and the rest of No. 1 is wound. They are bound by wires _gg_
-Fig. 13 to hold them when rotating. The object of this rather
-complicated winding is to get the three coils equi distant from the
-shaft in order that each coil will generate practically the same
-current. Now as will be seen the overlapping wires will form a nearly
-spherical armature. The armature is mounted on the shaft _x_ as an axis
-which extends far enough out from its bearings to put a pulley on the
-end _H_ and a commutator on the other end to the three parts of which
-are fastened the three wires marked one, two, three, Fig. 13.
-
-It has been urged that the repairs of this armature will be larger than
-on any other armature. If there should be a “burnout” it would
-necessitate the taking apart of the dynamo and sending the armature to
-the factory to be rewound. But it never burns out except through
-positive carelessness and it will be found that the repairs on this
-armature is less than on the armatures of its several powerful rivals
-taken separately even though they be of simpler construction.
-
-When the Thomson-Houston armature is rotated between the cup-shaped
-fieldmagnets alternate currents are generated in each coil in turn and
-now the next point to be considered is the
-
-
-
-
- _Commutator_
-
-
-which incites the alternate currents so formed into one continuous
-current. The commutator as before stated is fastened on the shaft at the
-end one, two, three Fig. 13. It consists of three copper plates in the
-form of a cylinder each segment _A´A´A´_ covering 115° of the dotted
-circle Fig. 14. They are screwed to rod _CCC_ and _DDD_ which are
-insulated by wood and gutta-percha plates _EE_ from the iron mounting
-_E´´_ which is in turnescrewed to shaft by set screws shown. The wires
-one, two, three, have respectively red, white and blue insulation and
-are put in binding posts _DDD_ marked one, two, three at the factory and
-if not so placed may work badly. The current enters _D_ goes to _B´B´_
-which there have direct contact with _A_.
-
-[Illustration:
-
- _Fig. 14._
- Half Sec. A.B.
-
- _Fig. 15._ _Air blast Nozzles._
-
- _Fig. 16._ _Air blast Mechanism._
-
- _Fig. 17._ _Section of Dynamos._
- Spherical Armature in Fig. 13.]
-
-Now in a three-part commutator the spark occurring as the segments pass
-under the brushes would very quickly destroy the surface and interfere
-with the currents in the coil. This difficulty is overcome by blowing
-out the spark by an air blast given at just the right place and time.
-The manner in which the blast is delivered is as follows: the segments
-of the commutator
-
-are separated by gaps of about 5° and in front of each of the leading
-brushes there projects a nozzle, Fig. 15, which discharges an air blast
-alternately three times in each revolution. The blast itself is supplied
-by an ingenious piece of mechanism known as the
-
-
-
-
- _Thomson Air Blast_.
-
-
-It consists of an elliptical box II whose sides have perforations II
-where air can enter while inside of this rotates a steel disk keyed to
-the armature shaft and having radial slots in which slide three wings
-RRR of ebonite which as they fly around drives air into the holes JJ
-leading to the nozzles Fig. 15. The result is that, since the spark is
-done away with, oil can be supplied to the commutator in limited
-quantities but still amply sufficient to reduce the wear on the
-commutator to such an extent that the life of a segment is greatly
-increased. The air blast is fastened to the dynamo frame just behind the
-commutator and can be see in Fig. 23.
-
-
-
-
- _The Field-Magnets_,
-
-
-as may be seen from Fig. 17, consists of two flanged iron tubes _AA_
-whose end consists of a convex segment of a sphere accurately turned to
-recieve the armature. Coils of wire _CC_ which are in the outside
-circuit and through which the entire current flows are wound upon the
-tubes. After the armature is placed between them the two tubes are
-bolted together by heavy wrought iron bars _BB_ and the whole carried on
-the frame work _PN_ shown also at _PN_ Fig. 23. Now a little magnetism
-only remains in the wrought iron bars and iron frame works when the
-armature first revolves, but the current even though slight, going
-through the coils makes an electromagnet out of each tube and heavily
-magnetizes the wrought iron bars and in two or three seconds after the
-armature first rotates it is entirely surrounded by a heavy magnetic
-field. One of the good points of these field magnets is that but very
-little magnetism is lost as compared with most other dynamos and since
-it takes power to maintain a heavy magnetic field, this dynamo is in
-this respect very economical.
-
-
-
-
- _The Thomson Regulating Gear_
-
-
-Later on we will show that pushing the brushes together or pulling them
-apart alter the strength of the current, but for the present just accept
-the fact and we will show how the brushes are varied. It is accomplished
-by the mechanism shown in Fig. 18. The brushes are fixed to the levers
-YY and Y_{2}Y_{2} united by the lever _l_. The automatic movement is
-obtained by the electromagnet _R_ while a dashpot _J_ prevents too
-sudden motion. Suppose the brushes to be in the position shown when the
-current would get too strong owing to lights being cut out. The
-electromagnet R getting stronger would raise _A_ and reduce the current
-taken off until current came to normal. If, instead, some lamps were
-thrown in the current would become weak and the electromagnet _R_ would
-become weak, drop A which would increase current and this will continue
-till current reaches normal.
-
-The foregoing regulating gear is used on small dynamos and old style
-large ones. On the large new style dynamo a more delicate regulating
-gear is used, the current which operates it being shown at Fig. 19.
-Normally the electromagnet _R_ is short circuited by the wire _r_ and
-only acts when this circuit is broken. At some point in the main circuit
-is a _wall controller_ or _controller magnet_ shown in Fig. 19, at ST,
-consisting of two electro magnet, Their yoke supported by a spring and
-the yoke operating the contact lever S. If the current becomes too
-strong the controller magnet circuit is broken and all the current of
-the main circuit goes through the electromagnet _R_ which by its sudden
-increase of strength quickly raises _A_ and thus alters the brushes.
-This only exists for a moment until the yoke of the controller magets
-fall because of their decrease of magnets strength, when current again
-flows through wire _r_ because when yoke drops contact is made. This
-decreases the strength of electro magnet _R_ thus dropping _A_ and
-increasing current. Hence _S_ will again raise and break contact and _R_
-again rais _A_. This is continually repeated.
-
-
-
-
- _The Brushes_,
-
-
-of which there are four in use on all machines, are made of a broad
-strip of springy copper having six slits two thirds the distance up, and
-thus touching at several points. They are held by clamps shown at Fig.
-23 which also shows the brushes. The brushes are held to the commutator
-by their own springiness and the variation of position due to strength
-of current. The brushes are set by a gauge sent with each dynamo which
-shows length from the end of brush to the holder. The holders are set at
-the correct angle by a gauge of brass of the shape of a right angled
-triangle the short side having a wide flange curved to fit the
-commutator for which it is sent, while the second side as regards length
-must fit to the holder when swung to it on the commutator as an axis.
-
-After describing the details of the dynamo, we will at once proceed to
-find how the
-
-
-
-
- _Thomson Houston Dynamo Operates._
-
-
-In the diagram Fig. 19 the rotation is as in practice against the hands
-of the watch when seen from the commutator end of shaft. The three coils
-of the armature are represented by three lines _A_, _B_, _C_, united at
-their inner extremities each being joined to a segment of the
-commutator. There are two positive brushes _P_ and _F_ and two negative
-ones _P´_ and _F´_. The current delivered to _P_ and _F_ goes round one
-of the field magnet coils, then to the outer circuit consisting of
-regulating gear, lamps, motors, etc., through the other field magnet
-coil to brushes P´ and F´. Now from Fig. 20, we observe that supposing
-the loop to be rotating against the hands of the watch in a magnetic
-field the diagram represents by arrows the direction of the
-electro-motive forces induced in those loops. The action is a maximum
-along the line of the resultant magnetic field m m´ and the minimum
-along the line n n´ which is at right angles to m m´. The reason that
-m m´ is not horizontal is that the induced poles of the armature is in
-advance of the poles of the field magnet and is constantly tending to be
-drawn back. Applying Fig. 20 to Fig. 19, we see that there will be an
-outward current in _B_, an inward one in _C_, _A_ generating no current
-for that moment.
-
-Now the following pair of brushes _F F´_ are shifted backward three
-times as far as _P P´_ is shifted forwards. When the current is the
-greatest possible the brushes P and F and P´ and F´ are 60° apart thus
-leaving _P_ and _F´_ and _P´_ and _F´_ just 120° apart and since the
-segments of the commutator are each 120° in length[3] there will always
-be two coils in parralel with one another and in series with the third.
-Taking one sixth of a revolution and continuing all the way round we
-find the following tabulated statement showing brushes in contact with
-coils, to be true viz:—
-
-
- { P - C } { P´ }
- From external circuit { } B { } to external circuit
- { F - A } { F´ }
-
- { P } { P´ - B }
- ” “ ” { } A { } ” “ ”
- { F } { F´ - C }
-
- { P - A } { P´ }
- ” “ ” { } C { } ” “ ”
- { F - B } { F´ }
-
- { P } { P´ - C }
- ” “ ” { } B { } ” “ ”
- { F } { F´ - A }
-
- { P - B } { P´ }
- ” “ ” { } A { } ” “ ”
- { F - C } { F }
-
- { P } { P´ - A }
- ” “ ” { } C { } ” “ ”
- { F } { F´ - B }
-
-
-Now suppose the current to become to strong owing to any cause, the
-following brushes are made to recede. This can but shorten the time that
-the brushes are in contact with the commutator when the coil is passing
-through that position in which it is generating the maximum amount of
-current and also hasten the time when it goes into parralel with a
-comparatively idle coil. If the current is to weak then the brushes are
-made to close up thus reducing the time that the most active coil is in
-parralel with one less active and also makes the brushes be longer in
-contact with the segment when the coil is generating its maximum amount
-of current. The motion of advance and retreat of the brushes is
-accomplished by the _Thomson Regulating Gear_ before described. On Fig.
-23 can be seen all the dynamo’s details except the _Controller magnet_.
-
-[Illustration:
-
- _Fig. 18._
-
- _Fig. 19._
-
- _Fig. 20._
-
- _Fig. 21._
-
- _Fig. 22._]
-
-As regards the _Thomson-Houston Dynamo_ it will be found to produce the
-steadiest and most uniform current of any dynamo now in use. It
-regulating gear is the simplest and most natural one ever used. In its
-ability to reduce the current simaltaneously to one tenth of its former
-quantity inside of one or two minutes _without injury to itself and
-lamps_ it stands alone, in practice.
-
-
- _Fig. 23._
-
-
- Your engraving representing “_Dynamo
- Electric Machine with Thomsons Spherical
- Armature_”
-
- —Taken from one of your catalogues, and
- pasted on a sheet of this paper—
-
-In a system the most important thing next to the dynamo is the lamps.
-The first experimenter who produced an electric glow was Otto von
-Guericke. But neither the glow nor electric spark have been used to
-produce electric light for practical purposes, this was left to the
-voltaic arc on the one hand and the incandescent lamp on the other. Davy
-in 1800 mentions experiments in which electric light was obtained by
-electric sparks between two carbon points. He showed the arc[4] light
-for the first time in 1810 at the Royal Institute, which with Foucalt’s
-hand regulator (1844) Deleuil lit the Place de la Concorde, Paris.
-Thomas Wright in London (1845) devised the first apparatus which
-automatically adjusted the carbons. W. C. Staite used the electric
-current for the regulation of the carbons in 1848. In 1855 Serrin
-constructed a lamp which would have been used on a large scale had it
-not been for the cost of generating electricity. In 1876 Paul
-Jablochkoff invented his electric candles and in 1881 there were 4000 in
-use, but as their use increased their defects were found out. Regulated
-lamps were again brought into use and with them experimenters again
-endeavored to solve the problem of dividing the electric light. In 1877
-Tschikoliff solved the problem in a very simple manner. He reasoned
-that, if the current be divided and part go through the carbons and make
-the arc and the rest go through an electromagnet and regulate the arc
-and the the current unite and when another light is wanted the current
-be again divided and reunited, the current may be divided any number of
-times and the scheme work nicely. When put in practice it worked very
-nicely and is used on most lamps at present. Suppose there be a lamp
-placed in the circuit. The current divides and the larger half goes
-through the carbons, as here there is no resistance as the carbons
-touche, while the remainder, going through a spiral of high resistance,
-is small. When the carbons burn away a little the arc is formed and the
-resistance increasing brings the regulating gear into operation. Now the
-strength of the current is the same after it has gone through the lamp
-as before because the current is going to get through either one way or
-the other, hence any number of lamps may go on in series, depending only
-upon the tension of the current.
-
-Incandescent lamps were produced as early as 1859 but not till 1879 when
-Swan, Edison, Sawyer and others were they ever in a practical form. The
-first glow lamp Edison constructed had platinum wire to be heated. He
-however examined the properties of organic substances and finally fixed
-on bamboo fibre. The bamboo is divided into fibres one millimeter in
-diameter and twelve millimeters long. These fibres are pressed in
-U-shaped moulds and baked in ovens where they are allowed to become
-carbonized. The carbonized filament is attached to platinum wires which
-are fused in a glass vessel from which the air has been exhausted. We
-will speak more fully of the incandescent lamp when describing the
-Thomson Houston System’s incandescent lamp.
-
-The Thomson Arc lamps was used by the Thomson Houston System since its
-begining till about two years ago when they stopped manufacturing them,
-only furnishing broken parts. The arc lamps at present used is
-
-
-
-
- _The Thomson Rice Arc Lamp._
-
-
-They are manufactured in two styles the single lamp used for stores,
-buildings etc., and the double lamp used for street service, all night
-work, etc. The light is produced by the voltaic arc between two carbons,
-the negative pole or lower carbon burning away about half as fast as the
-positive pole or upper carbon. The outside view of the single lamp is
-seen in Fig. 21 and of the double lamp in Fig. 22.
-
-The regulation of the double lamp is diagramatically shown in Fig. 24,
-which is a plan of the lamp with cover removed, showing only a plan of
-cylindrical part of the lamp. The wires marked _a b c d_ run along the
-top in order to be out of the way. In Fig. 24 the current comes in at
-the binding post and is at _A_ divided into three currents _A_, _B_, and
-_C_. The current _a_ goes to the yoke _I_ of the electromagnets _h_ and
-_i_ and when the yoke is not held down by magnets _h_ and _i_, it goes
-out wire _a_ to binding post _B_. This only continues a moment until the
-current _b_ which goes through the carbons and at the start has almost
-no resistance offered it, attracts the yoke _I_ thus breaking contact of
-curcuit _a_ until the current ceases or till both carbons burn away,
-when in the latter case the resistance of _b_ becoming very high as
-compared to _j_ and _k_ but little current goes through _h_ and _i_ and
-_I_ is raised by a weak spring not shown, thus making contact of circuit
-_a_, and since current _a_ has little resistance as compared to _b_ or
-_c_ most of the current goes through it, thus practically making a
-cut-out. The current _b_ goes round the electro-magnets _h_ and _i_,
-then to the “bed” through screw J, the “bed” being a cast iron bottom of
-the cylinder _E_ Fig. 22. From the bed it goes down carbon holder _C_
-(or _H_) through carbons and arc to frame bed _A_ Fig. 22. From there it
-comes up a wire by the side of frame _C_ Fig. 22 and joins other
-currents at _B_. The third current _a_ goes through electromagnets _j_
-and _k_ and joins other currents at _B_.
-
-This is when switch F Fig. 22 and _M_ Fig. 24, is turned _on_. Now since
-the dynamo will regulate all differences in current the lamps can be
-turned _on_ or _off_ at will by any one. This is accomplished at the
-lamp by turning _off_ the switch. When the switch is turned _off_, the
-current goes through _d_ to screw _K_ which is then touched by metal L
-(in contact with binding post B and worked by _M_).
-
-It will be perceived that any disorder in a lamp cannot affect other
-lamps in the circuit and will right itself or if not the lamp can
-immediately be switched out of circuit.
-
-Now as to the regulating gear. The two carbon holders are held up, _H_,
-by clutch operated by springs (not shown) till end _N_ of lever _ON_ is
-permanently held down, and _C_, by the raising and falling of yoke _D_.
-There is only _one_ arc burning at a time in a double lamp and the
-so-called positive carbon _C_ burns first. When the lamps are trimmed
-the switch is first turned _off_ the carbons put in and the switch
-turned _on_. This will draw the upper carbons up about a quarter of an
-inch.
-
-When the current is turned on the circuit _aa_ is almost instantly
-broken and most of the current goes through _c_ as the distance between
-carbons being a quarter of an inch the arc has a _very_ large
-resistance. The electromagnets _j_ an _k_ attract _D_ which lets loose
-_C_, which falls to lower carbon, and the resistance being almost
-nothing, most of the current goes through _b_. This weakens _j_ and _k_
-which lets _D_ up while _D_ takes _C_ up with it thus establishing the
-arc. The current _all_ goes down _C_ till the enlarged end of _C_
-strikes lever _ON_ thus letting _H_ drop and also putting it in
-electrical contact with “bd,” which it was not in before.
-After a short time the carbons burn away, the arc becomes longer and
-establishes itself and the resistance becoming greater in passing from
-carbon to carbon and a correspondingly less current flows through _b_
-and a greater one through _c_. This makes the electro-magnets _j_ and
-_k_ strong enough to draw _D_ to them in spite of spring _Q_. When _D_
-is attracted by _j_ and _k_, _C_ (or _H_) falls and again the arc
-lengthens, always being kept about 3/32 inch long. This is frequently
-and continually repeated, the delicacy depending upon the strengh of the
-spring _Q_ as compared to the electromagnets strength.
-
-[Illustration: _Fig. 24._]
-
-When the carbon in carbon holder _C_ burns to a length of about two
-inches in attempting to fall to maintain arc’s length, an enlarged port
-at the top of the carbon holder _C_ strikes and holds down lever _ON_
-pivoted at _O_ (and end _N_ held up by a spring _P_) thus letting loose
-a clutch by which electrical contact is made between _H_ and “bed” and
-letting _H_ fall till it touches lower carbon when an arc is established
-and regulated just as for _C_.
-
-The Thomson-Rice single lamp has the same gear with the exception of
-having only carbon holder _C_, _H_, lever _ON_, and spring clutch and
-spring _P_ being absent. The single lamp will burn eight hours and the
-double lamp fourteen hours continuous running.
-
-These lamps are intended only for a steady current and will not cut out
-of circuit if the current gets too strong. But with the Thomson Houston
-dynamo the current never gets too strong and because of this there are
-less power absorbing mechanism and as anything’s functions decrease the
-remaining functions are increasedly better. As the Thomson-Rice lamp has
-less functions and power consuming machinery, it can but be the most
-economical, delicately adjusted and steadiest lamp extant. They are made
-to stand a current of five amperes above the normal current for a short
-time, as, when forty lights are simultaneously cut out of a forty-five
-light circuit, the current runs up about four amperes above the normal
-current for about one half a minute.
-
-Prof. Thomson has gotten out a divided arc lamp which supplies a light
-of moderate candle power for locations where a 2000 candle power lamp
-gives more light than can be economically utilized. It is specially
-suited for factory and mill use where looms or other tall machines are
-liable to cast disadvantageous shadows. It is said that these lights are
-supplied cheaper per candle power than the standard lamp and up to date
-is sucessful.
-
-He has also arranged apparatus by which arc lamps are run in multiple
-series, series or multiple arc. It is said that divisions, redivisions
-and reunions are practicable. This is also sucessful as far as we can
-find out.
-
-
-
-
- _The Sawyer-Man Incandescent Lamps._
-
-
-As before stated Edison fixed upon carbonized filament of bamboo. The
-Sawyer-Man company however applied for a patent on carbonized filament
-for incandescent lamps on January 19^{th} 1880, and after five years
-litigation with Thos. A. Edison they were granted a patent No. 317,676,
-on May first, 1885, covering their invention. The Sawyer-Man lamp Fig.
-25, consists of a carbonized connected to platinum wires fused in a
-glass tube from which all the air possible had been extracted. The light
-is produced by the glow of the filament and heat of gases given from
-filament. The life of a lamp is from 1000 to 1500 hrs. and requires a
-current of 1¼ to 1.3 amperes and give 20 to 25 C.P. When the filament
-becomes brittle and breaks the tube is unscrewed from the key Fig. 26,
-and a new one screwed in. They are run on the arc light circuit by the
-use of an individual distributor Fig. 27 which consists of a brass case
-containing a magnet in the circuit of the lamps and a resistance coil
-automatically substituted in case the lamp should break or is turned off
-by key Fig. 26. The scheme of arranging lamps so as to get the right
-current is shown at Fig. 28. the number of lamps in a group depending on
-the current.
-
-Prof. Thomson has gotten out a lamp Fig. 29 in two styles one for 6.8
-amperes current and one for 10 amperes current. Three lamps of different
-candle power, due to different potential differences at binding post of
-lamp, are use on the same current. The method of connecting them is
-shown in Fig. 30. It will be perceived that the lamps carry the full
-current yet have a life of 1000 hrs. or more. This is a great invention
-indeed doing away with a great loss of power due to high resistance
-coils. It will be noticed however that a 125 C.P. incandescent lamp uses
-as much energy as a 2000 C.P. arc light, the 65 C.P. lamp one half as
-much and the 32 C.P. lamp one fourth as much.
-
-
-
-
- _General Remarks_
-
-
-The Thomson Houston system also furnish lightning arresters, ammeters,
-hanging boards, switchboards, hoods, insulators, lamp arms, etc, but,
-though in some respects many of these miscellaneous articles are
-ingenious and novel, yet they are not distinctive of the Thomson Houston
-or any other system. Be it said however that all these articles fill
-their proper places. The company also furnish a motor to go on their
-circuits but for the double reason that of the motor not being strictly
-related to electric lighting and of being unable to obtain a description
-of it, it must remain undescribed as far as this thesis is concerned.
-
-After describing all the parts of the system it may be interesting to
-know how a plant is arranged. The last plate is a photograph of the
-LaFayette Gas Company’s Plant of the Thomson Houston System taken at ten
-oclock one night. It shows the engine, dynamos, the wall controller on
-the left wall, and a view of the lamps which had hoods put before them
-to prevent the polarization of the negative.
-
-On the accompanying page will be found a table showing experiments with
-an old style dynamo given Purdue University by the Thomson Houston
-Company, which dynamo is now in the engine house of the Mechanical Hall.
-
-
-
-
- _Experiments with Three Light T-H. Dynamo No. 79_
-
-
-The dynamo was run by a large pulley (about four and one half feet in
-diameter) on the same shaft as the fly wheel and beside the latter. Two
-lamps were put in circuit with a Deprez-Carpentier ammeter and a volt
-meter of the same make was put in between the brushes. First one lamp
-(old Thomson style) was switched out of circuit, the dynamo started and
-when speed was reached the circuit made. The following readings were
-taken when the engine made 139 & the dynamo 1122 revolutions per minute.
-
-
- +-----------+----------+----------+---------------+----------------+
- | | One Lamp | Two | When 2^{nd} | When 2^{nd} |
- | | | Lamps | lamp was | Lamp was |
- | Readings | | | switched in | switched out |
- | At End of +----+-----+----+-----+-------+-------+-------+--------+
- | |Amp.|Volts|Amp.|Volts| Amp. | Volts | Amp. | Volts |
- |-----------+----+-----+----+-----+-------+-------+-------+--------+
- | 1 second | 10 | 55 | 10 | 110 | 6.7 | 55 | 14 | 110 |
- | 30 ” | 10 | 55 | 10 | 110 | 10 | 75 | 10 | 85 |
- | 2 Min | 10 | 55 | 10 | 110 | 10 | 109 | 10 | 60 |
- | 3 ” | 10 | 55 | 10 | 110 | 10 | 110 | 10 | 55 |
- +-----------+----+-----+----+-----+-------+-------+-------+--------+
-
-
- _Fig. 25_
-
-
- consisting of drawing of Sawyer Man lamp cut from
- catalogue, and trimmed to contour of drawing
-
-
- _Fig. 26_
-
-
- a drawing showing action of key in Sawyer Man lamp,
- cut to contour
-
-
- _Fig. 27_
-
-
- a drawing of the Thomson Rice Individual distributor
- cut from cataloug and pasted in.
-
-
- _Fig. 28_
-
-
- a drawing cut from pamphlet showing “Method of using
- Thomson Rice Individual distributor”
-
-
- _Fig. 29_
-
-
- a drawing cut from pamphlet showing “Prof. Thomsons
- incandescent lamp—series incandescent lamp”
-
-
- _Fig. 30_
-
-
- Drawing showing “method of using the Series
- Incandescent Lamp manufactured by the
- Thomson-Houston Elec. Co.” cut from your pamphlet
- and pasted on a similar sheet.
-
- ------------------------------------
-
-
- A photographer of La Fayette photoed the Gas
- Company’s plant of T & H in this city one evening at
- 10 o’clock when several lights were burning in room.
- I had a large one printed and pasted on a piece of
- bristol board of the same size as this sheet, and
- put in my original copy.
-
-
-
-
- _Footnotes_
-
-
------
-
-Footnote 1:
-
- The foregoing statement is quoted from Dr Urbitzkany’s work
- “Electricity in the Service of Man.”
-
-Footnote 2:
-
- Gravity does not enter, as a current is generated in lowering A.
-
-Footnote 3:
-
- Each segment is really only 115° in length but the brushes are set at
- a distance from the holder far enough to just reach over the five
- degree gap by the gauge above described.
-
-Footnote 4:
-
- An arc light is a light produced by the use of the voltaic arc, which
- is made by the sparks passing between two poles of a powerful battery
- which are brought together and then seperated a little.
-
-------------------------------------------------------------------------
-
-
-
-
- _Transcriber’s Note_
-
-
-The source for this e-book was a hand-written thesis.
-
-Footnotes have been moved to the end of the book.
-
-The captions for Figures 23, 25, 26, 27, 28, 29 and 30 are reproduced,
-however, the original drawings were not bound with the published thesis
-and are therefore not part of this e-book.
-
-The author’s spelling has been maintained, Some standardization of
-punctuation was done to improve readability.
-
-The following proper names as used by the author are reproduced here
-with their more commonly used spelling:
-
- Author Standard
-
- Thompson Thomson
- Wimhurst Wimshurst
- Dr Urbitzkany’s Alfred von Urbanitzsky
- Lentz Lenz
- Pacinnotti Pacinotti
- Foucalt’s Foucault’s
-
-Phrases which the author portrayed as underlined are presented by
-surrounding the text with _underscores_. Some standardization of these
-was also done particularly with regard to the presentation of
-illustration captions.
-
-
-
-
-
-End of the Project Gutenberg EBook of The Thompson-Houston System of
-Electric Lighting, by H. T. Cory
-
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-The Project Gutenberg EBook of The Thompson-Houston System of Electric
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-
-Title: The Thompson-Houston System of Electric Lighting
-
-Author: H. T. Cory
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-Release Date: January 5, 2017 [EBook #53893]
-
-Language: English
-
-Character set encoding: UTF-8
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-*** START OF THIS PROJECT GUTENBERG EBOOK THOMPSON-HOUSTON SYSTEM--ELECTRIC LIGHTING ***
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-
-<div>
- <h1 class='c000'><b>The Thompson-Houston</b> <br /> <b>System of Electric</b> <br /> <b>Lighting.</b></h1>
-</div>
-
-<div class='nf-center-c1'>
-<div class='nf-center c001'>
- <div>Thesis submitted for the degree of</div>
- <div>Bachelor of Science in Mechanical Engineering,</div>
- <div class='c001'>to the Faculty of Purdue University</div>
- <div class='c002'>June 1887</div>
- </div>
-</div>
-
-<div class='pbb'>
- <hr class='pb c001' />
-</div>
-
-<p class='c003'>“In its power to assume always
-that form of energy which happens
-to be the most useful lies the great
-importance of electricity.” This importance
-has been brought to the notice
-of the public by means of the many
-recent exhibitions. Public interest has
-been roused and there is everywhere a
-desire for information and a guide
-through this far reaching field for discovery
-and invention. And, although
-there are many works treating on electricity
-and electric light, people specially
-want a short and concise though thorough
-description of the various schemes
-by which electric light is produced. In
-this thesis the object is to give a brief
-treatise on one of the many schemes
-of producing light by electric currents
-viz—The Thomson-Houston System.</p>
-
-<p class='c004'>In pursuing the subject of electricity,
-the first thing noticed is the analogy
-and difference between the dynamo
-and its older and more powerful rival
-the steam engine. The resemblances are,
-First as in the development of the steam
-engine, but few of the improvements and
-inventions in electrical machines were
-made by mathematical leaders. Watt
-ran across the idea of the seperate
-condenser while repairing the Newcomen
-model and applied the
-expansion of steam to the steam
-engine by a mechanical accident
-rather than by his own ingenuity,
-and so we find the first designers
-of the dynamo were mechanics rather
-than philosophers. Secondly the
-tendency to disregard old methods
-and instruments because of new
-discoveries and inventions has, as in
-the steam engine, hindered the
-advancement in electrical science.
-As an example it has become customary
-to regard frictional and statical
-electric machines, for practical
-purposes, as obsolete, but recent discoveries
-seem to hint that they may
-yet be utilized. Lately Prof. Dodge has
-shown that dust and vapor whirling
-in the air may be settled by a
-discharge of electricity consisting of
-a continuous series of electric sparks.
-This has been utilized to clear the atmosphere
-in lead smelting works
-from the fumes of volatized lead
-and with its application comes the
-invention of Wimhurst which produces
-with a minimum of mechanical
-labor a continuous series of electric
-sparks and works admirably.</p>
-
-<p class='c004'>The differences between the engine’s
-and dynamo’s developement are:
-<i>First</i> the marvelously rapid developement
-of the dynamo as compared with
-that of the steam engine. Since 1867
-when the term “dynamo electric machinery”
-even to scientific men had
-but little signification, the dynamo
-has been brought to a very high
-degree of perfection. <i>Secondly</i>, the
-development of the dynamo has
-reached a much higher degree of
-perfection than that of the steam
-engine. Among the best steam engines
-twenty per cent effeciency is
-considered as very good while a good
-dynamo gives out in the form of
-electricity, ninety per cent of the
-mechanical energy put in it. But
-the class of people who improved and
-made the steam engine what it is
-were as well educated in one sense
-as were the men who brought out
-the dynamo. While it is true that in
-Watt’s time the knowledge concerning
-steam was very meagre, yet the
-practical men who <i>made</i> the dynamo,
-did it by themselves as nearly
-all the teachers of electricity knew
-nothing except what may be called
-electrical tricks. As has been said<a id='r1' /><a href='#f1' class='c005'><sup>[1]</sup></a>
-“The teachers and writers of textbooks,
-practically did not know that there
-was anything in common between
-the electricity from a rubbed glass machine
-and voltaic electricity, or to be
-brief, that there was a science of electricity
-as distinguished from mere
-natural history.” In fact as late as
-1870 there were really no textbooks
-on electricity. Even now electrical
-knowledge is so meagre as to warrant
-the same writer’s expression,
-“We can not imagine a mechanical
-engineer mistaking a few inches
-for a few miles or a grocer compounding
-an ounce of sugar with a carload,
-but this gives too truthful an
-idea of the vagueness that still exists.”</p>
-
-<p class='c004'>In the distant future, electricity will
-be used for electric lighting only as
-subordinate to other uses to which
-it may be applied such as heating
-houses, taking place of stoves for
-cooking, being used as a substitute
-for the steam engine. In fact the
-motor is rapidly becoming of as much
-practical use as the electric light.
-The principle of the motor is just
-this; a certain amount of mechanical
-energy say thirty four horsepower
-per minute into the form of
-electric currents, which by the way
-gives enough current to run 45,
-2000 candle power lamps, send the
-current and distance through suitable
-conductors and attach them
-to similar dynamo or dynamos but
-in such a manner that the current
-in the second set of dynamos flows
-in the reverse direction to that
-of the first; when, the armature of
-the second dynamo or dynamos will
-revolve and at the pulley or pulleys
-of the dynamos, aside from friction,
-will be given out 95% of the thirty-four
-horsepower, the loss being
-due to the resistance of the conductors.
-Now in practice a motor
-is placed on the arc light circuit
-the same as a lamp, for energy
-less than twelve horsepower. It
-does not affect the lights and is a
-clean, neat way of obtaining energy.</p>
-
-<p class='c004'>But however true the foregoing
-may be, the greatest present use
-of electricity is to start and maintain
-light. There are several so-called
-systems, embracing dynamos,
-lamps, regulators, etc, from
-which I select the Thomson-Houston
-as the one for the purpose of
-describing for several reasons, <i>first</i>,
-it is at least as good as the average
-system of which there is a mushroom
-growth; <i>second</i>, valuble information
-was kindly offered by the parent
-Company; <i>third</i>, a good plant is
-near to which free acess was given,
-and <i>fourth</i>, we have at the Mechanical
-Hall of this University, a dynamo,
-loaned by the parent Company,
-which affords information without
-any inconvenience. As each part
-of the system comes up to be described
-a little of its history will be given.
-As the first part of a system
-necessary to be produced is the current
-generator we will first describe</p>
-
-<div>
- <h2 class='c006'><i>The Thomson-Houston Dynamo.</i></h2>
-</div>
-
-<p class='c007'>In considering the current generator
-the first thing to be decided
-upon is the definition of the term
-dynamo. The following is thought
-to be a correct definition,—A dynamo
-or dynamo electric machine is
-a machine which is used to convert
-energy in the form of mechanical
-motion into energy of electric
-currents, or <i>vica-versa</i>. Those used
-to generate currents of electricity
-are called dynamos, those used to
-generate mechanical motion are
-known as motors.</p>
-
-<p class='c004'>In attempting to make clear
-the theory of the dynamo, we will
-recall some simple experiments.
-In Fig. 1, send a current around B from
-right to left. Now A being free to move
-vertically either up or down, connect
-its binding posts to a <i>galvanometer</i>
-(that is, an instrument used to tell the
-direction of a current and also used to
-test the <i>relative</i> strength of two or more
-currents) and move A up suddenly
-when a current will be generated
-in A whose direction will be the
-same as that of the current in B. Now
-this current is not created energy,
-because in lifting<a id='r2' /><a href='#f2' class='c005'><sup>[2]</sup></a> the coil A, work
-is expending against the attraction
-between the coils, as between two
-currents flowing in the same direction
-there is an attraction. If we pursue
-this experiment in its various forms
-we will find the following statement
-known as Lentz law is true, viz: “If
-the relative positions of two conductors
-A and B be changed of which B
-is traversed by a current, a current
-is induced in A in such a direction
-that by its electro dynamic action on
-the current in B it would have imparted
-to the conductor a motion
-of the contrary kind to that by which
-the inducing action was produced.”</p>
-
-<p class='c004'>The theory of this law is that
-around every wire carrying a current
-there is a magnetic whirl
-(Fig. 3). Now if the conducting wire
-be passed through a hole in a
-horizontal plate of glass and iron
-filings be sifted upon the latter
-they will arrange themselves,
-as shown in Fig. 2., along lines, radial
-in this case, known as lines
-of force, which arranging is due
-to the magnetic attraction of the
-current in the wire upon the
-iron filings. Now in B. Fig. 1, every
-portion of the wire has just such
-a whirl and just such lines of
-force, or magnetic field, and when
-A is moved each part of the wire of
-A cuts one or more lines of force of
-the many magnetic fields making
-up the magnetic field of the
-entire coil B. Now when the wire
-of coil A cuts magnetic field of B a
-current is generated in A acording
-to the following statement known
-as Faraday’s Law; “When a conductor
-in a field of force moves in any way
-so as to cut the lines of force there
-is an electromotive force produced
-in the conductor in such a direction
-that supposing a figure swimming
-in the conductor to turn to look
-along the positive direction of the
-lines of force (in Fig. 1, toward axis of B),
-and the conductor be moved to his
-right, he will be swimming with the
-current so induced.” Hence in Fig. 1, the
-current generated in it will be from
-left to right.</p>
-
-<p class='c004'>Practically Faraday’s principle
-means just this: by moving a wire
-across a space where there are magnetic
-lines, the motion of the wire as
-it cuts the magnetic lines sets up
-around the cutting wire a magnetic
-whirl or in other words sets
-up a current in that wire.</p>
-
-<p class='c004'>The foregoing laws are the
-“principles of the dynamo,” yet after
-their deduction, the progress of the
-evolution of the dynamo was slow
-and attended by many dificulties.
-Between 1860 and 1870 however, a working
-knowledge of these laws became
-the property of thousands of mechanics,
-and by comparing the number
-of inventions before and after
-that date (1860) the present generous
-growth of systems, dynamos and
-lamps, prove that inventions were
-almost in proportion to the number
-of people who had any electrical
-knowledge. In 1866 Wilde produced
-a toy magneto-electric machine
-for giving shocks, in which he used
-excited electromagnets. In the same
-years Varley and others produced a
-machine which excited its own
-field magnets the type of all machines
-used in practice. With this
-principle of Varley’s and Pacinnotti’s
-ring, Gramme produced in 1871 his
-since famous continuous current
-generator, one of which the second
-dynamo electric machine ever brought
-to this country can now be seen at
-the engine house at Purdue University.
-In 1877 Silas Brush brought out his
-famous dynamo and it may be interesting
-to know that he designed
-and had one made without experimenting
-in the least. In the following
-year a patent was issued to
-Messrs. Elihu Thomson and Edwin J.
-Houston, Professors of electricity in Philadelphia
-on the present though much
-improved <i>Thomson Houston Dynamo.</i></p>
-
-<div class='figcenter id001'>
-<img src='images/i031.jpg' alt='' class='ig001' />
-<div class='ic001'>
-<p><i>Fig. 1.</i><br /><br /><i>Fig. 2.</i><br /><br /><i>Fig. 3.</i><br /><br /><i>Fig. 4.</i><br /><br /><i>Fig. 5.</i><br /><br /><i>Fig. 6.</i><br /><br /><i>Fig. 7.</i></p>
-</div>
-</div>
-
-<p class='c004'>To go back to Lentz and Faraday’s
-laws and carefully consider them we
-can but assent to S. P. Thompson’s “fifteen
-propositions on the dynamo” which
-are:—1. A part of the energy of an electric
-current exists in the form of a magnetic
-whirl surrounding the wire.</p>
-
-<p class='c004'>2. Currents may be generated in a
-wire by setting up these whirls.</p>
-
-<p class='c004'>3. We can set up these whirls by
-increasing or decreasing the relative
-distance between magnets and wires.</p>
-
-<p class='c004'>4. To set up and maintain these
-whirls consumes power.</p>
-
-<p class='c004'>5. To induce currents in a conductor
-there must be motion between
-them so as to alter the number of
-lines of force (Fig. 4 to 7).</p>
-
-<p class='c004'>6. Increase in the number of
-lines of force in the circuit produces
-a current of the opposite sense to
-decrease (Fig. 7).</p>
-
-<p class='c004'>7. Approach induces electromotive force
-in the opposite direction
-to that induced by retreat.</p>
-
-<p class='c004'>8. The stronger the magnetic field
-the stronger the current.</p>
-
-<p class='c004'>9. The more rapid the motion the stronger
-the current.</p>
-
-<p class='c004'>10. The greater the length of the conductor
-which cuts lines of force the stronger
-the current.</p>
-
-<p class='c004'>11. The shorter the conductor not so
-employed the stronger the current.</p>
-
-<p class='c004'>12. Approach being a finite process
-the approaching and receeding must
-give alternating directions to the
-current.</p>
-
-<p class='c004'>13. By the use of a commutator all
-the currents can be turned in the same
-direction.</p>
-
-<p class='c004'>14. In a steady circuit it makes no
-difference what kind of magnets are
-used to procure the requisite magnetic
-field whether permanent
-or electromagnets.</p>
-
-<p class='c004'>15. Hence the current of the generator
-may be used to excite the magnetism
-of field magnets.</p>
-
-<p class='c004'>Now the Thomson-Houston dynamo
-comes under that class of dynamos
-in which there is a rotation of
-coils in a uniform field of force,
-such rotation (Fig. 6.) being affected
-round an axis in the plane of the
-coil. Of course this dynamo is made
-like all others of its class to have <i>first</i>,
-as powerful field-magnets as possible,
-<i>second</i>, the armature or rotating coil
-has as great a lenght of wire in it
-as possible the wire being thick to
-offer little resistance and <i>third</i>,
-built to stand high rotative speed.</p>
-
-<p class='c004'>The simple theoretical dynamo
-is shown at Fig. 8, consisting of a
-single rectangular loop of wire
-rotating in the magnetic field formed
-by large magnets, and in order
-to take the current so generated from
-the loop so as to give a continuous
-current, we use a two part commutator
-(Fig. 9) consisting of a metal
-tube split in two and mounted on
-wood, each half connected to one end
-of the loop. The current is taken off by
-brushes which lead to the main circuit.
-But manifestly this dynamo
-would give no appreciable current
-becase it has a very small length
-of wire on the armature, so a great
-number of loops were used which
-at present constitute the so-called
-<i>drum armature</i>.</p>
-
-<p class='c004'>We may rotate the loops of wire
-in Fig. 8, on one of its sides as an axis
-or even push it farther from the
-center of revolution than that. To do
-this, wrap the wire around a ring and
-connect both ends to a two part commutator
-(Fig. 10). If instead of the ring in
-Fig. 10, being solid it be a number of
-coils of wire and if instead of there
-being one coil around the ring there
-be thirty we will have Pacinnotti’s
-ring before spoken of. If we used
-four to ten coils or “bobbins” of large
-size which is shown diagramatically
-at Fig. 11, we would have the Brush dynamo.</p>
-
-<p class='c004'>So with exceptions we may say
-that there are practically two types
-of dynamos as regards armatures, the
-<i>ring</i> type as Brush, Pacinnotti’s Gramme,
-and the <i>drum</i> armature (page 20).</p>
-
-<p class='c004'>The Thomson-Houston dynamo
-is like the rest of that dynamo,
-unique. To quote S. P. Thompson; “The
-Thomson-Houston spherical armature
-is unique among armatures, its
-cup shaped field magnets are unique
-among field magnets, its three part
-commutator is unique commutators.”</p>
-
-<div class='figcenter id002'>
-<img src='images/i045.jpg' alt='' class='ig001' />
-<div class='ic001'>
-<p><i>Fig. 8.</i><br />Simple Dynamo.<br /><br /><i>Fig. 9.</i><br /><br /><i>Fig. 10.</i><br /><br /><i>Fig. 11.</i><br /><br /><i>Fig. 12.</i><br /><br /><i>Fig. 13.</i></p>
-</div>
-</div>
-
-<p class='c004'>An armature of a dynamo is
-the rotating coil or coils which generates
-currents of electricity by moving
-in a magnetic field of force. It is
-the most important part of a dynamo
-as it is literally the current generator. So we
-first consider the Thomson-Houston</p>
-
-<div>
- <h2 class='c006'><i>Armature</i></h2>
-</div>
-
-<p class='c007'>It is spheroidal in shape as is noted
-for the fact of its very seldom <i>burning
-out</i>, i. e., the electricity heating the
-wires of the armature to such an
-extent as to destroy the insulation or
-fuse the wires, either rendering the armature
-useless. It is made by keying
-two dish-shaped iron disks <i>SS</i> Fig. 12, to the
-shaft x and putting ribs <i>dd</i> about
-ten in number in the twenty-five
-light machine, and over the whole
-putting varnished paper. Then at stated
-intervals, pegs JJJ are driven into
-suitable holes in the disks and ribs
-to help in winding wire on the shell.
-Next three insulated wires of equal length
-are joined together at <i>h</i> Fig. 13, and the three
-wires are then wound over the shell
-in the following peculiar manner:
-one half of No. 1 is wound so as to form
-a zone of a sphere of which the shaft is in the
-same plane as the center circumference
-of the zone. The armature is then turned
-on the shaft as an axis 120° and one half
-of No. 2 is wound in the same manner
-as the first half of No. 1. The armature
-is moved 120° more and all of No. 3 is
-wound. The armature is then turned
-back, 120° on the shaft as an axis and
-the remainder of No. 2 is wound. Lastly
-the armature is turned back 120° more
-and the rest of No. 1 is wound. They are
-bound by wires <i>gg</i> Fig. 13 to hold them
-when rotating. The object of this rather complicated
-winding is to get the three coils
-equi distant from the shaft in order that
-each coil will generate practically the
-same current. Now as will be seen the
-overlapping wires will form a nearly spherical
-armature. The armature is mounted
-on the shaft <i>x</i> as an axis which extends
-far enough out from its bearings
-to put a pulley on the end <i>H</i> and a commutator
-on the other end to the three
-parts of which are fastened the three
-wires marked one, two, three, Fig. 13.</p>
-
-<p class='c004'>It has been urged that the repairs
-of this armature will be larger than
-on any other armature. If there should
-be a “burnout” it would necessitate the
-taking apart of the dynamo and sending
-the armature to the factory to be
-rewound. But it never burns out except
-through positive carelessness and it
-will be found that the repairs on this
-armature is less than on the armatures
-of its several powerful rivals
-taken separately even though they be
-of simpler construction.</p>
-
-<p class='c004'>When the Thomson-Houston armature
-is rotated between the cup-shaped
-fieldmagnets alternate currents are
-generated in each coil in turn and
-now the next point to be considered is
-the</p>
-
-<div>
- <h2 class='c006'><i>Commutator</i></h2>
-</div>
-
-<p class='c007'>which incites the alternate currents
-so formed into one continuous current.
-The commutator as before stated is
-fastened on the shaft at the end one, two,
-three Fig. 13. It consists of three copper
-plates in the form of a cylinder each segment
-<i>A´A´A´</i> covering 115° of the dotted circle
-Fig. 14. They are screwed to rod <i>CCC</i> and <i>DDD</i>
-which are insulated by wood and gutta-percha
-plates <i>EE</i> from the iron mounting
-<i>E´´</i> which is in turnescrewed to shaft by
-set screws shown. The wires one, two, three,
-have respectively red, white and blue
-insulation and are put in binding posts
-<i>DDD</i> marked one, two, three at the factory
-and if not so placed may work badly.
-The current enters <i>D</i> goes to <i>B´B´</i> which there
-have direct contact with <i>A</i>.</p>
-
-<div class='figcenter id003'>
-<img src='images/i057.jpg' alt='' class='ig001' />
-<div class='ic001'>
-<p><i>Fig. 14.</i><br />Half Sec. A.B.<br /><br /><i>Fig. 15.</i> <i>Air blast Nozzles.</i><br /><br /><i>Fig. 16.</i> <i>Air blast Mechanism.</i><br /><br /><i>Fig. 17.</i> <i>Section of Dynamos.</i><br />Spherical Armature in Fig. 13.</p>
-</div>
-</div>
-
-<p class='c004'>Now in a three-part commutator the
-spark occurring as the segments pass under
-the brushes would very quickly destroy
-the surface and interfere with the currents
-in the coil. This difficulty is overcome
-by blowing out the spark by an air blast
-given at just the right place and time. The
-manner in which the blast is delivered is
-as follows: the segments of the commutator</p>
-
-<p class='c004'>are separated by gaps of about 5° and in
-front of each of the leading brushes there
-projects a nozzle, Fig. 15, which discharges
-an air blast alternately three times in
-each revolution. The blast itself is supplied
-by an ingenious piece of mechanism
-known as the</p>
-
-<div>
- <h2 class='c006'><i>Thomson Air Blast</i>.</h2>
-</div>
-
-<p class='c007'>It consists of an elliptical box II
-whose sides have perforations II where
-air can enter while inside of this rotates
-a steel disk keyed to the armature
-shaft and having radial slots in
-which slide three wings RRR of ebonite
-which as they fly around drives
-air into the holes JJ leading to the
-nozzles Fig. 15. The result is that, since
-the spark is done away with, oil can
-be supplied to the commutator in
-limited quantities but still amply
-sufficient to reduce the wear on the
-commutator to such an extent that the
-life of a segment is greatly increased.
-The air blast is fastened to the dynamo
-frame just behind the commutator and
-can be see in Fig. 23.</p>
-
-<div>
- <h2 class='c006'><i>The Field-Magnets</i>,</h2>
-</div>
-
-<p class='c007'>as may be seen from Fig. 17, consists
-of two flanged iron tubes <i>AA</i> whose end
-consists of a convex segment of a sphere
-accurately turned to recieve the armature.
-Coils of wire <i>CC</i> which are in the outside
-circuit and through which the entire
-current flows are wound upon the
-tubes. After the armature is placed
-between them the two tubes are bolted
-together by heavy wrought iron bars
-<i>BB</i> and the whole carried on the frame
-work <i>PN</i> shown also at <i>PN</i> Fig. 23. Now
-a little magnetism only remains in the
-wrought iron bars and iron frame
-works when the armature first
-revolves, but the current even though slight,
-going through the coils makes an electromagnet
-out of each tube and heavily
-magnetizes the wrought iron bars and
-in two or three seconds after the armature
-first rotates it is entirely surrounded
-by a heavy magnetic field. One of
-the good points of these field magnets
-is that but very little magnetism is lost
-as compared with most other dynamos
-and since it takes power to maintain
-a heavy magnetic field, this dynamo is in
-this respect very economical.</p>
-
-<div>
- <h2 class='c006'><i>The Thomson Regulating Gear</i></h2>
-</div>
-
-<p class='c007'>Later on we will show that pushing the
-brushes together or pulling them apart alter
-the strength of the current, but for
-the present just accept the fact and
-we will show how the brushes are varied.
-It is accomplished by the mechanism
-shown in Fig. 18. The brushes are fixed to
-the levers YY and Y<sub>2</sub>Y<sub>2</sub> united by the lever <i>l</i>.
-The automatic movement is obtained by
-the electromagnet <i>R</i> while a dashpot <i>J</i>
-prevents too sudden motion. Suppose the
-brushes to be in the position shown when
-the current would get too strong owing to
-lights being cut out. The electromagnet R
-getting stronger would raise <i>A</i> and reduce
-the current taken off until current
-came to normal. If, instead, some
-lamps were thrown in the current would
-become weak and the electromagnet <i>R</i> would
-become weak, drop A which would increase
-current and this will continue till current
-reaches normal.</p>
-
-<p class='c004'>The foregoing regulating gear is used
-on small dynamos and old style large
-ones. On the large new style dynamo
-a more delicate regulating gear is used,
-the current which operates it being shown
-at Fig. 19. Normally the electromagnet <i>R</i> is
-short circuited by the wire <i>r</i> and only acts
-when this circuit is broken. At some point
-in the main circuit is a <i>wall controller</i>
-or <i>controller magnet</i> shown in Fig. 19, at ST,
-consisting of two electro magnet, Their yoke
-supported by a spring and the yoke operating
-the contact lever S. If the current becomes
-too strong the controller magnet
-circuit is broken and all the current of the
-main circuit goes through the electromagnet
-<i>R</i> which by its sudden increase of
-strength quickly raises <i>A</i> and thus alters the
-brushes. This only exists for a moment until
-the yoke of the controller magets fall because
-of their decrease of magnets strength,
-when current again flows through wire
-<i>r</i> because when yoke drops contact is made.
-This decreases the strength of electro magnet
-<i>R</i> thus dropping <i>A</i> and increasing current.
-Hence <i>S</i> will again raise and break
-contact and <i>R</i> again rais <i>A</i>. This is continually
-repeated.</p>
-
-<div>
- <h2 class='c006'><i>The Brushes</i>,</h2>
-</div>
-
-<p class='c007'>of which there are four in use on
-all machines, are made of a broad
-strip of springy copper having six slits
-two thirds the distance up, and thus
-touching at several points. They are
-held by clamps shown at Fig. 23 which
-also shows the brushes. The brushes are
-held to the commutator by their own
-springiness and the variation of position
-due to strength of current. The
-brushes are set by a gauge sent with
-each dynamo which shows length
-from the end of brush to the holder.
-The holders are set at the correct
-angle by a gauge of brass of the shape
-of a right angled triangle the short
-side having a wide flange curved to
-fit the commutator for which it is
-sent, while the second side as
-regards length must fit to the holder when
-swung to it on the commutator as
-an axis.</p>
-
-<p class='c004'>After describing the details of
-the dynamo, we will at once proceed
-to find how the</p>
-
-<div>
- <h2 class='c006'><i>Thomson Houston Dynamo Operates.</i></h2>
-</div>
-
-<p class='c007'>In the diagram Fig. 19 the rotation
-is as in practice against the hands
-of the watch when seen from the commutator
-end of shaft. The three coils
-of the armature are represented by
-three lines <i>A</i>, <i>B</i>, <i>C</i>, united at their inner
-extremities each being joined
-to a segment of the commutator. There
-are two positive brushes <i>P</i> and <i>F</i> and
-two negative ones <i>P´</i> and <i>F´</i>. The current
-delivered to <i>P</i> and <i>F</i> goes round one of the
-field magnet coils, then to the outer
-circuit consisting of regulating gear,
-lamps, motors, etc., through the other
-field magnet coil to brushes P´ and F´.
-Now from Fig. 20, we observe that supposing
-the loop to be rotating against
-the hands of the watch in a magnetic
-field the diagram represents by
-arrows the direction of the electro-motive
-forces induced in those loops.
-The action is a maximum along the
-line of the resultant magnetic field
-m&nbsp;m´ and the minimum along the
-line n&nbsp;n´ which is at right angles to
-m&nbsp;m´. The reason that m&nbsp;m´ is not horizontal
-is that the induced poles
-of the armature is in advance of
-the poles of the field magnet and is
-constantly tending to be drawn back.
-Applying Fig. 20 to Fig. 19, we see that
-there will be an outward current in
-<i>B</i>, an inward one in <i>C</i>, <i>A</i> generating no
-current for that moment.</p>
-
-<p class='c004'>Now the following pair of brushes
-<i>F&nbsp;F´</i> are shifted backward three times
-as far as <i>P&nbsp;P´</i> is shifted forwards. When
-the current is the greatest possible
-the brushes P and F and P´ and F´ are
-60° apart thus leaving <i>P</i> and <i>F´</i> and <i>P´</i>
-and <i>F´</i> just 120° apart and since the
-segments of the commutator are each
-120° in length<a id='r3' /><a href='#f3' class='c005'><sup>[3]</sup></a> there will always be
-two coils in parralel with one another
-and in series with the third. Taking
-one sixth of a revolution and continuing
-all the way round we find the
-following tabulated statement showing
-brushes in contact with coils, to
-be true viz:—</p>
-
-<table class='table0' summary=''>
- <tr>
- <td class='c008'>&nbsp;</td>
- <td class='c008'>{&nbsp;P&nbsp;-&nbsp;C&nbsp;}&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;{&nbsp;P´&nbsp;}</td>
- <td class='c009'>&nbsp;</td>
- </tr>
- <tr>
- <td class='c008'>From external circuit</td>
- <td class='c008'>{&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}&nbsp;B&nbsp;{&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}</td>
- <td class='c009'>to external circuit</td>
- </tr>
- <tr>
- <td class='c008'>&nbsp;</td>
- <td class='c008'>{&nbsp;F&nbsp;-&nbsp;A&nbsp;}&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;{&nbsp;F´&nbsp;}</td>
- <td class='c009'>&nbsp;</td>
- </tr>
- <tr>
- <td class='c008'>&nbsp;</td>
- <td class='c008'>&nbsp;</td>
- <td class='c009'>&nbsp;</td>
- </tr>
- <tr>
- <td class='c008'>&nbsp;</td>
- <td class='c008'>{&nbsp;P&nbsp;}&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;{&nbsp;P´&nbsp;-&nbsp;B&nbsp;}</td>
- <td class='c009'>&nbsp;</td>
- </tr>
- <tr>
- <td class='c008'>”&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;“&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;”</td>
- <td class='c008'>{&nbsp;&nbsp;&nbsp;&nbsp;}&nbsp;A&nbsp;&nbsp;{&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}</td>
- <td class='c009'>”&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;“&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;”</td>
- </tr>
- <tr>
- <td class='c008'>&nbsp;</td>
- <td class='c008'>{&nbsp;F&nbsp;}&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;{&nbsp;F´&nbsp;-&nbsp;C&nbsp;}</td>
- <td class='c009'>&nbsp;</td>
- </tr>
- <tr>
- <td class='c008'>&nbsp;</td>
- <td class='c008'>&nbsp;</td>
- <td class='c009'>&nbsp;</td>
- </tr>
- <tr>
- <td class='c008'>&nbsp;</td>
- <td class='c008'>{&nbsp;P&nbsp;-&nbsp;A&nbsp;}&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;{&nbsp;P´&nbsp;}</td>
- <td class='c009'>&nbsp;</td>
- </tr>
- <tr>
- <td class='c008'>”&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;“&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;”</td>
- <td class='c008'>{&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}&nbsp;C&nbsp;{&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}</td>
- <td class='c009'>”&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;“&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;”</td>
- </tr>
- <tr>
- <td class='c008'>&nbsp;</td>
- <td class='c008'>{&nbsp;F&nbsp;-&nbsp;B&nbsp;}&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;{&nbsp;F´&nbsp;}</td>
- <td class='c009'>&nbsp;</td>
- </tr>
- <tr>
- <td class='c008'>&nbsp;</td>
- <td class='c008'>&nbsp;</td>
- <td class='c009'>&nbsp;</td>
- </tr>
- <tr>
- <td class='c008'>&nbsp;</td>
- <td class='c008'>{&nbsp;P&nbsp;}&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;{&nbsp;P´&nbsp;-&nbsp;C&nbsp;}</td>
- <td class='c009'>&nbsp;</td>
- </tr>
- <tr>
- <td class='c008'>”&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;“&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;”</td>
- <td class='c008'>{&nbsp;&nbsp;&nbsp;&nbsp;}&nbsp;B&nbsp;{&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}</td>
- <td class='c009'>”&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;“&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;”</td>
- </tr>
- <tr>
- <td class='c008'>&nbsp;</td>
- <td class='c008'>{&nbsp;F&nbsp;}&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;{&nbsp;F´&nbsp;-&nbsp;A&nbsp;}</td>
- <td class='c009'>&nbsp;</td>
- </tr>
- <tr>
- <td class='c008'>&nbsp;</td>
- <td class='c008'>&nbsp;</td>
- <td class='c009'>&nbsp;</td>
- </tr>
- <tr>
- <td class='c008'>&nbsp;</td>
- <td class='c008'>{&nbsp;P&nbsp;-&nbsp;B&nbsp;}&nbsp;&nbsp;&nbsp;&nbsp;{&nbsp;P´&nbsp;}</td>
- <td class='c009'>&nbsp;</td>
- </tr>
- <tr>
- <td class='c008'>”&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;“&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;”</td>
- <td class='c008'>{&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}&nbsp;A&nbsp;{&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}</td>
- <td class='c009'>”&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;“&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;”</td>
- </tr>
- <tr>
- <td class='c008'>&nbsp;</td>
- <td class='c008'>{&nbsp;F&nbsp;-&nbsp;C&nbsp;}&nbsp;&nbsp;&nbsp;&nbsp;{&nbsp;F&nbsp;&nbsp;}</td>
- <td class='c009'>&nbsp;</td>
- </tr>
- <tr>
- <td class='c008'>&nbsp;</td>
- <td class='c008'>&nbsp;</td>
- <td class='c009'>&nbsp;</td>
- </tr>
- <tr>
- <td class='c008'>&nbsp;</td>
- <td class='c008'>{&nbsp;P&nbsp;}&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;{&nbsp;P´&nbsp;-&nbsp;A&nbsp;}</td>
- <td class='c009'>&nbsp;</td>
- </tr>
- <tr>
- <td class='c008'>”&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;“&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;”</td>
- <td class='c008'>{&nbsp;&nbsp;&nbsp;&nbsp;}&nbsp;C&nbsp;{&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}</td>
- <td class='c009'>”&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;“&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;”</td>
- </tr>
- <tr>
- <td class='c008'>&nbsp;</td>
- <td class='c008'>{&nbsp;F&nbsp;}&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;{&nbsp;F´&nbsp;-&nbsp;B&nbsp;}</td>
- <td class='c009'>&nbsp;</td>
- </tr>
-</table>
-
-<p class='c007'>Now suppose the current to become
-to strong owing to any cause, the
-following brushes are made to recede.
-This can but shorten the time that
-the brushes are in contact with the commutator
-when the coil is passing through
-that position in which it is generating
-the maximum amount of current and
-also hasten the time when it goes
-into parralel with a comparatively
-idle coil. If the current is to weak
-then the brushes are made to close
-up thus reducing the time that the
-most active coil is in parralel with
-one less active and also makes the
-brushes be longer in contact with the
-segment when the coil is generating
-its maximum amount of current. The
-motion of advance and retreat of the
-brushes is accomplished by the <i>Thomson
-Regulating Gear</i> before described.
-On Fig. 23 can be seen all the dynamo’s
-details except the <i>Controller magnet</i>.</p>
-
-<div class='figcenter id004'>
-<img src='images/i079.jpg' alt='' class='ig001' />
-<div class='ic001'>
-<p><i>Fig. 18.</i><br /><br /><i>Fig. 19.</i><br /><br /><i>Fig. 20.</i><br /><br /><i>Fig. 21.</i><br /><br /><i>Fig. 22.</i></p>
-</div>
-</div>
-
-<p class='c004'>As regards the <i>Thomson-Houston
-Dynamo</i> it will be found to produce
-the steadiest and most uniform current
-of any dynamo now in use. It
-regulating gear is the simplest and
-most natural one ever used. In its
-ability to reduce the current simaltaneously
-to one tenth of its former quantity
-inside of one or two minutes <i>without
-injury to itself and lamps</i> it stands
-alone, in practice.</p>
-
-<h3 class='c010'><i>Fig. 23.</i></h3>
-
-<p class='c011'>Your engraving
-representing
-“<i>Dynamo Electric
-Machine
-with Thomsons
-Spherical Armature</i>”</p>
-
-<p class='c012'>—Taken from one of
-your catalogues,
-and pasted on a
-sheet of this paper—</p>
-
-<p class='c004'>In a system the most important
-thing next to the dynamo is the
-lamps. The first experimenter who
-produced an electric glow was Otto
-von Guericke. But neither the glow nor
-electric spark have been used to produce
-electric light for practical purposes,
-this was left to the voltaic arc on the
-one hand and the incandescent lamp
-on the other. Davy in 1800 mentions experiments
-in which electric light
-was obtained by electric sparks between
-two carbon points. He showed the arc<a id='r4' /><a href='#f4' class='c005'><sup>[4]</sup></a>
-light for the first time in 1810 at the
-Royal Institute, which with Foucalt’s
-hand regulator (1844) Deleuil lit the
-Place de la Concorde, Paris. Thomas
-Wright in London (1845) devised the
-first apparatus which automatically
-adjusted the carbons. W. C. Staite
-used the electric current for the regulation
-of the carbons in 1848. In 1855
-Serrin constructed a lamp which would
-have been used on a large scale had
-it not been for the cost of generating
-electricity. In 1876 Paul Jablochkoff
-invented his electric candles and in
-1881 there were 4000 in use, but as
-their use increased their defects were
-found out. Regulated lamps were
-again brought into use and with
-them experimenters again endeavored
-to solve the problem of dividing the
-electric light. In 1877 Tschikoliff
-solved the problem in a very simple
-manner. He reasoned that, if the current
-be divided and part go through
-the carbons and make the arc and
-the rest go through an electromagnet
-and regulate the arc and the the current
-unite and when another light
-is wanted the current be again divided
-and reunited, the current may be divided
-any number of times and the
-scheme work nicely. When put in
-practice it worked very nicely and
-is used on most lamps at present.
-Suppose there be a lamp placed in
-the circuit. The current divides and
-the larger half goes through the
-carbons, as here there is no resistance
-as the carbons touche, while
-the remainder, going through a spiral
-of high resistance, is small. When
-the carbons burn away a little the
-arc is formed and the resistance
-increasing brings the regulating gear
-into operation. Now the strength
-of the current is the same after it
-has gone through the lamp as before
-because the current is going to get
-through either one way or the other,
-hence any number of lamps may go
-on in series, depending only upon the tension
-of the current.</p>
-
-<p class='c004'>Incandescent lamps were produced
-as early as 1859 but not till
-1879 when Swan, Edison, Sawyer and
-others were they ever in a practical
-form. The first glow lamp Edison
-constructed had platinum wire
-to be heated. He however examined the
-properties of organic substances and
-finally fixed on bamboo fibre. The bamboo
-is divided into fibres one millimeter
-in diameter and twelve millimeters
-long. These fibres are pressed
-in U-shaped moulds and baked in ovens
-where they are allowed to become
-carbonized. The carbonized filament is
-attached to platinum wires which
-are fused in a glass vessel from
-which the air has been exhausted. We
-will speak more fully of the incandescent
-lamp when describing the Thomson
-Houston System’s incandescent
-lamp.</p>
-
-<p class='c004'>The Thomson Arc lamps was used
-by the Thomson Houston System
-since its begining till about two years
-ago when they stopped manufacturing
-them, only furnishing broken parts.
-The arc lamps at present used is</p>
-
-<div>
- <h2 class='c006'><i>The Thomson Rice Arc Lamp.</i></h2>
-</div>
-
-<p class='c007'>They are manufactured in two styles
-the single lamp used for stores, buildings
-etc., and the double lamp used
-for street service, all night work, etc.
-The light is produced by the voltaic arc
-between two carbons, the negative pole
-or lower carbon burning away about
-half as fast as the positive pole or upper
-carbon. The outside view of the single
-lamp is seen in Fig. 21 and of the
-double lamp in Fig. 22.</p>
-
-<p class='c004'>The regulation of the double lamp
-is diagramatically shown in Fig. 24,
-which is a plan of the lamp with cover
-removed, showing only a plan of cylindrical
-part of the lamp. The wires marked
-<i>a&nbsp;b&nbsp;c&nbsp;d</i> run along the top in order to be
-out of the way. In Fig. 24 the current
-comes in at the binding post and is at
-<i>A</i> divided into three currents <i>A</i>, <i>B</i>, and <i>C</i>.
-The current <i>a</i> goes to the yoke <i>I</i> of the
-electromagnets <i>h</i> and <i>i</i> and when
-the yoke is not held down by magnets
-<i>h</i> and <i>i</i>, it goes out wire <i>a</i> to
-binding post <i>B</i>. This only continues
-a moment until the current <i>b</i> which
-goes through the carbons and at the
-start has almost no resistance offered
-it, attracts the yoke <i>I</i> thus breaking
-contact of curcuit <i>a</i> until the current
-ceases or till both carbons burn away,
-when in the latter case the resistance
-of <i>b</i> becoming very high as compared
-to <i>j</i> and <i>k</i> but little current goes through
-<i>h</i> and <i>i</i> and <i>I</i> is raised by a weak spring
-not shown, thus making contact of circuit
-<i>a</i>, and since current <i>a</i> has little
-resistance as compared to <i>b</i> or <i>c</i> most
-of the current goes through it, thus practically
-making a cut-out. The current <i>b</i>
-goes round the electro-magnets <i>h</i> and <i>i</i>,
-then to the “bed” through screw J, the
-“bed” being a cast iron bottom of the cylinder
-<i>E</i> Fig. 22. From the bed it goes down
-carbon holder <i>C</i> (or <i>H</i>) through carbons
-and arc to frame bed <i>A</i> Fig. 22. From
-there it comes up a wire by the side
-of frame <i>C</i> Fig. 22 and joins other currents
-at <i>B</i>. The third current <i>a</i> goes
-through electromagnets <i>j</i> and <i>k</i> and
-joins other currents at <i>B</i>.</p>
-
-<p class='c004'>This is when switch F Fig. 22 and
-<i>M</i> Fig. 24, is turned <i>on</i>. Now since the
-dynamo will regulate all differences
-in current the lamps can be turned
-<i>on</i> or <i>off</i> at will by any one. This is
-accomplished at the lamp by turning
-<i>off</i> the switch. When the switch is turned
-<i>off</i>, the current goes through <i>d</i> to
-screw <i>K</i> which is then touched by metal
-L (in contact with binding post B
-and worked by <i>M</i>).</p>
-
-<p class='c004'>It will be perceived that any
-disorder in a lamp cannot affect other
-lamps in the circuit and will right
-itself or if not the lamp can immediately
-be switched out of circuit.</p>
-
-<p class='c004'>Now as to the regulating gear. The
-two carbon holders are held up, <i>H</i>, by
-clutch operated by springs (not shown)
-till end <i>N</i> of lever <i>ON</i> is permanently
-held down, and <i>C</i>, by the raising and
-falling of yoke <i>D</i>. There is only <i>one</i> arc
-burning at a time in a double lamp
-and the so-called positive carbon <i>C</i> burns
-first. When the lamps are trimmed the
-switch is first turned <i>off</i> the carbons
-put in and the switch turned <i>on</i>. This
-will draw the upper carbons up about
-a quarter of an inch.</p>
-
-<p class='c004'>When the current is turned on the
-circuit <i>aa</i> is almost instantly broken
-and most of the current goes through
-<i>c</i> as the distance between carbons being
-a quarter of an inch the arc has
-a <i>very</i> large resistance. The electromagnets
-<i>j</i> an <i>k</i> attract <i>D</i> which lets loose <i>C</i>,
-which falls to lower carbon, and the
-resistance being almost nothing, most
-of the current goes through <i>b</i>. This weakens
-<i>j</i> and <i>k</i> which lets <i>D</i> up while <i>D</i>
-takes <i>C</i> up with it thus establishing
-the arc. The current <i>all</i> goes down <i>C</i> till
-the enlarged end of <i>C</i> strikes lever <i>ON</i> thus
-letting <i>H</i> drop and also putting it in electrical
-contact with “bd,” which it was
-not in before. After a short time the
-carbons burn away, the arc becomes longer
-and establishes itself and the resistance
-becoming greater in passing from carbon
-to carbon and a correspondingly less
-current flows through <i>b</i> and a greater
-one through <i>c</i>. This makes the electro-magnets
-<i>j</i> and <i>k</i> strong enough to draw
-<i>D</i> to them in spite of spring <i>Q</i>. When <i>D</i>
-is attracted by <i>j</i> and <i>k</i>, <i>C</i> (or <i>H</i>) falls and
-again the arc lengthens, always being kept
-about 3/32 inch long. This is frequently and
-continually repeated, the delicacy depending
-upon the strengh of the spring
-<i>Q</i> as compared to the electromagnets
-strength.</p>
-
-<div class='figcenter id005'>
-<img src='images/i105.jpg' alt='' class='ig001' />
-<div class='ic001'>
-<p><i>Fig. 24.</i></p>
-</div>
-</div>
-
-<p class='c004'>When the carbon in carbon holder
-<i>C</i> burns to a length of about two inches
-in attempting to fall to maintain arc’s
-length, an enlarged port at the top of
-the carbon holder <i>C</i> strikes and holds
-down lever <i>ON</i> pivoted at <i>O</i> (and end
-<i>N</i> held up by a spring <i>P</i>) thus letting loose
-a clutch by which electrical contact is
-made between <i>H</i> and “bed” and letting <i>H</i>
-fall till it touches lower carbon when
-an arc is established and regulated
-just as for <i>C</i>.</p>
-
-<p class='c004'>The Thomson-Rice single lamp
-has the same gear with the exception of
-having only carbon holder <i>C</i>, <i>H</i>, lever <i>ON</i>,
-and spring clutch and spring <i>P</i> being absent.
-The single lamp will burn eight
-hours and the double lamp fourteen
-hours continuous running.</p>
-
-<p class='c004'>These lamps are intended only
-for a steady current and will not cut
-out of circuit if the current gets too strong.
-But with the Thomson Houston dynamo
-the current never gets too strong and because
-of this there are less power absorbing
-mechanism and as anything’s
-functions decrease the remaining functions
-are increasedly better. As the Thomson-Rice
-lamp has less functions and
-power consuming machinery, it can but
-be the most economical, delicately adjusted
-and steadiest lamp extant. They
-are made to stand a current of five amperes
-above the normal current for a
-short time, as, when forty lights are simultaneously
-cut out of a forty-five light
-circuit, the current runs up about four
-amperes above the normal current for
-about one half a minute.</p>
-
-<p class='c004'>Prof. Thomson has gotten out a
-divided arc lamp which supplies a
-light of moderate candle power for locations
-where a 2000 candle power
-lamp gives more light than can be economically
-utilized. It is specially suited
-for factory and mill use where looms
-or other tall machines are liable to cast
-disadvantageous shadows. It is said
-that these lights are supplied cheaper
-per candle power than the standard
-lamp and up to date is sucessful.</p>
-
-<p class='c004'>He has also arranged apparatus
-by which arc lamps are run in multiple
-series, series or multiple arc. It is
-said that divisions, redivisions and reunions
-are practicable. This is also sucessful
-as far as we can find out.</p>
-
-<div>
- <h2 class='c006'><i>The Sawyer-Man Incandescent Lamps.</i></h2>
-</div>
-
-<p class='c007'>As before stated Edison fixed upon
-carbonized filament of bamboo. The
-Sawyer-Man company however applied
-for a patent on carbonized filament for
-incandescent lamps on January 19<sup>th</sup> 1880,
-and after five years litigation with Thos.
-A. Edison they were granted a patent No.
-317,676, on May first, 1885, covering their
-invention. The Sawyer-Man lamp Fig. 25,
-consists of a carbonized connected to
-platinum wires fused in a glass tube
-from which all the air possible had
-been extracted. The light is produced by
-the glow of the filament and heat of
-gases given from filament. The life of
-a lamp is from 1000 to 1500 hrs. and requires
-a current of 1¼ to 1.3 amperes and
-give 20 to 25 C.P. When the filament
-becomes brittle and breaks the tube is
-unscrewed from the key Fig. 26, and a
-new one screwed in. They are run on
-the arc light circuit by the use of an
-individual distributor Fig. 27 which
-consists of a brass case containing
-a magnet in the circuit of the lamps
-and a resistance coil automatically
-substituted in case the lamp should
-break or is turned off by key Fig. 26. The
-scheme of arranging lamps so as to get the
-right current is shown at Fig. 28. the
-number of lamps in a group depending
-on the current.</p>
-
-<p class='c004'>Prof. Thomson has gotten out a
-lamp Fig. 29 in two styles one for 6.8 amperes
-current and one for 10 amperes
-current. Three lamps of different candle
-power, due to different potential
-differences at binding post of lamp,
-are use on the same current. The method
-of connecting them is shown in Fig. 30.
-It will be perceived that the lamps
-carry the full current yet have a life
-of 1000 hrs. or more. This is a great
-invention indeed doing away with a
-great loss of power due to high resistance
-coils. It will be noticed however
-that a 125 C.P. incandescent lamp uses
-as much energy as a 2000 C.P. arc light,
-the 65 C.P. lamp one half as much and
-the 32 C.P. lamp one fourth as much.</p>
-
-<div>
- <h2 class='c006'><i>General Remarks</i></h2>
-</div>
-
-<p class='c007'>The Thomson Houston system
-also furnish lightning arresters, ammeters,
-hanging boards, switchboards,
-hoods, insulators, lamp arms, etc, but,
-though in some respects many of these
-miscellaneous articles are ingenious
-and novel, yet they are not distinctive
-of the Thomson Houston or any
-other system. Be it said however that
-all these articles fill their proper places.
-The company also furnish a motor to
-go on their circuits but for the double
-reason that of the motor not being strictly
-related to electric lighting and of being
-unable to obtain a description of it, it
-must remain undescribed as far as this
-thesis is concerned.</p>
-
-<p class='c004'>After describing all the parts of
-the system it may be interesting to know
-how a plant is arranged. The last plate
-is a photograph of the LaFayette Gas Company’s
-Plant of the Thomson Houston System
-taken at ten oclock one night. It shows
-the engine, dynamos, the wall controller
-on the left wall, and a view of the lamps
-which had hoods put before them to
-prevent the polarization of the negative.</p>
-
-<p class='c004'>On the accompanying page will be
-found a table showing experiments with
-an old style dynamo given Purdue University
-by the Thomson Houston Company,
-which dynamo is now in the engine house
-of the Mechanical Hall.</p>
-
-<div>
- <h2 class='c006'><i>Experiments with Three Light T-H. Dynamo No. 79</i></h2>
-</div>
-
-<p class='c007'>The dynamo was run by a large
-pulley (about four and one half feet in
-diameter) on the same shaft as the fly
-wheel and beside the latter. Two lamps
-were put in circuit with a Deprez-Carpentier
-ammeter and a volt meter
-of the same make was put in between
-the brushes. First one lamp (old Thomson
-style) was switched out of circuit, the dynamo
-started and when speed was reached
-the circuit made. The following readings
-were taken when the engine made 139 &amp;
-the dynamo 1122 revolutions per minute.</p>
-
-<table class='table1' summary=''>
-<colgroup>
-<col width='23%' />
-<col width='9%' />
-<col width='9%' />
-<col width='9%' />
-<col width='9%' />
-<col width='9%' />
-<col width='9%' />
-<col width='9%' />
-<col width='9%' />
-</colgroup>
- <tr>
- <td class='btt bbt blt brt c013'>Readings At End of</td>
- <td class='btt bbt brt c013' colspan='2'>One Lamp</td>
- <td class='btt bbt brt c013' colspan='2'>Two Lamps</td>
- <td class='btt bbt brt c013' colspan='2'>When 2<sup>nd</sup> lamp was switched in</td>
- <td class='btt bbt brt c013' colspan='2'>When 2<sup>nd</sup> Lamp was switched out</td>
- </tr>
- <tr>
- <td class='bbt blt brt c013'>&nbsp;</td>
- <td class='bbt brt c013'>Amp.</td>
- <td class='bbt brt c013'>Volts</td>
- <td class='bbt brt c013'>Amp.</td>
- <td class='bbt brt c013'>Volts</td>
- <td class='bbt brt c013'>Amp.</td>
- <td class='bbt brt c013'>Volts</td>
- <td class='bbt brt c013'>Amp.</td>
- <td class='bbt brt c013'>Volts</td>
- </tr>
- <tr>
- <td class='blt brt c013'>1 second</td>
- <td class='brt c013'>10</td>
- <td class='brt c013'>55</td>
- <td class='brt c013'>10</td>
- <td class='brt c013'>110</td>
- <td class='brt c013'>6.7</td>
- <td class='brt c013'>55</td>
- <td class='brt c013'>14</td>
- <td class='brt c013'>110</td>
- </tr>
- <tr>
- <td class='blt brt c013'>30 "</td>
- <td class='brt c013'>10</td>
- <td class='brt c013'>55</td>
- <td class='brt c013'>10</td>
- <td class='brt c013'>110</td>
- <td class='brt c013'>10</td>
- <td class='brt c013'>75</td>
- <td class='brt c013'>10</td>
- <td class='brt c013'>85</td>
- </tr>
- <tr>
- <td class='blt brt c013'>2 Min</td>
- <td class='brt c013'>10</td>
- <td class='brt c013'>55</td>
- <td class='brt c013'>10</td>
- <td class='brt c013'>110</td>
- <td class='brt c013'>10</td>
- <td class='brt c013'>109</td>
- <td class='brt c013'>10</td>
- <td class='brt c013'>60</td>
- </tr>
- <tr>
- <td class='bbt blt brt c013'>3 "</td>
- <td class='bbt brt c013'>10</td>
- <td class='bbt brt c013'>55</td>
- <td class='bbt brt c013'>10</td>
- <td class='bbt brt c013'>110</td>
- <td class='bbt brt c013'>10</td>
- <td class='bbt brt c013'>110</td>
- <td class='bbt brt c013'>10</td>
- <td class='bbt brt c013'>55</td>
- </tr>
-</table>
-
-<h3 class='c014'><i>Fig. 25</i></h3>
-
-<p class='c015'>consisting of
-drawing
-of Sawyer
-Man lamp
-cut from
-catalogue,
-and trimmed
-to contour
-of drawing</p>
-
-<h3 class='c014'><i>Fig. 26</i></h3>
-
-<p class='c015'>a drawing
-showing action
-of key in
-Sawyer Man
-lamp, cut to
-contour</p>
-
-<h3 class='c014'><i>Fig. 27</i></h3>
-
-<p class='c015'>a drawing
-of the Thomson
-Rice
-Individual
-distributor
-cut from cataloug
-and pasted
-in.</p>
-
-<h3 class='c014'><i>Fig. 28</i></h3>
-
-<p class='c015'>a drawing cut from
-pamphlet showing
-“Method of using
-Thomson Rice Individual
-distributor”</p>
-
-<h3 class='c014'><i>Fig. 29</i></h3>
-
-<p class='c015'>a drawing
-cut from
-pamphlet
-showing
-“Prof. Thomsons
-incandescent
-lamp—series
-incandescent
-lamp”</p>
-
-<h3 class='c014'><i>Fig. 30</i></h3>
-
-<p class='c015'>Drawing showing
-“method of using the
-Series Incandescent
-Lamp manufactured
-by the Thomson-Houston
-Elec. Co.” cut from
-your pamphlet
-and pasted on
-a similar sheet.</p>
-
-<hr class='c016' />
-
-<p class='c015'>A photographer of
-La Fayette photoed
-the Gas Company’s
-plant of T &amp; H in this
-city one evening at
-10 o’clock when several
-lights were burning in
-room. I had a large one
-printed and pasted on
-a piece of bristol
-board of the same
-size as this sheet,
-and put in my
-original copy.</p>
-
-<div class='chapter'>
- <h2 class='c006'><i>Footnotes</i></h2>
-</div>
-
-<hr class='c017' />
-<div class='footnote' id='f1'>
-<p class='c018'><span class='label'><a href='#r1'>1</a>.&nbsp;&nbsp;</span>The foregoing statement is quoted from
-Dr Urbitzkany’s work “Electricity in the
-Service of Man.”</p>
-</div>
-
-<div class='footnote' id='f2'>
-<p class='c018'><span class='label'><a href='#r2'>2</a>.&nbsp;&nbsp;</span>Gravity does not enter, as a current is
-generated in lowering A.</p>
-</div>
-
-<div class='footnote' id='f3'>
-<p class='c018'><span class='label'><a href='#r3'>3</a>.&nbsp;&nbsp;</span>Each segment is really only 115° in length
-but the brushes are set at a distance from
-the holder far enough to just reach over the
-five degree gap by the gauge above described.</p>
-</div>
-
-<div class='footnote' id='f4'>
-<p class='c018'><span class='label'><a href='#r4'>4</a>.&nbsp;&nbsp;</span>An arc light is a light produced by
-the use of the voltaic arc, which is
-made by the sparks passing between
-two poles of a powerful battery which are
-brought together and then seperated a little.</p>
-</div>
-
-<div class='pbb'>
- <hr class='pb c001' />
-</div>
-
-<div class='chapter'>
- <h2 class='c006'><i>Transcriber’s Note</i></h2>
-</div>
-<p class='c019'>The source for this e-book was a hand-written
-thesis.</p>
-
-<p class='c018'>Footnotes have been moved to the end of
-the book.</p>
-
-<p class='c018'>The captions for Figures 23, 25, 26, 27, 28, 29 and 30
-are reproduced, however, the original drawings
-were not bound with the published thesis and
-are therefore not part of this e-book.</p>
-
-<p class='c018'>The author’s spelling has been maintained,
-Some standardization of punctuation was
-done to improve readability.</p>
-
-<p class='c018'>The following proper names as used by
-the author are reproduced here with their
-more commonly used spelling:</p>
-
-<table class='table2' summary=''>
- <tr>
- <td class='c008'>Author</td>
- <td class='c009'>Standard</td>
- </tr>
- <tr>
- <td class='c008'>&nbsp;</td>
- <td class='c009'>&nbsp;</td>
- </tr>
- <tr>
- <td class='c008'>Thompson</td>
- <td class='c009'>Thomson</td>
- </tr>
- <tr>
- <td class='c008'>Wimhurst</td>
- <td class='c009'>Wimshurst</td>
- </tr>
- <tr>
- <td class='c008'>Dr Urbitzkany’s</td>
- <td class='c009'>Alfred von Urbanitzsky</td>
- </tr>
- <tr>
- <td class='c008'>Lentz</td>
- <td class='c009'>Lenz</td>
- </tr>
- <tr>
- <td class='c008'>Pacinnotti</td>
- <td class='c009'>Pacinotti</td>
- </tr>
- <tr>
- <td class='c008'>Foucalt’s</td>
- <td class='c009'>Foucault’s</td>
- </tr>
-</table>
-
-<p class='c020'>Phrases and titles which
-the author portrayed by underlying have been
-presented in italics. Some standardization
-of these was also done particularly with regard
-to the presentation of illustration captions.</p>
-
-
-
-
-
-
-
-
-<pre>
-
-
-
-
-
-End of the Project Gutenberg EBook of The Thompson-Houston System of
-Electric Lighting, by H. T. Cory
-
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