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diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..d7b82bc --- /dev/null +++ b/.gitattributes @@ -0,0 +1,4 @@ +*.txt text eol=lf +*.htm text eol=lf +*.html text eol=lf +*.md text eol=lf diff --git a/LICENSE.txt b/LICENSE.txt new file mode 100644 index 0000000..6312041 --- /dev/null +++ b/LICENSE.txt @@ -0,0 +1,11 @@ +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. + +Procedures for determining public domain status are described in +the "Copyright How-To" at https://www.gutenberg.org. + +No investigation has been made concerning possible copyrights in +jurisdictions other than the United States. Anyone seeking to utilize +this eBook outside of the United States should confirm copyright +status under the laws that apply to them. diff --git a/README.md b/README.md new file mode 100644 index 0000000..763ab90 --- /dev/null +++ b/README.md @@ -0,0 +1,2 @@ +Project Gutenberg (https://www.gutenberg.org) public repository for +eBook #67859 (https://www.gutenberg.org/ebooks/67859) diff --git a/old/67859-0.txt b/old/67859-0.txt deleted file mode 100644 index de03935..0000000 --- a/old/67859-0.txt +++ /dev/null @@ -1,2304 +0,0 @@ -The Project Gutenberg eBook of American Horological Journal, Vol. I, -No. 1, July 1869, by G. B. Miller - -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 -will have to check the laws of the country where you are located before -using this eBook. - -Title: American Horological Journal, Vol. I, No. 1, July 1869 - Devoted to Pratical Horology - -Editor: G. B. Miller - -Release Date: April 17, 2022 [eBook #67859] - -Language: English - -Produced by: The Online Distributed Proofreading Team at - https://www.pgdp.net (This file was produced from images - generously made available by The Internet Archive) - -*** START OF THE PROJECT GUTENBERG EBOOK AMERICAN HOROLOGICAL JOURNAL, -VOL. I, NO. 1, JULY 1869 *** - - - - - - AMERICAN - - Horological Journal. - - VOL. I. NEW YORK, JULY, 1869. NO. 1. - - - - - CONTENTS. - - - ASTRONOMY IN ITS RELATIONS TO HOROLOGY, 5 - - WATCH AND CHRONOMETER JEWELLING, 11 - - HINTS ON CLOCKS AND CLOCK MAKING, 15 - - NOTICES OF NEW TOOLS, 17 - - GREENWICH OBSERVATORY, 17 - - PINIONS, 20 - - NEW THREE-PIN ESCAPEMENT, 23 - - ENGLISH OPINION OF AMERICAN WATCH MANUFACTURE, 23 - - CORRESPONDENCE, 24 - - ECLIPSE OF THE SUN, 25 - - DIAMOND CUTTING, 25 - - ALLOYS OF ALUMINUM WITH COPPER, 25 - - EQUATION OF TIME TABLE, 28 - -⁂ _Address all communications for_ HOROLOGICAL JOURNAL _to_ G. B. -MILLER, _P. O. Box 6715, New York City. Publication Office 229 -Broadway._ - - - - -Astronomy in its Relations to Horology. - -NUMBER ONE. - - -However accurate an instrument for the mensuration of time may be, -it would be of little use for close observation unless we have some -standard by which to test its performance. We look to Astronomy to -furnish us with this desideratum, nor do we look in vain. The mean -sidereal day, measured by the time elapsed between any two consecutive -transits of any star at the same meridian, and the mean sidereal -year--which is the time included between two consecutive returns of the -sun to the same star--are immutable units with which all great periods -of time are compared; the oscillations of an isochronous pendulum -affording us a means of correctly dividing the intermediate space into -hours and days. - -We must premise that the whole theory of taking time by sidereal -observations is based on angular motion, the mensuration of one of -the angles of motion giving a measurement of space, so that to say -space, or distance, is equivalent to saying time. From noon of one -day to noon of another is the whole problem to be solved by correct -division. The astronomical day begins at noon, but in civil law the -day is dated from midnight. So in the year the astronomical day is -dated December 31, while in common reckoning the 1st of January is the -initial point. This day is divided into twenty-four hours, counted in -England, America, and the most of the Continental nations of Europe, by -twelve and twelve. The French astronomers, however, adopted the decimal -system, for ease in the computation. Thus they divided the day into -ten hours, the hour into one hundred minutes, and the minute into one -hundred seconds. This plan was in conformity with the French system -of decimal weights and measures. Again, in Italy, the day was divided -into twenty-four hours, but counting from one to twenty-four o’clock. -The French system presents some features well worthy of adoption, as it -gives results so much more easy in computation--a facility unattainable -in the common division; yet it did not come into general use in other -countries, and although some French astronomers still hold to the -system, it is gradually dying out. - -At one time during the Revolution in France a clock in the gardens of -the Tuileries was regulated to show time by the decimal system. - -For the Horologist the mean length of the day is sufficient to show the -rate of his instrument for that particular day, but the astronomical -and civil division requires a much longer period of observation. This -is obtained by the position of the mean annual equinoxes or solstices, -and is estimated from the winter solstice, the middle of the long -annual night under the North Pole; and the period between this solstice -and its return is a natural cycle, peculiarly suited for a standard of -measurement. - -Even with such a standard as the civil year of 365d. 5h. 48m. 49.7s., -the incommensurability that exists between the length of the day and -the real place of the sun makes it very difficult to adjust the ratio -of both in whole numbers. Were we to return to the point in the earth’s -orbit in exactly 365 days, we would have precisely the same number -of days in each year, and the sun would be at the same point on the -ecliptic at the same second at the beginning and end of the year. There -is, however, a fraction of a day, so that a solar year and civil are -not of equal duration. - -It is thus we have our bissextile year, from the fact that the -inequality amounts to nearly a quarter of a day, so that in four years -we have a whole day’s gain; but not exactly, because a fraction still -remains to be accounted for. Now, if we should suppress the one day -of leap-year once at the end of each three out of four centuries, the -civil would be within a very small fraction equal to the solar year, -as given by observation; this small fraction would be almost entirely -eliminated, provided we suppressed the bissextile at the end of every -four thousand years. Were this fraction neglected, the beginning of the -new civil year would precede the tropical by just that much, so that in -the course of 1507 years the whole day’s difference would obtain. - -The Egyptian year was dated from the heliacal rising of the star -Sirius; it contained only 365 days. By easy computation it can be -shown that in every 1461 years a whole year was lost; this cycle was -called the Sothaic period, in which the heliacal rising of Sirius -passed through the whole year and took place again on the same day. -The commencement of that cycle took place 1322 years before Christ. -The year by the Roman calendar was dated by Julius Cæsar the 1st of -January, that being the day of the new moon immediately following the -winter solstice in the 707th year of Rome. Christ’s nativity is dated -on the 25th of December, in Cæsar’s 45th year, and the 46th year of the -Julian calendar is assumed to be the 1st year of our era. The preceding -year is designated by chronologists the 1st year before Christ, the -dates thence running backward the same as they run forward subsequent -to that period. - -Astronomically, that year is registered 0; the astronomical year begins -at noon on the 31st of December, and the date of any observation -expresses the number of days and hours which have actually elapsed -since that time, the 31st of December--Year 0. - -The year is divided into months by old and almost universal consent, -but the period of seven days is by far the most permanent division -of a rotation of the earth around the sun. It was the division long -before the historic period. The Brahmins in India used it with the same -denominations as at the present day the Jews, Arabs, Egyptians, and -Assyrians. “It has survived the fall of empires, and has existed among -all successive generations, a proof of their common origin.” - -Nothing can be more interesting in the study of astronomy than its -chronological value. La Place says: “Whole nations have been swept -from the earth, with their languages, arts, and sciences, leaving but -confused masses of ruins to mark the place where mighty cities stood; -their history, with but the exception of a few doubtful traditions, has -perished; but the perfection of their astronomical observations marks -their high antiquity, fixes the periods of their existence, and proves -that even at that early time they must have made considerable progress -in science.” - -The earth revolving around the sun in an ellipse, the position of the -major axis of the orbit would indicate something in regard to eras in -astronomy extending not only beyond the historical period, but so far -back in the past that imagination is almost at fault. The position of -the major axis of the orbit depends on the direct motion of the perigee -and the precession of the equinoxes conjointly, the annual motions -respectively being 11´´.8 and 50´´.1, the two combined motions being -61´´.9 annually. A tropical revolution is made in 209.84 years. This -being a constant quantity, we may ascertain when the line of the major -axis coincided with the line of the equinoxes. This occurrence took -place about 4,000 or 4,090 years before the year 0. In the year 6,483 -the major axis will again coincide with the line of the equinoxes, -but then the solar perigee will coincide with the vernal equinox. So, -it will be seen that the period of revolution is 20,966 years. But in -the progress of this revolution there must have been a time when the -major axis was perpendicular to the line of the equinoxes. A simple -calculation will show that the eventful year was 1250; and so important -is this event considered, that La Place, the immortal author of the -_Méchanique Céleste_, proposed to make the vernal equinox of this year -the initial day of the year 1 of our era. Again, at the solstices the -sun is at the greatest distance from the equator; consequently the -declination of the sun is equal to the obliquity of the ecliptic. -The length of a shadow cast at noonday from the stile of an ordinary -sun-dial would accurately determine the precise time on which this -position occurs. - -Though wanting in accuracy, such a measurement is of interest, from the -fact that there are recorded observations of this kind that were taken -in the city of Layang, in China, 1100 years before our present era is -dated. This observation gives the zenith distance of the sun at the -moment of the observation. Half the sum of the zenith distances gives -the latitude, and half their difference gives the obliquity of the -ecliptic at the period. Now the law of the variation of the ecliptic -is well known, and modern computation has verified both the moment -of taking the observation and the latitude of the place. Eclipses -were the foundation of the whole of Chinese chronology, and recorded -observations prove the civilization of that strange race for 4700 years. - -Horology, with astronomy, was not neglected even as early as 3102 years -before Christ, as the following will show. - -The cycles of Jupiter and Saturn are very unequal, the latter being a -period of 918 years; the mean motion of the two planets was determined -by the Indians in that part of the respective orbits where Saturn’s -motion was the slowest and Jupiter’s the most rapid. This observed -event must have been 3102 years before, and 1491 after the year 0; but -the record shows that the observation was taken before the last-named -date. - -Since both solar and sidereal time is estimated from the passage of -the sun and the equinoctial point across the meridian of the place of -observation, the time will vary in different places by as much as the -passage precedes each. It being obvious that when the sun is in the -meridian at any one place, it is midnight at a point on the earth’s -surface diametrically opposite; so an observation taken at different -places at the same moment of absolute time, will be recorded as having -happened at different times. Therefore when a comparison of these -different observations is to be made, it becomes necessary to reduce -them by computation to what the result would have been had they been -taken under the same meridian at the same moment of absolute time. Sir -John Herschel proposed to employ mean equinoctial time, which is the -same for all the world. It is the time elapsed from the moment the -mean sun enters the mean vernal equinox, and is reckoned in mean solar -days and parts of days. This difference in time is really the angular -motion of the earth, and by measuring it the longitude of any place on -the surface of the earth can be determined, provided we have a standard -point of departure, and an instrument capable of accurately dividing -the time into small quantities during its transit from the meridian on -which it was rated. - -As will be hereafter shown, the axis of the earth’s rotation is -invariable. Were the position of the major axis of the earth’s orbit -as immutable, an observation of any star on the meridian taken at -any place would always be the same. Again, the form of the earth has -an important effect; the equatorial diameter exceeds the polar, thus -giving a large excess of matter at the equator. Now the attraction of -an external body not only draws another to it in its whole mass, but, -as the force of attraction is inversely as the square of the distance, -it follows that the attracted body would be revolved on its own centre -of gravity until its major diameter was in a straight line with the -attracting body. - -The sun and moon are both attracting bodies for the earth; the plane -of the equator is at an angle to the plane of the ecliptic of 23° 27´ -34´´.69, and the plane of the moon’s orbit is inclined to it 5° 8´ -47´´.9 Now from the oblate form of the earth, the sun and moon, acting -obliquely and unequally, urge the plane of the equator from its own -position from east to west, thus changing the equinoctial points to the -extent of 50´´.41 annually. - -This action, were it not compensated by another force, would in time -alter the angle of the ecliptic until the equatorial plane and the -ecliptic coincided. There are few but have seen the philosophical toy -called the Gyrascope. This toy, on a miniature scale, gives a fine -illustration of the force brought in to correct the combined action of -the sun and moon on the obliquity of the equator. The rotation of the -earth is held in its own plane by its own revolution, the same as the -gyrascope seems to overcome the laws of gravitation by its force of -revolution. - -But not only do the sun and moon disturb the plane of the ecliptic, -but the action of other planets on the earth and sun is to be taken -into account. A very slow variation in the position of the plane of the -ecliptic, in relation to the plane of the equator, is observed from -these influences. It must be remembered that a very slight deviation -in the angle can and would be detected by observation with modern -instruments. We do find that this attraction affects the inclination of -the ecliptic to the equator of 0´´.31 annually. - -This motion is entirely independent of the form of the earth. Now, -if we assume that the sun and moon give the equinoctial points a -retrograde motion on the ecliptic, we must deduct the influence of the -planets. We may then calculate the mean disturbance by subtracting -the latter from the former--the difference is settled by both theory -and observation to be 50´´.1 annually. This motion of the equinoxes -is called the precession of the equinoxes. Its consideration forms a -very important element in the estimation of time, as the position of -the various fixed stars, though so very distant, are all affected in -longitude by this quantity of 50´´.1--being an increase of longitude. -Therefore, if we were to calculate the position of any given star in -order to get a transit for mean time, or true time, we must take this -quantity into consideration. The increase is so great that the earliest -astronomers, even with their imperfect modes of observation, detected -it. Hipparchus, 128 years before Christ, compared his own observations -with those of Timocharis, 153 years before. He found the solution of -the problem the same as Diophantus found the solution of the squares -and cubes, by analysis. In the time of Hipparchus, the sun was at a -point 30° in advance of its present position, for it then entered into -the constellation of Aries near the vernal equinox. - -At the present time the position of the equinoctial points shows a -recession of the whole, 30° 1´ 40´´.2. At this rate of motion the -constellations called the Signs of the Zodiac are some distance from -the divisions of the ecliptic that bear their names. At the rate -of 50´´.1 the whole revolution of the equinoctial points will be -accomplished in 25,868 years; but this is again modified because the -precession must vary in different centuries for the following reasons: -the sun’s motion is direct, the precession retrograde; therefore, the -sun arrives at the equator sooner than he does at the same star of -observation. Now, the tropical year is 365d. 5h. 48´ 49´´.7; and as the -precession is exactly 50´´.1, we must suppose it takes some time for -the sun to move through that arc. By direct observation it is found -that the time required for such translation is 20´ 19´´.6. By adding -this amount to the tropical year we have the sidereal year of 365d. -6h. 9´ 9´´.6 in mean solar days. This amount of precession has been -on the increase since the days of its first recorder, Hipparchus, as -the augmentation amounts to no less than 0.´´455. By adding that to the -known precession we find that the civil year is shorter now by 4´´.21 -than in his time; but, as a great division of time, the year can be -changed by this cause not more than 43.´´ - -The action of the moon on the accumulation of matter at the earth’s -equator is a source of disturbance that in very accurate observations -for time should be eliminated. Thus the moon, with the conjoint action -of the sun, depending on relative position, causes the pole of the -equator to describe a small ellipse in the heavens with axes of 18´´.5 -for the major, and 13´´.674 for the minor; the longer axis being -directed to the pole of the ecliptic. This inequality has a period -of 19 years,--it being equal to the revolution of the nodes of the -lunar orbit. The combination of these disturbances changes, by a small -quantity, the position of the polar axis of the earth in regard to the -stars, but not in regard to its own surface. With so many disturbing -causes, we must add that of Jupiter, whose attraction is diminishing -the obliquity of the ecliptic by 0´´.457 according to M. Bessel. - -The results of all these forces must affect the position of all the -stars and planets as seen from our earth. Their longitudes being -reckoned from the equinoxes, the precession of these points would -increase the longitude; but as it affects all the stars and planets -alike, it would make no real or apparent change in their relative -positions. Nutation, however, affects the celestial latitudes and -longitudes, as the real motion of the earth’s polar axis changes the -relative positions. So great is the change that our present pole star -has changed from 12° to 1° 24; in regard to the celestial pole, the -gradual approximation will continue until it is with 0° 30´, after -which it will leave the pole indefinitely until in 12,934 years α Lyræ -will be the pole star. - -So far we have given only the causes that affect the meridian, and -consequently our standard for time; but that point being established -for the yearly and diurnal revolutions, it becomes necessary to find -some means to divide the day into minute fractional parts, such as -seconds and parts of seconds. This, it has been stated, is effected -by means of an isochronous pendulum. On this instrument no comment is -required but of the causes that disturb its accuracy much is needed. -In 1672, at Cayenne, the astronomer Richter, while taking transits -of fixed stars, found his clock lost 2´ 28´´ per day. This was an -error that arrested his attention, and he immediately attributed it -to some variation in the length of the pendulum--due to other causes -than atmospheric changes and expansion. He determined the length of a -pendulum beating seconds in that latitude, which was 5° N. in South -America. He found that that pendulum was shorter than one beating -seconds in Paris, by 0833+ of an inch. Now, if the earth was a sphere, -the attraction of gravitation at all places on its surface would be -equal, and the oscillations of a pendulum would also be equal, + or -- the disturbing effect of centrifugal force--an amount that can be -easily determined. The real reason of the variation is found in the -configuration of the earth. - -The amount of the attraction of gravitation at any point of the earth’s -surface is found by the distance traversed by any body during the -first second of its fall. The pendulum is a falling body, and may be by -the same analysis reasoned on that pertains to the laws of gravitation; -the centrifugal force is measured by any deflection from a tangent to -the earth’s surface in a second. - -It follows that the centrifugal force at the poles, where there is -the least motion, would not be equal to the force of gravitation, and -at the equator must be exactly equal; but the deflection of a circle -from a tangent measures the intensity of the earth’s attraction, and -is equal to the versed sine of the arc described during that time, -the velocity of the earth’s rotation being known, the value of the -arc is deducible. The centrifugal force at the equator is equal to -¹⁄₂₈₉th part of the attraction of gravitation. Again, the uniformity -of the earth’s mass becomes an object of consideration. Assuming that -the figure of the earth is an ellipsoid of rotation, we will show the -relation that form bears to the equal oscillation of a pendulum. - -Taking the earth as a homogeneous mass, analysis gives us the certainty -that if the intensity of gravitation at the equator be taken as unity, -the increase of gravity to the poles eliminating the differences of -the centrifugal force must be = to 2.5, the ratio of the centrifugal -force to that of gravitation at the equator. Now, taking the 2.5 of -.346 = 1/115.2, this then must be the total increase of gravitation. -Did we know the exact amount of increase at every point, from the -equator to the poles, a perfect map of the form of the earth could -be produced from calculation; experiment being from physical causes -totally impracticable. The following analysis, quoted from an eminent -physicist, gives a very lucid idea of the reasoning: - -“If the earth were a homogeneous sphere without rotation, its -attraction on bodies on its surface would be everywhere equal. If it -be elliptical and of variable density, the force of gravity ought to -increase in intensity from the equator to the pole as _unity plus_ -a constant quantity multiplied into the square of the sine of the -latitude. But for a spheroid in rotation the centrifugal varies by -the law of mechanics, as the square of the sine of the latitude from -the equator, where it is greatest, to the poles, where it is least. -And as it tends to make bodies fly off the surface, it diminishes the -force of gravity by a small quantity. Hence, by gravitation, which -is the difference of these two forces, the fall of bodies ought to -be accelerated from the equator to the poles proportionably to the -square of the sine of the latitude, and the weight of the body ought to -increase in that ratio.” - -Assuming the above reasoning to be correct, it follows, that the rate -of descent of falling bodies will be accelerated in the transition -from the equator to the poles. Now, it has been before stated that -the pendulum is a falling body; therefore, with the same length of -pendulum, the oscillations at the pole should be faster than at the -equator. Theory, in this case, is verified; for it has been proved by -experiments, repeated again and again, that a pendulum oscillating -86,400 times in a mean day at the equator, will give the same number of -oscillations at any other point, provided its length is made longer in -the exact ratio as the square of the sine of the latitude. - -The sequence to be derived from all the foregoing considerations is, -that the whole decrease of gravitation from the equator to the poles -is 0.005.1449, which subtracted from the 1/155.2 gives the amount -of compression of the earth to be nearly 1/285.26. But this form -of the earth would give the excess of the equatorial axis over the -polar about 26¹⁄₂ miles. The measurement is confirmed by Mr. Ivory -in his investigations on the five principal measurements of arcs of -the meridian in Peru, India, France, England, and Lapland. He found -that the law required an ellipsoid of revolution whose equatorial -radius should be 3,962.824 miles, and the polar 3,949.585 miles; the -difference is 13.239 miles; this quantity multiplied by two gives -26.478 as the excess of one diameter over the other. Thus, by two -different processes the figure of the earth has been determined; but -another remains that is the result of pure analysis, derived from the -nutation and precession of the equinoxes--for, as explained before, -these effects are caused by the excess of matter at the earth’s -equator. The calculation does not lead us to certainty, but it does -show the compression to be comprised between the two fractions ¹⁄₂₇₀ -and ¹⁄₅₇₃. There is this advantage in the lunar theory, that it takes -the earth as a whole, disregarding any irregularities of surface, or -the local attractions that influence the pendulum--the difficulties of -measuring an arc of the meridian being an obstacle to perfect accuracy. - -The form of the earth has, however, a value confined not alone to those -interested in horology--it furnishes us with a standard of weights and -measures. In England and the United States, the pendulum is the unit of -mensuration, or at least the common standard from which measurement is -derived. It has been shown that, deducting the effects of nutation, the -axis of the earth’s rotation is always in the same plane. Now, the mass -being the same constant quantity, a pendulum oscillating seconds at the -Greenwich Observatory, has been adopted by the English Government as -its standard of length. Oscillating in vacuo at the level of the sea, -at 62° Fahr., Captain Kater found its approximate length to be 39.1393 -inches; as this must be invariable under the same circumstances, it -becomes a standard for all time. The French deduced their standard from -the measurement of the ten-millionth part of a quadrant of the meridian -passing through Formentera and Greenwich. They have also adopted the -decimal system; yet it seems to prove that nothing under the sun is -new, for over forty centuries ago the Chinese used the decimal system -in the division of degrees, weights, and measures. - -The antiquity of the pendulum is also shown by the fact that the -Arabs were in the habit of dividing the time in observations, by its -oscillations, when Ibn Junis, in the year one thousand, was making -his astronomical researches. Before we lose sight of the influence -of the form of the earth on the pendulum, it may be well to state -another source of disturbance, arising from the combined influence of -the earth’s rotation and the fact that a body moving in its own plane -seeks to maintain that plane. It will be seen from the very beautiful -experiment showing the rotation of the earth, that if a body like a -pendulum be suspended so as to be free in every direction, and not be -influenced by the motion of the earth when set in oscillation in any -plane, that that plane will preserve its line of motion, while the -earth in its motion beneath the body can be seen to slowly move, as -though the minute hand of a watch were made stationary while the dial -revolved. The same principle is the one that maintains the spinning-top -in a parallel position to the horizon, or the gyrascope in its -apparently anomalous defiance of all the laws of gravitation. In the -pendulum this tendency to preserve the same plane of motion becomes a -cause of error--slight, it is true, but can be very easily remedied by -so placing it that the plane of oscillation shall be parallel to the -equator. It will be readily seen that this precaution will become more -important as we recede from the equator; for if we were to suspend a -pendulum at the pole in a true line with the axis of rotation, and if -the plane of vibration remained constant, the earth would turn once -around that plane in the diurnal period. During this time there would -be a continuous torsion on the point of suspension, that would in time -materially affect the accuracy of the instrument. The reasoning holds -good for every latitude--degree of influence being the only difference. - -Having given the action of the earth’s form, mass, and rotation on -the pendulum, there remain the disturbances due to expansion and -contraction, owing to changes of temperature and those of atmospheric -causes. The astronomical points to be observed are somewhat too fully -laid down, but it must be remembered that an exact science requires the -premises to be fully established before a sequence can be drawn. - -As the standard of time depends on the passage of a star or the sun, or -any known celestial object, at a certain time across the meridian of -the place where the observation is taken, it was absolutely necessary -to give the modes of calculation, together with the disturbing causes. -Moreover, a full appreciation of the indebtedness of horology to -astronomy could not be obtained without a general knowledge of the -change of the position of the major axis of the orbit described by the -earth around the sun. Also, the difference between mean and apparent -solar time was required to illustrate the use of the tables of equated -time, the necessity of which will become patent when the use of the -transit instrument for the establishment of time, or a fixed standard, -is introduced. Also, the disturbing effects of the sun and moon -collectively and relatively as to position, could not be passed, as -they produce the precession of the equinoxes and the nutation of the -pole--essential elements in the computation of time. - - - - -Watch and Chronometer Jewelling. - -NUMBER ONE. - - -This whole subject is well worthy an article both in a scientific and -mechanical sense, whether we consider the delicacy of the operations -or the intractable character of the material operated on--for there -has been no improvement in the horological trade of more importance to -accuracy and durability of time-keepers. - -The substitution of stone for common brass or gold bearings, was -prompted by the inevitable wear of the holes from frequent cleaning, -and the abrasion of the pivots, produced by the accumulation of -dust with viscid oil; the pivot being cut away, or the hole opened -too large. So long as the verge and cylinder were the prevailing -escapements, the necessity for jewelling was not so strongly felt, -except in the balance holes. The introduction of the lever escapement -brought with it a better watch,--capable of more accurate time, but -demanding an improved construction. - -An Italian, in 1723, first introduced the practice of using stone for -bearings. He not only conceived the idea, but was successful as an -artisan in making his own jewels; ingenious and skilful as he was, -however, he encountered obstacles almost insurmountable. - -The art of cutting gems, it is true, was at that time well understood, -but no one had attempted to drill a hole in a hard stone fine enough -for a properly sized pivot. The watches at that time that were jewelled -could boast of nothing more than the balance holes, and they were not -pierced to let the pivot _through_. - -It is a very difficult matter to polish a taper indentation in a stone, -even with modern appliances, in consequence of the tendency to create -a _tit_ at the bottom,--thus throwing the balance staff out of upright. -The difficulties in the then state of knowledge retarded the general -introduction of stone-work for many years. The Swiss, however, seeing -the advantages derived, finally struck out the various manipulations -with success. Time and experience gave more skill, and at the present -time it is impossible to find a Swiss watch, even of the cheapest -class, that is not jewelled in at least four holes. The English trade -adopted the art later; but even then it did not become general for many -years. Within a generation, only fine English levers were jewelled. - -The mere substitution of a harder substance was not the only -improvement; other conditions necessary to accuracy were insured. The -hole could be made _round_--the material of such a character that no -chemical action could be effected on the oil used for lubrication, -and the vertical section of the hole could be made so as to present -the least amount of frictional surface, yet still giving a perfectly -polished bearing, thus avoiding the cutting of the pivot. - -The whole “_modus operandi_” from the stone in the rough to the last -setting up is well worth the attention of the watch repairer, and -certainly that of the manufacturer. - -Of the materials used in the trade, the first and most important is -the diamond, used only in the time-piece as an end-stone--but at -the bench all-important, as a means of making the other jewels. The -diamond possesses the requisite susceptibility of polish, combined with -greatest hardness of any substance known; but this adamantine quality -precludes its being pierced with a through hole. Considered chemically, -the diamond is pure carbon,--its different varieties differing only -in structure--common charcoal, its lowest--plumbago, its intermediate -grade. Another variety, called the “black diamond,” or “diamond -carbon,” occurs, which is interesting as being a parallel with emery, -compared with crystallic sapphire. The form of diamond most in use for -mechanical manipulations, is almost always crystallized; yet it will be -seen that the agglomerated form of diamond carbon plays no unimportant -part in jewelling. As a jewel, no use is made of the diamond, other -than as an end-stone. Marine chronometers, in which the balance will -weigh from five to nine pennyweights, are almost invariably furnished -with a diamond end-stone, set in steel. Yet, hard as the substance is, -it is often that a pivot will cut an indentation in its face. The cause -of this apparent anomaly is to be found in the structural character of -the gem, and its value. The lapidary, saving in weight as possible, -does not care, in “Rose Diamonds,” to pay attention to the lines of -cleavage. If the face of the stone makes a slight angle with the -strata of the jewel, there occur innumerable small angles of extreme -thinness--the pivot, coming in contact with any of these thin portions, -may fracture it, and the fragment, becoming imbedded in the tempered -steel pivot, becomes a drilling tool. In our experience we have had -marine chronometers sent for repair, that have lost their rate so much -as to become utterly unreliable from this cause alone--the pivot having -produced an indentation of the stone, creating more friction, and thus -destroying the accuracy of the instrument. - -As a general rule, the rose diamonds sold for this purpose are -sufficiently good for general work. In a very fine watch or chronometer -the stone should be selected with reference to its polish on the face, -and its parallelism in the lines of cleavage. The diamond, however, -gets its great importance from being the only agent we can use in -working other stones. Without it the whole art of jewelling would not -be practicable. The various steps are all connected some way with -diamond in its different shapes. “Bort,” the technical name for another -variety, is merely fragments of the stone that have been cleaved off -from a gem in process of cutting, or gems that have been cut, but found -too full of flaws to become of use for ornamental jewelry purposes, -the cost depending on the size, varying from $5.50 to $18 per carat. -This “Bort” is used as turning tools--the larger pieces being selected -and “set” in a brass wire and used on the lathe, in the same manner, -and with the same facility, as the common graver. For tools, even -the diamond is not of equal value--a pure white and crystalline in -structure generally being too brittle (though hard) to endure the -work. Among the workmen the “London smoke,” a clouded, brownish stone, -is most prized--it possessing the twofold qualities of toughness and -hardness. - -Another form of “Bort” comes in the shape of a small globule, sometimes -the size of a pea; it is crystallic, and when fractured generally gives -very small, indeed minute pieces of a needle shape. These are carefully -selected, and form the drills with which the English hole-maker -perforates the jewel. These drills, when found perfect, for soundness, -form, and size, are very highly prized by the workman, as the choice of -another, together with the setting, will often take a vast deal of time -and labor. - -“Bort” is also used in the making of the laps or mills with which -the jeweller reduces the stones to a condition for the lathe and -subsequent processes. For this purpose such pieces as are not fit for -cutting-tools, or drills, are selected. A copper disk, having been -first surfaced and turned off in the lathe, is placed on a block or -small anvil; each piece of stone is then separately placed on the -copper, and driven in with a smart blow--care being taken that no place -shall occur in the disk that does not present, in revolution, some -cutting point. It would seem impossible to retain the diamond fragment, -but it must be remembered that the copper, being a very ductile metal, -receives the piece; the first rubbing of a hard stone then burnishes -the burred edges of the indentations over every irregular face of the -diamond, leaving only a cutting edge to project. The rapidity with -which such a lap, well charged, will reduce the hardest stone, is -somewhat marvellous. It is the first tool used in jewelling, and so -important that a more detailed and explicit description of its make -will be given when the process of manufacture is treated upon. - -Diamond powder is equally as important as “bort,” being used in nearly -every stage of jewel-making. The coarsest charges the “skives” or -saws used for splitting up the stone. These skives are made of soft -sheet-iron, and act on the same principle as the laps. The finer -grades, in bulk, resemble very much ordinary slate-pencil dust; -indeed, the latter is often used as an adulteration. This powder is -not uniform in fineness, and the jewel-maker is under the necessity of -separating the different grades. This is effected by a simple process -called “floating off,” and is conducted as follows: A certain quantity -of powder, say a carat, is put into a pint of pure sweet oil, contained -in some such shallow vessel as a saucer. Depending on the fluidity of -the oil, the mixture, after being thoroughly incorporated, is allowed -to stand undisturbed for about an hour or an hour and a half. During -this time, owing to their greater gravity, the largest particles are -precipitated, leaving held in suspension a powder of nearly uniform -fineness. The mixture is now carefully decanted into another similar -vessel, leaving the coarse powder at the bottom of the first. This -coarse deposit is denominated No. 1, and is used for skives, laps, and -other rough purposes. The decanted mixture in the second vessel is -allowed to remain quiescent for twelve hours, when the same operation -is performed; and the third vessel now contains most of the oil, -together with the finest particles of powder. The precipitate from the -second decantation is the ordinary opening powder; the finest being for -polishing both the holes and outsides of jewels, and giving the final -finish to the faces of pallets, roller pins, locking spring jewels, etc. - -The good workman is careful to keep the powder in this condition as -free as possible from any extraneous dust, and above all to preserve -the different grades from any intermixture, as a small quantity of a -coarser grade would destroy a finer one for all its purposes, and the -process of “floating off” would have to be repeated. - -The most important stone in jewelling, the diamond, becomes more of an -agent of the manufacture than an object. - -Properly, for jewelling the ruby and sapphire are pre-eminent; -inferior only to diamond in hardness, possessing a sufficient degree -of toughness, susceptible of an exquisite polish, this (for they -are one and the same) stone is the favorite of the Swiss, English, -and American, for all high class work--the Swiss, however, using it -indiscriminately in all watches. - -The ruby proper is of one color, but in its varieties of intensity -may change to a very light pink. When still lighter it is ranked a -sapphire, which comes in almost every possible color and shade, from -ruby to a perfect transparent colorless crystal. This stone differs -in degrees of hardness and capacity of working--the hardest being a -greenish yellow, in the shape of pebbles, with very slightly rounded -edges, difficult to work, but forming the strongest and most perfect -jewel known. - -It must be remembered that this description gives the value of the ruby -and sapphire as a material for jewelling only. For ornamental jewelry, -the value depending on color, of the most intense ruby or blue for -sapphire, together with brilliancy and weight. The ruby and sapphire -are formed on an aluminum base, the common emery being another form of -structural arrangement, but of the same chemical constitution. - -These stones possess every quality to make them the base of perfect -jewelling; and still the chrysolite is equally in favor with most -jewellers. It is not quite so hard, but it is more easily worked and -cheaper in price, and it would be difficult to tell wherein it is -inferior to either the ruby or sapphire. It has a yellowish tinge, -verging to the color of the olive. As a stone for jewelry it is not -fashionable, and only in Persia is it valued. There are, however, some -very strong objections to its use by the workman; it is not uniform -in hardness; in polishing it will _drag_, that is, the surface will -tear up in the process. Unfortunately the eye is not able to detect -the fault before working, and it is found only when much preliminary -time and trouble has been expended. It is susceptible, when good, of a -perfect polish, and is much used in chronometer work, especially for -jewelling the 4th hole, as its non-liability to fracture renders it -valuable. - -“Aqua Marine” is a brother to the emerald, differing from it only in -intensity of color, and composed of the same constituents. These two -gems are the only ones in which the rare metal, glucinum, has been -detected. It is extensively used in the American and English watches, -but never in the Swiss. It is soft, not much harder than quartz, but -comes in large pieces, perfectly transparent, and of a color which -is that pure green of sea-water, from which it takes its name, “Aqua -Marine.” - -The garnet in English watches plays an important part for pallets, also -for roller-pins; a very soft stone, but very porous. When set in the -pallet with a pointed toothed wheel, it is apt to act as a file from -its porosity, cutting the end of the tooth. This may be detected in any -pointed tooth lever watch, by observing the color of the back of the -tooth. “Black vomit” it used to be called in the Boston factory. Most -of the garnet used is an Oriental stone, the best quality coming in -bead form, the holes having been pierced by the natives. The cost of -piercing the stone in Europe or America would be far above its value. -The Oriental is the best for Horological purposes, though Hungary and -Bohemia furnish the most highly prized stones used for ornamental -purposes; indeed, in some German towns the cutting and setting of the -garnet is a specialty, giving employment to a large number of people. -And, strange to say, the best market for their sale is the United -States. - -This comprises about all the stones used in watch and chronometer -jewelling. Still in clock work the pallets are generally jewelled in -agate, a stone not at all suited to the purpose, it having, even in -the best specimens, a decided stratification that prevents an uniform -surface being formed by any process. The cornelian form of the agate -is not open to this objection, and makes capital bearings for knife -edges of fine balances, and compass stones for centres of magnetic -needles. For watch or chronometer purposes the only really useful -stones are sapphire, ruby, chrysolite, and aqua marine--all possessing -peculiarities that deserve some remarks, as they are of the utmost -importance to the hole maker. The sapphire is the hardest stone, next -to the diamond, and yet specimens can be, and are found, so soft as -to _drag_ in polishing. Again, if stratified very clearly, will “fire -crack” in opening the hole. The ruby is more uniform in its structure, -and is more highly prized on that account; its hardness being all that -is necessary, while its susceptibility of receiving a high polish -is equal to that of the sapphire or chrysolite. The aqua marine is -always uniform and may be polished both externally and in the hole with -“tripoli,” saving something in diamond powder in the process of making. -In our estimation, however, the chrysolite is the most valuable of all -the stones. True, when purchased in the rough, many pieces will be -found unfit for the jeweller’s purpose; but when the right quality is -found, nothing can be better adapted to jewelling. Hard, it is easily -wrought, taking a peculiar _unctious_ polish, retaining oil in its most -limpid condition for a long time. - -These stones form the general stock by and from which jewels are made. -The details of the various manufacturing manipulations, the tools -used, also the setting in the work, together with the important item -of the screws, will form the subject of the next article on Watch and -Chronometer Jewelling. Not having been able to get our engraving done -in time for publication, we are compelled to reserve the remainder for -the next number. - - - - -Hints on Clocks and Clock-Making. - -NUMBER ONE. - - -Twenty-five years of hard labor amidst the dust and din of machinery, -with hands cramped, and fingers stiffened by the continual use of -tools, and with a brain constantly occupied in ringing the changes upon -wheels and levers in their almost infinite combinations,--it requires a -degree of courage to undertake to write anything that can be dignified -with the name of an “article,” although it does propose to treat upon -a subject with which we are fairly familiar; but it is consoling to -think that one is not expected to write for the pages of this practical -journal with the same degree of elegance and polish that should grace -the columns of a review or magazine; that we can appear here as plain, -practical mechanics, and use good hard, round words to express our -ideas, backed by an experience which should add some weight--and we -welcome the appearance of the “American Horological Journal,” which -is to serve a good purpose by bringing out the actual experience of -men who have grown gray in the art and mystery of clock-making, and -preserving, by means of the “art preservative of all arts,” their -dearly bought knowledge and experience, for the benefit of those who in -their turn shall follow them; and it will also benefit the people in -general by giving information that will lead to the purchase of good -and tasteful clocks for household use. - -That such a journal is needed to enlighten us, is made plain by the -fact that in almost every newspaper we have a vivid account of some -wonderful clock “recently invented,” which may possess some merit, but -they are so grossly exaggerated by some ignorant “penny-a-liner,” that -we are almost led to believe in the Irishman’s marvellous “eight-day -clock, that actually ran three weeks.” Even the proverbially correct -“Scientific American,” of which I am a constant reader, has in its -issue of June 19th, an account in its “editorial summary” of a clock in -France containing “90,000 wheels,” and perhaps the most curious part -of the mechanism is that which gives “the additional day in leap-year,” -etc. Now, it will require but little knowledge of clocks to tell us -that one with 90,000 wheels was never made and never will be, but “the -additional day in leap-year” has been given by calendar clocks in this -country since the year 1853. - -It is not proposed in the series of articles to follow, to discuss -the early history of clocks. Reid and Dennison have written enough -to convince the most skeptical that the clock is an old invention. -It is not important to us who invented the pendulum, or this or that -escapement, but who makes the best pendulum, the best escapement, the -most perfect train of wheels and pinions. These are vital points, and -we shall endeavor to give them that attention that their importance -demands. It is proper to state here that any assertion made, or rule -given, has been tested, and is the result merely of our experience, -and we do not claim that it is all there is of the subject; for we are -aware that the experience of others may have led to results entirely -different; but if all clock-makers will avail themselves of the columns -of this journal, we shall not only become better acquainted by an -exchange of ideas, but better clock-makers. - -The subject of wheels and pinions is of the greatest importance in -clock-making, and the utmost care and skill are required to execute a -train which shall not only run with as little friction as possible, -but the friction must be equal; for if there is no variation in the -train force, the escapement and pendulum will always be actuated by the -same amount of power, and the performance of the clock can be relied -upon. Clock text-books do not fully impress this subject. We find a -great deal upon this or that escapement, and the different pendulums. -Dennison has a couple of pages full of abstruse calculations upon a -method of shifting an extra weight upon a rod, so that the going of a -clock can be varied one second per day; but if his wheels and pinions -are not perfect, a large tooth here and there will vary the clock more -than that. - -Reid overawes us with his knowledge of the proper curves of the teeth -of wheels; but it must have been only theory, for his practice was to -saw his teeth, and his cycloids, epicycloids, and hypocycloids were -left to the mercy of the “topping file” in the hands of his “wheel -teeth finishers,” instead of shaping up the teeth in the engine, as is -done now. We have generally cut the wheels of fine clocks over several -times with different cutters before taking them from the engine; the -last cutter having but one tooth, which can be made perfect as to cut -and shape, and, running with great speed, will leave the teeth the -proper shape, very smooth, and as true as the dial of the engine. -Escape wheels, especially, require great care in cutting, as the -teeth for dead-beat escapements are somewhat long and thin; the least -inaccuracy is certain to cause trouble. It is absolutely necessary that -the dial plate of the cutting engine should be perfectly true, with -clean, round holes, and a perfect fitting index point, with a cutter -arbor without end play or lateral motion--these are the essentials of a -good cutting engine, without which a good clock cannot be made. - -We have generally made a practice, upon the completion of the train for -a fine clock, to put in the place of the escape-wheel a very light, -well-balanced fly, to prevent “backlash,” and a very fine soft cord -on the barrel; then hang on a very light weight; so slight that--all -of the wheels being balanced, and no oil upon the pivots--the fly -will move so slowly that its revolutions may be counted. By taking -care that the weight be not too much in excess of the resistance, the -least inaccuracy in the wheels and pinions may be discovered by the -difference in the velocity of the fly, or by its suddenly stopping, -which will be occasioned by any inequality in the train teeth, which -would not have been discovered by the closest scrutiny. It was by means -of this test that we discovered an inaccuracy in a pinion, caused by -hardening, which could not have been discovered by a less delicate test. - -The wheels in the train should be as light as possible, for as the -whole train is stopped every time a tooth drops on the pallets, it is -plain that the driving weight must overcome the inertia as well as the -friction of the train at every beat. To this end it has been customary -to “arm out” the wheels, leaving a very light rim supported by light -arms, the wheels being generally of cast brass, turned up, and cut, -then lightened. We followed this plan for some time, but abandoned it, -as we found great difficulty in making a perfectly round wheel. The -arms serve as posts to support the rim in cutting or turning, but the -space between is very apt to spring down. We prefer making the wheels -of fine hard-rolled sheet brass; it is superior to cast brass, much -finer, harder, and more durable, and is freer from flaws. After the -wheels are cut, they are turned out on each side, leaving a thin web in -the centre; they can be made lighter, finished easier, and are round. - -As to the shape of the teeth in clock-wheels, the subject has been so -ably treated by Reid, Dennison, and Prof. Willis (who has invented an -instrument to assist in laying out the curves for the teeth of wheels), -that we shall not attempt it in this paper; besides, there is so little -of the entire theory that can be applied to a clock-wheel of two and -a half inches in diameter, with 120 to 140 teeth, farther than to -leave the wheel and pinion of the proper diameter, that we consider it -unnecessary; for if makers of regulators and other fine clocks will -use pinions of 16 or 20 teeth, the friction or driving is all after the -line of centres, and the whole subject of cycloids, epicycloids, and -hypocycloids is reduced to a very small point, and might be said to -“vanish into thin air.” - -Having given only a few practical hints, and not yet crossed the -threshold of the subject, we propose to continue from month to -month--if the readers of the JOURNAL do not weary--the discussion of -the various parts that go to make the sum total of a fine clock, with -notices of the various clocks made in this country. - - * * * * * - -It certainly comes within the province, and is the duty, of a journal -devoted to Horology, to make a note of any and all the new improvements -that pertain to the science. We give, then, some few, the merits of -which have struck us as being a very important matter of consideration. - -The best clock time-keeper is not absolutely perfect, so its rate must -be kept; but the watchmaker ordinarily has no means of correcting the -error of his regulator, until the accumulation renders it a serious -inconvenience. Did he possess a Transit instrument, properly set and -adjusted for meridian, together with the required books and knowledge -of observing, he could from day to day correct his clock and keep -accurate time; but these are all expensive, as well as involving time -and labor. Suited to the wants of the artisan is a little instrument -called the Dipleidescope; simple in its construction, and not liable -to get out of position or order, it forms the best substitute for the -transit we have seen. It is founded on the theory that the double -reflection from the two surfaces of planes at an angle of 60° will -coincide when the object reflected is in a true line with half the base -of the whole triangle. Having a prism cut in an equilateral triangle, -one angle is set directly down toward the centre of the earth, the base -being brought parallel with the line of the horizon. Now, if the axis -of the prism is in a line with the meridian, a reflection of the sun -will appear, at the instant of crossing the meridian, on itself--that -is, there would be but one image. If the instrument is well made, -there can be no doubt of its accuracy and value to those who, wishing -to verify their time, are not situated so as to use a transit. - -Another improvement is a Bench-Key for watchmaker’s use. No one who has -had any experience at the bench but will appreciate an article that -facilitates the setting of time-pieces for his customers. In winding, -it is equally valuable. It is not dependent for its strength of torsion -on the spring-chuck principle, the power being applied close to the -square by means of a pin that passes through the key. - -Hall’s Patent Cutting Nippers are a positive desideratum; a large -wire can be cut off without the least jar to the hand, the leverage -is so great. The smallest sizes are suitable to the ordinary run -of watch-work, and can be used in clock-work better than any -cutting-plyers extant. Strong and durable, they possess one quality -that all watchmakers will appreciate--if a cutting-jaw is broken it can -be replaced by another. - - - - -Greenwich Observatory. - - -About two hundred years ago, England began to take a lead in the -mercantile commerce of the world; her ships were daily passing across -the Atlantic, and India also was beginning to attract her attention. -It was therefore of the utmost importance that navigators should be -enabled to find their longitude when at sea, independently of watches -or clocks; and a reward was offered to any one who should discover a -method by which this result might be obtained. - -The plan proposed was, that the angular distance of the moon from -certain stars should be calculated beforehand, and published, so that, -for example, it might be stated that at ten minutes and five seconds -past nine on such a day, the moon should be distant from Mars 40 -degrees. If from a ship in the middle of the Atlantic, Mars and the -moon were found to be 40 degrees apart, then it would be known that the -time in England was ten minutes and five seconds past nine. - -Here, then, was one item ascertained, and the method was a good one; -but in consequence of the want of accuracy as regarded the moon’s -motions, and the exact positions of the stars, it could not be -practically carried out. - -Under these circumstances, Charles II. decided that a national -observatory should be built, and an astronomer appointed; and a site -was at once selected for the building. Wren, the architect, selected -Greenwich Park as the most suitable locality, because from thence -vessels passing up and down the Thames might see the time-signals, -and also because there was a commanding view north and south from -the hill selected for the site. The observatory was completed in -1676, and Flamsteed, the chief astronomer, immediately commenced his -observations, but with very imperfect instruments of his own. During -thirty years, Flamsteed labored indefatigably, and formed a valuable -catalogue of stars, and made a vast collection of lunar observations. -He was succeeded by Halley, who carried on similar observations; and -from that time to the present, Greenwich Observatory has been our -head-quarters for astronomical observations. - -The work carried on at Greenwich is entirely practical, and consists -in forming a catalogue of stars and planets, and so watching them -that every change in their movements is at once discovered. Now that -this work has been performed for several years, the movements of the -principal celestial bodies have been so accurately determined, that the -_Nautical Almanac_--the official guide on these subjects--is published -four years in advance, and thus we find that on a particular night in -1868, the moon will be at a certain angular distance from a star, and -the second satellite of Jupiter will disappear at a particular instant. -On the exterior wall of the observatory there is a large electric -clock, which, being placed in “contact” with the various other clocks -in the observatory, indicates exact Greenwich time. The face of this -clock shows twenty-four hours, so that it requires that a novice should -look at it twice before comparing his watch. On the left of this clock -are metal bars let into the wall, each of which represents the length -of a standard measure, such as a yard, foot, etc. And let us here say -a few words about these standards. To the uninitiated a yard is simply -three feet, and a foot is twelve inches--an inch being, we are told in -our “Tables,” the length of three barleycorns. Now, as the length of -a barleycorn varies considerably, it requires something more definite -than this to determine our national measures. Thus, the question, what -_is_ a foot? is more difficult to answer than at first sight appears. -Many years ago the French perceived the difficulty appertaining to the -national standard, and they, therefore, decided that a metre should be -the ten-millionth part of one-fourth of the earth’s circumference--that -is, ten-millionth of the distance from the Equator to the Pole. But -here another difficulty was encountered, because different calculators -found this arc of different lengths. By _law_, however, it was decided -that one measurement only was correct, and so the metre was fixed at -3.0794 Paris feet; though since then, more accurate observations and -improved instruments have shown these measured acres to have been -very incorrectly ascertained, and thus the French method failed when -practically tried. - -The length of a seconds pendulum oscillating in a certain latitude has -been our method of obtaining a standard; but this also has its weak -points, so that to obtain a constant standard it is necessary to have -some pattern which is unchangeable, and thus a metal has been chosen -that expands or contracts but little either with heat or cold; and -this, at a certain temperature, is _the_ standard measure, and such a -standard may be seen on the exterior wall of Greenwich Observatory. - -On entering the doorway--which is guarded by a Greenwich pensioner, -who will possibly first peep at the visitor, in order to see who -the individual may be who is desirous to tread within the sacred -precincts--one finds a court-yard, on the left of which are the -transit-room, the computing-room, and the chronometer-room. The -transit room takes its name from the instrument therein, which is -a large “transit.” This consists of a large telescope, the outside -of which is not unlike a heavy cannon, as it is of solid iron. The -instrument is supported by trunnions, which allow the telescope to be -elevated or depressed to point south or north, and, in fact, to make -a complete revolution, but never to diverge from the north or south -line. The magnifying power of this instrument is not very great, so -that it admits plenty of light, for it is intended, not as a searcher -for or for gazing at celestial objects, but for the purpose of noting -the exact time at which stars and planets pass south or north of -Greenwich. Upon looking through this telescope, the observer’s eye -is first attracted by a vertical row of what seem to be iron bars, -placed at equal distances from each other. These, however, prove to be -only spiders’ webs, and are used for the purpose of taking the time -of passage of a star over each wire, and thus to ascertain the exact -instant of its being in the centre of the telescope. During even the -finest and calmest nights, there is occasionally found a tremulousness -in the instrument, which, as it is rigidly fixed to the walls of the -building, must be due to a slight vibration in the ground itself. Thus, -many a feeble earthquake unfelt by the outsider may be perceived by the -astronomer by the aid of his delicate instruments. - -The various stars seem to be travelling at an immense rate when -seen in the field of the transit telescope, and it is really nervous -work noting the exact time when each wire is passed. The experienced -observer, however, not only will give the minute and second, but also -the decimal of a second when the star was on the wire. The result is -obtained by counting the beats of a clock the face of which is opposite -the observer. Thus, if at three the star seems as much short of the -wire as at four it had passed it, then 3.5 might be the instant of -“transit.” - -At noon each day the sun’s passage is observed by nearly the whole -staff of observers. One individual looks through the telescope, and -gives the time for each wire, while others examine a variety of -micrometers in order to ascertain the fractional parts of seconds, -etc.,--these micrometers being placed at the side of the instrument. - -In the morning, the principal work consists in making what are termed -the “reductions” to the observations of the previous night. These -reductions are the corrections requisite for the slight instrumental -inaccuracy, for the refraction of the atmosphere, and for the known -constant error of the observer. When, therefore, a bright winter’s -night has occurred, the work on the following morning is usually very -heavy. At noon the sun’s time of transit is taken, and at one o’clock -the “ball” is dropped, by means of which the various vessels in the -Docks and in the Thames set their chronometers, or ascertain their -rate. In addition to this, the time is sent by electricity to Deal and -one or two other seaports, in order that every vessel may be able to -know the accurate time, if within sight of those places. - -Not the least interesting portion of the observatory is the chronometer -room. For a very small charge, manufacturers or owners may have their -chronometers rated at Greenwich, which is accomplished in the following -manner: - -The chronometer is placed in the chronometer room, and compared with -the large electric clock in the room, this clock being kept in order -by the stars. Each day the chronometer is examined, and thus its rate -is ascertained in its then temperature. It is afterwards placed in a -sort of closet warmed by gas, a condition supposed to represent the -tropics, and it is there kept for a certain period, being tested each -day as before. This change of temperature is found to produce very -little effect on the best instruments, which, when they have passed -the ordeal, are returned to the owners with their character ticketed -to them. Some hundred chronometers are often placed in this room; and -to compare them is a science, the “expert” by a glance discovering the -difference between the two instruments, whilst a novice would require -to mentally add or subtract, and thus slowly to arrive at the same -results. - -As soon as it becomes dark enough to see stars by the aid of a -telescope, one of the staff commences his observations. These are -continued during the night; and a register is kept of each star, -planet, comet or moon, which is “doctored” in the morning by the -computers. - -As all mortals are fallible, it is desirable to bring machinery into -use where possible, and this has been managed in connection with -astronomical observations. Instead of the computer registering by -judgment the time of a star’s transit over the various wires, he -strikes a small indicator, which, completing the electric circuit, -causes a pricker to fall and make a hole in a piece of paper that -is attached to a slowly revolving barrel. Each time the star passes -a wire, the pricker descends and leaves its mark; and the interval -between these marks being measured by scale, the mean time of transit -may be obtained. - -There is usually a feeling of the sublime that comes over us when we -reflect upon the vast unexplored regions of space, or contemplate the -stellar world that shines upon us. The magnitude and grandeur of some -of the planets in the solar system strike us with a feeling of awe -and wonder, while we are puzzled at the mysteries attending comets, -double stars, nebulæ, etc. No such feelings or sentiments, however, -are allowed to enter into the constitution or mind of an observer at -Greenwich. Saturn, the glorious ringed planet, with its galaxy of -moons, is simply “Saturn, Right Ascension 10 hours 8 min. 12 sec., -North declination 16° 12´ 2´´.” Anything appertaining to the physical -constitution, the probable cause of the ring, or the object of so -grand an orb, does not come within the range of the observations at -Greenwich, which are limited to bare matter-of-fact business work. - -The southern portion of the observatory ground is devoted to -the investigation of meteorological subjects, and is under the -superintendence of Mr. Glaisher, who is now well known as an aerial -voyager. It is here that an exact record is kept of the amount of -rain that daily falls, of the direction and force of the wind, of -the magnetic changes, of the temperature, amount of ozone, etc.--all -matters which may, and probably will, lead us eventually to the -discovery of some laws connected with the states of weather, and enable -us to predict what may be expected from day to day. Whilst we are now -able to calculate to a few seconds, and for years in advance, the -instant when an eclipse may occur, and to explain the causes of the -various planetary movements, yet we are in a sad state of ignorance -as regards the causes of hurricanes, thunder-storms, continued rains -and droughts; and thus we find that all the would-be prophets who -from time to time spring up and oracularly announce a coming frost -or fine weather, or the reverse, are perpetually meeting with most -signal failures, which, however, does not deter future adventurers from -attempting to gain a cheap temporary renown by trying their luck at a -prophecy. - -The perpetual accumulation of facts at Greenwich, whether these be of -an astronomical nature, or appertaining to the air we breathe and its -subtle changes, is a proceeding that must eventually lead us on to a -correct knowledge of the laws which govern these matters, and also keep -us acquainted with any variations that may be occurring in the elements -that surround us. - -The order and quietness necessary in such calculations as those carried -on at Greenwich prevent it from being a “show” establishment, and -hence visitors are not admitted except on special business. Then, -however, every aid and assistance are offered to the student and -inquirer; the use of books and instruments is freely given, and such -information supplied as the little spare time of those belonging to the -establishment enables them to afford. Thus a visit to or a period of -study at Greenwich Observatory will amply repay those who wish to gain -the latest and most accurate information on astronomical subjects, or -to practise themselves at the adjustments and use of the instruments; -and to those who have not such opportunity, we offer this slight sketch. - - [_Chambers’ Journal._ - - - - -Pinions. - - -Well made as to truth of centring, of division, of form of leaves, and -polish, are, as the trade well knows, of vital importance to the value -of the time-piece. - -The making and finishing is one of the most troublesome, as well -as most expensive of all the processes in watch work. The nature -of the material renders it difficult as it approaches so nearly in -hardness to the tools used in cutting. In the ordinary Yankee clock, -the _lantern pinion_ has entirely superseded the solid leaf, which -substitution was the greatest element of success in their cheap -construction. The lantern pinion is really a nearer approximation to -the required anti-frictional form than a majority of cut pinions in -ordinary clocks. In the process of manufacture of the cut variety, the -first consideration is the quality of the steel to be used. For this -purpose it should be carefully selected by trial, thus ascertaining -its fineness, uniformity, softness when annealed, together with its -capacity for taking a good temper, with the least amount of springing -during the hardening process. Very few pinions are cut from the solid -piece--the drawn pinion wire being quite good enough, when milled and -finished, for the ordinary run of watch work. - -The steel wire having been selected, the first process is to cut it -up in lengths a trifle larger than the required pinion. The separated -pieces are then centred with care, and having been placed in a lathe, -the staff and pivot are turned up to nearly the required gauge, leaving -a portion of the whole piece the full size for the leaves. They are -now taken to the milling tool to have the proper form given to the -leaves. As this form is of the highest importance, it may be as well to -give here the reasons. Supposing a wheel of 60 teeth, depthing into a -pinion of 8 leaves, it can readily be seen that the arc of the motion -of the wheel tooth is of greater radius than that of the leaf of the -pinion, and it follows that if the teeth and the leaves are made in -taper form with straight sections, there must occur a sliding motion -on the surfaces of both--the power thus absorbed being totally wasted; -but if we curve the surfaces we may approach a form so nearly perfect -that the wheel teeth, being motors, really roll on the leaves, avoiding -almost entirely the friction caused by sliding; the necessity for this -curvature becoming greater the more the wheel exceeds the pinion in -diameter. This curve, which has been demonstrated by very profound -mathematical researches, is the “epicycloidal;” theoretically it should -give no more sliding motion than the surfaces of two plain wheels -revolving on each other. To obtain this perfect form, very great pains -have been taken and expenses incurred, especially by the makers of the -best time-keepers. - -In the American factories the cutters are very elaborately made, -the section being an object of great solicitude--it being an exact -counterpart of the space between any two leaves, and also of one-half -the top of the leaf from the curvature to the point, so that in -milling, the space made by the cutter is its shape, leaving the leaf -of the proper form. Generally the pinion passes under two cutters; the -first to strike down the rough stock, the other to dress it to size and -shape, with a light cut. The care and skill required to make these is -certainly very great, and it is a proof of the wonderful ingenuity of -man that they are made so perfect as to shape and cutting power. - -A very ingenious device is used for dividing the leaves under the -cutter, which revolves at a moderate speed over a slide, carrying a -pair of centres, between which the turned up piece of pinion wire is -placed. The slide is now pushed up to and under the cutter, and in -its passage as much of a cut is taken as is desirable; in drawing -back the slide the fresh cut space passes under a flat piece of thin -steel, screwed on the frame, and set at a slight angle to the axis of -the centres. On moving the slide towards the cutter for a fresh cut, -the steel plate takes the last cut, and in passing by it the pinion -is turned just as much as the angularity of the plate, which must be -just one leaf. By this very clever device the division is effected -without an index plate. This process, however, is not good enough for -work intended to be very accurate--the pinion wire not being always, or -indeed rarely correctly divided, the original error will be perpetuated -in all the subsequent processes. These are all milled, with oil or soda -water for a lubricator, and it follows that the speed of the cutter is -regulated to get the greatest cut without dulling the tool. When dull, -however, the mill is sharpened on the _face_ of the cutting tooth by -means of small grinders of iron, using Arkansas oil-stone dust for the -first grinding, and giving the necessary delicacy of the edge by means -of crocus, or sharp, followed, when fine work is needed, by rouge. - -It is necessary that this care should be taken, for if the edge is -left coarse it will become speedily dulled, and leave a very unequal -and rough surface on the cut of the pinion, which in the subsequent -grinding gives rise to error in shape and size. The pinions, thus cut -to gauge, are dried in sawdust, hardened, and tempered; the staff and -pivots are now turned up to size, and then pass to the polishers. In -the factory they are finished by means of what are called _Wig-Wags_, -which it may be interesting to the reader to have a general description -of. - -Two Vs are arranged as centres, the pinion is placed between them, -the circular parts resting in each V, but free to turn on its own -axis. Immediately above the Vs is a frame on which a slide, carrying -the polisher, may traverse--generally about two inches. This slide is -movable vertically so as to accommodate itself to the pinion; attached -to the slide is a connection which leads to a vertical lever, which -is put in motion from a crank on the counter shaft. The grinding is -effected by bringing the grinder, charged with oil-stone dust in oil, -in one of the spaces of the pinion, which, of course, is so arranged -as to bring it parallel and central with the grinder. The power being -applied, the slide takes a very rapid reciprocatory motion, and the -face of the grinder, so charged, rapidly reduces the uneven surface -left by the cutter to what is called the _gray_. - -The form of this grinder must be as perfect as the cutters, and the -care taken to get the requisite parallelism is in equal proportion, -and in all the best polishers is planed up while in its position. The -grinder is composed of tin and lead, with sometimes a slight admixture -of antimony, rolled to an even thickness, cut off in suitable lengths, -and then mounted in the carrier of the Wig-Wag to be planed up to -shape. There are too many minute adjustments in the machine to render a -full description in this article admissible. It is large compared with -the work it has to perform, but it is very admirably made, as indeed -all the tools are, in the American factories. - -The polishing of the leaves is the next step, and this is effected by -means precisely the same as grinding. In each stage the pinions are -thoroughly cleansed before entering on another. The polisher is made -precisely like the grinder; but instead of oil-stone dust, crocus mixed -with oil is substituted. Owing to the less cutting quality of the -material used, the polisher loses its form sooner than the grinder, -and has to be more frequently reshaped. In very fine work the crocus -is succeeded by fine well-levigated rouge to bring up that jet black -polish, which is considered a mark of quality by chronometer and watch -makers. - -With the exception of turning up the staff and pivots, all the work -hitherto described has been expended on the leaves--a very tedious -process, yet done, when the tools and materials are in proper order, -with marvellous rapidity; but tedious as these have been, there are two -others quite as much so before the leaves are finished. - -The ends are to be faced--they must be flat (that is a true plane) and -receive the same finish that the leaves took, and is effected by the -wig-wag; only the pinion revolves between centres, at a high speed, the -grinder being brought up to the turned face. Two motions operate--one -rectilinear, the other circular--the result being a compound motion -which prevents the grinder from touching the same spot twice in -succession. To effect this more surely, the operator gives the grinder -a slight vibratory vertical motion. The polishing of the two faces is -effected in the same manner as the grinding; in all cases the cutting -face of the grinders and polishers being kept in a plane perpendicular -to the axis of the pinion, both vertical and horizontal. - -The staff and pivots being in the same condition they came from the -lathe, the next step is to grind and polish them. Before, however, we -treat on this process, it may not be amiss to give the general watch -repairer a process by which the facing may be done on a small scale. - -As a rule, when the watch repairer has to replace a pinion he selects -one from the material dealer, finished in the leaves, but not on the -ends or faces. The following operations are simple, and any one may -finish these faces with little trouble. Having turned up your pivots -and squared down the face of the leaves with the turning tool, grind -it in the lathe by means of a ring of metal, the inside diameter being -somewhat larger than the diameter of the staff. This ring is held -between two centres, thus allowing it a vibratory motion, so that -when it comes up to the face it accommodates itself to its plane, and -thus has no tendency to force it out of a true flat; the ring, being -larger than the staff or pivot, admits a small lateral motion, enough -to effect a continuous change of surface. The same little tool may be -used for polishing by substituting another polisher and using crocus -and rouge. For the repairer, perhaps on general work the rouge would -be superfluous. Vienna lime, used with a little slip of boxwood, -brings up a very fine and brilliant polish, and in replacing new work -in an injured time-piece, the steel may always be polished with great -rapidity by using the lime on the gray surface left from the oil-stone -dust; being quickly done and affording a very handsome finish. - -To resume the consideration of the pinion, the last stage is the -polishing of the circular portions. Here again the wig-wag is the -most useful tool, but it operates somewhat differently, for the -grinder or polisher is pressed down by the finger of the operator, -the pinion being held between the centres of a small lathe attached -to the wig-wag; the staff is first ground and polished as the leaves -have been before, and this is the last operation performed with the -pinion between centres. From this stage it is chucked in a lathe very -peculiarly fitted, the mandrel being hollow; and in it is fitted what -is called a pump-centre, which is movable in direction of the axis of -the mandrel, and capable of being securely fastened at any desired -point. On the nose of the mandrel is secured a hollow steel chuck, -the two sides of which have been filed out, thus leaving an open -space between the end of the pump-centre and the end of the chuck. On -this end a small steel plate, extremely thin, is fastened by means -of shellac, and a hole drilled in the plate capable of taking in the -chamfer on the shoulder of the pivot. The pump-centre being drawn -back, the pinion is introduced into the chuck, the pivot placed in the -hole in the steel plate, and the pump centre is drawn forward until -it forces the chamfer to fill the hole; the pivot projecting from -the chuck is now ready for all the grinding and polishing processes. -Here the wig-wag steps in again, and from the delicacy of the pivots -is modified to suit the case; this is done by having a polisher hung -in the wig-wag on centres, so it may revolve; when in operation one -side of the polisher rests on the pivot, the other on a ruby placed -in a screw, and which screw enables the operative to insure the -parallelism of the pivot. The ends of the pivots are next rounded off -and finished in another set of tools. The pinion is now ready for use, -assuming it to be of the proper gauge. In the American watches the -scape and fourth wheels are generally staked on the staff pinch tight; -the third and centre are staked on the pinion leaves, a rebate having -been turned down on the ends, the wheel set on the shoulder, and the -projecting ends of the leaves riveted down. This has not been designed -as an exhaustive article on pinions; it is merely intended to open the -subject as pursued in the factories. There is much more to be said; and -the various processes on the small scale, as performed by the Swiss -and English, together with their tools, will bear more than a general -description, as they are applicable at any watch bench. - -The subject will be continued, in the effort to give a full and useful -article. - - - - -New Three-Pin Escapement. - - -A contributor to the _London Horological Journal_ gives the following -description of his invention: - - “The merit of this escapement is in a newly invented escape-wheel - which is self-locking and requires no banking pins; the pallets are - curved inside the impulse and outside the locking, to work with the - curved points of the teeth of the wheel; being made of gold the wheel - will go without oil. From its form it has the power of double impulse - and double locking with the lever. The first takes place at the - discharge of the escapement, the second does not act unless the watch - receives a sudden motion, and then the pin or pallet in the roller - strikes lightly on the lever, when the propellant power drives it back - again. The balance passes through two turns before the second locking - takes place, and is formed so as to be able to take up the lever, - and the watch soon rights itself, and its time will not be affected. - Another advantage is, that the lever is made of a flat piece of steel, - as I have introduced a gold stud to receive the ruby impulse stone, - which is made to adjust easily so as to bring the escapement to the - closest geometrical accuracy. By its formation this ruby guides the - impulse to the external edge of the roller notch. These advantages, - and its simplicity, render it suitable to the best chronometer - watches.” - -A FEW years ago, in 1859 or ’60, Mr. Peabody, a very talented -gentleman of this city, patented a three-pin escapement that performed -extremely well. A full description of his patent and plan is not at -hand, but we will endeavor to give it to our readers in our next issue. - - - - -English Opinion of American Watch Manufacture. - - -In the London circle of Horologists, more attention is paid to the -scientific departments than the mercantile; but for all that, a Mr. -Henry Ganney has held forth before the “British Horological Institute,” -on “American Watch Manufacture.” Though an Englishman, with English -prejudices, he certainly gives a very fair and impartial statement -of the subject; yet he views it almost entirely in the money-making -aspect. He gives all the credit deserved to American enterprise and -ingenuity, and yet there is a certain sense of a drawback. He had -before him samples of machine work; among others, to quote, “several -movements made by the British Watch Company, which flourished and -failed about twenty-five years ago; these were machine-made, and the -perfection and completeness of the machinery they used for producing -these frames has not been equalled, I believe, in America; several -machines being used there to accomplish what was begun and completed by -one here.” - -Mr. Ganney is right in his statement, but the example given by the -British Watch Company was the rock seen by the American navigators. One -tool, for facing off, truing up, drilling, depthing, and doing all the -work on the pillar plate, having cost, before completion, some three -thousand pounds sterling, and from its very complexity being utterly -inefficient--worse than useless. In the very inception of the American -watch manufacture a similar mistake was almost made. Experience and -sound reasoning proved, however, that a multiplicity of operations in -any one machine rendered it entirely too complex, the adjustments too -numerous, and the work totally worthless. We shall in another number -refer again to Mr. Ganney’s lecture, and perhaps give some beamings of -light on the early history of the American watch manufacture, derived -from personal observation at the time. - - - - -Correspondence. - - - EDITORS HOROLOGICAL JOURNAL: - - I received a Prospectus a few days ago advising me of your - contemplated existence. I could hardly believe the fact; “the news - was too good to be true.” However, I shall take it for granted, for I - cannot see why somebody has not before had the enterprise to launch - out in the periodical line on subjects connected with Horology, the - field being so extensive and the want so severely felt. Enclosed - I send you the subscription price; in this much I have accepted - your invitation, but I also enclose some few lines on a subject not - particularly practical or theoretical, but very near the truth, and - may perhaps give you a view of our wants. - - To tell the “plain unvarnished truth,” I am a watch repairer, located - in a small country village, with a decent stock of tools and a - moderate trade. In all this I am no exception; so I write this in - the name of all who are similarly situated. Isolated as we are, we - (the country village watch repairers) have few means to improve our - knowledge of the trade, but work on the same old principles learned - when we were boys and apprentices, and of better and more expeditious - ways of doing our work we are entirely oblivious. True, our friends - of the Hebraic persuasion, who, angel like, bring us face to face - with the outer horological world by selling us material and tools, - occasionally present to our benumbed vision something new, such as a - Swiss lathe, or lathes used in the factories; but of what use are they - to us? We purchase one; well, on the bench it may be an ornament, but - for use, drilling large holes is the height of our ambition. We have - not the time to learn by self-experience all the boasted usefulness - and capacities of the tool; so we go back to our old verge or Jacot - lathe when we have to put in a pivot or a new staff. We may know all - about the escapement and be able to detect the cause of any trouble - with it, but we have no knowledge of the latest modes of repairing the - injury when it is discovered, and this knowledge is what I hope to - find in your journal. I live in a section where the general class of - work is of a very low grade, even the old verge being very common. Our - stock of material has to be heavy in proportion to our trade, and then - once in a while we are compelled to send our work to the city, some - sixty miles distant, in consequence of not being able to do it, either - from a lack of the material or want of a proper tool. To all intents - and purposes we remain as stationary as the oyster. Not only do we - have these vexations, but the ignorance of the public at large as to - the treatment of their time-keepers is a fruitful source of annoyance; - we are often charged with fraudulent practices, and a certain degree - of caution is observed by more than the most ignorant. Thus, a few - days ago, a stalwart son of the Green Isle made his appearance in - front of the counter, and, projecting in front of our optics a huge - English double-cased verge watch, spoke in almost dramatic tones: - - “Plase, sir, av’ ye could make me ticker here go, sir?” - - Answering in the affirmative we reached for the silent “ticker.” He - drew back with alarm. - - “Bedad, an’ ye’ll not stale a morsle frae this?” - - “Well, but let me see the watch.” - - “An’ will ye let me eyes be on yes all the time?” - - “Yes.” - - “An’ yes’ll not stale a jewil?” - - “No.” - - “Thin, there it is.” - - On looking at the movement the verge was found broken, the injury - explained, and the price given. He decided on the repairs being done, - but said, “Give me the watch now and when ye gets the thing fixed its - meself will come and git it and pay yes.” - - “But we cannot repair the watch without having it.” - - “Faith, thin, ye’ll not have it; ye’ll be taking something frae it.” - - Now, this is an extreme case of ignorance, pardonable, perhaps, in - this instance, but the public embraces multitudes just as ignorant - where an allowance cannot be made. I do not expect the JOURNAL to - reach such cases, or to influence the general mass, but my hope is - that it will, by raising the general self-respect and tone of the - repairers, indirectly elevate the respect felt for them by the public - at large. - - But I am writing too long and rambling a letter. I wish to express my - hearty wishes for your prosperity. And, in conclusion, will you allow - me to express a hope that you will give us the knowledge we need--that - is, post us up on the minutiæ of repairing in the latest styles, the - newest processes devised, and, above all, give us an article on the - lathe and its uses? - - Yours truly, - W. L. C. - - -We have the pleasure to give our correspondent the assurance that an -expert will contribute to our next number an article interesting as -well as valuable in instruction as to the use of the lathe. - - - - -Eclipse of the Sun. - - -The approaching total eclipse of the sun, on the 7th of August next, -is exciting much interest. The obscuration first occurs in latitude -39° 53´ 3´´ north, longitude 138° 37´ 4´´ west--Washington being the -meridian. The first totality is on the Pacific coast of Siberia, at -sunrise, in lat. 52° 41´ 9´´ north, and long. 165° 26´ 4´´ west. The -eclipse is total at noon in Alaska, lat. 61° 46´ 9´´ north, and long. -68° 4´ 6´´ west. The line of the total eclipse now runs south-easterly, -grazing the coast near Sitka, thence north into British America; then -entering the United States, near the head of Milk River, long. 30° W.; -thence through the south-west corner of Minnesota, diagonally through -Iowa, crosses the Mississippi at Burlington; thence through Illinois, -a little north of Springfield, crosses the Ohio river at or near -Louisville, Ky., passes through the south-west corner of West Virginia, -through North Carolina, just south of Raleigh, ending on the Atlantic -coast at sunset, just north of Beaufort, N. C., in lat. 31° 15´ 2´´ -north, and long. 9° 36´ 6´´ east. The line thus described will be that -of totality, only partial in any other part of the United States. - -The United States Government is, or has been, establishing a meridian -line at Springfield, partly to make observations on this coming -eclipse, and with the further view of determining a standard of -surveyed lines--all of the Government surveys in Illinois having been -geodetic. Professor Austin, of the Smithsonian Institute, is in charge -of the work, aided by an able corps of assistants. - - - - -Diamond-Cutting. - - -At the Great Exhibition in Paris, in a part of the park contiguous to -the Netherland section, M. Coster, of Amsterdam, has erected a building -wherein all the processes of diamond-cutting are carried on. - -The first rough shaping of the more important facets of the brilliants -is here seen performed by the workman, who operates on two diamonds at -once, by bruising each against the other, angle against angle. The dust -that falls from the stones is preserved for the subsequent processes -of grinding and polishing those facets that distinguish the many-sided -brilliant from the dull, original crystal of the diamond. It is used, -mingled with oil, on a flat iron disk, set revolving with vast rapidity -by steam-power, the stone itself being held upon this disk or wheel by -a tool to which it is attached by a mass of fusible metallic alloy, -into which the stone is skilfully inserted. Skill of eye and hand, only -attainable by great practice, is needed for this work; but a skill not -less exact is needed for another process, which may here be seen in -daily operation--the process of cleavage. The diamond, when a blow is -struck on an edged tool placed parallel to one of the octahedral faces -of the crystal, readily splits in that direction. But to recognize the -precise direction on the complex and generally rounded form of the -diamond crystal; to cut a little notch by means of a knife edge of -diamonds formed of one of the slices cleaved from a crystal, and to -cut that notch exactly the right spot; then to plant the steel knife -that is to split the diamond precisely in the right position; finally, -with a smart blow, to effect the cleavage so as to separate neither -too large nor small a portion of the stone--these various steps in the -process need great skill and judgment, and present to the observer -the interesting spectacle which a handicraft dependent on experience -of hand and eye always affords. But Mr. Coster’s exhibition has other -objects of interest. For the first time, we may see here, side by side, -the diamond with the minerals that accompany it in the river beds of -Brazil; and there are even examples in which crystals of diamonds -are included within a mass of quartz crystals, which have all the -appearance of having been formed simultaneously with deposits of the -diamond. - -The different districts of Rio and of Bahia are thus represented--the -former producing a confusedly crystallized sort of diamond termed -“bort,” and the latter an opaque black variety; both these kinds being -found associated with the crystallized diamonds used for jewelry. -Though useful in state of powder, the black carbon and “bort” are -incapable of being cut as a jewel.--_“Maskelyne’s Report,” Great -Exhibition._ - - - - -The Alloys of Aluminum with Copper. - - -When Sir Humphrey Davy announced the fact that soda, lime, potash, -magnesia, and the other alkalies were but oxides of a metallic base, it -would have been deemed chimerical to have supposed that the discoveries -he made by the expensive aid of the battery would at later date become -of really commercial value. He did obtain both sodium and potassium -in the metallic state. The substances in this form were new to the -chemical world, still more strange to the popular. So new was it to the -chemists, that, on a globule of the reduced sodium being presented to -a very distinguished chemist, he, with some enthusiasm, examined it; -and, admitting the fact of its being a metal, exclaimed, “how heavy -it is!”--when the real fact was that its specific gravity was less -than water; the expression was the result of the general preconceived -opinion that a high specific gravity was a test of a metallic body. It -was reserved for a French chemist, Henry St. Claire Deville, to utilize -the metal sodium, and that, too, in such a manner that the demand -aroused attention to its production;--demand will inevitably bring a -supply. - -The original reduction was made by Davy, by means of the voltaic -battery. After it had been proved that these bases were really metals -capable of reduction, chemistry brought all its resources to bear on -the problem, and they were produced by other methods than the battery. -All the processes adopted, however, were too expensive and laborious, -involving an extraordinary amount of complicated manipulations with but -inadequate results. The metal sodium, which is the immediate subject of -our inquiry, long remained an object simply of curiosity or experiment -in the laboratory. - -The methods of reducing the metal have of late years been so simplified -that, to quote Prof. Chas. A. Joy in the _Journal of Applied -Chemistry_: “A few years ago a pound of this metal could not have been -purchased for two hundred dollars, and even at that price there were -few manufacturers hardy enough to take the order. At the present time -it can be readily manufactured for seventy-five cents, if not for fifty -cents a pound; and the probabilities are that we shall soon be able to -obtain it for one-quarter of a dollar.” - -Deville found that by the reaction of the metallic sodium on common -chloride of aluminum a reduction was effected; the chlorine taking -up the sodium, forming chloride of sodium (common salt), while the -aluminum was left free in the metallic state. It is hardly necessary -to go into the particulars of the process; but a metal well known to -exist, had, for the first time, been brought to the world in such a -condition of structure that its qualities could be tested, not only -chemically, but mechanically. This was the direct result of Deville’s -metallurgic process of obtaining the reducing agent--sodium. - -Aluminum in itself would be of but little use, so that a brief -description will be all that is necessary. It is about the color of -silver, but susceptible of a higher polish, especially on a fresh-cut -surface; it is much less susceptible of oxidization than silver; its -specific gravity is but little more than pine wood, and its tenacity, -ductility, and laminating qualities are nearly equal to silver. Its use -in the mechanical arts is limited, notwithstanding all these qualities, -from the fact of its low point of fusibility, and at the heat of -the fusible point being easily oxidized, so much so as to prevent -soldering, except by an autogenous process. But aluminum does possess -a property peculiar to itself--that of forming a purely and strictly -_chemical alloy_ with copper. It unites with it in any proportion; -the compound formed by the addition of 10 per cent. of aluminum to 90 -per cent. of copper has been found to possess all the properties of -an entirely new metal, with qualities that render it a very valuable -material in all fine work, such as astronomical instruments; and very -fine machinery, such as watch-lathes, etc. - -The French reports on the alloy are somewhat voluminous, but we give -the following. - -The color of this bronze so closely resembles that of 18 carat gold, -such as is used for the best jewelry and watch-cases, that it is -capable of receiving the highest polish, and is far superior in beauty -to any gilding. - -Samples taken from different parts of the largest castings, when -analyzed, show the most complete uniformity of composition, provided -only that the two metals have originally been properly mixed while in -a state of fusion. These experiments have been made upon cylinders -weighing many hundreds of pounds, and are entirely conclusive. - -This valuable quality is not found in any of the more ordinary alloys -of copper. The alloy of copper with tin, for example, known as _gun -metal_, is notoriously subject to a phenomenon known as _liquation_; -in consequence of which a great difference is found in the composition -of the same casting, both in the top as compared with the bottom, and -in the centre as compared with the circumference. - -This phenomenon often causes great inconvenience, as the different -parts of large objects will in consequence vary greatly in hardness -as well as in strength. In casting artillery the difficulty becomes a -serious one, and no means have yet been discovered by which it can be -entirely removed. - -This homogeneousness of aluminum bronze is a natural consequence of the -great affinity existing between the two metals of which it is composed; -and that there is such an affinity is clearly proved by the phenomenon -attending the manufacture of the alloy. The copper is first melted in -a crucible and the aluminum is then added to it _in ingots_. At first -there is, of course, a reduction of temperature, because the aluminum -in melting absorbs the heat from the melted copper; and this absorption -is so great, in consequence of the great capacity for heat of aluminum, -that a part of the copper may even become solid. But let the mixture -be stirred a moment with an iron bar, and the two metals immediately -unite; and in an instant, although the crucible may have been removed -from the furnace, the temperature of the metals rises to incandescence, -while the mass becomes as fluid as water. - -This enormous disengagement of heat, not seen in the preparation of -any other ordinary alloy, indicates, not a simple mixture, but a real -chemical combination of the two metals. The 10 per cent. bronze may -therefore be properly compared to a salt, the more so as it is found by -calculation to contain, within a very minute fraction, four equivalents -of copper to one equivalent of aluminum. - -The 10 per cent. bronze may be forged cold, and becomes extremely dense -under the action of the hammer. The blades of dessert-knives are thus -treated in order to give them the requisite hardness and elasticity. -But it has another valuable quality which is found in no other kind -of brass or bronze: it may be forged hot, as well as, if not better -than the very best iron. It thus becomes harder and more rigid, and -its fracture shows a grain similar to that of cast steel. On account -of the hardness of the aluminum bronze, rolling it into sheets would -be a tedious and expensive process, were it not for this property of -being malleable at a red heat. But it may in this manner be rolled into -sheets of any thickness or drawn into wire of any size. It may also be -drawn into tubes of any dimension. - -From several experiments made at different times at Paris, it appears -that the breaking weight of the cast bronze varies from 65 to 70 -kilogrammes the square millimetre. The same bronze drawn into wire -supported a weight of 90 kilogrammes the square millimetre. The iron -used for suspension bridges, tested in the same manner, did not show an -average of more than 30 kilogrammes. Some experiments were also made by -Mr. Anderson, at the Royal Arsenal at Woolwich, in England, who tested -at the same time the aluminum bronze, the brass used for artillery -and commonly called _gun metal_, and the cast steel made by Krupp in -Prussia. Taking for the maximum strength of the bronze the lowest of -the numbers found as above, we are thus enabled to form the following -table of comparative tenacities: - - Aluminum bronze 10 per cent. 65 - Crupp’s Cast Steel 53 - Refined Iron 30 - Brass for cannon 28 - -The comparative toughness of these same four metals was also tested in -the following manner: A bar of each was prepared of the same size, and -each bar was then notched with a chisel to precisely the same depth. -The bars were broken separately, upon an anvil, by blows from a hammer. -The last three metals in the table broke each at the first blow, with -a clean and square fracture. The aluminum bronze only began to crack -at the eighth blow, and required a number of additional blows before -the two pieces were entirely separated. And the irregular, torn surface -of the fracture showed the peculiarly tough and fibrous nature of the -metal. - -The elasticity of the aluminum bronze was tested by M. Tresca, -Professor at the _Conservatoire des Arts et Métiers_. The experiment -was made upon a bar of simple cast metal, and the following is his -report: “The coefficient of elasticity of the aluminum bronze, the -cast metal, is half that of the best wrought-iron. This coefficient is -double that of brass and four times that of gun metal, under the same -conditions.” - -The specific gravity is 7.7, about the same as iron. Another very -valuable quality is presented in the fact that it is acted on by -atmospheric influences less than are silver, brass, or bronze. This -places it in the same rank with gold, platinum and aluminum. - -Very stiff and very elastic, tougher than iron, very little acted upon -chemically, and in certain cases not at all, capable of being cast like -ordinary bronze or brass, forged like iron and steel, of being worked -in every way like the most malleable metals or alloys, having, added -to these properties, a color analogous to that of the most precious -metal, this bronze proves itself adapted to uses almost innumerable. -At first sight, it seems difficult to admit that the relatively small -proportions of aluminum which enters into the composition of this -bronze can be sufficient to modify so extraordinarily the properties -of the copper which constitutes so large a portion of its weight. But -we must remember that the specific gravity of aluminum is very low, -and that a given weight of this metal possesses a bulk four times as -large as the same weight in silver. It follows from this that the ten -per cent. of aluminum contained in the bronze equals in bulk forty per -cent. in silver. - -The specimens of the ware we have seen, such as spoons, forks, cups, -watch-cases, etc., are certainly very beautiful, having the color and -high polish of gold, while dilute acids do not affect the surface. - - - - -On the Reduction of Silver in the Wet Way. - - -Every chemist is familiar with the reduction of chloride of silver -in the form of powder by means of metallic zinc in the presence of a -little free acid. It is not easy to bring two such substances as the -silver salt and the metal into close contact, and after the work is -accomplished the removal of the excess of zinc has its difficulties. -Dr. Grager suggests a modification of the old method that ought to -be more generally made known. The chloride of silver is dissolved -in ammonia and poured into a well-stopped bottle, and into this is -introduced an excess of metallic zinc, in not too small fragments, so -that any reduced metal adhering to it may be readily washed off. - -The decomposition begins immediately, and is rapidly accomplished, -especially if the contents of the flask be well shaken up. Three hours -will suffice to reduce one-quarter of a pound of chloride of silver. -It is easy to ascertain when the reduction is ended, by testing a -portion of the ammoniacal solution with hydrochloric acid. As soon as -no cloudiness or curdy precipitate is formed, the work may be regarded -as completed. - -A slight excess of ammonia is said to be favorable. The reduced silver -must be washed with water until all odor of ammonia has disappeared. -The pieces of zinc are removed by pouring the contents of the flask -through a funnel, the opening of which is too narrow for the passage -of the zinc fragments, while the reduced silver can be easily washed -through. The finely divided silver can be digested in hydrochloric -acid to restore it to a pure white color, and it is then ready for -solution or fusion, and will be found to be perfectly pure. In dealing -with large quantities it would be economical to recover a portion of -the ammonia by distillation. In the same way an ammoniacal solution -of nitrate of silver can also be reduced by zinc, and the silver -obtained pure, even when the original solution of the nitrate contains -copper--provided a small quantity of silver be kept in the bath. - -It is better where copper is present not to take all of the zinc that -may be requisite for the reduction of the silver. It will prove a -great convenience to be spared the necessity of converting the silver -into the chloride, as it is no easy task to wash out this salt on -filters--and it will be found to be applicable to alloys which do not -contain more than 25 per cent. of silver.--_From Prof. Joy in the -Journal of Applied Chemistry._ - - - - -Transcriber’s Notes - -Obvious errors in punctuation have been fixed. - -Page 7: “Mechanique Celeste” changed to “Méchanique Céleste” - -Page 12: “ou rexperience” changed to “our experience” - -Page 18: “head-quarters far astronomical observations” changed to -“head-quarters for astronomical observations” - -Page 22: “it accomodates” changed to “it accommodates” - -The Table of Contents lists “Equation of the Time Table” as the article -on page 28. The actual article is named “On the Reduction of Silver in -the Wet Way.” This has intentionally been left as per the original. -Similarly, there is no actual section titled “Notices of New Tools” -despite its inclusion in the Table of Contents, and this has been left -as per the original. - -*** END OF THE PROJECT GUTENBERG EBOOK AMERICAN HOROLOGICAL JOURNAL, -VOL. I, NO. 1, JULY 1869 *** - -Updated editions will replace the previous one--the old editions will -be renamed. - -Creating the works from print editions not protected by U.S. copyright -law means that no one owns a United States copyright in these works, -so the Foundation (and you!) can copy and distribute it in the -United States without permission and without paying copyright -royalties. Special rules, set forth in the General Terms of Use part -of this license, apply to copying and distributing Project -Gutenberg-tm electronic works to protect the PROJECT GUTENBERG-tm -concept and trademark. 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B. Miller</p> -<div style='display:block; margin:1em 0'> -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 <a href="https://www.gutenberg.org">www.gutenberg.org</a>. If you -are not located in the United States, you will have to check the laws of the -country where you are located before using this eBook. -</div> - -<p style='display:block; margin-top:1em; margin-bottom:0; margin-left:2em; text-indent:-2em'>Title: American Horological Journal, Vol. I, No. 1, July 1869</p> -<p style='display:block; margin-left:2em; text-indent:0; margin-top:0; margin-bottom:1em;'>Devoted to Pratical Horology</p> -<p style='display:block; margin-top:1em; margin-bottom:0; margin-left:2em; text-indent:-2em'>Editor: G. B. Miller</p> -<p style='display:block; text-indent:0; margin:1em 0'>Release Date: April 17, 2022 [eBook #67859]</p> -<p style='display:block; text-indent:0; margin:1em 0'>Language: English</p> - <p style='display:block; margin-top:1em; margin-bottom:0; margin-left:2em; text-indent:-2em; text-align:left'>Produced by: The Online Distributed Proofreading Team at https://www.pgdp.net (This file was produced from images generously made available by The Internet Archive)</p> -<div style='margin-top:2em; margin-bottom:4em'>*** START OF THE PROJECT GUTENBERG EBOOK AMERICAN HOROLOGICAL JOURNAL, VOL. I, NO. 1, JULY 1869 ***</div> - - - - - -<h1 class="bb"><span class="small">AMERICAN</span><br /><span class="big">Horological Journal</span>.</h1> - -<p class="center"><span class="smcap"><abbr title="colume">Vol.</abbr> I.</span><span class="ml">NEW YORK, JULY, 1869.</span><span class="smcap ml"><abbr title="number">No.</abbr> 1.</span> -</p> - - -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<h2 class="nobreak" id="CONTENTS">CONTENTS.</h2> -</div> -<hr class="r5" /> -<table class="autotable"> -<tr> -<td class="tdl"> -<a href="#Astronomy_in_its_Relations_to_Horology"><span class="smcap">Astronomy in its Relations to Horology</span>,</a> -</td> -<td class="tdr page"> -<a href="#Page_5">5</a> -</td> -</tr><tr> -<td class="tdl"> -<a href="#Watch_and_Chronometer_Jewelling"><span class="smcap">Watch and Chronometer Jewelling</span>,</a> -</td> -<td class="tdr page"> -<a href="#Page_11">11</a> -</td> -</tr><tr> -<td class="tdl"> -<a href="#Hints_on_Clocks_and_Clock-Making"><span class="smcap">Hints on Clocks and Clock Making</span>,</a> -</td> -<td class="tdr page"> -<a href="#Page_15">15</a> -</td> -</tr><tr> -<td class="tdl"> -<a href="#newtools"><span class="smcap">Notices of New Tools</span>,</a> -</td> -<td class="tdr page"> -<a href="#Page_17">17</a> -</td> -</tr><tr> -<td class="tdl"> -<a href="#Greenwich_Observatory"><span class="smcap">Greenwich Observatory</span>,</a> -</td> -<td class="tdr page"> -<a href="#Page_17">17</a> -</td> -</tr><tr> -<td class="tdl"> -<a href="#Pinions"><span class="smcap">Pinions</span>,</a> -</td> -<td class="tdr page"> -<a href="#Page_20">20</a> -</td> -</tr><tr> -<td class="tdl"> -<a href="#New_Three-Pin_Escapement"><span class="smcap">New Three-Pin Escapement</span>,</a> -</td> -<td class="tdr page"> -<a href="#Page_23">23</a> -</td> -</tr><tr> -<td class="tdl"> -<a href="#English_Opinion_of_American_Watch_Manufacture"><span class="smcap">English Opinion of American Watch Manufacture</span>,</a> -</td> -<td class="tdr page"> -<a href="#Page_23">23</a> -</td> -</tr><tr> -<td class="tdl"> -<a href="#Correspondence"><span class="smcap">Correspondence</span>,</a> -</td> -<td class="tdr page"> -<a href="#Page_24">24</a> -</td> -</tr><tr> -<td class="tdl"> -<a href="#Eclipse_of_the_Sun"><span class="smcap">Eclipse of the Sun</span>,</a> -</td> -<td class="tdr page"> -<a href="#Page_25">25</a> -</td> -</tr><tr> -<td class="tdl"> -<a href="#Diamond-Cutting"><span class="smcap">Diamond Cutting</span>,</a> -</td> -<td class="tdr page"> -<a href="#Page_25">25</a> -</td> -</tr><tr> -<td class="tdl"> -<a href="#The_Alloys_of_Aluminum_with_Copper"><span class="smcap">Alloys of Aluminum with Copper</span>,</a> -</td> -<td class="tdr page"> -<a href="#Page_25">25</a> -</td> -</tr><tr> -<td class="tdl"> -<a href="#On_the_Reduction_of_Silver_in_the_Wet_Way"><span class="smcap">Equation of Time Table</span>,</a> -</td> -<td class="tdr page"> -<a href="#Page_28">28</a> -</td></tr> -</table> -<hr class="r65" /> -<p class="center">⁂ <i>Address all communications for</i> <span class="smcap">Horological Journal</span> -<i>to</i> <span class="smcap">G. B. Miller</span>, <i>P. O. Box 6715, New York City. -Publication Office 229 Broadway.</i></p> -<p><span class="pagenum" id="Page_5">[Pg 5]</span></p> - -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<h2 class="nobreak" id="Astronomy_in_its_Relations_to_Horology">Astronomy in its Relations to Horology.</h2> -</div> -<hr class="r5" /> -<h3>NUMBER ONE.</h3> -<hr class="r5" /> - -<p>However accurate an instrument for the mensuration of time may be, -it would be of little use for close observation unless we have some -standard by which to test its performance. We look to Astronomy to -furnish us with this desideratum, nor do we look in vain. The mean -sidereal day, measured by the time elapsed between any two consecutive -transits of any star at the same meridian, and the mean sidereal -year—which is the time included between two consecutive returns of the -sun to the same star—are immutable units with which all great periods -of time are compared; the oscillations of an isochronous pendulum -affording us a means of correctly dividing the intermediate space into -hours and days.</p> - -<p>We must premise that the whole theory of taking time by sidereal -observations is based on angular motion, the mensuration of one of -the angles of motion giving a measurement of space, so that to say -space, or distance, is equivalent to saying time. From noon of one -day to noon of another is the whole problem to be solved by correct -division. The astronomical day begins at noon, but in civil law the -day is dated from midnight. So in the year the astronomical day is -dated December 31, while in common reckoning the 1st of January is the -initial point. This day is divided into twenty-four hours, counted in -England, America, and the most of the Continental nations of Europe, by -twelve and twelve. The French astronomers, however, adopted the decimal -system, for ease in the computation. Thus they divided the day into -ten hours, the hour into one hundred minutes, and the minute into one -hundred seconds. This plan was in conformity with the French system -of decimal weights and measures. Again, in Italy, the day was divided -into twenty-four hours, but counting from one to twenty-four o’clock. -The French system presents some features well worthy of adoption, as it -gives results so much more easy in computation—a facility unattainable -in the common division; yet it did not come into general use in other -countries, and although some French astronomers still hold to the -system, it is gradually dying out.</p> - -<p>At one time during the Revolution in France a clock in the gardens of -the Tuileries was regulated to show time by the decimal system.</p> - -<p>For the Horologist the mean length of the day is sufficient to show the -rate of his instrument for that particular day, but the astronomical -and civil division requires a much longer period of observation. This -is obtained by the position of the mean annual equinoxes or solstices, -and is estimated from the winter solstice, the middle of the long -annual night under the North Pole; and the period between this solstice -and its return is a natural cycle, peculiarly suited for a standard of -measurement.</p> - -<p>Even with such a standard as the civil year of 365d. 5h. 48m. 49.7s., -the incommensurability that exists between the length of the day and -the real place of the sun makes it very difficult<span class="pagenum" id="Page_6">[Pg 6]</span> to adjust the ratio -of both in whole numbers. Were we to return to the point in the earth’s -orbit in exactly 365 days, we would have precisely the same number -of days in each year, and the sun would be at the same point on the -ecliptic at the same second at the beginning and end of the year. There -is, however, a fraction of a day, so that a solar year and civil are -not of equal duration.</p> - -<p>It is thus we have our bissextile year, from the fact that the -inequality amounts to nearly a quarter of a day, so that in four years -we have a whole day’s gain; but not exactly, because a fraction still -remains to be accounted for. Now, if we should suppress the one day -of leap-year once at the end of each three out of four centuries, the -civil would be within a very small fraction equal to the solar year, -as given by observation; this small fraction would be almost entirely -eliminated, provided we suppressed the bissextile at the end of every -four thousand years. Were this fraction neglected, the beginning of the -new civil year would precede the tropical by just that much, so that in -the course of 1507 years the whole day’s difference would obtain.</p> - -<p>The Egyptian year was dated from the heliacal rising of the star -Sirius; it contained only 365 days. By easy computation it can be -shown that in every 1461 years a whole year was lost; this cycle was -called the Sothaic period, in which the heliacal rising of Sirius -passed through the whole year and took place again on the same day. -The commencement of that cycle took place 1322 years before Christ. -The year by the Roman calendar was dated by Julius Cæsar the 1st of -January, that being the day of the new moon immediately following the -winter solstice in the 707th year of Rome. Christ’s nativity is dated -on the 25th of December, in Cæsar’s 45th year, and the 46th year of the -Julian calendar is assumed to be the 1st year of our era. The preceding -year is designated by chronologists the 1st year before Christ, the -dates thence running backward the same as they run forward subsequent -to that period.</p> - -<p>Astronomically, that year is registered 0; the astronomical year begins -at noon on the 31st of December, and the date of any observation -expresses the number of days and hours which have actually elapsed -since that time, the 31st of December—Year 0.</p> - -<p>The year is divided into months by old and almost universal consent, -but the period of seven days is by far the most permanent division -of a rotation of the earth around the sun. It was the division long -before the historic period. The Brahmins in India used it with the same -denominations as at the present day the Jews, Arabs, Egyptians, and -Assyrians. “It has survived the fall of empires, and has existed among -all successive generations, a proof of their common origin.”</p> - -<p>Nothing can be more interesting in the study of astronomy than its -chronological value. La Place says: “Whole nations have been swept -from the earth, with their languages, arts, and sciences, leaving but -confused masses of ruins to mark the place where mighty cities stood; -their history, with but the exception of a few doubtful traditions, has -perished; but the perfection of their astronomical observations marks -their high antiquity, fixes the periods of their existence, and proves -that even at that early time they must have made considerable progress -in science.”</p> - -<p>The earth revolving around the sun in an ellipse, the position of the -major axis of the orbit would indicate something in regard to eras in -astronomy extending not only beyond the historical period, but so far -back in the past that imagination is almost at fault. The position of -the major axis of the orbit depends on the direct motion of the perigee -and the precession of the equinoxes conjointly, the annual motions -respectively being 11´´.8 and 50´´.1, the two combined motions being -61´´.9 annually. A tropical revolution is made in 209.84 years. This -being a constant quantity, we may ascertain when the line of the major -axis coincided with the line of the equinoxes. This occurrence took -place about 4,000 or 4,090 years before the year 0. In the year 6,483 -the major axis will again coincide with the line of the equinoxes, -but then the solar perigee will coincide with the vernal equinox. So, -it will be seen that the period of revolution is 20,966 years. But in -the progress of this revolution there must have been a time when the -major axis was perpendicular to the line of the equinoxes. A simple<span class="pagenum" id="Page_7">[Pg 7]</span> -calculation will show that the eventful year was 1250; and so important -is this event considered, that La Place, the immortal author of the -<i lang="fr" xml:lang="fr">Méchanique Céleste</i>, proposed to make the vernal equinox of this -year the initial day of the year 1 of our era. Again, at the solstices -the sun is at the greatest distance from the equator; consequently -the declination of the sun is equal to the obliquity of the ecliptic. -The length of a shadow cast at noonday from the stile of an ordinary -sun-dial would accurately determine the precise time on which this -position occurs.</p> - -<p>Though wanting in accuracy, such a measurement is of interest, from the -fact that there are recorded observations of this kind that were taken -in the city of Layang, in China, 1100 years before our present era is -dated. This observation gives the zenith distance of the sun at the -moment of the observation. Half the sum of the zenith distances gives -the latitude, and half their difference gives the obliquity of the -ecliptic at the period. Now the law of the variation of the ecliptic -is well known, and modern computation has verified both the moment -of taking the observation and the latitude of the place. Eclipses -were the foundation of the whole of Chinese chronology, and recorded -observations prove the civilization of that strange race for 4700 years.</p> - -<p>Horology, with astronomy, was not neglected even as early as 3102 years -before Christ, as the following will show.</p> - -<p>The cycles of Jupiter and Saturn are very unequal, the latter being a -period of 918 years; the mean motion of the two planets was determined -by the Indians in that part of the respective orbits where Saturn’s -motion was the slowest and Jupiter’s the most rapid. This observed -event must have been 3102 years before, and 1491 after the year 0; but -the record shows that the observation was taken before the last-named -date.</p> - -<p>Since both solar and sidereal time is estimated from the passage of -the sun and the equinoctial point across the meridian of the place of -observation, the time will vary in different places by as much as the -passage precedes each. It being obvious that when the sun is in the -meridian at any one place, it is midnight at a point on the earth’s -surface diametrically opposite; so an observation taken at different -places at the same moment of absolute time, will be recorded as having -happened at different times. Therefore when a comparison of these -different observations is to be made, it becomes necessary to reduce -them by computation to what the result would have been had they been -taken under the same meridian at the same moment of absolute time. Sir -John Herschel proposed to employ mean equinoctial time, which is the -same for all the world. It is the time elapsed from the moment the -mean sun enters the mean vernal equinox, and is reckoned in mean solar -days and parts of days. This difference in time is really the angular -motion of the earth, and by measuring it the longitude of any place on -the surface of the earth can be determined, provided we have a standard -point of departure, and an instrument capable of accurately dividing -the time into small quantities during its transit from the meridian on -which it was rated.</p> - -<p>As will be hereafter shown, the axis of the earth’s rotation is -invariable. Were the position of the major axis of the earth’s orbit -as immutable, an observation of any star on the meridian taken at -any place would always be the same. Again, the form of the earth has -an important effect; the equatorial diameter exceeds the polar, thus -giving a large excess of matter at the equator. Now the attraction of -an external body not only draws another to it in its whole mass, but, -as the force of attraction is inversely as the square of the distance, -it follows that the attracted body would be revolved on its own centre -of gravity until its major diameter was in a straight line with the -attracting body.</p> - -<p>The sun and moon are both attracting bodies for the earth; the plane -of the equator is at an angle to the plane of the ecliptic of 23° 27´ -34´´.69, and the plane of the moon’s orbit is inclined to it 5° 8´ -47´´.9 Now from the oblate form of the earth, the sun and moon, acting -obliquely and unequally, urge the plane of the equator from its own -position from east to west, thus changing the equinoctial points to the -extent of 50´´.41 annually.</p> - -<p>This action, were it not compensated by another force, would in time -alter the angle of the ecliptic until the equatorial plane and<span class="pagenum" id="Page_8">[Pg 8]</span> the -ecliptic coincided. There are few but have seen the philosophical toy -called the Gyrascope. This toy, on a miniature scale, gives a fine -illustration of the force brought in to correct the combined action of -the sun and moon on the obliquity of the equator. The rotation of the -earth is held in its own plane by its own revolution, the same as the -gyrascope seems to overcome the laws of gravitation by its force of -revolution.</p> - -<p>But not only do the sun and moon disturb the plane of the ecliptic, -but the action of other planets on the earth and sun is to be taken -into account. A very slow variation in the position of the plane of the -ecliptic, in relation to the plane of the equator, is observed from -these influences. It must be remembered that a very slight deviation -in the angle can and would be detected by observation with modern -instruments. We do find that this attraction affects the inclination of -the ecliptic to the equator of 0´´.31 annually.</p> - -<p>This motion is entirely independent of the form of the earth. Now, -if we assume that the sun and moon give the equinoctial points a -retrograde motion on the ecliptic, we must deduct the influence of the -planets. We may then calculate the mean disturbance by subtracting -the latter from the former—the difference is settled by both theory -and observation to be 50´´.1 annually. This motion of the equinoxes -is called the precession of the equinoxes. Its consideration forms a -very important element in the estimation of time, as the position of -the various fixed stars, though so very distant, are all affected in -longitude by this quantity of 50´´.1—being an increase of longitude. -Therefore, if we were to calculate the position of any given star in -order to get a transit for mean time, or true time, we must take this -quantity into consideration. The increase is so great that the earliest -astronomers, even with their imperfect modes of observation, detected -it. Hipparchus, 128 years before Christ, compared his own observations -with those of Timocharis, 153 years before. He found the solution of -the problem the same as Diophantus found the solution of the squares -and cubes, by analysis. In the time of Hipparchus, the sun was at a -point 30° in advance of its present position, for it then entered into -the constellation of Aries near the vernal equinox.</p> - -<p>At the present time the position of the equinoctial points shows a -recession of the whole, 30° 1´ 40´´.2. At this rate of motion the -constellations called the Signs of the Zodiac are some distance from -the divisions of the ecliptic that bear their names. At the rate -of 50´´.1 the whole revolution of the equinoctial points will be -accomplished in 25,868 years; but this is again modified because the -precession must vary in different centuries for the following reasons: -the sun’s motion is direct, the precession retrograde; therefore, the -sun arrives at the equator sooner than he does at the same star of -observation. Now, the tropical year is 365d. 5h. 48´ 49´´.7; and as the -precession is exactly 50´´.1, we must suppose it takes some time for -the sun to move through that arc. By direct observation it is found -that the time required for such translation is 20´ 19´´.6. By adding -this amount to the tropical year we have the sidereal year of 365d. -6h. 9´ 9´´.6 in mean solar days. This amount of precession has been -on the increase since the days of its first recorder, Hipparchus, as -the augmentation amounts to no less than 0.´´455. By adding that to the -known precession we find that the civil year is shorter now by 4´´.21 -than in his time; but, as a great division of time, the year can be -changed by this cause not more than 43.´´</p> - -<p>The action of the moon on the accumulation of matter at the earth’s -equator is a source of disturbance that in very accurate observations -for time should be eliminated. Thus the moon, with the conjoint action -of the sun, depending on relative position, causes the pole of the -equator to describe a small ellipse in the heavens with axes of 18´´.5 -for the major, and 13´´.674 for the minor; the longer axis being -directed to the pole of the ecliptic. This inequality has a period -of 19 years,—it being equal to the revolution of the nodes of the -lunar orbit. The combination of these disturbances changes, by a small -quantity, the position of the polar axis of the earth in regard to the -stars, but not in regard to its own surface. With so many disturbing -causes, we must add that of Jupiter, whose attraction is diminishing -the<span class="pagenum" id="Page_9">[Pg 9]</span> obliquity of the ecliptic by 0´´.457 according to M. Bessel.</p> - -<p>The results of all these forces must affect the position of all the -stars and planets as seen from our earth. Their longitudes being -reckoned from the equinoxes, the precession of these points would -increase the longitude; but as it affects all the stars and planets -alike, it would make no real or apparent change in their relative -positions. Nutation, however, affects the celestial latitudes and -longitudes, as the real motion of the earth’s polar axis changes the -relative positions. So great is the change that our present pole star -has changed from 12° to 1° 24; in regard to the celestial pole, the -gradual approximation will continue until it is with 0° 30´, after -which it will leave the pole indefinitely until in 12,934 years α Lyræ -will be the pole star.</p> - -<p>So far we have given only the causes that affect the meridian, and -consequently our standard for time; but that point being established -for the yearly and diurnal revolutions, it becomes necessary to find -some means to divide the day into minute fractional parts, such as -seconds and parts of seconds. This, it has been stated, is effected -by means of an isochronous pendulum. On this instrument no comment is -required but of the causes that disturb its accuracy much is needed. -In 1672, at Cayenne, the astronomer Richter, while taking transits -of fixed stars, found his clock lost 2´ 28´´ per day. This was an -error that arrested his attention, and he immediately attributed it -to some variation in the length of the pendulum—due to other causes -than atmospheric changes and expansion. He determined the length of a -pendulum beating seconds in that latitude, which was 5° N. in South -America. He found that that pendulum was shorter than one beating -seconds in Paris, by 0833+ of an inch. Now, if the earth was a sphere, -the attraction of gravitation at all places on its surface would be -equal, and the oscillations of a pendulum would also be equal, + or -- the disturbing effect of centrifugal force—an amount that can be -easily determined. The real reason of the variation is found in the -configuration of the earth.</p> - -<p>The amount of the attraction of gravitation at any point of the earth’s -surface is found by the distance traversed by any body during the -first second of its fall. The pendulum is a falling body, and may be by -the same analysis reasoned on that pertains to the laws of gravitation; -the centrifugal force is measured by any deflection from a tangent to -the earth’s surface in a second.</p> - -<p>It follows that the centrifugal force at the poles, where there is -the least motion, would not be equal to the force of gravitation, and -at the equator must be exactly equal; but the deflection of a circle -from a tangent measures the intensity of the earth’s attraction, and -is equal to the versed sine of the arc described during that time, -the velocity of the earth’s rotation being known, the value of the -arc is deducible. The centrifugal force at the equator is equal to -¹⁄₂₈₉th part of the attraction of gravitation. Again, the uniformity -of the earth’s mass becomes an object of consideration. Assuming that -the figure of the earth is an ellipsoid of rotation, we will show the -relation that form bears to the equal oscillation of a pendulum.</p> - -<p>Taking the earth as a homogeneous mass, analysis gives us the certainty -that if the intensity of gravitation at the equator be taken as unity, -the increase of gravity to the poles eliminating the differences of -the centrifugal force must be = to 2.5, the ratio of the centrifugal -force to that of gravitation at the equator. Now, taking the 2.5 of -.346 = 1/115.2, this then must be the total increase of gravitation. -Did we know the exact amount of increase at every point, from the -equator to the poles, a perfect map of the form of the earth could -be produced from calculation; experiment being from physical causes -totally impracticable. The following analysis, quoted from an eminent -physicist, gives a very lucid idea of the reasoning:</p> - -<p>“If the earth were a homogeneous sphere without rotation, its -attraction on bodies on its surface would be everywhere equal. If it -be elliptical and of variable density, the force of gravity ought to -increase in intensity from the equator to the pole as <em>unity plus</em> -a constant quantity multiplied into the square of the sine of the -latitude. But for a spheroid in rotation the centrifugal varies by -the law of mechanics, as the square of the sine of the latitude from -the equator, where it is greatest,<span class="pagenum" id="Page_10">[Pg 10]</span> to the poles, where it is least. -And as it tends to make bodies fly off the surface, it diminishes the -force of gravity by a small quantity. Hence, by gravitation, which -is the difference of these two forces, the fall of bodies ought to -be accelerated from the equator to the poles proportionably to the -square of the sine of the latitude, and the weight of the body ought to -increase in that ratio.”</p> - -<p>Assuming the above reasoning to be correct, it follows, that the rate -of descent of falling bodies will be accelerated in the transition -from the equator to the poles. Now, it has been before stated that -the pendulum is a falling body; therefore, with the same length of -pendulum, the oscillations at the pole should be faster than at the -equator. Theory, in this case, is verified; for it has been proved by -experiments, repeated again and again, that a pendulum oscillating -86,400 times in a mean day at the equator, will give the same number of -oscillations at any other point, provided its length is made longer in -the exact ratio as the square of the sine of the latitude.</p> - -<p>The sequence to be derived from all the foregoing considerations is, -that the whole decrease of gravitation from the equator to the poles -is 0.005.1449, which subtracted from the 1/155.2 gives the amount -of compression of the earth to be nearly 1/285.26. But this form -of the earth would give the excess of the equatorial axis over the -polar about 26¹⁄₂ miles. The measurement is confirmed by Mr. Ivory -in his investigations on the five principal measurements of arcs of -the meridian in Peru, India, France, England, and Lapland. He found -that the law required an ellipsoid of revolution whose equatorial -radius should be 3,962.824 miles, and the polar 3,949.585 miles; the -difference is 13.239 miles; this quantity multiplied by two gives -26.478 as the excess of one diameter over the other. Thus, by two -different processes the figure of the earth has been determined; but -another remains that is the result of pure analysis, derived from the -nutation and precession of the equinoxes—for, as explained before, -these effects are caused by the excess of matter at the earth’s -equator. The calculation does not lead us to certainty, but it does -show the compression to be comprised between the two fractions ¹⁄₂₇₀ -and ¹⁄₅₇₃. There is this advantage in the lunar theory, that it takes -the earth as a whole, disregarding any irregularities of surface, or -the local attractions that influence the pendulum—the difficulties of -measuring an arc of the meridian being an obstacle to perfect accuracy.</p> - -<p>The form of the earth has, however, a value confined not alone to those -interested in horology—it furnishes us with a standard of weights and -measures. In England and the United States, the pendulum is the unit of -mensuration, or at least the common standard from which measurement is -derived. It has been shown that, deducting the effects of nutation, the -axis of the earth’s rotation is always in the same plane. Now, the mass -being the same constant quantity, a pendulum oscillating seconds at the -Greenwich Observatory, has been adopted by the English Government as -its standard of length. Oscillating in vacuo at the level of the sea, -at 62° Fahr., Captain Kater found its approximate length to be 39.1393 -inches; as this must be invariable under the same circumstances, it -becomes a standard for all time. The French deduced their standard from -the measurement of the ten-millionth part of a quadrant of the meridian -passing through Formentera and Greenwich. They have also adopted the -decimal system; yet it seems to prove that nothing under the sun is -new, for over forty centuries ago the Chinese used the decimal system -in the division of degrees, weights, and measures.</p> - -<p>The antiquity of the pendulum is also shown by the fact that the -Arabs were in the habit of dividing the time in observations, by its -oscillations, when Ibn Junis, in the year one thousand, was making -his astronomical researches. Before we lose sight of the influence -of the form of the earth on the pendulum, it may be well to state -another source of disturbance, arising from the combined influence of -the earth’s rotation and the fact that a body moving in its own plane -seeks to maintain that plane. It will be seen from the very beautiful -experiment showing the rotation of the earth, that if a body like a -pendulum be suspended so as to be free in every direction, and not be -influenced by the motion of the earth when set in oscillation in<span class="pagenum" id="Page_11">[Pg 11]</span> any -plane, that that plane will preserve its line of motion, while the -earth in its motion beneath the body can be seen to slowly move, as -though the minute hand of a watch were made stationary while the dial -revolved. The same principle is the one that maintains the spinning-top -in a parallel position to the horizon, or the gyrascope in its -apparently anomalous defiance of all the laws of gravitation. In the -pendulum this tendency to preserve the same plane of motion becomes a -cause of error—slight, it is true, but can be very easily remedied by -so placing it that the plane of oscillation shall be parallel to the -equator. It will be readily seen that this precaution will become more -important as we recede from the equator; for if we were to suspend a -pendulum at the pole in a true line with the axis of rotation, and if -the plane of vibration remained constant, the earth would turn once -around that plane in the diurnal period. During this time there would -be a continuous torsion on the point of suspension, that would in time -materially affect the accuracy of the instrument. The reasoning holds -good for every latitude—degree of influence being the only difference.</p> - -<p>Having given the action of the earth’s form, mass, and rotation on -the pendulum, there remain the disturbances due to expansion and -contraction, owing to changes of temperature and those of atmospheric -causes. The astronomical points to be observed are somewhat too fully -laid down, but it must be remembered that an exact science requires the -premises to be fully established before a sequence can be drawn.</p> - -<p>As the standard of time depends on the passage of a star or the sun, or -any known celestial object, at a certain time across the meridian of -the place where the observation is taken, it was absolutely necessary -to give the modes of calculation, together with the disturbing causes. -Moreover, a full appreciation of the indebtedness of horology to -astronomy could not be obtained without a general knowledge of the -change of the position of the major axis of the orbit described by the -earth around the sun. Also, the difference between mean and apparent -solar time was required to illustrate the use of the tables of equated -time, the necessity of which will become patent when the use of the -transit instrument for the establishment of time, or a fixed standard, -is introduced. Also, the disturbing effects of the sun and moon -collectively and relatively as to position, could not be passed, as -they produce the precession of the equinoxes and the nutation of the -pole—essential elements in the computation of time.</p> - - -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<h2 class="nobreak" id="Watch_and_Chronometer_Jewelling">Watch and Chronometer Jewelling.</h2> -</div> -<hr class="r5" /> -<h3>NUMBER ONE.</h3> - -<hr class="r5" /> -<p>This whole subject is well worthy an article both in a scientific and -mechanical sense, whether we consider the delicacy of the operations -or the intractable character of the material operated on—for there -has been no improvement in the horological trade of more importance to -accuracy and durability of time-keepers.</p> - -<p>The substitution of stone for common brass or gold bearings, was -prompted by the inevitable wear of the holes from frequent cleaning, -and the abrasion of the pivots, produced by the accumulation of -dust with viscid oil; the pivot being cut away, or the hole opened -too large. So long as the verge and cylinder were the prevailing -escapements, the necessity for jewelling was not so strongly felt, -except in the balance holes. The introduction of the lever escapement -brought with it a better watch,—capable of more accurate time, but -demanding an improved construction.</p> - -<p>An Italian, in 1723, first introduced the practice of using stone for -bearings. He not only conceived the idea, but was successful as an -artisan in making his own jewels; ingenious and skilful as he was, -however, he encountered obstacles almost insurmountable.</p> - -<p>The art of cutting gems, it is true, was at that time well understood, -but no one had attempted to drill a hole in a hard stone fine enough -for a properly sized pivot. The watches at that time that were jewelled -could boast of nothing more than the balance holes, and they were not -pierced to let the pivot <em>through</em>.</p> - -<p>It is a very difficult matter to polish a taper indentation in a stone, -even with modern appliances,<span class="pagenum" id="Page_12">[Pg 12]</span> in consequence of the tendency to create -a <em>tit</em> at the bottom,—thus throwing the balance staff out of -upright. The difficulties in the then state of knowledge retarded -the general introduction of stone-work for many years. The Swiss, -however, seeing the advantages derived, finally struck out the various -manipulations with success. Time and experience gave more skill, and -at the present time it is impossible to find a Swiss watch, even of -the cheapest class, that is not jewelled in at least four holes. The -English trade adopted the art later; but even then it did not become -general for many years. Within a generation, only fine English levers -were jewelled.</p> - -<p>The mere substitution of a harder substance was not the only -improvement; other conditions necessary to accuracy were insured. The -hole could be made <em>round</em>—the material of such a character that -no chemical action could be effected on the oil used for lubrication, -and the vertical section of the hole could be made so as to present -the least amount of frictional surface, yet still giving a perfectly -polished bearing, thus avoiding the cutting of the pivot.</p> - -<p>The whole “<i lang="la" xml:lang="la">modus operandi</i>” from the stone in the rough to the -last setting up is well worth the attention of the watch repairer, and -certainly that of the manufacturer.</p> - -<p>Of the materials used in the trade, the first and most important is -the diamond, used only in the time-piece as an end-stone—but at -the bench all-important, as a means of making the other jewels. The -diamond possesses the requisite susceptibility of polish, combined with -greatest hardness of any substance known; but this adamantine quality -precludes its being pierced with a through hole. Considered chemically, -the diamond is pure carbon,—its different varieties differing only -in structure—common charcoal, its lowest—plumbago, its intermediate -grade. Another variety, called the “black diamond,” or “diamond -carbon,” occurs, which is interesting as being a parallel with emery, -compared with crystallic sapphire. The form of diamond most in use for -mechanical manipulations, is almost always crystallized; yet it will be -seen that the agglomerated form of diamond carbon plays no unimportant -part in jewelling. As a jewel, no use is made of the diamond, other -than as an end-stone. Marine chronometers, in which the balance will -weigh from five to nine pennyweights, are almost invariably furnished -with a diamond end-stone, set in steel. Yet, hard as the substance is, -it is often that a pivot will cut an indentation in its face. The cause -of this apparent anomaly is to be found in the structural character of -the gem, and its value. The lapidary, saving in weight as possible, -does not care, in “Rose Diamonds,” to pay attention to the lines of -cleavage. If the face of the stone makes a slight angle with the -strata of the jewel, there occur innumerable small angles of extreme -thinness—the pivot, coming in contact with any of these thin portions, -may fracture it, and the fragment, becoming imbedded in the tempered -steel pivot, becomes a drilling tool. In our experience we have had -marine chronometers sent for repair, that have lost their rate so much -as to become utterly unreliable from this cause alone—the pivot having -produced an indentation of the stone, creating more friction, and thus -destroying the accuracy of the instrument.</p> - -<p>As a general rule, the rose diamonds sold for this purpose are -sufficiently good for general work. In a very fine watch or chronometer -the stone should be selected with reference to its polish on the face, -and its parallelism in the lines of cleavage. The diamond, however, -gets its great importance from being the only agent we can use in -working other stones. Without it the whole art of jewelling would not -be practicable. The various steps are all connected some way with -diamond in its different shapes. “Bort,” the technical name for another -variety, is merely fragments of the stone that have been cleaved off -from a gem in process of cutting, or gems that have been cut, but found -too full of flaws to become of use for ornamental jewelry purposes, -the cost depending on the size, varying from $5.50 to $18 per carat. -This “Bort” is used as turning tools—the larger pieces being selected -and “set” in a brass wire and used on the lathe, in the same manner, -and with the same facility, as the common graver. For tools, even -the diamond is not of equal value—a<span class="pagenum" id="Page_13">[Pg 13]</span> pure white and crystalline in -structure generally being too brittle (though hard) to endure the -work. Among the workmen the “London smoke,” a clouded, brownish stone, -is most prized—it possessing the twofold qualities of toughness and -hardness.</p> - -<p>Another form of “Bort” comes in the shape of a small globule, sometimes -the size of a pea; it is crystallic, and when fractured generally gives -very small, indeed minute pieces of a needle shape. These are carefully -selected, and form the drills with which the English hole-maker -perforates the jewel. These drills, when found perfect, for soundness, -form, and size, are very highly prized by the workman, as the choice of -another, together with the setting, will often take a vast deal of time -and labor.</p> - -<p>“Bort” is also used in the making of the laps or mills with which -the jeweller reduces the stones to a condition for the lathe and -subsequent processes. For this purpose such pieces as are not fit for -cutting-tools, or drills, are selected. A copper disk, having been -first surfaced and turned off in the lathe, is placed on a block or -small anvil; each piece of stone is then separately placed on the -copper, and driven in with a smart blow—care being taken that no place -shall occur in the disk that does not present, in revolution, some -cutting point. It would seem impossible to retain the diamond fragment, -but it must be remembered that the copper, being a very ductile metal, -receives the piece; the first rubbing of a hard stone then burnishes -the burred edges of the indentations over every irregular face of the -diamond, leaving only a cutting edge to project. The rapidity with -which such a lap, well charged, will reduce the hardest stone, is -somewhat marvellous. It is the first tool used in jewelling, and so -important that a more detailed and explicit description of its make -will be given when the process of manufacture is treated upon.</p> - -<p>Diamond powder is equally as important as “bort,” being used in nearly -every stage of jewel-making. The coarsest charges the “skives” or -saws used for splitting up the stone. These skives are made of soft -sheet-iron, and act on the same principle as the laps. The finer -grades, in bulk, resemble very much ordinary slate-pencil dust; -indeed, the latter is often used as an adulteration. This powder is -not uniform in fineness, and the jewel-maker is under the necessity of -separating the different grades. This is effected by a simple process -called “floating off,” and is conducted as follows: A certain quantity -of powder, say a carat, is put into a pint of pure sweet oil, contained -in some such shallow vessel as a saucer. Depending on the fluidity of -the oil, the mixture, after being thoroughly incorporated, is allowed -to stand undisturbed for about an hour or an hour and a half. During -this time, owing to their greater gravity, the largest particles are -precipitated, leaving held in suspension a powder of nearly uniform -fineness. The mixture is now carefully decanted into another similar -vessel, leaving the coarse powder at the bottom of the first. This -coarse deposit is denominated <abbr title="number">No.</abbr> 1, and is used for skives, laps, and -other rough purposes. The decanted mixture in the second vessel is -allowed to remain quiescent for twelve hours, when the same operation -is performed; and the third vessel now contains most of the oil, -together with the finest particles of powder. The precipitate from the -second decantation is the ordinary opening powder; the finest being for -polishing both the holes and outsides of jewels, and giving the final -finish to the faces of pallets, roller pins, locking spring jewels, etc.</p> - -<p>The good workman is careful to keep the powder in this condition as -free as possible from any extraneous dust, and above all to preserve -the different grades from any intermixture, as a small quantity of a -coarser grade would destroy a finer one for all its purposes, and the -process of “floating off” would have to be repeated.</p> - -<p>The most important stone in jewelling, the diamond, becomes more of an -agent of the manufacture than an object.</p> - -<p>Properly, for jewelling the ruby and sapphire are pre-eminent; -inferior only to diamond in hardness, possessing a sufficient degree -of toughness, susceptible of an exquisite polish, this (for they -are one and the same) stone is the favorite of the Swiss, English, -and American, for all high class work—the Swiss, however, using it -indiscriminately in all watches.</p> - -<p><span class="pagenum" id="Page_14">[Pg 14]</span></p> - -<p>The ruby proper is of one color, but in its varieties of intensity -may change to a very light pink. When still lighter it is ranked a -sapphire, which comes in almost every possible color and shade, from -ruby to a perfect transparent colorless crystal. This stone differs -in degrees of hardness and capacity of working—the hardest being a -greenish yellow, in the shape of pebbles, with very slightly rounded -edges, difficult to work, but forming the strongest and most perfect -jewel known.</p> - -<p>It must be remembered that this description gives the value of the ruby -and sapphire as a material for jewelling only. For ornamental jewelry, -the value depending on color, of the most intense ruby or blue for -sapphire, together with brilliancy and weight. The ruby and sapphire -are formed on an aluminum base, the common emery being another form of -structural arrangement, but of the same chemical constitution.</p> - -<p>These stones possess every quality to make them the base of perfect -jewelling; and still the chrysolite is equally in favor with most -jewellers. It is not quite so hard, but it is more easily worked and -cheaper in price, and it would be difficult to tell wherein it is -inferior to either the ruby or sapphire. It has a yellowish tinge, -verging to the color of the olive. As a stone for jewelry it is not -fashionable, and only in Persia is it valued. There are, however, some -very strong objections to its use by the workman; it is not uniform in -hardness; in polishing it will <em>drag</em>, that is, the surface will -tear up in the process. Unfortunately the eye is not able to detect -the fault before working, and it is found only when much preliminary -time and trouble has been expended. It is susceptible, when good, of a -perfect polish, and is much used in chronometer work, especially for -jewelling the 4th hole, as its non-liability to fracture renders it -valuable.</p> - -<p>“Aqua Marine” is a brother to the emerald, differing from it only in -intensity of color, and composed of the same constituents. These two -gems are the only ones in which the rare metal, glucinum, has been -detected. It is extensively used in the American and English watches, -but never in the Swiss. It is soft, not much harder than quartz, but -comes in large pieces, perfectly transparent, and of a color which -is that pure green of sea-water, from which it takes its name, “Aqua -Marine.”</p> - -<p>The garnet in English watches plays an important part for pallets, also -for roller-pins; a very soft stone, but very porous. When set in the -pallet with a pointed toothed wheel, it is apt to act as a file from -its porosity, cutting the end of the tooth. This may be detected in any -pointed tooth lever watch, by observing the color of the back of the -tooth. “Black vomit” it used to be called in the Boston factory. Most -of the garnet used is an Oriental stone, the best quality coming in -bead form, the holes having been pierced by the natives. The cost of -piercing the stone in Europe or America would be far above its value. -The Oriental is the best for Horological purposes, though Hungary and -Bohemia furnish the most highly prized stones used for ornamental -purposes; indeed, in some German towns the cutting and setting of the -garnet is a specialty, giving employment to a large number of people. -And, strange to say, the best market for their sale is the United -States.</p> - -<p>This comprises about all the stones used in watch and chronometer -jewelling. Still in clock work the pallets are generally jewelled in -agate, a stone not at all suited to the purpose, it having, even in -the best specimens, a decided stratification that prevents an uniform -surface being formed by any process. The cornelian form of the agate -is not open to this objection, and makes capital bearings for knife -edges of fine balances, and compass stones for centres of magnetic -needles. For watch or chronometer purposes the only really useful -stones are sapphire, ruby, chrysolite, and aqua marine—all possessing -peculiarities that deserve some remarks, as they are of the utmost -importance to the hole maker. The sapphire is the hardest stone, next -to the diamond, and yet specimens can be, and are found, so soft as to -<em>drag</em> in polishing. Again, if stratified very clearly, will “fire -crack” in opening the hole. The ruby is more uniform in its structure, -and is more highly prized on that account; its hardness being all that -is necessary, while its susceptibility of receiving a high polish -is equal to<span class="pagenum" id="Page_15">[Pg 15]</span> that of the sapphire or chrysolite. The aqua marine is -always uniform and may be polished both externally and in the hole with -“tripoli,” saving something in diamond powder in the process of making. -In our estimation, however, the chrysolite is the most valuable of all -the stones. True, when purchased in the rough, many pieces will be -found unfit for the jeweller’s purpose; but when the right quality is -found, nothing can be better adapted to jewelling. Hard, it is easily -wrought, taking a peculiar <em>unctious</em> polish, retaining oil in its -most limpid condition for a long time.</p> - -<p>These stones form the general stock by and from which jewels are made. -The details of the various manufacturing manipulations, the tools -used, also the setting in the work, together with the important item -of the screws, will form the subject of the next article on Watch and -Chronometer Jewelling. Not having been able to get our engraving done -in time for publication, we are compelled to reserve the remainder for -the next number.</p> - - -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<h2 class="nobreak" id="Hints_on_Clocks_and_Clock-Making">Hints on Clocks and Clock-Making.</h2> -</div> -<hr class="r5" /> -<h3>NUMBER ONE.</h3> -<hr class="r5" /> - -<p>Twenty-five years of hard labor amidst the dust and din of machinery, -with hands cramped, and fingers stiffened by the continual use of -tools, and with a brain constantly occupied in ringing the changes upon -wheels and levers in their almost infinite combinations,—it requires a -degree of courage to undertake to write anything that can be dignified -with the name of an “article,” although it does propose to treat upon -a subject with which we are fairly familiar; but it is consoling to -think that one is not expected to write for the pages of this practical -journal with the same degree of elegance and polish that should grace -the columns of a review or magazine; that we can appear here as plain, -practical mechanics, and use good hard, round words to express our -ideas, backed by an experience which should add some weight—and we -welcome the appearance of the “American Horological Journal,” which -is to serve a good purpose by bringing out the actual experience of -men who have grown gray in the art and mystery of clock-making, and -preserving, by means of the “art preservative of all arts,” their -dearly bought knowledge and experience, for the benefit of those who in -their turn shall follow them; and it will also benefit the people in -general by giving information that will lead to the purchase of good -and tasteful clocks for household use.</p> - -<p>That such a journal is needed to enlighten us, is made plain by the -fact that in almost every newspaper we have a vivid account of some -wonderful clock “recently invented,” which may possess some merit, but -they are so grossly exaggerated by some ignorant “penny-a-liner,” that -we are almost led to believe in the Irishman’s marvellous “eight-day -clock, that actually ran three weeks.” Even the proverbially correct -“Scientific American,” of which I am a constant reader, has in its -issue of June 19th, an account in its “editorial summary” of a clock in -France containing “90,000 wheels,” and perhaps the most curious part -of the mechanism is that which gives “the additional day in leap-year,” -etc. Now, it will require but little knowledge of clocks to tell us -that one with 90,000 wheels was never made and never will be, but “the -additional day in leap-year” has been given by calendar clocks in this -country since the year 1853.</p> - -<p>It is not proposed in the series of articles to follow, to discuss -the early history of clocks. Reid and Dennison have written enough -to convince the most skeptical that the clock is an old invention. -It is not important to us who invented the pendulum, or this or that -escapement, but who makes the best pendulum, the best escapement, the -most perfect train of wheels and pinions. These are vital points, and -we shall endeavor to give them that attention that their importance -demands. It is proper to state here that any assertion made, or rule -given, has been tested, and is the result merely of our experience, -and we do not claim that it is all there is of the subject; for we are -aware that the experience of others may have led to results entirely -different; but if all clock-makers will avail themselves of the columns -of this journal, we shall not only become<span class="pagenum" id="Page_16">[Pg 16]</span> better acquainted by an -exchange of ideas, but better clock-makers.</p> - -<p>The subject of wheels and pinions is of the greatest importance in -clock-making, and the utmost care and skill are required to execute a -train which shall not only run with as little friction as possible, -but the friction must be equal; for if there is no variation in the -train force, the escapement and pendulum will always be actuated by the -same amount of power, and the performance of the clock can be relied -upon. Clock text-books do not fully impress this subject. We find a -great deal upon this or that escapement, and the different pendulums. -Dennison has a couple of pages full of abstruse calculations upon a -method of shifting an extra weight upon a rod, so that the going of a -clock can be varied one second per day; but if his wheels and pinions -are not perfect, a large tooth here and there will vary the clock more -than that.</p> - -<p>Reid overawes us with his knowledge of the proper curves of the teeth -of wheels; but it must have been only theory, for his practice was to -saw his teeth, and his cycloids, epicycloids, and hypocycloids were -left to the mercy of the “topping file” in the hands of his “wheel -teeth finishers,” instead of shaping up the teeth in the engine, as is -done now. We have generally cut the wheels of fine clocks over several -times with different cutters before taking them from the engine; the -last cutter having but one tooth, which can be made perfect as to cut -and shape, and, running with great speed, will leave the teeth the -proper shape, very smooth, and as true as the dial of the engine. -Escape wheels, especially, require great care in cutting, as the -teeth for dead-beat escapements are somewhat long and thin; the least -inaccuracy is certain to cause trouble. It is absolutely necessary that -the dial plate of the cutting engine should be perfectly true, with -clean, round holes, and a perfect fitting index point, with a cutter -arbor without end play or lateral motion—these are the essentials of a -good cutting engine, without which a good clock cannot be made.</p> - -<p>We have generally made a practice, upon the completion of the train for -a fine clock, to put in the place of the escape-wheel a very light, -well-balanced fly, to prevent “backlash,” and a very fine soft cord -on the barrel; then hang on a very light weight; so slight that—all -of the wheels being balanced, and no oil upon the pivots—the fly -will move so slowly that its revolutions may be counted. By taking -care that the weight be not too much in excess of the resistance, the -least inaccuracy in the wheels and pinions may be discovered by the -difference in the velocity of the fly, or by its suddenly stopping, -which will be occasioned by any inequality in the train teeth, which -would not have been discovered by the closest scrutiny. It was by means -of this test that we discovered an inaccuracy in a pinion, caused by -hardening, which could not have been discovered by a less delicate test.</p> - -<p>The wheels in the train should be as light as possible, for as the -whole train is stopped every time a tooth drops on the pallets, it is -plain that the driving weight must overcome the inertia as well as the -friction of the train at every beat. To this end it has been customary -to “arm out” the wheels, leaving a very light rim supported by light -arms, the wheels being generally of cast brass, turned up, and cut, -then lightened. We followed this plan for some time, but abandoned it, -as we found great difficulty in making a perfectly round wheel. The -arms serve as posts to support the rim in cutting or turning, but the -space between is very apt to spring down. We prefer making the wheels -of fine hard-rolled sheet brass; it is superior to cast brass, much -finer, harder, and more durable, and is freer from flaws. After the -wheels are cut, they are turned out on each side, leaving a thin web in -the centre; they can be made lighter, finished easier, and are round.</p> - -<p>As to the shape of the teeth in clock-wheels, the subject has been so -ably treated by Reid, Dennison, and <abbr title="professor">Prof.</abbr> Willis (who has invented an -instrument to assist in laying out the curves for the teeth of wheels), -that we shall not attempt it in this paper; besides, there is so little -of the entire theory that can be applied to a clock-wheel of two and -a half inches in diameter, with 120 to 140 teeth, farther than to -leave the wheel and pinion of the proper diameter, that we consider it -unnecessary; for if makers of regulators and<span class="pagenum" id="Page_17">[Pg 17]</span> other fine clocks will -use pinions of 16 or 20 teeth, the friction or driving is all after the -line of centres, and the whole subject of cycloids, epicycloids, and -hypocycloids is reduced to a very small point, and might be said to -“vanish into thin air.”</p> - -<p>Having given only a few practical hints, and not yet crossed the -threshold of the subject, we propose to continue from month to -month—if the readers of the <span class="smcap">Journal</span> do not weary—the -discussion of the various parts that go to make the sum total of a fine -clock, with notices of the various clocks made in this country.</p> - -<hr id="newtools" class="tb" /> - -<p>It certainly comes within the province, and is the duty, of a journal -devoted to Horology, to make a note of any and all the new improvements -that pertain to the science. We give, then, some few, the merits of -which have struck us as being a very important matter of consideration.</p> - -<p>The best clock time-keeper is not absolutely perfect, so its rate must -be kept; but the watchmaker ordinarily has no means of correcting the -error of his regulator, until the accumulation renders it a serious -inconvenience. Did he possess a Transit instrument, properly set and -adjusted for meridian, together with the required books and knowledge -of observing, he could from day to day correct his clock and keep -accurate time; but these are all expensive, as well as involving time -and labor. Suited to the wants of the artisan is a little instrument -called the Dipleidescope; simple in its construction, and not liable -to get out of position or order, it forms the best substitute for the -transit we have seen. It is founded on the theory that the double -reflection from the two surfaces of planes at an angle of 60° will -coincide when the object reflected is in a true line with half the base -of the whole triangle. Having a prism cut in an equilateral triangle, -one angle is set directly down toward the centre of the earth, the base -being brought parallel with the line of the horizon. Now, if the axis -of the prism is in a line with the meridian, a reflection of the sun -will appear, at the instant of crossing the meridian, on itself—that -is, there would be but one image. If the instrument is well made, -there can be no doubt of its accuracy and value to those who, wishing -to verify their time, are not situated so as to use a transit.</p> - -<p>Another improvement is a Bench-Key for watchmaker’s use. No one who has -had any experience at the bench but will appreciate an article that -facilitates the setting of time-pieces for his customers. In winding, -it is equally valuable. It is not dependent for its strength of torsion -on the spring-chuck principle, the power being applied close to the -square by means of a pin that passes through the key.</p> - -<p>Hall’s Patent Cutting Nippers are a positive desideratum; a large -wire can be cut off without the least jar to the hand, the leverage -is so great. The smallest sizes are suitable to the ordinary run -of watch-work, and can be used in clock-work better than any -cutting-plyers extant. Strong and durable, they possess one quality -that all watchmakers will appreciate—if a cutting-jaw is broken it can -be replaced by another.</p> - - -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<h2 class="nobreak" id="Greenwich_Observatory">Greenwich Observatory.</h2> -</div> -<hr class="r5" /> - -<p>About two hundred years ago, England began to take a lead in the -mercantile commerce of the world; her ships were daily passing across -the Atlantic, and India also was beginning to attract her attention. -It was therefore of the utmost importance that navigators should be -enabled to find their longitude when at sea, independently of watches -or clocks; and a reward was offered to any one who should discover a -method by which this result might be obtained.</p> - -<p>The plan proposed was, that the angular distance of the moon from -certain stars should be calculated beforehand, and published, so that, -for example, it might be stated that at ten minutes and five seconds -past nine on such a day, the moon should be distant from Mars 40 -degrees. If from a ship in the middle of the Atlantic, Mars and the -moon were found to be 40 degrees apart, then it would be known that the -time in England was ten minutes and five seconds past nine.</p> - -<p>Here, then, was one item ascertained, and the method was a good one; -but in consequence of the want of accuracy as regarded the moon’s -motions, and the exact positions of the stars, it could not be -practically carried out.</p> - -<p>Under these circumstances, Charles II. decided<span class="pagenum" id="Page_18">[Pg 18]</span> that a national -observatory should be built, and an astronomer appointed; and a site -was at once selected for the building. Wren, the architect, selected -Greenwich Park as the most suitable locality, because from thence -vessels passing up and down the Thames might see the time-signals, -and also because there was a commanding view north and south from -the hill selected for the site. The observatory was completed in -1676, and Flamsteed, the chief astronomer, immediately commenced his -observations, but with very imperfect instruments of his own. During -thirty years, Flamsteed labored indefatigably, and formed a valuable -catalogue of stars, and made a vast collection of lunar observations. -He was succeeded by Halley, who carried on similar observations; and -from that time to the present, Greenwich Observatory has been our -head-quarters for astronomical observations.</p> - -<p>The work carried on at Greenwich is entirely practical, and consists -in forming a catalogue of stars and planets, and so watching them -that every change in their movements is at once discovered. Now that -this work has been performed for several years, the movements of the -principal celestial bodies have been so accurately determined, that -the <i>Nautical Almanac</i>—the official guide on these subjects—is -published four years in advance, and thus we find that on a particular -night in 1868, the moon will be at a certain angular distance from -a star, and the second satellite of Jupiter will disappear at a -particular instant. On the exterior wall of the observatory there is -a large electric clock, which, being placed in “contact” with the -various other clocks in the observatory, indicates exact Greenwich -time. The face of this clock shows twenty-four hours, so that it -requires that a novice should look at it twice before comparing his -watch. On the left of this clock are metal bars let into the wall, -each of which represents the length of a standard measure, such as a -yard, foot, etc. And let us here say a few words about these standards. -To the uninitiated a yard is simply three feet, and a foot is twelve -inches—an inch being, we are told in our “Tables,” the length of three -barleycorns. Now, as the length of a barleycorn varies considerably, it -requires something more definite than this to determine our national -measures. Thus, the question, what <em>is</em> a foot? is more difficult -to answer than at first sight appears. Many years ago the French -perceived the difficulty appertaining to the national standard, and -they, therefore, decided that a metre should be the ten-millionth part -of one-fourth of the earth’s circumference—that is, ten-millionth -of the distance from the Equator to the Pole. But here another -difficulty was encountered, because different calculators found this -arc of different lengths. By <em>law</em>, however, it was decided -that one measurement only was correct, and so the metre was fixed at -3.0794 Paris feet; though since then, more accurate observations and -improved instruments have shown these measured acres to have been -very incorrectly ascertained, and thus the French method failed when -practically tried.</p> - -<p>The length of a seconds pendulum oscillating in a certain latitude -has been our method of obtaining a standard; but this also has its -weak points, so that to obtain a constant standard it is necessary to -have some pattern which is unchangeable, and thus a metal has been -chosen that expands or contracts but little either with heat or cold; -and this, at a certain temperature, is <em>the</em> standard measure, -and such a standard may be seen on the exterior wall of Greenwich -Observatory.</p> - -<p>On entering the doorway—which is guarded by a Greenwich pensioner, -who will possibly first peep at the visitor, in order to see who -the individual may be who is desirous to tread within the sacred -precincts—one finds a court-yard, on the left of which are the -transit-room, the computing-room, and the chronometer-room. The -transit room takes its name from the instrument therein, which is -a large “transit.” This consists of a large telescope, the outside -of which is not unlike a heavy cannon, as it is of solid iron. The -instrument is supported by trunnions, which allow the telescope to be -elevated or depressed to point south or north, and, in fact, to make -a complete revolution, but never to diverge from the north or south -line. The magnifying power of this instrument is not very great, so -that it admits plenty of light, for it is intended, not as a searcher -for or for gazing at celestial objects, but for the purpose of noting -the exact time at which stars and planets pass south or north of -Greenwich. Upon looking through this telescope, the observer’s eye -is first attracted by a vertical row of what seem to be iron bars, -placed at equal distances from each other. These, however, prove to be -only spiders’ webs, and are used for the purpose of taking the time -of passage of a star over each wire, and thus to ascertain the exact -instant of its being in the centre of the telescope. During even the -finest and calmest nights, there is occasionally found a tremulousness -in the instrument, which, as it is rigidly fixed to the walls of the -building, must be due to a slight vibration in the ground itself. Thus, -many a feeble earthquake unfelt by the outsider may be perceived by the -astronomer by the aid of his delicate instruments.</p> - -<p>The various stars seem to be travelling at<span class="pagenum" id="Page_19">[Pg 19]</span> an immense rate when -seen in the field of the transit telescope, and it is really nervous -work noting the exact time when each wire is passed. The experienced -observer, however, not only will give the minute and second, but also -the decimal of a second when the star was on the wire. The result is -obtained by counting the beats of a clock the face of which is opposite -the observer. Thus, if at three the star seems as much short of the -wire as at four it had passed it, then 3.5 might be the instant of -“transit.”</p> - -<p>At noon each day the sun’s passage is observed by nearly the whole -staff of observers. One individual looks through the telescope, and -gives the time for each wire, while others examine a variety of -micrometers in order to ascertain the fractional parts of seconds, -etc.,—these micrometers being placed at the side of the instrument.</p> - -<p>In the morning, the principal work consists in making what are termed -the “reductions” to the observations of the previous night. These -reductions are the corrections requisite for the slight instrumental -inaccuracy, for the refraction of the atmosphere, and for the known -constant error of the observer. When, therefore, a bright winter’s -night has occurred, the work on the following morning is usually very -heavy. At noon the sun’s time of transit is taken, and at one o’clock -the “ball” is dropped, by means of which the various vessels in the -Docks and in the Thames set their chronometers, or ascertain their -rate. In addition to this, the time is sent by electricity to Deal and -one or two other seaports, in order that every vessel may be able to -know the accurate time, if within sight of those places.</p> - -<p>Not the least interesting portion of the observatory is the chronometer -room. For a very small charge, manufacturers or owners may have their -chronometers rated at Greenwich, which is accomplished in the following -manner:</p> - -<p>The chronometer is placed in the chronometer room, and compared with -the large electric clock in the room, this clock being kept in order -by the stars. Each day the chronometer is examined, and thus its rate -is ascertained in its then temperature. It is afterwards placed in a -sort of closet warmed by gas, a condition supposed to represent the -tropics, and it is there kept for a certain period, being tested each -day as before. This change of temperature is found to produce very -little effect on the best instruments, which, when they have passed -the ordeal, are returned to the owners with their character ticketed -to them. Some hundred chronometers are often placed in this room; and -to compare them is a science, the “expert” by a glance discovering the -difference between the two instruments, whilst a novice would require -to mentally add or subtract, and thus slowly to arrive at the same -results.</p> - -<p>As soon as it becomes dark enough to see stars by the aid of a -telescope, one of the staff commences his observations. These are -continued during the night; and a register is kept of each star, -planet, comet or moon, which is “doctored” in the morning by the -computers.</p> - -<p>As all mortals are fallible, it is desirable to bring machinery into -use where possible, and this has been managed in connection with -astronomical observations. Instead of the computer registering by -judgment the time of a star’s transit over the various wires, he -strikes a small indicator, which, completing the electric circuit, -causes a pricker to fall and make a hole in a piece of paper that -is attached to a slowly revolving barrel. Each time the star passes -a wire, the pricker descends and leaves its mark; and the interval -between these marks being measured by scale, the mean time of transit -may be obtained.</p> - -<p>There is usually a feeling of the sublime that comes over us when we -reflect upon the vast unexplored regions of space, or contemplate the -stellar world that shines upon us. The magnitude and grandeur of some -of the planets in the solar system strike us with a feeling of awe -and wonder, while we are puzzled at the mysteries attending comets, -double stars, nebulæ, etc. No such feelings or sentiments, however, -are allowed to enter into the constitution or mind of an observer at -Greenwich. Saturn, the glorious ringed planet, with its galaxy of -moons, is simply “Saturn, Right Ascension 10 hours 8 min. 12 sec., -North declination 16° 12´ 2´´.” Anything appertaining to the physical -constitution, the probable cause of the ring, or the object of so -grand an orb, does not come within the range of the observations at -Greenwich, which are limited to bare matter-of-fact business work.</p> - -<p>The southern portion of the observatory ground is devoted to -the investigation of meteorological subjects, and is under the -superintendence of Mr. Glaisher, who is now well known as an aerial -voyager. It is here that an exact record is kept of the amount of -rain that daily falls, of the direction and force of the wind, of -the magnetic changes, of the temperature, amount of ozone, etc.—all -matters which may, and probably will, lead us eventually to the -discovery of some laws connected with the states of weather, and enable -us to predict what may be expected from day to day. Whilst we are now -able to calculate to a few seconds, and for years in advance, the -instant when an eclipse may occur, and to explain the causes of the -various planetary movements, yet we are in a sad state of ignorance -as regards the<span class="pagenum" id="Page_20">[Pg 20]</span> causes of hurricanes, thunder-storms, continued rains -and droughts; and thus we find that all the would-be prophets who -from time to time spring up and oracularly announce a coming frost -or fine weather, or the reverse, are perpetually meeting with most -signal failures, which, however, does not deter future adventurers from -attempting to gain a cheap temporary renown by trying their luck at a -prophecy.</p> - -<p>The perpetual accumulation of facts at Greenwich, whether these be of -an astronomical nature, or appertaining to the air we breathe and its -subtle changes, is a proceeding that must eventually lead us on to a -correct knowledge of the laws which govern these matters, and also keep -us acquainted with any variations that may be occurring in the elements -that surround us.</p> - -<p>The order and quietness necessary in such calculations as those carried -on at Greenwich prevent it from being a “show” establishment, and -hence visitors are not admitted except on special business. Then, -however, every aid and assistance are offered to the student and -inquirer; the use of books and instruments is freely given, and such -information supplied as the little spare time of those belonging to the -establishment enables them to afford. Thus a visit to or a period of -study at Greenwich Observatory will amply repay those who wish to gain -the latest and most accurate information on astronomical subjects, or -to practise themselves at the adjustments and use of the instruments; -and to those who have not such opportunity, we offer this slight sketch.</p> - -<p class="right"> -[<i>Chambers’ Journal.</i><br /> -</p> - - -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<h2 class="nobreak" id="Pinions">Pinions.</h2> -</div> -<hr class="r5" /> - -<p>Well made as to truth of centring, of division, of form of leaves, and -polish, are, as the trade well knows, of vital importance to the value -of the time-piece.</p> - -<p>The making and finishing is one of the most troublesome, as well -as most expensive of all the processes in watch work. The nature -of the material renders it difficult as it approaches so nearly in -hardness to the tools used in cutting. In the ordinary Yankee clock, -the <em>lantern pinion</em> has entirely superseded the solid leaf, -which substitution was the greatest element of success in their cheap -construction. The lantern pinion is really a nearer approximation to -the required anti-frictional form than a majority of cut pinions in -ordinary clocks. In the process of manufacture of the cut variety, the -first consideration is the quality of the steel to be used. For this -purpose it should be carefully selected by trial, thus ascertaining -its fineness, uniformity, softness when annealed, together with its -capacity for taking a good temper, with the least amount of springing -during the hardening process. Very few pinions are cut from the solid -piece—the drawn pinion wire being quite good enough, when milled and -finished, for the ordinary run of watch work.</p> - -<p>The steel wire having been selected, the first process is to cut it -up in lengths a trifle larger than the required pinion. The separated -pieces are then centred with care, and having been placed in a lathe, -the staff and pivot are turned up to nearly the required gauge, leaving -a portion of the whole piece the full size for the leaves. They are -now taken to the milling tool to have the proper form given to the -leaves. As this form is of the highest importance, it may be as well to -give here the reasons. Supposing a wheel of 60 teeth, depthing into a -pinion of 8 leaves, it can readily be seen that the arc of the motion -of the wheel tooth is of greater radius than that of the leaf of the -pinion, and it follows that if the teeth and the leaves are made in -taper form with straight sections, there must occur a sliding motion -on the surfaces of both—the power thus absorbed being totally wasted; -but if we curve the surfaces we may approach a form so nearly perfect -that the wheel teeth, being motors, really roll on the leaves, avoiding -almost entirely the friction caused by sliding; the necessity for this -curvature becoming greater the more the wheel exceeds the pinion in -diameter. This curve, which has been demonstrated by very profound -mathematical researches, is the “epicycloidal;” theoretically it should -give no more sliding motion than the surfaces of two plain wheels -revolving on each other. To obtain this perfect form, very great pains -have been taken and expenses incurred, especially by the makers of the -best time-keepers.</p> - -<p>In the American factories the cutters are very elaborately made, -the section being an object of great solicitude—it being an exact -counterpart of the space between any two leaves, and also of one-half -the top of the<span class="pagenum" id="Page_21">[Pg 21]</span> leaf from the curvature to the point, so that in -milling, the space made by the cutter is its shape, leaving the leaf -of the proper form. Generally the pinion passes under two cutters; the -first to strike down the rough stock, the other to dress it to size and -shape, with a light cut. The care and skill required to make these is -certainly very great, and it is a proof of the wonderful ingenuity of -man that they are made so perfect as to shape and cutting power.</p> - -<p>A very ingenious device is used for dividing the leaves under the -cutter, which revolves at a moderate speed over a slide, carrying a -pair of centres, between which the turned up piece of pinion wire is -placed. The slide is now pushed up to and under the cutter, and in -its passage as much of a cut is taken as is desirable; in drawing -back the slide the fresh cut space passes under a flat piece of thin -steel, screwed on the frame, and set at a slight angle to the axis of -the centres. On moving the slide towards the cutter for a fresh cut, -the steel plate takes the last cut, and in passing by it the pinion -is turned just as much as the angularity of the plate, which must be -just one leaf. By this very clever device the division is effected -without an index plate. This process, however, is not good enough for -work intended to be very accurate—the pinion wire not being always, or -indeed rarely correctly divided, the original error will be perpetuated -in all the subsequent processes. These are all milled, with oil or soda -water for a lubricator, and it follows that the speed of the cutter is -regulated to get the greatest cut without dulling the tool. When dull, -however, the mill is sharpened on the <em>face</em> of the cutting tooth -by means of small grinders of iron, using Arkansas oil-stone dust for -the first grinding, and giving the necessary delicacy of the edge by -means of crocus, or sharp, followed, when fine work is needed, by rouge.</p> - -<p>It is necessary that this care should be taken, for if the edge is -left coarse it will become speedily dulled, and leave a very unequal -and rough surface on the cut of the pinion, which in the subsequent -grinding gives rise to error in shape and size. The pinions, thus -cut to gauge, are dried in sawdust, hardened, and tempered; the -staff and pivots are now turned up to size, and then pass to the -polishers. In the factory they are finished by means of what are called -<em>Wig-Wags</em>, which it may be interesting to the reader to have a -general description of.</p> - -<p>Two Vs are arranged as centres, the pinion is placed between them, -the circular parts resting in each V, but free to turn on its own -axis. Immediately above the Vs is a frame on which a slide, carrying -the polisher, may traverse—generally about two inches. This slide is -movable vertically so as to accommodate itself to the pinion; attached -to the slide is a connection which leads to a vertical lever, which -is put in motion from a crank on the counter shaft. The grinding is -effected by bringing the grinder, charged with oil-stone dust in oil, -in one of the spaces of the pinion, which, of course, is so arranged -as to bring it parallel and central with the grinder. The power being -applied, the slide takes a very rapid reciprocatory motion, and the -face of the grinder, so charged, rapidly reduces the uneven surface -left by the cutter to what is called the <em>gray</em>.</p> - -<p>The form of this grinder must be as perfect as the cutters, and the -care taken to get the requisite parallelism is in equal proportion, -and in all the best polishers is planed up while in its position. The -grinder is composed of tin and lead, with sometimes a slight admixture -of antimony, rolled to an even thickness, cut off in suitable lengths, -and then mounted in the carrier of the Wig-Wag to be planed up to -shape. There are too many minute adjustments in the machine to render a -full description in this article admissible. It is large compared with -the work it has to perform, but it is very admirably made, as indeed -all the tools are, in the American factories.</p> - -<p>The polishing of the leaves is the next step, and this is effected by -means precisely the same as grinding. In each stage the pinions are -thoroughly cleansed before entering on another. The polisher is made -precisely like the grinder; but instead of oil-stone dust, crocus mixed -with oil is substituted. Owing to the less cutting quality of the -material used, the polisher loses its form sooner than the grinder, -and has to be more frequently reshaped. In very fine work the crocus -is succeeded by fine well-levigated rouge to bring<span class="pagenum" id="Page_22">[Pg 22]</span> up that jet black -polish, which is considered a mark of quality by chronometer and watch -makers.</p> - -<p>With the exception of turning up the staff and pivots, all the work -hitherto described has been expended on the leaves—a very tedious -process, yet done, when the tools and materials are in proper order, -with marvellous rapidity; but tedious as these have been, there are two -others quite as much so before the leaves are finished.</p> - -<p>The ends are to be faced—they must be flat (that is a true plane) and -receive the same finish that the leaves took, and is effected by the -wig-wag; only the pinion revolves between centres, at a high speed, the -grinder being brought up to the turned face. Two motions operate—one -rectilinear, the other circular—the result being a compound motion -which prevents the grinder from touching the same spot twice in -succession. To effect this more surely, the operator gives the grinder -a slight vibratory vertical motion. The polishing of the two faces is -effected in the same manner as the grinding; in all cases the cutting -face of the grinders and polishers being kept in a plane perpendicular -to the axis of the pinion, both vertical and horizontal.</p> - -<p>The staff and pivots being in the same condition they came from the -lathe, the next step is to grind and polish them. Before, however, we -treat on this process, it may not be amiss to give the general watch -repairer a process by which the facing may be done on a small scale.</p> - -<p>As a rule, when the watch repairer has to replace a pinion he selects -one from the material dealer, finished in the leaves, but not on the -ends or faces. The following operations are simple, and any one may -finish these faces with little trouble. Having turned up your pivots -and squared down the face of the leaves with the turning tool, grind -it in the lathe by means of a ring of metal, the inside diameter being -somewhat larger than the diameter of the staff. This ring is held -between two centres, thus allowing it a vibratory motion, so that -when it comes up to the face it accommodates itself to its plane, and -thus has no tendency to force it out of a true flat; the ring, being -larger than the staff or pivot, admits a small lateral motion, enough -to effect a continuous change of surface. The same little tool may be -used for polishing by substituting another polisher and using crocus -and rouge. For the repairer, perhaps on general work the rouge would -be superfluous. Vienna lime, used with a little slip of boxwood, -brings up a very fine and brilliant polish, and in replacing new work -in an injured time-piece, the steel may always be polished with great -rapidity by using the lime on the gray surface left from the oil-stone -dust; being quickly done and affording a very handsome finish.</p> - -<p>To resume the consideration of the pinion, the last stage is the -polishing of the circular portions. Here again the wig-wag is the -most useful tool, but it operates somewhat differently, for the -grinder or polisher is pressed down by the finger of the operator, -the pinion being held between the centres of a small lathe attached -to the wig-wag; the staff is first ground and polished as the leaves -have been before, and this is the last operation performed with the -pinion between centres. From this stage it is chucked in a lathe very -peculiarly fitted, the mandrel being hollow; and in it is fitted what -is called a pump-centre, which is movable in direction of the axis of -the mandrel, and capable of being securely fastened at any desired -point. On the nose of the mandrel is secured a hollow steel chuck, -the two sides of which have been filed out, thus leaving an open -space between the end of the pump-centre and the end of the chuck. On -this end a small steel plate, extremely thin, is fastened by means -of shellac, and a hole drilled in the plate capable of taking in the -chamfer on the shoulder of the pivot. The pump-centre being drawn -back, the pinion is introduced into the chuck, the pivot placed in the -hole in the steel plate, and the pump centre is drawn forward until -it forces the chamfer to fill the hole; the pivot projecting from -the chuck is now ready for all the grinding and polishing processes. -Here the wig-wag steps in again, and from the delicacy of the pivots -is modified to suit the case; this is done by having a polisher hung -in the wig-wag on centres, so it may revolve; when in operation one -side of the polisher rests on the pivot, the other on a ruby placed -in a screw, and which screw enables the operative to insure<span class="pagenum" id="Page_23">[Pg 23]</span> the -parallelism of the pivot. The ends of the pivots are next rounded off -and finished in another set of tools. The pinion is now ready for use, -assuming it to be of the proper gauge. In the American watches the -scape and fourth wheels are generally staked on the staff pinch tight; -the third and centre are staked on the pinion leaves, a rebate having -been turned down on the ends, the wheel set on the shoulder, and the -projecting ends of the leaves riveted down. This has not been designed -as an exhaustive article on pinions; it is merely intended to open the -subject as pursued in the factories. There is much more to be said; and -the various processes on the small scale, as performed by the Swiss -and English, together with their tools, will bear more than a general -description, as they are applicable at any watch bench.</p> - -<p>The subject will be continued, in the effort to give a full and useful -article.</p> - - -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<h2 class="nobreak" id="New_Three-Pin_Escapement">New Three-Pin Escapement.</h2> -</div> -<hr class="r5" /> - -<p>A contributor to the <i>London Horological Journal</i> gives the -following description of his invention:</p> - -<div class="blockquot"> - -<p>“The merit of this escapement is in a newly invented escape-wheel -which is self-locking and requires no banking pins; the pallets are -curved inside the impulse and outside the locking, to work with the -curved points of the teeth of the wheel; being made of gold the wheel -will go without oil. From its form it has the power of double impulse -and double locking with the lever. The first takes place at the -discharge of the escapement, the second does not act unless the watch -receives a sudden motion, and then the pin or pallet in the roller -strikes lightly on the lever, when the propellant power drives it back -again. The balance passes through two turns before the second locking -takes place, and is formed so as to be able to take up the lever, -and the watch soon rights itself, and its time will not be affected. -Another advantage is, that the lever is made of a flat piece of steel, -as I have introduced a gold stud to receive the ruby impulse stone, -which is made to adjust easily so as to bring the escapement to the -closest geometrical accuracy. By its formation this ruby guides the -impulse to the external edge of the roller notch. These advantages, -and its simplicity, render it suitable to the best chronometer -watches.”</p> -</div> - -<p>A <span class="allsmcap">FEW</span> years ago, in 1859 or ’60, Mr. Peabody, a very talented -gentleman of this city, patented a three-pin escapement that performed -extremely well. A full description of his patent and plan is not at -hand, but we will endeavor to give it to our readers in our next issue.</p> - - -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<h2 class="nobreak" id="English_Opinion_of_American_Watch_Manufacture">English Opinion of American Watch Manufacture.</h2> -</div> -<hr class="r5" /> - -<p>In the London circle of Horologists, more attention is paid to the -scientific departments than the mercantile; but for all that, a Mr. -Henry Ganney has held forth before the “British Horological Institute,” -on “American Watch Manufacture.” Though an Englishman, with English -prejudices, he certainly gives a very fair and impartial statement -of the subject; yet he views it almost entirely in the money-making -aspect. He gives all the credit deserved to American enterprise and -ingenuity, and yet there is a certain sense of a drawback. He had -before him samples of machine work; among others, to quote, “several -movements made by the British Watch Company, which flourished and -failed about twenty-five years ago; these were machine-made, and the -perfection and completeness of the machinery they used for producing -these frames has not been equalled, I believe, in America; several -machines being used there to accomplish what was begun and completed by -one here.”</p> - -<p>Mr. Ganney is right in his statement, but the example given by the -British Watch Company was the rock seen by the American navigators. One -tool, for facing off, truing up, drilling, depthing, and doing all the -work on the pillar plate, having cost, before completion, some three -thousand pounds sterling, and from its very complexity being utterly -inefficient—worse than useless. In the very inception of the American -watch manufacture a similar mistake was almost made. Experience and -sound reasoning proved, however, that a multiplicity of operations in -any one machine rendered it entirely too complex, the adjustments too -numerous, and the work totally worthless. We shall in another number -refer again to Mr. Ganney’s lecture, and perhaps give some beamings of -light on the early history of the American watch manufacture,<span class="pagenum" id="Page_24">[Pg 24]</span> derived -from personal observation at the time.</p> - - -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<h2 class="nobreak" id="Correspondence">Correspondence.</h2> -</div><hr class="r5" /> - - -<div class="blockquot"> - -<p> - -<span class="smcap">Editors Horological Journal</span>:<br /> -</p> - -<p>I received a Prospectus a few days ago advising me of your -contemplated existence. I could hardly believe the fact; “the news -was too good to be true.” However, I shall take it for granted, for I -cannot see why somebody has not before had the enterprise to launch -out in the periodical line on subjects connected with Horology, the -field being so extensive and the want so severely felt. Enclosed -I send you the subscription price; in this much I have accepted -your invitation, but I also enclose some few lines on a subject not -particularly practical or theoretical, but very near the truth, and -may perhaps give you a view of our wants.</p> - -<p>To tell the “plain unvarnished truth,” I am a watch repairer, located -in a small country village, with a decent stock of tools and a -moderate trade. In all this I am no exception; so I write this in -the name of all who are similarly situated. Isolated as we are, we -(the country village watch repairers) have few means to improve our -knowledge of the trade, but work on the same old principles learned -when we were boys and apprentices, and of better and more expeditious -ways of doing our work we are entirely oblivious. True, our friends -of the Hebraic persuasion, who, angel like, bring us face to face -with the outer horological world by selling us material and tools, -occasionally present to our benumbed vision something new, such as a -Swiss lathe, or lathes used in the factories; but of what use are they -to us? We purchase one; well, on the bench it may be an ornament, but -for use, drilling large holes is the height of our ambition. We have -not the time to learn by self-experience all the boasted usefulness -and capacities of the tool; so we go back to our old verge or Jacot -lathe when we have to put in a pivot or a new staff. We may know all -about the escapement and be able to detect the cause of any trouble -with it, but we have no knowledge of the latest modes of repairing the -injury when it is discovered, and this knowledge is what I hope to -find in your journal. I live in a section where the general class of -work is of a very low grade, even the old verge being very common. Our -stock of material has to be heavy in proportion to our trade, and then -once in a while we are compelled to send our work to the city, some -sixty miles distant, in consequence of not being able to do it, either -from a lack of the material or want of a proper tool. To all intents -and purposes we remain as stationary as the oyster. Not only do we -have these vexations, but the ignorance of the public at large as to -the treatment of their time-keepers is a fruitful source of annoyance; -we are often charged with fraudulent practices, and a certain degree -of caution is observed by more than the most ignorant. Thus, a few -days ago, a stalwart son of the Green Isle made his appearance in -front of the counter, and, projecting in front of our optics a huge -English double-cased verge watch, spoke in almost dramatic tones:</p> - -<p>“Plase, sir, av’ ye could make me ticker here go, sir?”</p> - -<p>Answering in the affirmative we reached for the silent “ticker.” He -drew back with alarm.</p> - -<p>“Bedad, an’ ye’ll not stale a morsle frae this?”</p> - -<p>“Well, but let me see the watch.”</p> - -<p>“An’ will ye let me eyes be on yes all the time?”</p> - -<p>“Yes.”</p> - -<p>“An’ yes’ll not stale a jewil?”</p> - -<p>“No.”</p> - -<p>“Thin, there it is.”</p> - -<p>On looking at the movement the verge was found broken, the injury -explained, and the price given. He decided on the repairs being done, -but said, “ Give me the watch now and when ye gets the thing fixed its -meself will come and git it and pay yes.”</p> - -<p>“But we cannot repair the watch without having it.”</p> - -<p>“Faith, thin, ye’ll not have it; ye’ll be taking something frae it.”</p> - -<p>Now, this is an extreme case of ignorance, pardonable, perhaps, -in this instance, but the public embraces multitudes just as -ignorant where an allowance cannot be made. I do not expect the -<span class="smcap">Journal</span> to reach such cases, or to influence the general -mass, but my hope is that it will, by raising the general self-respect -and tone of the repairers, indirectly elevate the respect felt for -them by the public at large.</p> - -<p>But I am writing too long and rambling a letter. I wish to express my -hearty wishes for your prosperity. And, in conclusion, will you allow -me to express a hope that you will give us the knowledge we need—that -is, post us up on the minutiæ of repairing in the latest styles, the -newest processes devised, and, above all, give us an article on the -lathe and its uses?</p> - -<p class="right"> -<span class="mr">Yours truly,</span><br /> -W. L. C.<br /> -</p> -</div> - - -<p>We have the pleasure to give our correspondent the assurance that an -expert will contribute to our next number an article interesting as -well as valuable in instruction as to the use of the lathe.</p> -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<p><span class="pagenum" id="Page_25">[Pg 25]</span></p> - -<h2 class="nobreak" id="Eclipse_of_the_Sun">Eclipse of the Sun.</h2> -</div> -<hr class="r5" /> - -<p>The approaching total eclipse of the sun, on the 7th of August next, -is exciting much interest. The obscuration first occurs in latitude -39° 53´ 3´´ north, longitude 138° 37´ 4´´ west—Washington being the -meridian. The first totality is on the Pacific coast of Siberia, at -sunrise, in lat. 52° 41´ 9´´ north, and long. 165° 26´ 4´´ west. The -eclipse is total at noon in Alaska, lat. 61° 46´ 9´´ north, and long. -68° 4´ 6´´ west. The line of the total eclipse now runs south-easterly, -grazing the coast near Sitka, thence north into British America; then -entering the United States, near the head of Milk River, long. 30° W.; -thence through the south-west corner of Minnesota, diagonally through -Iowa, crosses the Mississippi at Burlington; thence through Illinois, -a little north of Springfield, crosses the Ohio river at or near -Louisville, Ky., passes through the south-west corner of West Virginia, -through North Carolina, just south of Raleigh, ending on the Atlantic -coast at sunset, just north of Beaufort, N. C., in lat. 31° 15´ 2´´ -north, and long. 9° 36´ 6´´ east. The line thus described will be that -of totality, only partial in any other part of the United States.</p> - -<p>The United States Government is, or has been, establishing a meridian -line at Springfield, partly to make observations on this coming -eclipse, and with the further view of determining a standard of -surveyed lines—all of the Government surveys in Illinois having been -geodetic. Professor Austin, of the Smithsonian Institute, is in charge -of the work, aided by an able corps of assistants.</p> - - -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<h2 class="nobreak" id="Diamond-Cutting">Diamond-Cutting.</h2> -</div> -<hr class="r5" /> - -<p>At the Great Exhibition in Paris, in a part of the park contiguous to -the Netherland section, M. Coster, of Amsterdam, has erected a building -wherein all the processes of diamond-cutting are carried on.</p> - -<p>The first rough shaping of the more important facets of the brilliants -is here seen performed by the workman, who operates on two diamonds at -once, by bruising each against the other, angle against angle. The dust -that falls from the stones is preserved for the subsequent processes -of grinding and polishing those facets that distinguish the many-sided -brilliant from the dull, original crystal of the diamond. It is used, -mingled with oil, on a flat iron disk, set revolving with vast rapidity -by steam-power, the stone itself being held upon this disk or wheel by -a tool to which it is attached by a mass of fusible metallic alloy, -into which the stone is skilfully inserted. Skill of eye and hand, only -attainable by great practice, is needed for this work; but a skill not -less exact is needed for another process, which may here be seen in -daily operation—the process of cleavage. The diamond, when a blow is -struck on an edged tool placed parallel to one of the octahedral faces -of the crystal, readily splits in that direction. But to recognize the -precise direction on the complex and generally rounded form of the -diamond crystal; to cut a little notch by means of a knife edge of -diamonds formed of one of the slices cleaved from a crystal, and to -cut that notch exactly the right spot; then to plant the steel knife -that is to split the diamond precisely in the right position; finally, -with a smart blow, to effect the cleavage so as to separate neither -too large nor small a portion of the stone—these various steps in the -process need great skill and judgment, and present to the observer -the interesting spectacle which a handicraft dependent on experience -of hand and eye always affords. But Mr. Coster’s exhibition has other -objects of interest. For the first time, we may see here, side by side, -the diamond with the minerals that accompany it in the river beds of -Brazil; and there are even examples in which crystals of diamonds -are included within a mass of quartz crystals, which have all the -appearance of having been formed simultaneously with deposits of the -diamond.</p> - -<p>The different districts of Rio and of Bahia are thus represented—the -former producing a confusedly crystallized sort of diamond termed -“bort,” and the latter an opaque black variety; both these kinds being -found associated with the crystallized diamonds used for jewelry. -Though useful in state of powder, the black carbon and “bort” are -incapable of being cut as a jewel.—<i>“Maskelyne’s Report,” Great -Exhibition.</i></p> - - -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<h2 class="nobreak" id="The_Alloys_of_Aluminum_with_Copper">The Alloys of Aluminum with Copper.</h2> -</div> -<hr class="r5" /> - -<p>When Sir Humphrey Davy announced the fact that soda, lime, potash, -magnesia, and the other alkalies were but oxides of a metallic base, it -would have been deemed chimerical to have supposed that the discoveries -he made by the expensive aid of the battery would at later date become -of really commercial value. He<span class="pagenum" id="Page_26">[Pg 26]</span> did obtain both sodium and potassium -in the metallic state. The substances in this form were new to the -chemical world, still more strange to the popular. So new was it to the -chemists, that, on a globule of the reduced sodium being presented to -a very distinguished chemist, he, with some enthusiasm, examined it; -and, admitting the fact of its being a metal, exclaimed, “how heavy -it is!”—when the real fact was that its specific gravity was less -than water; the expression was the result of the general preconceived -opinion that a high specific gravity was a test of a metallic body. It -was reserved for a French chemist, Henry <abbr title="saint">St.</abbr> Claire Deville, to utilize -the metal sodium, and that, too, in such a manner that the demand -aroused attention to its production;—demand will inevitably bring a -supply.</p> - -<p>The original reduction was made by Davy, by means of the voltaic -battery. After it had been proved that these bases were really metals -capable of reduction, chemistry brought all its resources to bear on -the problem, and they were produced by other methods than the battery. -All the processes adopted, however, were too expensive and laborious, -involving an extraordinary amount of complicated manipulations with but -inadequate results. The metal sodium, which is the immediate subject of -our inquiry, long remained an object simply of curiosity or experiment -in the laboratory.</p> - -<p>The methods of reducing the metal have of late years been so simplified -that, to quote <abbr title="professor">Prof.</abbr> Chas. A. Joy in the <i>Journal of Applied -Chemistry</i>: “A few years ago a pound of this metal could not have -been purchased for two hundred dollars, and even at that price there -were few manufacturers hardy enough to take the order. At the present -time it can be readily manufactured for seventy-five cents, if not for -fifty cents a pound; and the probabilities are that we shall soon be -able to obtain it for one-quarter of a dollar.”</p> - -<p>Deville found that by the reaction of the metallic sodium on common -chloride of aluminum a reduction was effected; the chlorine taking -up the sodium, forming chloride of sodium (common salt), while the -aluminum was left free in the metallic state. It is hardly necessary -to go into the particulars of the process; but a metal well known to -exist, had, for the first time, been brought to the world in such a -condition of structure that its qualities could be tested, not only -chemically, but mechanically. This was the direct result of Deville’s -metallurgic process of obtaining the reducing agent—sodium.</p> - -<p>Aluminum in itself would be of but little use, so that a brief -description will be all that is necessary. It is about the color of -silver, but susceptible of a higher polish, especially on a fresh-cut -surface; it is much less susceptible of oxidization than silver; its -specific gravity is but little more than pine wood, and its tenacity, -ductility, and laminating qualities are nearly equal to silver. Its use -in the mechanical arts is limited, notwithstanding all these qualities, -from the fact of its low point of fusibility, and at the heat of -the fusible point being easily oxidized, so much so as to prevent -soldering, except by an autogenous process. But aluminum does possess -a property peculiar to itself—that of forming a purely and strictly -<em>chemical alloy</em> with copper. It unites with it in any proportion; -the compound formed by the addition of 10 per cent. of aluminum to 90 -per cent. of copper has been found to possess all the properties of -an entirely new metal, with qualities that render it a very valuable -material in all fine work, such as astronomical instruments; and very -fine machinery, such as watch-lathes, etc.</p> - -<p>The French reports on the alloy are somewhat voluminous, but we give -the following.</p> - -<p>The color of this bronze so closely resembles that of 18 carat gold, -such as is used for the best jewelry and watch-cases, that it is -capable of receiving the highest polish, and is far superior in beauty -to any gilding.</p> - -<p>Samples taken from different parts of the largest castings, when -analyzed, show the most complete uniformity of composition, provided -only that the two metals have originally been properly mixed while in -a state of fusion. These experiments have been made upon cylinders -weighing many hundreds of pounds, and are entirely conclusive.</p> - -<p>This valuable quality is not found in any of the more ordinary alloys -of copper. The alloy of copper with tin, for example, known as -<em>gun metal</em>, is notoriously subject to a phenomenon<span class="pagenum" id="Page_27">[Pg 27]</span> known as -<em>liquation</em>; in consequence of which a great difference is found -in the composition of the same casting, both in the top as compared -with the bottom, and in the centre as compared with the circumference.</p> - -<p>This phenomenon often causes great inconvenience, as the different -parts of large objects will in consequence vary greatly in hardness -as well as in strength. In casting artillery the difficulty becomes a -serious one, and no means have yet been discovered by which it can be -entirely removed.</p> - -<p>This homogeneousness of aluminum bronze is a natural consequence of the -great affinity existing between the two metals of which it is composed; -and that there is such an affinity is clearly proved by the phenomenon -attending the manufacture of the alloy. The copper is first melted in -a crucible and the aluminum is then added to it <em>in ingots</em>. At -first there is, of course, a reduction of temperature, because the -aluminum in melting absorbs the heat from the melted copper; and this -absorption is so great, in consequence of the great capacity for heat -of aluminum, that a part of the copper may even become solid. But let -the mixture be stirred a moment with an iron bar, and the two metals -immediately unite; and in an instant, although the crucible may have -been removed from the furnace, the temperature of the metals rises to -incandescence, while the mass becomes as fluid as water.</p> - -<p>This enormous disengagement of heat, not seen in the preparation of -any other ordinary alloy, indicates, not a simple mixture, but a real -chemical combination of the two metals. The 10 per cent. bronze may -therefore be properly compared to a salt, the more so as it is found by -calculation to contain, within a very minute fraction, four equivalents -of copper to one equivalent of aluminum.</p> - -<p>The 10 per cent. bronze may be forged cold, and becomes extremely dense -under the action of the hammer. The blades of dessert-knives are thus -treated in order to give them the requisite hardness and elasticity. -But it has another valuable quality which is found in no other kind -of brass or bronze: it may be forged hot, as well as, if not better -than the very best iron. It thus becomes harder and more rigid, and -its fracture shows a grain similar to that of cast steel. On account -of the hardness of the aluminum bronze, rolling it into sheets would -be a tedious and expensive process, were it not for this property of -being malleable at a red heat. But it may in this manner be rolled into -sheets of any thickness or drawn into wire of any size. It may also be -drawn into tubes of any dimension.</p> - -<p>From several experiments made at different times at Paris, it appears -that the breaking weight of the cast bronze varies from 65 to 70 -kilogrammes the square millimetre. The same bronze drawn into wire -supported a weight of 90 kilogrammes the square millimetre. The iron -used for suspension bridges, tested in the same manner, did not show an -average of more than 30 kilogrammes. Some experiments were also made by -Mr. Anderson, at the Royal Arsenal at Woolwich, in England, who tested -at the same time the aluminum bronze, the brass used for artillery and -commonly called <em>gun metal</em>, and the cast steel made by Krupp in -Prussia. Taking for the maximum strength of the bronze the lowest of -the numbers found as above, we are thus enabled to form the following -table of comparative tenacities:</p> - -<table class="autotable"> -<tr><td class="tdl">Aluminum bronze 10 per cent.</td><td class="tdr">65</td></tr> -<tr><td class="tdl">Crupp’s Cast Steel</td><td class="tdr">53</td></tr> -<tr><td class="tdl">Refined Iron</td><td class="tdr">30</td></tr> -<tr><td class="tdl">Brass for cannon</td><td class="tdr">28</td></tr> -</table> - -<p>The comparative toughness of these same four metals was also tested in -the following manner: A bar of each was prepared of the same size, and -each bar was then notched with a chisel to precisely the same depth. -The bars were broken separately, upon an anvil, by blows from a hammer. -The last three metals in the table broke each at the first blow, with -a clean and square fracture. The aluminum bronze only began to crack -at the eighth blow, and required a number of additional blows before -the two pieces were entirely separated. And the irregular, torn surface -of the fracture showed the peculiarly tough and fibrous nature of the -metal.</p> - -<p>The elasticity of the aluminum bronze was tested by M. Tresca, -Professor at the <i lang="la" xml:lang="la">Conservatoire des Arts et Métiers</i>. The -experiment was made upon a bar of simple cast metal,<span class="pagenum" id="Page_28">[Pg 28]</span> and the following -is his report: “The coefficient of elasticity of the aluminum bronze, -the cast metal, is half that of the best wrought-iron. This coefficient -is double that of brass and four times that of gun metal, under the -same conditions.”</p> - -<p>The specific gravity is 7.7, about the same as iron. Another very -valuable quality is presented in the fact that it is acted on by -atmospheric influences less than are silver, brass, or bronze. This -places it in the same rank with gold, platinum and aluminum.</p> - -<p>Very stiff and very elastic, tougher than iron, very little acted upon -chemically, and in certain cases not at all, capable of being cast like -ordinary bronze or brass, forged like iron and steel, of being worked -in every way like the most malleable metals or alloys, having, added -to these properties, a color analogous to that of the most precious -metal, this bronze proves itself adapted to uses almost innumerable. -At first sight, it seems difficult to admit that the relatively small -proportions of aluminum which enters into the composition of this -bronze can be sufficient to modify so extraordinarily the properties -of the copper which constitutes so large a portion of its weight. But -we must remember that the specific gravity of aluminum is very low, -and that a given weight of this metal possesses a bulk four times as -large as the same weight in silver. It follows from this that the ten -per cent. of aluminum contained in the bronze equals in bulk forty per -cent. in silver.</p> - -<p>The specimens of the ware we have seen, such as spoons, forks, cups, -watch-cases, etc., are certainly very beautiful, having the color and -high polish of gold, while dilute acids do not affect the surface.</p> - - -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter"> -<h2 class="nobreak" id="On_the_Reduction_of_Silver_in_the_Wet_Way">On the Reduction of Silver in the Wet Way.</h2> -</div> -<hr class="r5" /> - -<p>Every chemist is familiar with the reduction of chloride of silver -in the form of powder by means of metallic zinc in the presence of a -little free acid. It is not easy to bring two such substances as the -silver salt and the metal into close contact, and after the work is -accomplished the removal of the excess of zinc has its difficulties. -<abbr title="doctor">Dr.</abbr> Grager suggests a modification of the old method that ought to -be more generally made known. The chloride of silver is dissolved -in ammonia and poured into a well-stopped bottle, and into this is -introduced an excess of metallic zinc, in not too small fragments, so -that any reduced metal adhering to it may be readily washed off.</p> - -<p>The decomposition begins immediately, and is rapidly accomplished, -especially if the contents of the flask be well shaken up. Three hours -will suffice to reduce one-quarter of a pound of chloride of silver. -It is easy to ascertain when the reduction is ended, by testing a -portion of the ammoniacal solution with hydrochloric acid. As soon as -no cloudiness or curdy precipitate is formed, the work may be regarded -as completed.</p> - -<p>A slight excess of ammonia is said to be favorable. The reduced silver -must be washed with water until all odor of ammonia has disappeared. -The pieces of zinc are removed by pouring the contents of the flask -through a funnel, the opening of which is too narrow for the passage -of the zinc fragments, while the reduced silver can be easily washed -through. The finely divided silver can be digested in hydrochloric -acid to restore it to a pure white color, and it is then ready for -solution or fusion, and will be found to be perfectly pure. In dealing -with large quantities it would be economical to recover a portion of -the ammonia by distillation. In the same way an ammoniacal solution -of nitrate of silver can also be reduced by zinc, and the silver -obtained pure, even when the original solution of the nitrate contains -copper—provided a small quantity of silver be kept in the bath.</p> - -<p>It is better where copper is present not to take all of the zinc that -may be requisite for the reduction of the silver. It will prove a -great convenience to be spared the necessity of converting the silver -into the chloride, as it is no easy task to wash out this salt on -filters—and it will be found to be applicable to alloys which do not -contain more than 25 per cent. of silver.—<i>From <abbr title="professor">Prof.</abbr> Joy in the -Journal of Applied Chemistry.</i></p> - - -<hr class="chap x-ebookmaker-drop" /> - -<div class="chapter transnote"> -<h2 class="nobreak" id="Transcribers_Notes">Transcriber’s Notes</h2> -<hr class="r5" /> - -<p>Obvious errors in punctuation have been fixed.</p> - -<p><a href="#Page_7">Page 7</a>: “Mechanique Celeste” changed to “Méchanique Céleste”</p> - -<p><a href="#Page_12">Page 12</a>: “ou rexperience” changed to “our experience”</p> - -<p><a href="#Page_18">Page 18</a>: “head-quarters far astronomical observations” changed to -“head-quarters for astronomical observations”</p> - -<p><a href="#Page_22">Page 22</a>: “it accomodates” changed to “it accommodates”</p> - -<p>The <a href="#CONTENTS">Table of Contents</a> lists “Equation of the Time Table” as the article -on page 28. The actual article is named “On the Reduction of Silver in -the Wet Way.” This has intentionally been left as per the original. Similarly, there is no -actual section titled “Notices of New Tools” despite its inclusion in the Table of Contents, -and this has been left as per the original.</p> -</div> -<div style='display:block; margin-top:4em'>*** END OF THE PROJECT GUTENBERG EBOOK AMERICAN HOROLOGICAL JOURNAL, VOL. I, NO. 1, JULY 1869 ***</div> -<div style='text-align:left'> - -<div style='display:block; margin:1em 0'> -Updated editions will replace the previous one—the old editions will -be renamed. -</div> - -<div style='display:block; margin:1em 0'> -Creating the works from print editions not protected by U.S. copyright -law means that no one owns a United States copyright in these works, -so the Foundation (and you!) can copy and distribute it in the United -States without permission and without paying copyright -royalties. 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