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THE ELECTRIC TIME SERVICE
Harper's Monthly, April 1878

(Written prior to the adoption of Standard Time in 1883)

AS we ride over one of the main routes of travel between the East and West, the immense movement of freight and passenger traffic can hardly fail to strike the most careless observer. During the day the rush of passing cars is incessant; at nearly every stopping-place we observe others drawn up on sidings to let us go by; and when night comes on, the noise of panting-engines, which pass the window with a crescent shriek, makes it seem as if our broken sleep had been passed in the vicinity of interminable rumbling trains. The amount and intricacy of this movement grow on us the more we study it, so that we shall not be far wrong if we suppose that for hundreds of miles the road would present to an eye which could survey the whole at once two endless processions of trains separated from each other by but few minutes' distance processions, however, moving in opposite directions, and in each of which portions were constantly dropping out of the moving line or being added to it, with all the risk of accident from such incessant interruption.

We readily understand that there can be no possible safeguard in this intricate movement without a most exact observance of the prearranged time at which each train should be found at each of the hundreds of miles in its journey. Time exactly obtained and kept is the regulator of this complex system of moving parts, which, in theory at least, should resemble one great piece of clock-work. To make things "move like clock-work" is not merely a figure of speech, then, here, where our lives depend on the accuracy of a conductor's watch, but it should be, and it is, the aim of every officer of the road to make them do so in reality.

A great safeguard against accidents arising from mistakes as to time, which in the past have been so fruitful in disaster, has been introduced of late years by some of our leading roads, which have called in the aid of astronomical and electrical science in the manner to be described. That adopted by the extensive system of roads uniting New York, Philadelphia, Pittsburgh, and Chicago, in connection with the Alleghany Observatory, near Pittsburgh, is selected for illustration here, not as the only example, but as the one with whose details the responsibility of initiation and superintendence has made the writer most familiar.

We have all at some time noticed the convenience of an accurately striking public clock, by which all the watches of the community within sound of the bell may be set

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to the same minute; and remembering that our object here is to obtain an exact agreement of times at very distant points, we readily see that if it were possible to have a clock strike so as to be heard along the whole railroad at once, our end would be directly attained, and that most of the accidents or delays arising from discrepancies of this sort would disappear, To make not only the stroke of the hour, but the very ticking of the seconds, from one clock, audible, the country over, might have seemed a few years ago to have demanded a miracle for its accomplishment. Yet very much such a miracle science works now for us daily in the way which the employment of the electric telegraph has already made familiar.

In one of the vague speculations which long preceded the era of modern discovery it was suggested that two friends might converse with each other at a distance if each had a magnet so powerful and so delicately suspended that either would respond by its "magnetic virtue" to a particular motion of the other. But though no ordinary magnet can directly influence another through any but the shortest distance, yet by the intervention of a wire carrying the "magnetic virtue" (or by whatever more modern term we describe a still mysterious force) we now make a magnet move by all impulse conveyed from one end of the country to the other. Without attempting to describe details, we need only to see how this is applied to our present use. Imagine a piece of iron (called the "armature") suspended in every telegraph station between a plate of sonorous metal and a coil of wire, the coil being a continuation of the telegraph wire outside, which conducts the electric current into the building through the coil, round an iron core, out, and on again to the next station.

While the current is passing through the coil it exercises that very "magnetic virtue" the early speculator dreamed of, the "armature" being attracted and held as firmly to it as by a common magnet. If the wire on the telegraph poles were cut, and the severed ends separated by so much as the hundredth of all inch, the current would cease all along the line at once; at once every "armature" would be set free, and, falling back against the resonant metal behind it, produce a sound distinctly and simultaneously heard at every station. When the wires are joined, the current leaps in a fraction of a second through thousands of miles, the coils regain their attractive power as suddenly as they lost it, the armatures move again, to fall back and sound once more when the next interruption comes, and so oil, without end, so long as the "circuit" is unbroken, and the distant battery, which sends the impulse, is fed with its zinc and acid fuel.

At a certain hour in every day, in any one of the principal offices of the railroad—at Jersey City or at Philadelphia, for instance—there is a moment's pause in the rattle of the telegraphic instruments, and then in one of them we see and hear the armature moving back and forth, not with the irregular motion impressed upon it by the operator's finger, but with a uniform beat every second. It sounds like a clock ticking somewhere in the room: it is a clock ticking, but the clock is many hundreds of miles away, and it is marking off minutes and seconds in this manner, at one and the same moment, in hundreds of points, in distant cities, or scattered along some thousands of miles of main or branch roads.

If we wish to see how this is done, let us take up the wires which lead the current through the instrument, and follow their course beside the railway to Pittsburgh, where they leave the track, and, ascending the table-land on the north of the Ohio, finally bring us into the Alleghany Observatory. They enter the eastern wing of the building, and passing beneath the dome, which contains the large equatorial telescope (not used in these observations), come up in an apartment on the western extremity, called the "transit room." An aperture traverses this room from north to south, opening a narrow view of the sky when the shutters are thrown back. The dome is made to revolve, so that its shutters can be opened to any quarter, and the telescope it covers can be turned in any direction, but the range of the instrument in this room with this fixed opening must evidently be different, as we see from its external disposition. Within this room, then, the wires terminate inside the works of a very accurate clock, where one, ending in a little plate of gold, rests lightly upon the other, so that the metallic connection being thus still complete, the electric impulse flows through them unimpeded. But close to the golden end of the wire is a jewel, so placed as to be very lightly brushed by each tooth of the wheel that turns the minute-hand. As each tooth passes, it raises the jewel by a touch which, though light as the brush of a fly's wing, causes it to move the gold terminal. This is lifted through a distance so small as to be invisible without a magnifying-glass, yet this hair-breadth gap the electric current which moves in a moment from Chicago to New York can not leap over. It is stopped in its course as completely as though a mile intervened, and compelled to wait, during something like the fiftieth part of a second, till the passing tooth has let the jewel fall, and bridged the little space over.

During this time, which to ordinary reckoning is infinitesimally small, the current has ceased along a thousand miles, the magnets in the "sounders" of the telegraph lines

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have lost their virtue, and let go the armature, whose click is heard in each remote station, recurrent with each beat of the pendulum and each advance of a tooth, for the whole operation is repeated with every second, save at a brief pause caused by the absence of certain teeth, whose position corresponds to the closing seconds of the minute, the short silence marking the point at which each new minute begins.

Many of the instruments of the observatory have been obtained of European artists, but the delicate mechanism just described is the product of American skill, the standard mean time clock being the work of the Howard Company, of Boston, and its electric attachments of Mr. J. Hamblet, their electrician.

If we now turn again to the wires we shall find them passing from the clock into an apartment in the eastern wing, where a contrivance to be found in every main telegraph office, and technically called a "switchboard," is used for directing the currents into one course or another. It is fastened to the wall of the room, as shown in the illustration, and it consists of a great number of strips of metal separated from one an other and from a second series, hidden from view, and which they overlie at right angles. The pegs which are seen stuck into the numerous holes are disposed so as to form a connection between any two of the strips, for by putting in one of these brass pins a metallic roadway is furnished for the current, which is thus diverted on to any wire, and sent at pleasure in any direction, just as on a railroad the 'switch," by moving the rails a few inches one way or another, directs the course of trains from a centre of divergence to different and distant destinations. Beneath the switch-board are two little instruments called "indicators," in each of which the upright needle moves back and forth with each passing second, so as to give ocular evidence that the time is passing. A cessation of the current, though caused by an accidental severance of the circuit as far away as New York or Chicago, would at once stop their motion, and notify the attendant that the clock beats had been interrupted there.

Now, taking up the course of the wires again, we find one set connecting the observatory with the turret clock of the Municipal Hall in Pittsburgh, whose mechanism, similar in some respects to that in the standard clock, and by the same makers, causes every third hour a single stroke on a heavy bell to be audible through the city, where the comparison of watches at the sound is so general as to offer satisfactory evidence of the public appreciation of the convenience. Another wire carries the beats of the observatory clock into the stores of the principal watch-makers and jewellers, who thus enable their customers to set their watches by "regulators," themselves regulated with astronomical precision. Still other wires perform the more important service of uniting the standard clock with the private telegraph lines of the railways, by which several thousand miles of main and branch roads, from Erie on the north to Baltimore on the south, and from New York to Chicago, are supplied with exact time in the manner already described. At Philadelphia these wires are connected with the offices of the Gold and Stock Telegraph Company of that city. Mr. Bentley, its president, has recently added to the other functions of these city telegraph lines that of distributing accurate time to the company's customers by means of very beautiful and exact apparatus which the makers of that at Alleghany have furnished for the purpose—an apparatus whose completeness and extensive character it has

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been found with regret impracticable to present an adequate illustration of within the limits of the present article. It may be mentioned, however, that by an arrangement with the officers of the Pennsylvania Central Railroad the exact time of Philadelphia is sent over the railway telegraph from nightly observations at Alleghany, distributed by the Philadelphia local wires, and that an exact coincidence of the clocks of the principal roads leading from the city with that of most watches used in it is thus secured, to the convenience of the wearers of the latter.

Other uses of the clock signals from Alleghany, for the convenience of distant points or for the determination of longitudes, have been made through the courtesy of the officers of the Western Union Telegraph Company; but enough has been said to indicate the extension which the system (commenced at Alleghany in 1869) has already reached, and to justify the hope that it would prove of public utility, which led to its trial. The considerable expenses attendant upon its inauguration have been met from the private means of a citizen of Pittsburgh, whose generous aim it was to make an institution, of which he had been one of the founders, and always the foremost promoter, thus useful not only through scientific research, but in immediate utilities, and for the public convenience and safety.

We have traced the supply of the time from a certain clock, which directly or indirectly regulates thousands of others, but the inquiry remains as to how this clock is regulated, since, left to itself, the most accurate time-piece will go wrong. Strictly speaking, indeed, no such thing as a perfect time-keeper exists, if we use the word "Perfect" in its rigorous sense. But, in fact, we usually employ it in its relative meaning; and while the clock in the kitchen is said to keep "perfect" time if it is never a minute out of the way, we should not say as much of a jeweller's regulator under the same circumstances, though this too we should probably call "exactly" right if it was on the very second. But for an observatory, whose time is like a national standard measure, which all other standards in turn copy, and which can never be too accurate, this word "exact" is little used. With instruments which measure not only the second, but its hundredth part, it is found that no clock which has ever been made is exact, and that not even the clocks made for the astronomers' special use can be caused to run with perfect uniformity for it single hour. The time at which the principal stars cross the meridian will be found, however, in astronomical ephemerides, printed years in advance, with an error of very much less than a second, and it is evident that astronomy must possess some means of ascertaining time with corresponding precision to venture the prediction.

Nothing is commoner than to find that persons—even those of education—believe that this is done by means of the sun, which is popularly supposed to come on to the meridian at twelve every day. But the sun is in fact a most irregular time-keeper, arriving sometimes a quarter of an hour before this and sometimes a quarter of an hour after, and varying more than half an hour in the year, so that a watch which kept no better time than the sun does would be a poor one indeed.

We must set our clock, however, by something, and this is done, in the first place, by setting it by another: at Alleghany, for instance, by a clock on the opposite side of the room, resting on a massive stone pier, isolated from the floor so as to be secure from the least jar. This second time-piece is called the "sidereal clock." It is of very perfect workmanship, but as the other is so too, it would appear that we have only pushed the difficulty a step farther off; but we are here, in fact, comparing with a new standard of time, unknown to common use, for the principal hand of the sidereal clock turns coincidently, not with the apparent motion of the sun, but of the stars, and revolves through a complete circle while the earth turns once upon its axis. The use of this construction is seen when we learn that our turning globe itself is to be made the standard that this clock is set by; for this revolution of our own planet is the final measure of uniformity in time. We make the earth mark off the hours for us by first selecting some fixed object, like a star, whose real place we know can not be altered by any motion of our own. Then if a telescope, with a tube of metal so massive that it can not bend or alter, be bolted against some solid wall of stone at such an angle as to be directed to the star at any one moment, our telescope will in spite of us directly be moved away again, for its stone foundation forms it part of the great globe beneath us, which, as it revolves, sweeps in the course of a day and night the telescope through the whole circuit of the heavens. If, looking through it, then, we notice the instant it is passing any point in the sky, and at this moment start the sidereal clock, whose hour-hand is meant to revolve about its centre just as fast as the earth does about its axis, we have an evidently simple way of knowing whether it does this or not, for on looking through the instrument we shall see the star swept past again just when the hand should have got round to its starting-point on the dial. If it has done less, the clock is slow; if more, it is fast, and we can thus regulate it to extreme exactness.

The telescope used for this purpose is

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called the "transit," and the one employed at Alleghany is shown in the engraving. In practice it is not fastened to a single pier of stone, but placed between two (as the illustration shows), to which it is firmly bolted, so that it can not be moved to the right or left, while, it can still be elevated or lowered, so that its use is not confined to any particular height in the sky. To see any star, then, we have no way but to wait patiently, after setting to the proper height, till the motion of the earth brings the object into view; and we must make good use of the brief time in which it posses, for, this over, nearly twenty-four hours must elapse before it appears again. The telescope is made so large in order that we may see any bright star even in the daytime, and for greater accuracy fibres from the cocoon of the little wood-spider (common cobweb is too coarse) are stretched up and down in the middle of the field of view to serve as pointers. The instant that the star appears to cross the middle line is the moment at which to compare the clock; but here comes a difficulty, for we are, it must be remembered, aiming at such exactness that an error of a tenth part of a second would be quite too large to pass over. Now how shall the observer, who lies on a low chair beneath the instrument, see the clock and the star at once? He can not; and if he turn his eyes from one to the other, however quickly, he has lost in the very time required for the motion that minute fraction of the second be would secure. Here comes in the aid of electricity again, for within reach of his hand is an ivory key (seen in the illustration resting against the further pier), a pressure on which causes an instrument at the other extremity of the building to write down the hour, the minute, the second, and the hundredth part of a second, by the sidereal clock, when the finger touched the key. This instrument (the chronograph) is seen in the prior illustration, on the left of the switch-board, but its explanation must be dispensed with here as foreign to a description which only deals with general methods, and not with mechanical detail.

The processes which we have described in connection with the Alleghany Observatory are essentially the same as those by which indications of time are distributed from the National Observatory at Washington. At the hour of noon each day a ball, suspended from the top of the flag-staff attached to the Signal Service stations in different parts of the country, is dropped, precisely as the armature in the telegraph station is set free by the interruption of an electric current. Our illustration on page 670 shows the interior of the chronometer room of the Washington Observatory at the moment of dropping the time-ball. This use of a time-ball is not entirely novel. Twenty years ago such a ball was used on the old New York Custom-House, in telegraphic connection with the Dudley Observatory, at Albany. The ball is shown in the illustration on page 671.

As instruments have been made to measure not only the hundredth part, but the hundred-thousandth part of a second, and even less, it might seem as if there were no

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limit to the accuracy thus attainable; but in fact we very soon reach one, and in aiming after what has proved to be in so me cases superhuman exactness, astronomers have been led to some curious discoveries as to the minute and obscure causes of failure which interpose a barrier to indefinite progress in this direction. Thus, we see the telescope resting on two massive piers, each hewn from a single stone, and these rest on still heavier foundations, which are carried down to the bedrock. Nothing can be made more solid, yet, while the observer is gazing, a tap of his naked hand on either pier will make a, star passing through the field of view of the telescope appear to tremble in the sky. Since the motion is not really in the star, and since the pier has not stirred from its base, this compels us to admit that a tremor has been set up in the substance of the solid stones (of several tons weight) by a tap of the fingers, and that though the motion must be all but infinitesimal, the magnifying power of the telescope detects it. Movements absolutely non-existent to our unaided sense may, then, at any time affect the direction of the instrument and impair the observation, and this is found to be the case in practice. Thus a beam of sunshine falling on either pier will, by expanding the stone, lift the axle and tilt the telescope out of the meridian; and such a cause, or currents of warmer or cooler air, or movements of the rock foundation, are constantly doing this. By levels of extreme delicacy, constructed for the purpose, and by the telescope itself, it is found that one pier is moving up, the other down, one forward, the other back, every hour of the day or night, so that the instrument is literally swaying about at all times, while to the eye it seems at absolute rest. This minute incessant movement of course is a feature not peculiar to the piers of an observatory, but is one shared by every structure of man's hands (and, indeed, of nature's), though the means for detecting it do not commonly exist.

There is the same inevitable failure to attain perfect accuracy as to obtain perfect stability; thus the axles on which the transit revolves, and which have been turned with a diamond, though of exquisite exactness, are not perfectly equal cylinders even when they leave the maker's hands, for mathematical perfection is not attainable by the nicest art; but however little the short-coming it will affect the observation, an error of a very appreciable part of a second being caused by an unnoticed difference of less than one-ten-thousandth of an inch in their diameters.

All these difficulties, however, might be more easily overcome than another class arising in the observer himself, and due to the fallibility of the human eye, hand, and brain. Thus it has been abundantly proved, as a general rule, that the best observer even does not really press the key at the instant of the star's passage (as he fully intends to do), and that, a small part of a second is somehow lost. It is a small thing to hunt for, but the astronomer must know what becomes of it, in order to understand the cause, and apply a correction.

The deficiency was perceived in the last century for the first time by Maskelyne, the then Astronomer Royal, who was led to discharge his assistant, Kinnebrook, because the latter always noted the star's passage a fraction of a second later than he himself did. Then, when examination was made, it proved that every observer lost a certain time, in spite of every effort, or else that, in his endeavor to correct an ineradicable fault, he went into the other extreme, and anticipated the true moment. Volumes have been

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written since on the subject, which has occupied the attention of eminent physiologists, and is deserving of our own, for the peculiarity is one inherent in the human organization; and the reader may be sure it exists in himself, and affects every act and motion of his life, whether he knows it or not. The observer's, then, is merely a particular case, which offers facilities for the study of an imperfection common to as, all. We may be interested, therefore, in knowing that it has been found that time is lost in seeing the star (or any other object)—lost, that is, in the passage to the brain of the impression of what the eye pictures. More time is lost while the impulse from the brain journeys down the nerve to the finger which the brain directs to press the key (or to the hand which it bids carry food to the mouth, or the fist or foot we will to strike or kick). There are other causes of delay of a like order; but when the time thus lost has all been measured (as it has been), it is found that a remnant is yet unaccounted for. Perhaps it is spent in the act of volition, for these curious researches appear to give us the number of hundredths of a second which it takes for the mind to will the hand to touch the key, or the voice to speak. These causes operate differently in each observer; the lost time is not the same in one as in another, and the sum of all the losses we have mentioned is rarely more than one-third of a second. Yet this time must be measured; for though we can not get rid of the faults of the mechanism employed, whether it be of stone or brass, or that of our nerves and brain, we can, after observing, allow in computation corrections for their effects, and so finally evolve truth from what appears a maze of error.

Again, then, let us observe that these actions of our mind and will, which appear to be independent of time, really take place in time—in periods so minute, perhaps, that it is bewildering to contemplate them, but which are no less real than if they extended over hours. Their effects are sensible in all of us, and their amount must, in the astronomer's case, be known, in order to perfect observations where exactness has an indisputable importance in its bearing on the affairs of practical life.


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