Time study

“ There is no class of work which cannot be profitably submitted to time study, by dividing it into its time elements, except such operations as take place in the head of the worker; and the writer has even seen a time study made of the speed of an average and first-class boy in solving problems in mathematics. ”

“ Appreciation of Time Study by Workers the First Step. — The first step of the workers in this direction must be the appreciation of time study, for on time study hangs the entire subject of Scientific Management. ”

“ Leaving, then, this constant error in time-appreciation, we will pass to the variable and more palpable errors in the retrospective measurement of time. Each person's experience will have told him that in estimating the distance of a past event by a mere retrospective sense of duration, he is liable to extraordinary fluctuations of judgment. Sometimes when the clock strikes we are surprised at the rapidity of the hour. At other times the timepiece seems rather to have lagged behind its usual pace. ”

“ The study of single small elements is simpler, quicker, and more certain to be successful than that of a large number of elements combined. The greater the length of time involved in a single item of time study, the greater will be the likelihood of interruptions or accidents, which will render the results obtained by the observer questionable or even useless. ”

“ But cycles of correction, which are both short and close to exactness, like that of Meton, may perhaps be the original form of the knowledge which they imply; and certainly require both accurate facts and sagacious arithmetical reasonings. The discovery of such a cycle must always have the appearance of a happy guess, like other discoveries of laws of nature. Beyond this point, the interest of the study of calendars, as bearing on our subject, ceases: they may be considered as belonging rather to Art than to Science ”

“ But time is short, and science is infinite,—how infinite only those who study astronomy fully realize,—and perhaps I shall be worn out before I make my mark.’
She seemed to be greatly struck by the odd mixture in him of scientific earnestness and melancholy mistrust of all things human. ”

“ Our only way of knowing it accurately is by counting, or noticing the clock, or through some other symbolic conception. When the times exceed hours or days, the conception is absolutely symbolic. We think of the amount we mean either solely as a name, or by running over a few salient dates therein, with no pretence of imagining the full durations that lie between them. No one has anything like a perception of the greater length of the time between now and the first century than of that between now and the tenth. ”

“ These questions lead us at once into another department of inquiry of immense importance in science—the measurement of time, and more especially the measurement of minute periods of time. We all recognise more or less the value of time, and the busier we are the more we value what we call fragments of time. On a long summer day in the holidays, when we have not much to do except gratefully to enjoy the beauties of nature and the sense of physical well-being, a quarter of an hour, or even an hour, is not appreciated as of much value ”

“ To railroad-men and watch-makers as a matter of necessity, to manufacturers and business-men as a matter of economy, and to individuals as a matter of convenience, it has come to be highly important to know what is the exact time of day to the second, in circumstances where half a century ago it would have quite sufficed to know the minute or even the hour. ”

“ I pressed the lever over to its extreme position. The night came like the turning out of a lamp, and in another moment came tomorrow. The laboratory grew faint and hazy, then fainter and ever fainter. Tomorrow night came black, then day again, night again, day again, faster and faster still. An eddying murmur filled my ears, and a strange, dumb confusedness descended on my mind.
“I am afraid I cannot convey the peculiar sensations of time travelling. They are excessively unpleasant. There is a feeling exactly like that one has upon a switchback—of a helpless headlong motion! ”

“ Perhaps the readiest way of removing this difficulty, and also of illustrating generally the principles on which the determination of the most probable mean value of many different estimates depends, is by considering a familiar experience of many, a case in which the point to be determined is the most probable time of day. Suppose that we are walking along a route where there are several clocks, the time shown by our own watch being, for whatever reason, open to question. ”

“ Absolute, true, and mathematical time, in and of itself, of its own nature, without reference to anything external, flows uniformly, and is otherwise called duration. Relative, apparent, and commonplace time is any sensible and external measure, whether accurate or approximate, of duration by means of motion. This kind of measure, for example, hour, day, month, year, is used by common people instead of true time. ”

“ These dry facts may serve to whet the curiosity of the student in regard to the measurement of time and its origin. They add a piquancy to the clock dial as we now know it. Scientific it is, as one of man's most exact recorders of natural phenomena. That an exact timekeeper should be found in the pocket of every schoolboy would seem an astounding miracle to our ancestors two hundred years ago, or even less than a hundred years ago:
'Tis with our judgments as our watches, none
Go just alike, yet each believes his own,
writes Pope in his Essay on Criticism in 1725. ”

“ We have, however, seen reasons, which, applied to time, would lead us to declare that an absolute insight would view the temporal order as a discrete series of facts ordered as any succession of facts expressing one purpose would be ordered, viz. like the whole numbers. On the other hand, we have no reason to suppose that our human consciousness distinctly observes intervals of time that in brevity anywhere nearly approach to the final truth about the temporal order. Within what is for us the least observable happening, a larger insight may indeed discriminate multitudes of events. ”

“ You see from this that the revolution of the Earth round the Sun gives us a means of measuring time, by which we are able to bring order and regularity into our business and transactions of life. For the making of clocks and watches is but a late invention, and we should be left entirely in the dark as regards the history of former ages, and a great many people would, at this present moment, be incapable of forming a correct estimate of time, if Providence had not given to all this appropriate means of measuring it. ”

“ Why, you might almost say it ran by clock-work! The millions of watches in millions of pockets, the millions of clocks on millions of walls, all running steadily together—these were what kept the complicated machinery of modern life from getting tangled and confused.
Yes; but what did people do before they had such timepieces? Back in the very beginning, before they had invented or manufactured anything—far back in the days of the caveman—even those people must have had some method of telling time. ”

“ We will deal with the sun first. From the motions of the sun we can observe the time. This is done in every garden by means of sun-dials, and I will now describe how they are constructed. If a light, such as the light of a candle, be moved round in a circle at a uniform pace so as to go round once in some given period, such as twenty-four hours, it is obvious that it would serve to measure time. ”

“ Our real day of 24 hours is a theoretical day. Still more remarkable, this theoretical day is the unit by which we express motions in the solar system. A lunar month is days—hours—minutes—and seconds of this theoretical day, and so for planetary motions. And still more remarkable, the earth's rotation which is itself the foundation is expressed in this imaginary time! This looks like involution involved, yet our 24-hour day is as real as reality; and the man has not yet spoken who can tell whether a mathematical conception, sustained in practical life, is less real than a physical fact. ”

“ I saw his famous clock last winter at Mr. George Graham’s: the sweetness of its motion, the contrivances to take off friction, to defeat the lengthening and shortening of the pendulum through heat and cold, and to prevent the disturbance of motion by that of the ship, cannot be sufficiently admired.”—Ms. Journal. [18]
An exact measure of time is of the utmost importance to many of the sciences. Horology is indispensable to astronomy, in which the variation even of two or three seconds is of the greatest consequence. ”

“ If one clock is so constructed as to keep exactly with the sun, going faster or slower, according as the lengths of the solar days vary, and another clock [62] is regulated to mean time, then the difference of the two clocks, at any period, would be the equation of time for that moment. If the apparent clock were faster than the mean, then the equation of time must be subtracted; but if the apparent clock were slower than the mean, then the equation of time must be added, to give the mean time. ”

“ We do not know the length of the interval separating any two events not recorded in history, nor are we possessed of any natural chronometer by which to fix a date in the historical sense. We are dealing merely with time relative, and not time absolute. ”

“ The Man Animal and Nature's Timepieces The story of the watch that you hold in your hand to-day began countless centuries ago, and is as long as the history of the human race. When our earliest ancestors, living in caves, noted the regular succession of day and night, and saw how the shadows changed regularly in length and direction as day grew on toward night, then was the first, faint, feeble germ of the beginning of time-reckoning and time-measurement. ”

“ When the exact sciences began at last to make some progress, watch and clock making followed in their path, though it was always arrested by an insurmountable difficulty,—the regular and continuous measurement of time. ”

“ The improvement of the balance-watch upon the clepsydra or the hour-glass and other early time-keepers caused the change to be made from apparent to mean time, and the increasing requirements of a complex civilization demand more and more attention to the keeping of accurate standard time. ”

“ But for the primitive intellect the year is a very long period, and it is only with difficulty and at a later stage that it can be conceived and surveyed as a whole. Day and night, on the other hand, are short units which immediately become obvious. Their fusion into a single unit, the day of 24 hours, did not take place till later, for this unit as we employ it is abstract and numerical: the primitive intellect proceeds upon immediate perceptions and regards day and night separately. ”

“ The Earth does the very same thing; and its two different Motions were always of use to Men to measure the Time of their Duration. The Tour which it makes upon its own Axis, forms our Natural Day of Twenty-four Hours; and the Time it takes in its grand Circle round the Sun, makes our Year of 365 Days and 6 Hours, wanting a few Minutes. 'Tis true, that this Computation or Measure for the Year was not known always alike to all Nations. The Egyptians, the Chaldeans, the Jews, and other ancient People, computed their Years differently, and made them longer or shorter, some than others. ”

“ Thus if A compares his clocks with those of B it will appear to A that 's clocks are running faster than 's clocks; on the other hand, if B compares his clocks with those of A it will appear to B that 's clocks are running faster than 's clocks. Thus the two observers are in hopeless disagreement as to the measurement of time. An analysis of this divergence is made below in section V.
Another matter of fundamental importance in the measurement of time will be brought to attention by the question: When are two events which happen at different places to be considered simultaneous? ”

“ The examples just given are not numerous, and this corresponds to the actual state of affairs, since we have here to do with the treatment of a genuine calendarial science by certain peoples,—only at a quite undeveloped stage can questions of the time-reckoning be dealt with in a deliberative assembly—and our researches are concerned with primitive peoples. The end which the calendar-maker has in view is the establishing of an ordered series of days marked out into divisions, the series being kept in place by certain fixed points, and recurring cyclically. ”

“ The units of duration, on the other hand, which the time-sense is able to take in at a single stroke, are groups of a few seconds, and within these units very few subdivisions—perhaps forty at most, as we shall presently see—can be clearly discerned. The durations we have practically most to deal with—minutes, hours, and days—have to be symbolically conceived, and constructed by mental addition, after the fashion of those extents of hundreds of miles and upward, which in the field of space are beyond the range of most men's practical interests altogether. ”

“ Thus, to take the simplest case, a period of time may seem long because the kinæsthetic strain of waiting becomes intense, or because a great number of perceptions and ideas occur during its course; the strain and the number of ideas have come to mean length of time, and the primary experience of duration, so to say, drops out of sight. If, therefore, we wish our observers in the laboratory to compare periods of time; if we wish to find out accurately what durations can be grasped by the attention and held in the memory ”

“ Calling this one hundredth year a common year gives a gain of one day, or 24 hours, which puts computed time ahead of actual time, 24-18·6 5·4 hours, which, in 400 years, equals 21·6 hours, gain. Calling the four hundredth a leap-year brings back computed time 24 21·6 2·4 hours behind real time. To lose a whole day at this rate will require 10 400 4,000 years. ”

“ Now, just as she wrote, the clock, which I was careful not to meddle with, had been rapidly gaining time, and I was standing before it, watching it from hour to hour, and slightly changing its rate by dropping small weights upon its pendulum. Time is so important an element with the astronomer, that all else is subordinate to it. ”