Timer

“ So we have a complete striking clock made by a man so poor that he had only his anvil, hammer and file. The weights are hung on cords as thick as an ordinary lead pencil and pass over pulleys having spikes set around them to prevent the cords from slipping. The weights descend 7 ft. in 12 hours, so they must be pulled up—not wound up—twice a day. The single hour hand is a work of art and is cut through like lace. Public clocks may still be seen in Europe with only one hand. ”

“ But the moon alone moves with sufficient rapidity to act as a time indicator for terrestrial voyagers. It is hardly necessary to explain why rapidity of motion is important; but the following illustration may be given for the purpose. The hour-hand of a clock does in reality indicate the minute as well as the hour; yet, owing to the slowness of its motion, we regard the hour-hand as an unsatisfactory time-indicator, and only consider it as showing what hour is in progress. ”

“ We must find a little space for striking clocks. The simplest is one blow at each hour just to draw attention to the clock. Striking the hours and also one blow at each half hour as well as the quarter double blow, called “ting tong” quarters, are too well known to need description. The next stage after this is “chiming quarters” with three or more musical gongs, or bells. One of the best strikers I have has three trains, three weights and four bells. It strikes the hour on a large bell and two minutes after the hour it strikes it again, so as to give you another chance to count correctly. ”

“ The application of electricity for winding, driving, or regulating clocks is not fundamental, for the timekeeping is done by the master clock with its pendulum and wheels, just as by any grandfather's clock 200 years old. This broad survey of time measuring does not permit us to go into minute mechanical details. ”

“ In instances where it is requisite that the clock face should be visible at a great distance, it is necessary that the dial should be made of semi-transparent glass and be illuminated by gas, which is usually turned as low as possible by day and turned on at night by means of the 24-hour wheel, as shown in the annexed illustration, the time for the turning on being regulated by the man in charge of the clock, who takes out or screws in the pins placed in the rim for that purpose. ”

“ We find, say, that as compared with our watch time, one clock is two minutes fast, the next three minutes fast, the next one minute slow, and so on, two or three perhaps being as much as six or seven minutes fast, and two or three being as much as three or four minutes slow as compared with the watch. We note, however, that these wider ranges of difference occur only in the case of clocks presumably inferior—cheap clocks in small [Pg 68] shops, old clocks in buildings where manifestly the flight of time is not much noted, and so forth. ”

“ A clock need not be a very perfect timepiece, but if provided with an electric regulator its hands are brought up to the correct time every hour in response to an impulse sent from an accurate master clock which in turn has its time corrected daily from the National Observatory in Washington. ”

“ The Several Branches of a Great Art.—The timekeeper—whether it be the scientific astronomical clock, or the chronometer used by mariners, or the modern watch, minute in size but recording time with accuracy, or the bracket or table clock, or the long-case clock—has proceeded on parallel lines of development. ”

“ Any one restoring old clocks for amusement and pleasure will be astonished at the high-class mechanics displayed in them—nearly always by unknown inventors. Here is an example: The old clock-maker found that when he wished to drill a hole in a piece of thick wire so as to make a short tube of it, he could only get the hole central and straight by rotating the piece and holding the drill stationary. By this method the drill tends to follow the center line of rotation; and our great guns as well as our small rifles are bored just that way to get bores which will shoot straight. ”

“ A kitchen clock or a cheap watch is usually thought of as a machine to tell the "time of day," but it may be used to time a horse or a bicycler upon a race course, and then it becomes an instrument to measure the amount of time required for covering the length of the course. ”

“ How It Works Having traced out the history of the clock and watch mechanism all the way from De Vick's first clock and the clumsy old Nuremberg Egg down to the perfect time-keeping device which we have today, it may be interesting to look a little more closely at the result of so many years and so many inventions—to see what its parts are, and how they are put together, and to observe how the wonderful little machine does its work. ”

“ This contrivance is in constant use on my Equatoreal at the present time. You will observe it is essential to have a machine moving uniformly. In the motion of a common clock, though the movement from day to day, from hour to hour, and from minute to minute, is uniform, yet it is not so with the smaller divisions of seconds: the clock works with jerks, and does not go uniformly. ”

“ In regard to hands, it is curious that the fashion of placing a minute hand to travel around the dial with the hour hand has established a method of reckoning time in a popular manner not in accordance with scientific exactitude. The eye glances at the dial and sees that the minute hand has so many minutes to travel before reaching the next hour. ”

“ The “dead beat” escapement is shown in Fig. 29, and is used in clocks of a high grade, generally with a seconds pendulum. It has no recoil as you can easily see that the surfaces O O on which the teeth fall, are portions of a circle around the center P. The beveled ends of these pallets are called the impulse surfaces, and a tooth is just giving the little push on the right-hand pallet. It is found in good railroad clocks, watch-makers' regulators and in many astronomical clocks. These terms are merely comparative, a “regulator” being a good clock and an “astronomical,” an extra good one. ”

“ We must commence with the known data that the earth revolves on its axis in twenty-four hours, or, to be more exact, in 23 hours 56 minutes 4 seconds. Astronomical clocks recording with scientific exactitude this phenomenon are on a plane apart, as are chronometers used by mariners. The astronomer uses a clock with numbers on its dial plate up to twenty-four; the common clock has only twelve hour numerals.
To come straight to modernity, it must be recognized that the measurement of time scientifically and the measurement of time according to civil law are two different things. ”

“ As an illustration, let us suppose that in a certain shop where hangs a regulator are two clocks to be regulated. Both are set with the regulator at 8 a. m. to see how they will run for ten consecutive hours. It was found that when it was 6 p. m., by the first clock, it was 5:50 by the regulator, the clock having gained one minute every hour.
To rectify this discrepancy we must intercalate 10 minutes by stopping the clock until it is 6 by the regulator. ”

“ A simple contrivance, connected with the tubes and the clock, lets off a puff of air every minute or half-minute, and the fingers of all the clocks in the system are in that manner pushed forward with unerring accuracy, in accordance with the time indicated by the standard timepieces in the observatory, so that exact uniformity can be maintained without difficulty in the time shown on any number of dials. ”

“ On this dial, Fig. 19, nine is noon, as usual, and is on top side of dial. Hand points to three quarters past seven, that is, a quarter to six, near sunset. Between the bell and the top of the clock body two horizontal balances, having small weights hung on them, are plainly shown, and the clock has two verge escapements—one connected with each balance, or “foliot.” Let us suppose a long day coming to a close at sunset, just as the hand indicates. The upper balance, which is the slow one, has been swinging backwards and forwards measuring the long hours of the day. ”

“ The latter are made with such accuracy as to correct the time of other clocks, such as turret and church clocks, which are more exposed to the influence of the weather, and are necessarily made upon a coarser scale. In large mansions there is no handsomer or more necessary appointment for the hall or vestibule than a fine eight-day clock, 'to welcome the coming, speed the parting guest,' and to give the time of day to the entire household. ”

“ Note here that the big weight does not directly drive the clock; it only rewinds it every minute. The minutes are shown on the dial to the right and its hand jumps forward one minute at each sixtieth second as the lever remounts; so if you wish to set your watch to this clock the proper way is to set it to the even minute “on the jump.” The hour hand is on the dial to the left. By this remounting, or rewinding, the clock receives the same amount of driving force each minute. The complete clock is shown in Fig. ”

“ This clock actuates two levers whereby electric contacts are made at predetermined intervals to open and close the lens. This mechanism can be set so as to give exposures at intervals ranging from a minute to several hours, and will run for twenty-four hours without attention. The apparatus is as accurate as it is ingenious.
It is obvious, however, in such work, that a great deal depends upon the personality of the worker himself. If he is skilful he will find no difficulty in devising a reliable timing apparatus which he can trust for hours together. ”

“ And I can stop clocks.
Take this morning, for example. I had set my alarm for five-thirty because I had to catch the seven o'clock plane at San Francisco International Airport. This being earlier than I usually get up, it seems all I did during the night was feel my way past the escapement and balance wheel to see where the notch for the alarm was. The last time I did it there was just the merest fraction of an inch between the pawl and the notch. So I sighed and moved to the balance wheel and its delicate ribbon of spiraling steel. ”

“ As the hour hand revolves it carries a cam so arranged as to be deeper cut away for the twelfth hour, less for the eleventh, and so on. When the minute hand comes to the hour it releases the striking mechanism, which, urged by a weight, begins to revolve, and, driving an arm carrying a pin, raises a hammer, which goes on striking away as the arm revolves. ”

“ The clock hand is the heavy arrow and sweeps the dial once in a whole day, same direction as our clocks. This circle of the months moves along with the hand, but a little faster, so as to gain one number in a month. As shown on the figure it is about one week into the sixth month. Next outward is the broad band having twelve curved lines for the hours ending outwardly in a ring divided into 100 parts, marked off in tens by dots. These curved lines are numbered with the Japanese numerals for hours which you must now be able to read easily. ”

“ But since then many improvements have been made in it, so that makers are now enabled to produce a pocket watch, with the short angle lever escapement, which marks time at a steady rate of within four or five seconds weekly,—a rate which approaches so near to the time-keeping of a pocket chronometer, that unless the minutest exactness for some specific purpose is required, the last-named watch is all that can be wished for. ”

“ From being very untrustworthy, astronomical clocks are now made to great perfection by the application of the pendulum and by its compensation, while the invention of chronometers has placed a portable and equally trustworthy timekeeper in the hands of travellers. ”

“ If we cut a screw with eighteen threads to the inch on the bottom of the pendulum rod, and put a circular nut on it, with the rim divided into sixty parts, then each turn through one division will raise or lower the bob by 1/1080th of an inch, and this first causes an alteration of time of the clock by one second in the day. ”

“ The most modern clocks have what is called a “deadbeat” escapement, and a compensating pendulum. Clocks are liable to alter by reason of the state of the air and varying temperature, and until all our clocks are placed in vacuo we must be content to have them lose or gain a little. There is a magnet arrangement by which the Greenwich Observatory clocks keep time by compensation, corresponding with the fall or rise of the syphon barometer attached to it. ”

“ Daily at midday a gun is fired to announce the time to the people, and those who have clocks and watches set them accordingly. Comparatively few, however, of the people are able to tell the time from a clock, and many have the most hazy idea of the length of time expressed by an hour or half an hour. ”

“ In the second place, that clock is automatically corrected every minute. It wouldn't do you any good to push it to an incorrect time, because it would be readjusted at the end of the minute. Watch." He pointed. The hand was nearing twelve. ”

“ 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. ”

“ When the clock strikes 38twelve, a piece of steel like a needle rises, and entering a hole in the rim of the watch-case, comes in contact with a piece which carries the minute-hand, and by pressure makes the hand of the watch correspond with that of the clock, provided the difference be not more than twenty minutes. ”