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Here the large figures are the hours and the small ones the half-hours. Only one bell is used, because there being no one and two among the hours, the half-hours cannot be mistaken. This is not all, for you can tell what half hour it is within two hours. For example, suppose you know approximately that it is somewhere between 9 and 7 and you hear the clock strike 2, then you know it is half past 8. See the large and small figures above. This is far superior to our method of one at each half-hour.

MODERN CLOCKS

DeVick's clock of 1364. -- Original "verge" escapement. -- "Anchor" and "dead beat" escapements. -- "Remontoir" clock. -- The pendulum. -- Jeweling pallets. -- Antique clock with earliest application of pendulum. -- Turkish watches. -- Correct designs for public clock faces. -- Art work on old watches. -- Twenty-four hour watch. -- Syrian and Hebrew hour numerals. -- Correct method of striking hours and quarters. -- Design for twenty-four hour dial and hands. -- Curious clocks. -- Inventions of the old clockmakers.

Modern clocks commence with De Vick's of 1364 which is the first unquestioned clock consisting of toothed wheels and containing the fundamental features of our present clocks. References are often quoted back to about 1000 A. D., but the words translated "clocks" were used for bells and dials at that date; so we are forced to consider the De Vick clock as the first till more evidence is obtained. It has been pointed out, however, that this clock could hardly have been invented all at once; and therefore it is probable that many inventions leading up to it have been lost to history. The part of a clock which does the ticking is called the "escapement" and the oldest form known is the "verge," Fig. 25, the date of which is unknown, but safely 300 years before De Vick. The "foliot" is on the vertical verge, or spindle, which has the pallets A B. As the foliot swings horizontally, from rest to rest, we hear one tick, but it requires two of these single swings, or two ticks, to liberate one tooth of the escape wheel; so there are twice as many ticks in one turn of the escape wheel as it has teeth. We thus see that an escapement is a device in which something moves back and forth and allows the teeth of an "escape wheel" to escape. While this escapement is, in some respects, the simplest one, it has always been difficult to make it plain in a drawing, so I have made an effort to explain it by making the side of the wheel and its pallet B, which is nearest the eye, solid black, and farther side and its pallet A, shaded as in the figure. The wheel moves in the direction of the arrow, and tooth D is very near escaping from pallet B. The tooth C on the farther side of wheel is moving left, so it will fall on pallet A, to be in its turn liberated as the pallets and foliot swing back and forth. It is easy to see that each tooth of the wheel will give a little push to the pallet as it escapes, and thus keep the balance swinging. This escapement is a very poor time-keeper, but it was one of the great inventions and held the field for about 600 years, that is, from the days when it regulated bells up to the "onion" watches of our grandfathers. Scattered references in old writings make it reasonably certain that from about 1,000 to 1,300 bells were struck by machines regulated with this verge escapement, thus showing that the striking part of a clock is older than the clock itself. It seems strange to us to say that many of the earlier clocks were strikers, only, and had no dials or hands, just as if you turned the face of your clock to the wall and depended on the striking for the time. Keeping this action of the verge escapement in mind we can easily understand its application, as made by De Vick, in Fig. 26, where I have marked the same pallets A B. A tooth is just escaping from pallet B and then one on the other side of the wheel will fall on pallet A. Foliot, verge and pallets form one solid piece which is suspended by a cord, so as to enable it to swing with little friction. For the purpose of making the motions very plain I have left out the dial and framework from the drawing. The wheel marked "twelve hours," and the pinion which drives it, are both outside the frame, just under the dial, and are drawn in dash and dot. The axle of this twelve-hour wheel goes through the dial and carries the hand, which marks hours only. The winding pinion and wheel, in dotted lines, are inside the frame. Now follow the "great wheel"--"intermediate"--"escape wheel" and the two pinions, all in solid lines, and you have the "train" which is the principal part of all clocks. This clock has an escapement, wheels, pinions, dial, hand, weight, and winding square. We have only added the pendulum, a better escapement, the minute and second hands in over 500 years! The "anchor" escapement, Fig. 27, came about 1680 and is attributed to Dr. Hooke, an Englishman. It gets its name from the resemblance of the pallets to the flukes of an anchor. This anchor is connected to the pendulum and as it swings right and left, the teeth of the escape wheel are liberated, one tooth for each two swings from rest to rest, the little push on the pallets A B, as the teeth escape, keeping the pendulum going. It is astonishing how many, even among the educated, think that the pendulum drives the clock! The pendulum must always be driven by some power.

It runs with an error under one second a week. This is surpassed only by some of the astronomical clocks which run sometimes two months within a second. This wonderful timekeeping is done with seconds pendulums of about 39 in., so the theoretical advantage of long pendulums is lost in the difficulties of constructing them. Fractions are left out of these lengths as they would only confuse the explanations. At the Naval observatory in Washington, D. C., the standard clocks have seconds pendulums, the rods of which are nickel steel, called "Invar," which is little influenced by changes of temperature. These clocks are kept in a special basement, so they stand on the solid earth. The clock room is kept at a nearly uniform temperature and each clock is in a glass cylinder exhausted to about half an atmosphere. They are electric remontoirs, so no winding is necessary and they can be kept sealed up tight in their glass cylinders. Nor is any adjustment of their pendulums necessary, or setting of the hands, as the correction of their small variations is effected by slight changes in the air pressure within the glass cylinders. When a clock runs fast they let a little air into its cylinder to raise the resistance to the pendulum and slow it down, and the reverse for slow. Don't forget that we are now considering variations of less than a second a week.

The clock room has double doors, so the outer one can be shut before the inner one is opened, to avoid air currents. Visitors are not permitted to see these clocks because the less the doors are opened the better; but the Commander will sometimes issue a special permit and detail a responsible assistant to show them, so if you wish to see them you must prove to him that you have a head above your shoulders and are worthy of such a great favor.

The best thing the young student could do at this point would be to grasp the remarkable fact that the clock is not an old machine, since it covers only the comparatively short period from 1364 to the present day. Compared with the period of man's history and inventions it is of yesterday. Strictly speaking, as we use the word clock, its age from De Vick to the modern astronomical is only about 540 years. If we take the year 1660, we find that it represents the center of modern improvements in clocks, a few years before and after that date includes the pendulum, the anchor and dead beat escapements, the minute and second hands, the circular balance and the hair spring, along with minor improvements. Since the end of that period, which we may make 1700, no fundamental invention has been added to clocks and watches. This becomes impressive when we remember that the last 200 years have produced more inventions than all previous known history--but only minor improvements in clocks! 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. Those wishing to follow up the subject would require a large "horological library"--and Dr. Eliot's five-foot shelf would be altogether too short to hold the books.

A good idea of the old church clocks may be obtained from Fig. 32 which is one of my valued antiques. Tradition has followed it down as the "English Blacksmith's Clock." It has the very earliest application of the pendulum. The pendulum, which I have marked by a star to enable the reader to find it, is less than 3 in. long and is hung on the verge, or pallet axle, and beats 222 per minute. This clock may be safely put at 250 years old, and contains nothing invented since that date. Wheels are cast brass and all teeth laboriously filed out by hand. Pinions are solid with the axles, or "staffs," and also filed out by hand. It is put together, generally by mortise, tenon and cotter, but it has four original screws all made by hand with the file. How did he thread the holes for these screws? Probably made a tap by hand as he made the screws. But the most remarkable feature is the fact that no lathe was used in forming any part--all staffs, pinions and pivots being filed by hand. This is simply extraordinary when it is pointed out that a little dead center lathe is the simplest machine in the world, and he could have made one in less than a day and saved himself weeks of hard labor. It is probable that he had great skill in hand work and that learning to use a lathe would have been a great and tedious effort for him. 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. Many have been puzzled by finding that old, rudely made clocks often have fine dials, but this is not remarkable when we state that art and engraving had reached a high level before the days of clocks. It is worthy of note that clocks in the early days were generally built in the form of a church tower with the bell under the dome and Figs. 32, 33 show a good example. It is highly probable that the maker of this clock had access to some old church clock--a wonderful machine in those days--and that he laboriously copied it. It strikes the hours, only, by the old "count wheel" or "locking plate" method. Between this and our modern clocks appeared a type showing quarter hours on a small dial under the hour dial. No doubt this was at that time a great advance and looked like cutting time up pretty fine. As the hand on the quarter dial made the circuit in an hour the next step was easy, by simply dividing the circle of quarters into sixty minutes. The old fellows who thought in hours must have given it up at this point, so the seconds and fifths seconds came easily.

Our boys' watches costing one dollar keep much better time than this type of watch. Comparing the Syrian dial, Fig. 42, with that on Fig. 35, it is evident that the strange hour numerals on both are a variation of the same characters. These, so-called, "Turkish watches" were made in Europe for the Eastern trade. First-class samples of this triple-case type are getting scarce, but I have found four, two of them in Constantinople. Figure 36 shows the double-case style, called "pair cases," the outer case thin silver, the figures and ornaments being hammered and punched up from the inside and called "repouss?." Before we leave the old watches, the question of art work deserves notice, for it looks as if ornamentation and time-keeping varied inversely in those days--the more art the worse the watch. I presume, as they could not make a good time-keeper at that date, the watch-maker decided to give the buyer something of great size and style for his money. In Fig. 37 four old movements are shown, and there is no doubt about the art, since the work is purely individual and no dies or templates used. In examining a large number of these watches, I have never found the art work on any two of them alike. Note the grotesque faces in these, and in Fig. 39 which is a fine example of pierced, engraved work. Figure 38 is a fine example of pierced work with animals and flowers carved in relief. Figure 40 is a "Chinese" watch but made in Europe for the Chinese market. In Fig. 41 we have what remains of a quarter repeater with musical attachment. Each of the 24 straight gongs, commencing with the longest one, goes a little nearer the center of the large wheel, so a circle of pins is set in the wheel for each gong, or note, and there is plenty of room for several tunes which the wearer can set off at pleasure. Figure 43 is a modern watch with Hebrew hour numerals. Figure 44 is a modern 24-hour watch used on some railroads and steamship lines. I have a pretty clean-cut recollection of one event in connection with the 24-hour system, as I left Messina between 18 and 19 o'clock on the night of the earthquake! Dials and hands constitute an important branch of the subject. The general fault of hands is that they are too much alike; in many instances they are the same, excepting that the minute hand is a little longer than the hour. The dial shown on the left of Fig. 24 was designed by me for a public clock and can be read twice as far away as the usual dial. Just why we should make the worst dials and hands for public clocks in the United States is more than I can find out, for there is no possible excuse, since the "spade and pointer" hands have been known for generations. Figure 45 is offered as a properly designed dial for watches and domestic clocks, having flat-faced Gothic figures of moderate height, leaving a clear center in the dial, and the heavy "spade" hour hand reaching only to the inner edges of the figures. For public clocks the Arabic numerals are the worst, for at a distance they look like twelve thumb marks on the dial; while the flat-faced Roman remain distinct as twelve clear marks.

Do you know that you do not read a public clock by the figures, but by the position of the hands? This was discovered long ago. Lord Grimthorp had one with twelve solid marks on the dial and also speaks of one at the Athenaeum Club, both before 1860. The Philadelphia City Hall clock has dials of this kind as shown on right side of Fig. 24. It has also good hands and can be read at a great distance. Very few persons, even in Philadelphia, know that it has no hour numerals on its dials. Still further, there is no clock in the tower, the great hands being moved every minute by air pressure which is regulated by a master clock set in a clock room down below where the walls are 10 ft. thick. Call and see this clock and you will find that the City Hall officials sustain the good name of Philadelphia for politeness. Generally, we give no attention to the hour numerals, even of our watches, as the following proves. When you have taken out your watch and looked at the time, for yourself, and put it back in your pocket, and when a friend asks the time you take it out again to find the time for him! Why? Because, for yourself, you did not read hours and minutes, but only got a mental impression from the position of the hands; so we only read hours and minutes when we are called on to proclaim the time.

Of curious clocks there is no end, so I shall just refer to one invented by William Congreve, an Englishman, over one hundred years ago, and often coming up since as something new. A plate about 8 in. long and 4 in. wide has a long zigzag groove crosswise. This plate is pivoted at its center so either end can be tipped up a little. A ball smaller than a boy's marble will roll back and forth across this plate till it reaches the lower end, at which point it strikes a click and the mainspring of the clock tips the plate the other way and the ball comes slowly back again till it strikes the disk at the other end of the plate, etc. Every time the plate tips, the hands are moved a little just like the remontoir clock already described. Clocks of this kind are often used for deceptive purposes and those ignorant of mechanics are deceived into the belief that they see perpetual motion. The extent to which modern machine builders are indebted to the inventions of the ancient clock-maker, I think, has never been appreciated.

ASTRONOMICAL FOUNDATION OF TIME

Astronomical motions on which our time is founded. -- Reasons for selecting the sidereal day as a basis for our 24-hour day. -- Year of the seasons shorter than the zodiacal year. -- Precession of the equinoxes. -- Earth's rotation most uniform motion known to us. -- Time Stars and Transits. -- Local time. -- The date line. -- Standard time. -- Beginning and ending of a day. -- Proposed universal time. -- Clock dial for universal time and its application to business. -- Next great improvement in clocks and watches indicated. -- Automatic recording of the earth's rotation. -- Year of the seasons as a unit for astronomers. -- General conclusions.

The difference between 1st and 2nd is that part of the sun's error due to the elliptical orbit of the earth.

The other part of the sun's error--and the larger--between 2nd and 3rd is that due to the obliquity of the ecliptic to the equator.

The whole error between 1st and 3rd is the "equation of time" as shown for even minutes in the first chapter under the heading, "Sun on Noon Mark 1909."

Stated simply, for our present purpose, 1st is sundial time, and 3rd our 24-hour clock time.

This 2nd day is therefore a refinement of the astronomers to separate the two principal causes of the sun's error, and I think we ought to handle it cautiously, or my friend, Professor Todd, might rap us over the knuckles for being presumptuous.

In we see that a "precession" of 50 seconds of arc will bring the Spring equinox around in 26,000 years.

In we see, as 50 seconds of arc represents the distance the earth will rotate in 3-1/3 seconds, a difference of one day will result in 26,000 years. That is since the clock regulated by the stars, or absolute rotations of the earth, would get behind 3-1/3 seconds per year, it would be behind a day in 26,000 years, as compared with a sidereal clock regulated by the Spring equinoctial point.

In we see that as 50 seconds of arc is traversed by the earth, in its annual revolution, in 20-1/3 minutes, a complete circle of the Zodiac will be made in 26,000 years.

As what is to follow relates to the growing difficulties of local time and a proposed method of overcoming them, let us recapitulate:--

Having stated my proposal for universal time as fully as space will permit and given my guess as to the coming cosmic watch, let us in this closing paragraph indulge in a little mental exercise. Suppose we copy the old time lecturer on astronomy and "allow our minds to penetrate into space." Blessed be his memory, he was a doer of good. How impressive as he repeatedly dropped his wooden pointer, and lo! It always moved straight to the floor; thus triumphantly vindicating universal gravitation!!!

Transcriber's note:

Original spelling and grammar have mostly been retained. However, on page 31, "clepsydral" was changed to "clepsydra".

Figures were moved from within paragraphs to between paragraphs. In addition, some figures were originally out of numerical sequence; they are now in sequence.

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