Part 36
How Did Men Tell Time When the Sun Cast No Shadows?
[Illustration:
Photo by James Arthur.
WATER CLOCKS FOR TELLING TIME
This picture shows the hour-glass or sand-glass. It is really a type of water-clock, being based on the same principle. The upper glass bulb was filled with sand and this sand fell through a little hole between the two bulbs. When the sand had all gone through, the glass was turned upside down and the operation repeated.
TIME-BOY OF INDIA.--WATER-CLOCK.
The Water-clock consisted of a large vessel filled with water, on the surface of which was placed a smaller vessel, really a gong, with a hole in the bottom. The water gradually filled the smaller vessel, and it sank. The Time-boy sat beside the Water-clock and as soon as the vessel sank he fished it out, emptied it, struck the gong one or more times and set it on the water again.]
During the night and also in cloudy weather the sun-dial was useless, and we read that the priests of the temples and monks of more modern times “went out to observe the stars” to make a guess at the time of night. The most prominent type after the shadow devices was the “water-clock” or “clepsydra,” but many other methods were used, such as candles, oil lamps, and in comparatively late times, the sand-glass. The fundamental principle of all water-clocks is the escape of water from a vessel through a small hole. It is evident that such a vessel would empty itself each time it is filled in very nearly the same time. The reverse of this has been used, as shown in the picture of the Time-boy of India. He sat in front of a large vessel of water and floated a bronze cup having a small hole in its bottom in this large vessel, and as the water ran in through the hole the cup sank. The boy then fished it up and struck one or more blows on it as a gong. This he continued and a rude division of time was obtained--while the boy kept awake!
[Illustration: Drawing from description by James Arthur.
The “Hon-woo-et-low,” Canton, China. Copper jars dropping water.]
The most interesting of all water-clocks was undoubtedly the “copper jars dropping water,” in Canton, China, where it can still be seen. Referring to the picture herewith and reading the four Chinese characters downwards the translation is “Canton City.” To the left and still downwards, “Hon-woo-et-low,” which is, “Copper jars dropping water.” Educated Chinamen inform me that it is over 3000 years old. The little open building or tower in which it stands is higher than surrounding buildings. It is, therefore, reasonably safe to state that the Chinese had a weather and time station over 1000 years before our era.
[Illustration:
Photo by James Arthur.
TOWER OF THE WINDS.
This tower is located at Athens, Greece. It was built about 50 B.C. It is octagonal in shape and had at one time sun-dials on each of its eight sides. On top was a bronze weather vane from which it derived its name.]
~A PRIMITIVE TWELVE-HOUR CLOCK~
It is a 12-hour clock, consisting of four copper jars partially built in masonry forming a stair-like structure. Commencing at the top jar each one drops into the next downward until the water reaches the solid bottom jar. In this lowest one a float, “the bamboo stick,” is placed and indicates the height of the water, and thus in a rude way gives the time. It is said to be set morning and evening by dipping the water from jar 4 to jar 1, so it runs 12 hours of our time. What are the uses of jars 2 and 3, since the water simply enters them and drips out again? No information could be obtained, but I venture an explanation and hope the reader can do better, as we are all of a family and there is no jealousy. When the top jar is filled for a 12-hour run it would drip out too fast during the first six hours and too slow during the second six hours, on account of the varying “head” of water. Now, the spigot of jar 2 could be set so that it would gain water during the first six hours, and lose during the second six hours, and thus equalize a little by splitting the error of jar 1 in two parts. Similarly, these two errors of jar 2 could be again split by jar 3 making four small variations in lowest jar, instead of one large error in the flow of jar 1. This could be extended to a greater number of jars, another jar making eight smaller errors.
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 is 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 time-keeping 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.
[Illustration: THE FIRST MODERN CLOCK
Drawing by James Arthur.
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. That part of a clock which does the ticking is called the “escapement,” and the oldest form known is the “Verge.”]
~EARLIEST CLOCKS HAD NO DIALS OR HANDS~
Scattered references in old writings make it reasonably certain that from about 1000 A.D. to 1300 A.D. 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.
[Illustration:
Photo by James Arthur.
ENGLISH BLACKSMITH’S CLOCK.]
A good idea of the old church clocks may be obtained from the picture herewith. Tradition has followed it down as the “English Blacksmith’s Clock.” It has the very earliest application of the pendulum. The pendulum is less than 3 inches 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 feet 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.
[Illustration: THE LARGEST CLOCK IN THE WORLD
Courtesy of Colgate and Company.
THE HANDS OF THE LARGEST CLOCK IN THE WORLD--ON THE ROOF OF THE COLGATE FACTORY.
This big clock faces the giant office buildings of down-town New York. Its dial is 38 feet in diameter and can be read easily at a distance of three miles, so that passengers on the incoming liners pick out the clock as one of their first sights of New York.
The next largest clock (on the Metropolitan Tower) is 26¹⁄₂ feet in diameter; the Westminster clock of London, 22¹⁄₂ feet.
The great clock weighs approximately 6 tons. The minute hand, 20 feet long, travels at its point 23 inches every minute; more than one-half mile each day.
The bed of this clock is 4 feet in length, the wheels and gears being made of bronze and pinions of hardened steel. The time train occupies about one-third of the bedplate, and has a main time wheel measuring 18¹⁄₃ inches in diameter. This train is equipped with Dennison’s double three-legged gravity escapement, which was invented by Sir Edmund Becket, chiefly for use on the famous Westminster clock, installed in the Parliament Buildings, in London, England. The use of this escapement is most advantageous for a gigantic clock of this kind as it allows the impulse given the pendulum rod to be always constant, and therefore does not permit any change of power or driving force of the clock to affect its time-keeping qualities.
It requires about 600 pounds of cast-iron to propel this time train, and the clock is arranged to run eight days without winding. The gravity arms of the escapement are fastened at a point very near the suspension spring, and the arms are fitted with bronze roller beat pins.
The dial contains 1134 square feet, or about one thirty-fifth of an acre. The numerals consist of heavy black strokes, 5 feet 6 inches long and 30 inches wide at the outer end, tapering to a point at the inner end. The circumference of the dial is approximately 120 feet. The distance from center to center of numerals is 10 feet, and the minute spaces are 2 feet.
The background on dial is painted white, and in the daytime the black numerals show up distinctly. At night the numerals, or hour marks, are designated by a row of incandescent bulbs placed in a trough 5 inches wide and 5 inches deep. The hands at night are outlined with incandescent electric lights, there being 27 lamps on the hour hand and 42 lamps on the minute hand.]
[Illustration: THE MACHINERY WHICH RUNS A BIG CLOCK]
This picture shows the machinery necessary to operate a large modern tower clock.
The mechanism is held in place and confined entirely within a cast-iron structure which is firmly bolted to the floor. The wheels are composed of bronze, the pinions of steel (hardened) and the gears are machine cut. At the front of the clock is a small dial which enables one to tell exactly the position of the hands on the outside dials, and there is also a second hand to permit of very close regulation and adjustment.
Three ways are provided for the regulation. First by a knurled screw at the top of bed frame. Second by a revolving disc at the bottom of the pendulum ball. Very often by either of these two methods it is impossible to bring the clock to fractional seconds, and in order to permit of a nicety of adjustment there is a cup fitted at the top of the ball so that by inserting or taking out lead pellets, the rating can be brought to absolute time.
[Illustration: THE CLOCK IN INDEPENDENCE HALL
INDEPENDENCE HALL, PHILADELPHIA]
[Illustration: NEW YORK CITY HALL]
Where Does the Day Begin?
To understand this subject we must first appreciate that a day as we think of it is a division of time made by man for the purpose of his own reckoning. So far as the beginning of day is concerned, it begins at a different place in the world every hour; yes, every minute and every second in the day. As, however, the distance in feet where the day begins from one minute to another is so short that we can hardly notice it in such short measurements of time, we will look at the answer to the question from hour to hour. When you understand the subject from that point you can yourself see that the day actually begins at a different point of the earth every minute and every second of time.
How Much of the Earth Does the Sun Shine on at One Time?
The sun is shining on some part of the earth all the time and the shining of the sun makes the difference between day and night. Wherever the sun is shining it is day-time, and where the sun is not shining it is night-time.
To illustrate we will make use of an ordinary orange and a lighted gas jet. Let us take a long hat-pin and stick it through the orange from stem to stem. Now hold the orange by the ends of the hat-pin up before the lighted gas jet. You will notice that one-half of the orange is lighted, while the other half is dark. Of course, it is the half of the orange away from the light that is dark. Now, revolve the orange slowly on the hat-pin axis toward the light. When you have turned the orange half way round the part that was formerly dark is now lighted up and the other part is now dark.
Now examine closely and you will see that just one-half of the orange is lighted at one time and the other half is dark. You revolve the orange in front of the light slowly and a portion of the surface of the orange is always coming into the light, while a corresponding portion of it on the opposite side is constantly going into the dark. In other words, whatever the speed at which you revolve the orange toward the light, one-half of it is always light and the other half is always dark.
This is exactly what happens in the relation of the earth to the sun every day. One-half of the earth, which is continually revolving on its axis, is facing the sun, and is, therefore, in the daylight, while the other half of the earth’s surface is in darkness, because the light from the sun does not strike any portion of it. If the earth did not revolve one-half of it would always be in day-time, while the other half would be continually having night-time. As the earth is always moving or revolving the half where it is day-time is constantly changing, so that the day is beginning on one-half of the earth’s surface every second of the day. Actually, of course, then, if you live on the east side of town day begins with you a little sooner than with your chum who lives on the west side of town. We have come to measure the beginning of day as sunrise and the beginning of night as sunset, wherever we happen to be.
For convenience in setting clocks and in measuring time we do not take into consideration these very slight differences in the rising and setting of the sun, but set our clocks all alike in different parts of the same town or city to avoid confusion. In fact, in order to overcome the difficulties and confusions arising in reckoning the time of the clock in different localities, and still keep the beginning of what we call day-time constant with the hands of the clock, we have agreed upon what we call standard time. We agreed upon this system of fixing standard time because the actual sun time by which people set their clocks up to a few years ago led to so many mistakes in catching trains, keeping engagements and other misunderstandings where the question of time was involved. Then when this system of standard time was adopted the confusion became even worse, and the mistakes and misses more numerous, because some people insisted on setting their clocks to standard time and others insisted on sticking to the old sun time schedule. So you could never tell by looking at the clock what time it really was unless they put a sign on the clock saying what kind of time they were going by. Finally, however, most of the people came to appreciate that it would be a good idea to use one uniform system of setting the clocks and of having them in harmony in a sense with the other clocks in the world, and the adoption of the standard time plan became universal. To make this system practical and effective, certain points about equally distant from each other were selected, at which point
Where Is the Hour Changed?
the hour would change for all points within that zone. Under this system all timepieces in any one zone point to the same hour. So the clock time changes only as you go east or west. All points on a north and south line have the same time as the zone in which it is located.
For convenience in adjusting the time in America the country was divided into four east and west zones. The first zone takes in everything on a straight north and south line east of Pittsburg, and is called Eastern time. The second zone extends from Pittsburg to Chicago, and is called Central time; the third zone extends from Chicago to Denver, and is called Mountain time; while the fourth zone extends from Denver to the Pacific Ocean. These selections were made because the sun actually rises about one hour later in Pittsburg than in New York; one hour later in Chicago than in Pittsburg; one hour later in Denver than in Chicago, and one hour later on the Pacific Coast than in Denver. Under this plan when it is nine o’clock in New York it is only eight o’clock at Pittsburg and all points in the Central zone; seven o’clock in all points in the Mountain zone; six o’clock in Denver and five o’clock in San Francisco. As you keep travelling westward you drop one hour of the clock time in every zone, and as under this system the earth’s east to west distance is divided into twenty-four such zones, if you went west entirely around the world you would lose a whole day of clock time.
If, however, you went around the world from west to east in the same manner you would gain a whole day.
Where Does the Day Change?
This system of agreeing on fixed places where the hour changes made it necessary to also fix a point where for the purposes of the calendar the day also changes. This imaginary north and south line is fixed upon at 180 degrees west longitude, which would cut the Pacific Ocean in two. This line makes it possible for a person to travel all day before approaching this line and then find himself after crossing it travelling all the next day with the same name for the day of the week. Thus he could spend all of Sunday travelling toward the International Day Line, as this is called, and after crossing it spend another Sunday, which would be the next day, going away from it. This would give him the novel experience of having two Sundays on successive days. The same thing would happen if he were travelling to the Day Line on Monday, Tuesday, Wednesday, Thursday, Friday or Saturday. He would live through two succeeding days of the same name in the same week, one right after the other. This would be in going westward.
If you were traveling eastward and crossed the International Day Line on Sunday at midnight you would lose a day completely out of the week, for when you woke up the next morning it would be Tuesday.
Why Do We Cook the Things We Eat?
We have several reasons for doing this. The first and most important reason to us is that the application of heat to food makes it more easy to digest. Other reasons are that when cooked our food is more palatable; the process of cooking kills all microbes, which, if taken into our bodies alive, would give us diseases, and also it is easier for us to chew food that has been cooked.
[Illustration: WONDERS PERFORMED BY ELECTRIC LIFT MAGNET
This picture shows the construction of a successful electric lift magnet. This device, by means of magnetic attraction, fastens itself to practically all kinds of iron and steel without the aid of slings, cables or chains.]
The Story in a Magnet
What Makes an Electro Magnet Lift Things?
The working parts of an electric lift magnet are as follows:
_A Shell._--This is a steel casting heavily ribbed on the top for strength, and also to assist in radiating the heating effect from the coil.
It is usually made circular in shape, the outside rim forming one pole, while the lug in the center forms the other. The coil fits in between these poles, thus making a magnet similar to the ordinary horseshoe type.
_A Bottom Plate._--The under side of the magnet is closed by a very tough and hard non-magnetic steel plate, in order to protect the coil.
As well as being non-magnetic, this plate also has sufficient strength to resist the severe wear to which a magnet is necessarily subjected.
_A Terminal Box._--A one-piece heavily-constructed steel casting bolted to the top of the shell, containing and protecting the brass sockets into which the wires from the coil terminate, forms the Terminal Box.
The sockets are made to receive plugs placed on the end of the conductor wire, by which the magnet is connected with the generator.
_A Coil._--This consists of a round insulated wire which is passed, while being wound, through a cement-like substance, heavily coating each individual strand.