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.