The mirror., 1922-04-13
CLOCKS AND WATCHES


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in refnements of construction. 1t was
largely intended for permanent mounting
in the garden or on the roofs of houses,
but there are records of pocket dials that
were small enough to be carried about
but which could not be used until merid-
ian had been established, so that time
reading was laborious and could only be
done by the educated. However, the most
refined of sun-dials was useless on cloudy
days and at night This led to the develop
ment of devices that. would measure out
equal intervals of time without reference
to the sun.
The earliest form of record was the clep-
sydra or water clock, in its simplest form
an earthen-ware vessel with small hole
at the bottom which would empty itself
at fairly uniform rate. This was first
used in the Grecian era to set limit to
the speeches in the courts of justice. Ap-
parently the modern lawyer has a very
ancient and honorable precedent for love
of the sound of his own voice. Indicating
mechanisms were added later, Plato being
credited with the invention of clepsydra
that would indicate the hours of both the
day and night. A water clock made in
Alexandria about 135 B. c. consisted of
series of wheels which upon rotation by
stream of water caused the gradual rise
of little figure which pointed out the
hours on graduated scale with tiny
wand. In the time of the Cssars one of
the favorite forms consisted of large
copper vessel containing holes at the bot
tom, which was hoated in a fountain AMI
would gradually sink as it filled, and as
it submerged would automatically ring :;
gong, upon which servant would empty
the vessel, reset the gong and await the
completion of the next cycle. Man power
was cheap in the good old days.
Various other devices were used in the
home for the marking of time intervals,
such as the hour glass using the flow of
sand which has descended to us as an egg
timer, and the marked candle and lamp.
The candle of standard diameter and wick
size was marked with rings at equal dis
tances, the spaces being sometimes num-
bered with the hours of the night; and
the lamp containing float and indicating
rod in the fuel chamber showing roughly
the passage of time.
No change took place in the fundamen
tails of the timing mechanisms until about
the thirteenth century. The invention and
development of balance clocks correspond
ing very closely in form to those of today,
are ascribed on rather poor authority to
Pope Sylvester II, in about 996 A. d. 1t
is recorded, however, that balance clock
was installed in one of the towns of West
minister in 1888.
The clock of this period consisted of
weights as the power source, and train
of gear wheels terminating in verge
escapment driving balance wheel.
The first great step in the improvement
of the clock is due to the great inventor
and physicist Calico in the 18th century.
The story has it that sitting in church,
apparently thinking of anything but the
service, he suddenly noticed that censer
swinging from the ceiling synchronized
with his pulse beat, and even upon a
greatly decreased swing, when almost
stopped, maintained its rate of oscillation.
Further tests brought out the true isochron-
ism of free pendulum. Calico himself,
however, made no practical application of
his discovery except to construct some port
able pendulums that physicians of the day
used in taking the pulse of their patients.
The germ of the idea of modern time
piece was due to Galileo's son, who built
an entirely practicable mechanism which
not only connected the pendulum to an in
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