THE CONJURER'S CLOCK.
A clock, invented by Mr. Stewart, is exhibited at Newcastle. All that
can be seen in the way of mechanism are two pointers, each having a
cylindrical brass box at one end and a steel balancing-piece at the
other. That the works were contained in the brass boxes was obvious,
but how they moved the pointers was a problem that few could solve. Yet
their motion depends on a very simple natural law, namely, that the
centre of gravity of a body always seeks its lowest position. For
example, if the centre of gravity lay in the centre line of the
pointers, and on the same side of the pivot as the brass boxes, the
pointers would point to twelve o'clock, as then the centre of gravity
would be in its lowest position, namely, directly under the pivot. Now,
if the centre of gravity could be moved into a new position, tbe
pointers must turn round a certain distance, in order to bring it to
its lowest point. Therefore, if the centre of gravity could be kept
moving, the pointer would be kept turning. This is just what is done.
By means of clock-work contained in the brass boxes, a weight is made
to move round the inside of each box. In the minute-hand the weight
moves round once in an hour, and in the hour-hand once in twelve hours.
As the weight moves it alters the centre of gravity, and consequently
turns the pointers. There are two peculiarities about this
clock—1, each pointer moves independently of the other ; 2, the
time indicated by the pointers cannot be altered by turning them round
with the finger, as when the finger is taken away they will instantly
return to their proper position.
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