site logo


Against the wall of a room, near the ceiling, fix a wheel of twelve or

eighteen inches diameter; on the rim of which place a number of bells

in tune, and, if you please, of different sizes. To the axis of this

wheel there should be fixed a fly to regulate its motion; and round

the circumference there must be wound a rope, to the end of which is

hung a weight.

Near to the wheel let a stand be fixed, on whi
h is an upright piece

that holds a balance or moveable lever, on one end of which rests the

weight just mentioned; and to the other end must hang an inverted

hollow cone, or funnel, the aperture of which is very small. This cone

must be graduated on the inside, that the sand put in may answer to

the number of hours it is to run. Against the upright piece, on the

side next the cone, there must be fixed a check, to prevent it from

descending. This stand, together with the wheel, may be enclosed in a

case, and so contrived, as to be moved from one room to another with

very little trouble.

It is evident, from the construction of this machine, that when a

certain quantity of the sand is run out, the weight will descend, and

put the wheel in motion, which motion will continue till the weight

comes to the ground. If the wheel be required to continue longer in

motion, two or more pulleys may be added, over which the rope may run.