Lectures on select subjects in mechanics, hydrostatics, hydraulics, pneumatics, and optics, with the use of the globes, the art of dialing, and the calculation of the mean times of new and full moons and eclipses / [James Ferguson].

  • Ferguson, James, 1710-1776.
Date:
1790
Catalogue details

Licence: Public Domain Mark

Credit: Lectures on select subjects in mechanics, hydrostatics, hydraulics, pneumatics, and optics, with the use of the globes, the art of dialing, and the calculation of the mean times of new and full moons and eclipses / [James Ferguson]. Source: Wellcome Collection.

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    flide up and down upon the wires which make the corners of each tower. The balls and plates being thus connected, each by its particular line, .. it is plain, that if the balls be drawn outward, — or toward the ends 14 and. of their refpective bearers, the round plates § and 7 will be drawn up to the top of their refpective towers O and 2. There are feveral brafs weights, fome of two ounces, fome of three, and fome of four, tobe occafionally put within the towers O and P, upon the round plates § and T: each weight having — a round hole in the middle of it, for going upon the fockets or axes of the plates, and is flit from the edge to the hole, for allowing it to be flipt over the aforefaid line which comes from each ball to its refpective plate. (See Fig. 2.) The experiments to be made by this machine are as follows: | als 1. Take away the bearer 4 X, and take. the Fig. 1. ivory ball a, to which the:line or fill cord @ 1s fattened at one end; and having mace a loop on the other end of the cord, put the loop over a pin fixt in the center of the board d. ‘Then, The pro- = motion, you will fee that the ball does not imme- deanna ae : keep the diately begin to move with the board, but, ON gate it is account of its inactivity, it endeavours to con-in. tinue in the ftate of reft which it was in before.— an equal degree of motion with its own to the ball, and then turning on, you will perceive that the ball will remain upon one part of the board, keeping the fame velocity with it, and having no relative motion upon it, as is the cafe with every. thing that lies loofe upon the plane furface of the earth, which, having the motion of the earth from