32.(Pg. [53]) What is said respecting two bodies united by an inflexible rod?
33.(Pg. [53]) What is [fig. 7, plate 3], intended to illustrate? What [fig. 8]; what [fig. 9]?
CONVERSATION V.
ON THE MECHANICAL POWERS.
OF THE POWER OF MACHINES. OF THE LEVER IN GENERAL. OF THE LEVER OF THE FIRST KIND, HAVING THE FULCRUM BETWEEN THE POWER AND THE WEIGHT. OF THE LEVER OF THE SECOND KIND, HAVING THE WEIGHT BETWEEN THE POWER AND THE FULCRUM. OF THE LEVER OF THE THIRD KIND, HAVING THE POWER BETWEEN THE FULCRUM AND THE WEIGHT.
MRS. B.
We may now proceed to examine the mechanical powers; they are six in number: The lever, the pulley, the wheel and axle, the inclined plane, the wedge and the screw; one or more of which enters into the composition of every machine.
A mechanical power is an instrument by which the effect of a given force is increased, whilst the force remains the same.
In order to understand the power of a machine, there are four things to be considered. 1st. The power that acts: this consists in the effort of men or horses, of weights, springs, steam, &c.