[1]: As we shall have frequent occasion to mention this magnitude, it would be well that the reader should be familiar with it. It is a square, each side of which is an inch. Such as A B C D, [Fig. 1].
[2]: This experiment with the tube A requires to be very carefully executed, and the tube should be one of small bore.
[3]: Temperatures above 650° cannot be measured by the mercurial thermometer. They can be inferred only with probability by pyrometers.
[4]: The terms cubic inch and cubic foot are easily explained. A common die, used in games of chance, has the figure which is called a cube. It is a solid having twelve straight edges equal to one another. It has six sides, each of which is square, and which are also equal to one another. If its edges be each one inch in length, it is called a cubic inch, if one foot, a cubic foot, if one yard, a cubic yard, &c. This figure is represented in perspective, in [fig. 6].
[5]: A common glass flask with a long neck will answer the purpose.
[6]: Recueil de diverses pièces touchant quelques nouvelles machines, p. [38].
[7]: This pipe in [fig. 9]. is represented as proceeding from the force-pipe above the cistern C.
[8]: Not in the diagram.
[9]: Hot water being lighter than cold, it floats on the surface.
[10]: In the diagrams used for explaining the principles and operations of machines, I have found it contribute much to the clearness of the description to adopt an arrangement of parts somewhat different from that of the real machine. When once the nature and principles on which the machine acts are well understood, the reader will find no difficulty in transferring every part to its proper place, which is represented in the perspective drawings.