[7] The design, construction and operation of submarine torpedoes will be found in [Chapter V.]
[8] The storage battery was invented by Gaston Planté in 1860. The electric motor was discovered in 1876, by whom nobody knows.
[9] These pipes can be bought cut to length and threaded to suit of The Chicago Model Works, 166 West Madison Street, Chicago, Ills., or of Luther H. Wightman, 132 Milk Street, Boston, Mass.
[10] The L. E. Knott Apparatus Company, of Boston, Mass., sell a standard motor, as they call it in their catalogue, for $3.75. It weighs 1½ pounds and takes up a space of about 3½ inches square. Powerful little motors can be bought at almost any electrical supply house, and you can use one of these by building up the base.
[11] Cells of this kind that measure 2 x 2½ x 6 inches on the sides can be bought of the Manhattan Electrical Supply Company, of 17 Park Place, New York City.
[12] A machinist’s saw for sawing metal.
[13] The pulley can be bought of dealers in model makers supplies. See footnote on page 32.
[14] You can certainly get it of the F. W. Devoe and C. T. Raynolds Company, 101 Fulton Street, New York City.
[15] The top of the conning tower is called the bridge.
[16] The hull is the body or shell of a boat or ship.