Note 10 — Chapter II · HOW TO MAKE AND WORK A MODEL SUBMARINE
Reading edition
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.