Ninth Form.—Transitional Form.
Our knowledge of this form is derived solely from information and sketches supplied by Mr. E. Horkheimer, who assisted Reis in its construction. Figs. [15] and [16] are engraved after Mr. Horkheimer’s sketches. The conical mouthpiece was of wood: the contact pieces of platinum. The point c was attached to a springy slip of brass, g, fixed across the wooden box; and the adjusting-screw, h, served to regulate the degree of initial pressure at the point of contact which controlled the current.
Tenth Form.—The Square Box.
Fig. 17.
Fig. 18.