A portable call-bell, or alarm, is one of the most convenient things in any home. It may be temporarily rigged up from one room to another, or from one floor to the next, the small, flexible wire being run over the tops of door-casings, where it is held by slim nails or pins driven into the wood-work. The main terminal of this portable outfit consists of a wooden box that will hold a large dry-cell, and to the side of which an electric bell or buzzer may be attached. Binding-posts are arranged at another side, to which the ends of the flexible wire-cord can be made fast, and a cover fitted to the box to hide the battery and wiring. The complete outfit, except the flexible wire-cord and push-button, will appear as shown in Fig. 11. No definite size can be laid down for the construction of this box, as dry-cells vary in size and shape, some being long and thin, while others are short and fat. By removing the cover and looking into the box, it will appear as shown in Fig. 12. The carbon is connected with one binding-post and the zinc to one of the poles of the bell. The other bell-pole is connected with the remaining binding-post, and it requires but a switch or push-button to close the circuit between the two binding-posts. This is done by the long line of flexible wire-cord, which may be of the silk or cotton covered kind, having the two strands twisted together as is customary with flexible electric-light wire. A pear-shaped push-button may be connected at the end of the line, and this may be arranged at the head of a bed or on a chair placed conveniently near an invalid’s couch. This same apparatus is a very convenient thing for a lecturer where a stereopticon is used. A buzzer takes the place of the bell, which would be too loud in a hall or lecture-room, and the cord, passing from the apparatus close to the operator, is hung over the lecturer’s stand, or the button held by him in the hand, to be pressed whenever he desires the pictures changed. [Illustration: FIG. 11] [Illustration: FIG. 12] [Illustration: FIG. 13]