438 



NEGRETTI AND ZAMBRA, HOLBORN VIADUCT, E.C., 



FIG. 2571. 



Each. 

 B. d. 



2596 Self-acting Electric Lamp, arranged on convenient 



stand (as fig. 2596), with adjustments to the Carbon 



Points 2 10 



2597 Electric Lamp, without adjustments .... 220 



2598 Carbon Points or Rods from 016 



2599 Parabolic Reflectors, for Electric Light, thickly plated, from each 220 



2600 Insulated (Gutta Percha) Copper Wire, 8d. to Is. 4d. per yard, price variable. 



2601 Glass Tubes, of large size, for exhibiting the Aurora 



Borealis; mounted with Stopcock and Metal terminals, 

 for experimenting with various Gases, &c. ; on a firm 

 base (fig. 2571) 330 



2602 Electric Lantern, an improved arrangement, having 



two sets of Condensers. With it the direct ray as well 

 as the Spectrum may be projected upon the same 

 screen without moving the Lantern. A gas jet is 

 placed inside the Lantern, and suitable adjustments 

 are provided for keeping the Carbon Points uniform 

 in height. Price in the most complete form (fig. 2602) 25 



45 Cells of Bunsen's Batteries are required for effectively working the Electric 

 Light, or 45 Cells of Grove's Batteries; Price for 40 Bunsen's 20; 

 45 Grove's, 23. 



For further particulars respecting Batteries, &c., see pages 428 to 432. 



