686 OPTIC PROJECTION 



In perfecting cameras to make ribbon pictures, and projectors for exhibiting 

 ribbon transparencies of these pictures on the screen, many inventors have 

 taken part. Among these should be mentioned Marey and his assistant, 

 Demney, and the Lumieres in France; Green and Evans, Donisthrope and 

 Crofts in England; Jenkins and Edison in America. These were among the 

 first to work out practical apparatus that made moving pictures possible and 

 practical. For the present perfection of cameras, films, and projectors, and 

 the general methods employed, the number of manufacturers and inventors is 

 legion. 



The first light used was sunlight, and that remains the most brilliant of all. 

 Animal and vegetable oils were burned in lamps without a chimney (fig. 403- 

 405), and very recently mineral oil (kerosene) has been used in lamps with a 

 chimney (fig. 65-67). 



FIG. 413. DAVY'S CARPON ARC. 



(From Davy's Collected Works, vol. iv, pi. Hi, fig. 17) 



See p. 1 10 of vol. iv for a discussion of the carbon arc. The carbons are 

 horizontal, and the arc arches upward hence the name arc. 



The lime light, the most brilliant after sunlight and the arc light, came in 

 with the discovery by Hare in 1802 that the oxyhydrogen flame when blown 

 against lime, etc., gave a dazzling light. This was applied to projection by 

 Birkbeck in 1824 for the magic lantern; and in the same year by Woodward for 

 the phantasmagoria. (Goring and Pritchard's Micrographia, pp. 170-171; 

 also the Microscopical Journal and Structural Record, Vol. I, 1841). This 

 light is still much used for all forms of projection. For the oxygen ether lime 

 light, see Ives, in the Bibliography. 



The electric light. This most satisfactory and powerful artificial light yet 

 devised, was first shown by Humphrey Davy in Sept., 1800, and recorded in 

 Nicholson's Journal of October in that year (See Cantor Lectures of Silvanus 

 P. Thompson on the arc light, Journal of the Royal Society of Arts, Oct. 25, 

 1895, and fig. 413 for Davy's carbon arc). According to the same lecturer, 

 W. E. Straite devised the first automatic electric lamp in 1846. 



The first arc lamps wore for direct current. As it was not desirable to have 

 the carbons burn off unequally with the Jablochoff lamp where the carbons 

 were parallel and close together, alternating currents were used (1877). (S. P. 



