Figure 78. — Mobile arc-light unit, 

 using a Gramme generator. From 

 Chro7}ique de rindustrie, 1879, p. 93. 



Figure 79. — Arc light on HMS ,. 

 Thunderer. From La Lumiere elec 

 trique, October 1882, vol. 7, p. 347 



394 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



