INCANDESCENT LAMPS. 



211 



such a manner as to be able to turn by the tangential pres- 

 sure against it, in proportion as the illuminated rod B B is 

 consumed. This lamp works well, and can henceforth be ap- 

 plied to domestic illumination under the influence of a current 

 from 6 Bunsen cells. The rod of carbon is of a more slender 

 diameter than those used by Reynier. 



E. Arnould has lately invented a lamp the arrangement of 

 which is exactly that of the preceding apparatus, but under 

 much less excellent conditions, and yet certain newspapers 

 have not hesitated to announce it as something new. 



Ducretet's form of Reynier's Lamp. An arrange- 

 ment of the kind just al- 

 luded to has also been 

 given to Reynier's lamp by 

 Ducretet. In this form, 

 shown in Fig. 60, the rod 

 of carbon c M, instead of 

 being pushed by a counter- 

 poise, is plunged in a 

 column of mercury, filling 

 a long iron tube T, which 

 forms the body of* the lamp. 

 A cap and an elastic collar 

 B guide the rod, and, as 

 well as the mercury, impart 

 to it the positive polarity. 

 A carbon cylinder H, sup- 

 ported by a metallic arm s, 

 movable in a socket with 

 a regulating screw, allows 

 any required length to be 

 given to the incandescent 

 portion. The current 

 reaches the apparatus by 

 the conductor /, and leaves 



FIG. 60. 



142 



