690 



HANDBOOK OF PHOTOGRAPHY 



The mechanism of a high-intensity arc is portrayed in the photograph of Fig. 39. 

 The angle between the positive (horizontal) and negative electrodes is 127°. The 



1,900 



1,800 



1,700 

 ^ 1,600 

 E2_ 1,500 



1,400 

 1,300 



I E 1.200 



S^ 1,100 



7^0 1,000 



900 

 800 

 700 

 600 

 600 

 400 

 300 

 200 

 100 

 



oi h 



Oi o 



St 



^: 



c 



24 20 16 12 8 4 4 8 12 16 20 24 



Degrees of Divergence 

 Fig. 36. — Light-distribution diagram of 5,000-watt incandescent. 



lamp is struck manually to minimize chipping of the rim of the positive crater. The 

 positive electrode rotates at a speed of 14 r.p.m., maintaining a symmetrical crater or, in 

 the event of damage, restoring symmetry quicklj^. Both electrodes are fed forward by 



Table I. — Characteristics of Typical Spotlights 



Spot 



Incandescent 



lamps 

 power, kw. 



36-in. reflector 

 24-in. reflector 



18-in. reflector 



Lens, large . . . , 

 Lens, medium. 



Baby 



"Lupe" lights 



