176 TRANSACTIONS OF THE 
Substituting this value for n and solving for a, we find 
that its value depends upon the size of the lamps. This 
was to have been expected since no two curves pass through 
the same origin. For the 25 watt lamp it is .0102, the 40 
watt, .0173, and the 60 watt .0231. These values are found 
to be roughly proportional to the rated watts of the lamps. 
A comparison between the observed and calculated values 
of the watts shows a close agreement throughout the en- 
tire range. This seems to confirm the uniform variation 
indicated by the curves. 
It would seem, therefore, that whatever the cause of 
the anomalous characteristics in the candle power curves 
for high voltages, it must be looked for elsewhere than in 
the direct relation between volts and watts. If the pres- 
sure-power relationship is uniform throughout the entire 
range of voltage, as it seems to be, and the candle power 
relationship is non-uniform, as it undoubtedly is, the true 
cause must appear in some intermediate step resulting pro- 
bably from a change in the properties, either physical or 
chemical, of tungsten. Since drawn wire tungsten under- 
goes certain mechanical and heat treatment in its prepara- 
tion it may be that such changes take place in the region of 
high temperatures even though no such changes have 
been observed in the native metal. 
TABLE I. 
WATTS. 
a = .0102 a= 01%3 a= O28 
25 25cal. 40 40cal. 60 60cal. 
Ohms 
rls 40 60 
Amperes 
e 25 40 60 
80 | .185 | .242 | .822 | 592 | 331 | 248 | 10.5 | 11.3 | 19.4 | 19.1 | 25.8 | 25.9 
100 | .158 | .274 | .365 | 633 | 364 | 274 | 15.8 | 16.2 | 27.4 | 27.4 | 36.5 | 36.8 
120 | .180 | .309 | .410 | 668 | 388 | 293 | 20.6 | 20.5 | 36.1 | 36.6 | 48.2 | 48.9 
140 | .200 | .3839 | .450 | 700 | 413 | 311 | 28.0 | 28.1 | 47.5 | 46.9 | 62.9 | 62.9 
160 | .220 | .364 |-.487 | 728 | 440 | 328 | 35.2 | 34.4 | 58.2 | 58.1 | 77.9 | 77.6 
180 | .235 | .391 | .525 | 765 | 460 | 343 ; 42.3 | 41.4 | 70.4 | 70.3 | 94.5 | 94.0 
200 | .255 | .415 | .555 | 785 | 483 | 361 | 50.1 | 49.5 | 83.0 | 83.0 |111.0 |111.1 
220 | .267 | .489 | .585 | 824 | 502 | 376 | 58.6 | 57.0 | 95.5 | 96.5 [128.8 |128.9 
240 | .280 | .461 | .617 | 850 | 520 | 389 | 68.1 | 65.5 |111.9 [111.2 |148.0 |148.1 
260 | .292 | .480 | .645 | 890 | 540 { 412 | 76.0 | 74.6 [124.9 [126.5 |167.5 |169.0 
| 
280 | .298 | 495 | er 946 | 566 415*| 83.0 | 83.9 ‘eae 142.3 |176.0*|179.0* 
n 
* e= 270 volts. Wave hc w= watts, e=volts. 
a and n = constants. 
