Cit sis 
Arc-lamps. 
THOMSON-HOUSTON. WESTON. 
Direction Electro- Intensity 0 Direction Electro- Intensit 
pot Current. | motive Watts. | in terms of 1S of Current. | motive Watts. | in terms vf dail 
light. force. standard. wi light. force. standard... WY 
= 10.2 45.9 467 16.2 34.7 & 20.7 23.9 495 25.9 52.4 
ao 10.2 46.7 475 138.2 27.8 ~ 20.1 23.3 469 17.6 37.4 
eR 10.2 46.3 471 85.0 180.3 Cs 19.8 21.9 435 32.3 74.4 
Other lamps. 
= 10.1 46.1 465 | 18.0 38.8 = 20.0 25.6 512 30.7 59.9 
ke 10.2 46.3 474 | 98.8 209.0 i 20.8 25.0 522 51.7 99.2 
Means. 
- - - - iff 36.7 - - ~ - 28.3 56.1 
~~ = - - 13.2 27.8 aS - - - 17.6 - 37.4 
i - - - 91.9 194.6 a - - - 42.0 86.8 
General means. 
- ~ 40.7 86.4 ~ - | - 29.3 60.1 
—_ | == 
tion. The numbers under the head of ‘General a lamp were designated as ‘ flat’ (| ), ‘ edge- 
means’ show the average light in terms of the 
standard, in all directions measured, and the 
relative illuminating-power per unit of energy. 
There is a difference of more than forty per 
cent in favor of the Thomson-Houston. 
Photometry of incandescent lamps. 
The table below, showing the results of the 
photometric comparison of the incandescent 
lamps, will need but little explanation. In the 
first column the relative position of the carbon 
filaments is shown: thus, | | means that they 
were parallel to each other, and at right angles 
to the photometer-bar. The three positions of 
wise’ (—), and ‘forty-five degrees’ (\or/). 
E 
Wes 
the Watts of the Maxim. 
denotes the Watts of the Edison divided by 
The column headed 
E 
M shows the actual illuminating-power of the 
Edison, compared with the Maxim as a unit; 
and the numbers are the squares of the ratios 
of their respective distances from the pho- 
tometer-box. ‘The numbers in this column, 
divided by those in the one preceding, give the 
Ey 
numbers in the last column, headed M2 the 
Fi ) 
_ Incandescent lamps. 
POSITION. EDISON. | Maxim. 
ae Bat EE |e eealn € We ee, Er 
Edison. | Maxim. || Current. aioe Watts. Current. See Watts. Wis He Ms 
| | 648 | 113.0 13.2 .887 63.7 56.5 
Ye | .639 114.7 725 887 64.5 57.2 
— | .636 114.6 72.9 .870 61.8 SB 
—_ IN -622 115.4 71.8 .853 62.2 53.0 
— — .631 115.4 72.8 .853 61.4 52.3 
Yo — 631 116.1 73.3 .887 63.0 55.8 
| _— .631 115.7 73.0 .870 62.6 54.4 
| IN .639 116.5 74.5 .887 63.0 55.8 
va SS .648 114.7 73.5 .853 62.6 53.4 
| ’ 
t 
