100 L. Schwendler— On Electric Light measurements. [March, 
Results. 
Economy of Electric Eight. 
The energy of the standard candle was ascertained by direct experi¬ 
ment. See Appendix VIII. 
It was found that the standard candle, in order to produce the unit 
of light, does work at the rate of 610 meg-ergs per second, at the least. 
In fact it is highly probable that the standard candle, in order to 
produce the unit of light, works up to more than double that amount 
(1965 meg-ergs per second). 
Further, by direct experiment, it was ascertained that the unit of 
light, as produced in an electric arc, by any one of the dynamo-electric 
machines under trial, and through a leading wire offering not more than 
0-1 S.U. resistance, is produced at the rate of not more than 20 meg-ergs 
per second, including all the work transmitted , and the light measured in 
a line which passes through the centre of the arc, and stands normal to its 
axis. Hence the probable engineering margin in favour of the electric 
light is between 30 to 70, or equal to a mean of 50. 
Dynamo-electric machine A produces the unit of light at a rate of 
not more than 10 meg-ergs per second. 
Hence it may be safely asserted that the electric light produced by 
dynamo-electric machines is as an average 50 times cheaper than light 
by combustion. 
This is, however, true only as long as the light is produced in one arc. 
If more than one light is produced in the same circuit by the same 
cun ent the external or available light becomes rapidly dearer with increase 
of the number of lights produced. 
I oi this leason already, if not for many others, the division of light 
must result in an engineering failure. 
It is in the nature of the electric light that it should be used in 
great intensity in one point, instead of small intensities in many points. 
1 or the experimental details and complete information on this in¬ 
teresting point. See Appendix IX. 
Current produced by Dynamo-Electric Machines. See Appendix XI. 
These currents, as the insertion of a bell-telephone (used as a shunt) 
will easily prove, are not steady. 
The dynamo-electric machine with the greatest number of sections 
in the induction cylinder gives the steadiest current. Twelve sections I 
find necessary and sufficient. 
Influence of Speed. See Appendix X. 
The current produced by any dynamo-electric machine through a 
given constant total resistance in circuit increases permanently with the 
speed of the induction cylinder. 
