83 
1879.] L. Schwendler— On Electric Light Measurements. 
You all have beard no doubt a great deal about tbe division of tbe 
electric light. During tbe last two years this question has been before tbe 
public almost permanently. This is not to be wondered at if we consider 
that on tbe solution of this problem it will ultimately depend whether tbe 
new mode of lighting becomes a successful and general rival to tbe illumina¬ 
tion by gas, or other combustive means. But before entering on tbe subject 
it will be best to formulate tbe question definitely, to avoid any misunder¬ 
standing with respect to tbe answer I am about to give. The question 
is : A given permanent current (C), no matter bow produced, does work 
in a closed single circuit of total resistance (R), of which a part (r), 
represents tbe resistance of one electric arc. This electric arc produces an 
electric light of measured intensity (I). Now if we introduce instead of 
one arc, two arcs of resistance r and r" and measured light intensities i' 
and i" respectively, and suppose tbe current to be the same as before—or 
the E. M. F. and total resistance in the single circuit the same, then a priori 
we should conclude that I = i' + i" for r = r' + r". Experiments, how¬ 
ever, show that this is not the case, i. e., tbe sum of the measured inten¬ 
sities of two small lights is perceptibly smaller than the measured intensity 
of one large light, and this difference becomes larger and larger as we 
increase the number of lights produced by the same current, i. e., by the 
same E. M. F. with the same total resistance in circuit. This appears at 
first sight an inconsistency with the known laws of cause and effect. How 
is it possible that the same current through the same resistance should 
produce more light in one point than in two points, although the total 
amount of work done by the given and constant current is exactly the 
same in one point as in tivo points ? 
That the measured intensity of one light, is invariably greater than 
the sum of the measured intensities of n lights, is an undoubted fact 
proved by my own experiments very conclusively. But we may well 
ask what has become of the energy which is expended and does not appear 
as light ? 
A careful analysis of all the physical facts connected with the subject 
will, however, show easily enough how this apparent loss^of energy is to be 
accounted for, without reverting to far-fetched explanations, and without 
the necessity of making such statements as : “ the division of the electric 
light is in contradiction to dynamic principles or “ the laws of nature 
must be reversed”—whatever that may mean ; or “ new laws have to be 
discovered first, before a solution of this important problem could be even 
attempted &c. &c., which I have read frequently in scientific or pro¬ 
fessional journals and newspapers. Statements of this kind appear very 
clever to the uninitiated, and they are exceedingly cheap to make, but they 
