JANUARY 4, 1884.] 
during the 100 days of the exposition, with 
over 4,000 lights burning, there was not at any 
time a suspension of light from failure of the 
appliances of the Edison electric lighting com- 
pany.”’ 
Of the arc-lights, lamps were chosen, one 
at a time, from the circuits, and inserted in 
the same circuit in the photometer-room, care 
being taken that no change was made in the 
circuit adjustments. Indicator-cards were 
taken from the engine used, during the test- 
ing of each lamp. The strength of current, 
and fall in electromotive force, were also de- 
termined with an amperemeter and voltmeter ; 
but, as only relative results were desired, these 
instruments were not graduated. 
The photometer-bar was fifty feet long ; and 
tests showed that there was no reflection vi- 
tiating the results, from the dead-black surface 
of the walls of the room. The photometric 
tests were made with an Edison incandescent 
light as a standard. Fifteen tests from candle 
to incandescent, and ten from incandescent to 
arc lights, were made for each lamp, five arc- 
light tests being between the same number of 
tests of the standard. 
_ The are-light was cut out during the tests 
of the standard, and a new cup was allowed 
to form before the next set of tests was made. 
The dynamos were worked to their full 
advertised capacity in regard to the number 
of lights in the circuits; and four lights were 
tested in each case, with the following re- 
sults : — 
_ | Thomson 
Jenney. Houston. 
Total number of lightsin circuit. . .. 16 12 
Total mechanical horse- -power. . - 26.92 11.79 
Average horizontal intensity in candles 496.5 291.8 
Average intensity per horse-power . . 306.5 296.9 
Relative efficiency of lamps from light, 
current, and fall in electromotive force . 1.055 i 
From these tests, and an examination of 
the dynamos, lamps, regulators, etc., the 
awards were made as follows: to the Edison 
company, for isolated lighting, medals for the 
best incandescent system and light, and for 
the best dynamo and lamp for the incandes- 
cent light; to the Fort Wayne Jenney electric 
lighting company, medals for the best system 
and dynamo for arc-lighting; but, to the 
Thomson Houston electric lighting company, 
a medal for the best arc-light, because, ‘‘ while 
the light of the Jenney was slightly stronger 
per horse-power of electrical energy used in 
the lamp, it was not quite so steady as the 
Thomson Houston.”’ H. W. Eaton. 
SCIENCE. , 15 
THE LATE MR. DARWIN ON INSTINCT.! 
AT the meeting of the Linnean society this even- 
ing (Dec. 6) a highly interesting posthumous paper 
on Instinct, by Charles Darwin, will be read and 
discussed. We have been favored with an early 
abstract of the same, which we here present to our 
readers. 
After detailing sundry facts with reference to the 
migratory instincts of different animals, Mr. Darwin 
proceeds to suggest a theory to account for them. 
This theory is precisely the same as that which was 
subsequently and independently enunciated by Mr. 
Wallace in Nature, vol. x. p. 459. Thus, to quote 
from the essay: ‘‘ During the long course of ages, let 
valleys become converted into estuaries, and then 
into wider and wider arms of the sea; and still I 
can well believe that the impulse [originally due to 
seeking food] which leads the pinioned goose to 
scramble northward would lead our bird over the 
trackless waters; and that, by the aid of the un- 
known power by which many animals (and savage 
men) can retain a true course, it would safely cross 
the sea now covering the submerged path of its 
ancient journey.”’ 
The next topic considered is that of instinctive 
fear. Many facts are given showing the gradual 
acquisition of such instinctive fear, or hereditary 
dread, of man, during the period of human observa- 
tion. ‘These facts led Mr. Darwin to consider the 
instinct of feigning death, as shown by sundry species 
of animals, when in the presence of danger. Seeing 
that ‘death is an unknown state to each living crea- 
ture,’ this seemed to him ‘a remarkable instinct:’ 
and accordingly he tried a number of experiments 
upon the subject with insects, which proved that in 
no one case did the attitude in which the animal 
‘feigned death’ resemble that in which the animal 
really died; so that the instinct really amounts to 
nothing else, in the case of insects at all events, than 
an instinct to remain motionless, and therefore incon- 
spicuous, in the presence of danger. From the facts 
given with regard to certain vertebrated animals, 
however, it is doubtful how far this explanation Ps 
be applied to them. 
A large part of the essay is devoted to Aen 
and habitation,’ with the object of showing, by an 
accumulation of facts, that the complex instincts of 
nest-building in birds and of constructing various 
kinds of habitations by mammals, all probably arose 
by gradual stages under the directing influence of 
natural selection. 
The essay concludes with a number of ‘ miscella- 
neous remarks’ on instincts in general. First the 
variability of instinct is proved by sundry examples; 
next the fact of double instincts occurring in the same 
species; after which, ‘‘as there is often much diffi- 
culty in imagining how an instinct could first have 
arisen,’’ it is thought ‘‘ worth while to, give a few 
out of many cases of occasional and curious habits, 
which cannot be considered as regular instincts, but 
which might, according to our views, give rise to 
1 From Nature of Dec. 6. 
