208 
cultivate. Given this desire for research, 
which is the inevitable result of the habit 
of experimentation in every one whose 
mind is fit for scientific pursuits, and all 
other difficulties, those of time, opportunity 
and equipment can be overcome. Certain 
lines of investigation which one would 
gladly follow must indeed be abandoned 
for lack of means with which to pursue 
them; but he who keeps alive his knowledge 
of scientific progress by the systematic 
reading of the literature of first sources 
need never lack topics of research. 
The proper stimulus for scientific work is 
the love of experimentation for its own 
sake rather than any desire or expectation 
of fame; the delight of witnessing the 
wonderful performances of matter under 
conditions conceived and imposed by our- 
selves, rather than the hope of achieving 
some momentous result. At the same time 
we should not forget that the very simplest 
phenomenon of nature is worthy of our 
closest, even of our reverent attention and 
that some experiment as seemingly unim- 
portant as the shooting of quartz fibers, 
may, like that now famous operation of a 
fellow teacher (Boys), be ultimately of in- 
estimable value to science. 
Epwarp L. Nicuots. 
PHYSICAL LABORATORY OF 
CORNELL UNIVERSITY. 
ON ECLIPSE PHOTOGRAPHY. 
Some months ago the writer suggested 
that the dangers of over-exposure in photo- 
graphing eclipses might be avoided by a 
long exposure covering the entire totality 
of the eclipse, and a development of the 
plate as a positive in the light. Since that 
time the interval of exposure in the camera 
has been considerably reduced by increas- 
ing the illumination of the plate while in 
the developing bath. Plates can with proper 
exposure be developed in direct sunlight, 
with a reflected beam of sunlight also 
SCIENCE. 
[N. S. Von. XIII. No. 319. 
thrown down upon the plate. But while 
such pictures leave nothing to be desired 
for clearness and sharpness of detail, they 
do not show any details which can not be 
brought out in a negative. Moreover, the 
exposure required to produce a good pos- 
itive is still rather too long to make this 
method in its present condition seem of 
much advantage in eclipse work. 
But it has also been found that the de- 
veloper best suited to producing fine pos- 
itives will develop beautiful negatives in 
the dark-room, on plates that have been 
over-exposed as much as two thousand 
times. Such plates thus exposed may be 
developed either as negatives in a perfectly 
dark roém, or as equally good positives in 
a light room, and with the same developer. 
Where the normal camera time is a tenth 
of a second, the exposure may be as great as 
three minutes and a half, and still secure a 
sharp crisp negative. With greater ex- 
posures it is better to develop the plate 
as a positive in the light room. 
The developer recommended, as the best 
so far tried, is hydrochinone made up ac- 
cording to Cramer’s formula, with the 
bromide left out. The sodium carbonate 
solution may be made up at half the 
strength given in the formula if the devel- 
oping is to go on slowly. To half an ounce 
of the mixture of solutions one and two, 
add an ounce and a half of water and four 
or five drops of saturated hypo solution. 
When the plate has been normally ex- 
posed and it is treated with this developer 
containing two drops of hypo, in a covered 
tray in the dark room, nothing will de- 
velop for 30 or 40 minutes. But in course 
of an hour and a half the picture will be 
fully developed. The details will show 
sharply through the film. The tray should 
be uncovered as little as possible. The 
plate is sensitive even to red light. Until 
the last stages of development are reached, 
the exposures for examination of the plate 
