9 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
and its entrance are of tin, so modeled, painted, and sanded as to give the appearance 
of having’ been built in solid freestone. Practically all the light that gets into tin- 
place is through the glass fronts of the series of aquaria and the doorway passage 
It is an admirable arrangement and admits of the study of the forms of many kinds 
of fish and plants, and certain iuvertebrata as well. To a limited extent it likewise 
permits the study of some of the habits of the forms exhibited. 
To one having but little knowledge of the use of the camera, it would appear to 
be but a simple matter to photograph under such apparently favorable conditions, 
but such is by no means the case. In the iirst place, in most instances the incessant, 
rapid, and often erratic movements of the tish themselves have to be taken into 
account; the aquaria being large, we have in the second place the difficulty of prompt 
focussing to contend with, due to the latitude enjoyed by the smaller and more active 
forms. Thirdly, there is the question of reflection, and this, taken in connection with 
the light, is a serious problem. Reflections are especially troublesome, as the glass 
fronts of the aquaria receive them from all directions, so that, after focussing, a careful 
study of the image upon the ground-glass will show these reflections not only from 
some of the other aquaria, but possibly the photographer and his camera besides. 
All this must be carefully guarded against. 
In the early part of July, 1897, I made a number of attempts to photograph the 
fish contained in these aquaria through the glass-fronts, and in several instances I 
was successful. Where failure resulted it was due to some of the causes enumerated 
above, or, as in the case of a catfish, due to the high light upon the fish itself. High 
lights on the bodies of fish, if present at the time the exposure is made, will in the 
prints made from such a negative produce areas of white wherein all detail is absent. 
This is to be especially avoided, and often can only be overcome by shielding the 
aquarium from the suu above. An umbrella will in nearly all cases serve this purpose. 
The camera employed upon this occasion was an old-model Blair tomograph, with 
a Voigtlauder lens (No. 1) (27,967), an instantaneous shutter of the Low pattern, Seed’s 
gilt-edge plates (5 by 8). I used stops as any special case demanded. A tripod is 
absolutely essential to success in this kind of work. The instrument was set up in 
front of one of the more favorable aquaria and focussed upon the part desired and an 
inch or two beyond the surface of the glass. An armed plate-holder was inserted in 
place and the “ snap ” set. Patient waiting for an exposure when the fish swims to 
the place where you want it is necessary. Care must be taken in drawing or pushing 
back the slide to the plate-holder, and some of niy failures were due to complications 
of this nature. 
The first exposure was made upon a large pike [Lucius lucius), some 18 or 20 inches 
long and in good color and condition. It had a duration of about 2 seconds, at which 
time the plane of the left side of the fish’s body was nearly parallel to the plane of the 
glass, and about 3 inches from its inner surface. A quarter of an inch diaphragm 
was used, and the subject remained practically motionless during the time of exposure. 
Overhead the light was somewhat diffused, and an additional disadvantage presented 
itself in the fact that the color of the pike closely simulated the shade of the metal-back 
of the aquarium, thus rendering strong outlines of the resulting negative a matter 
of doubt. However, the picture (plate 7, lower figure) was fairly good, and on com- 
paring it with the figure of this species in “The Fisheries and Fishery Industries of 
the United States” (plate 183, upper figure) it is to be observed that in the living 
fish the pectoral fins are extended almost directly downward; and further, that the 
