JANUARY 18, 1884.] 
phy has been advancing rapidly in the number of 
its applications to the arts and to the industrial and 
applied sciences. The Institute of technology has 
not been behindhand in recognizing this fact; and 
in the new building, now nearly completed, a large 
room in the south-west corner of the basement has 
been appropriated to the establishment of a photo- 
graphic laboratory, perhaps the first ever constructed 
in connection with a scientific institution, for the 
especial instruction of students in photographic 
manipulations, and for purposes of original research, 
in this most interesting department of applied science. 
The following plan shows the arrangement of a 
portion of the room, which measures sixty feet in 
length by thirty in breadth. 
P, P, are two brick piers surmounted by solid stone 
slabs, and constructed on foundations entirely in- 
dependent of the building, in order to avoid all pos- 
sibility of shock or jarring. Upon one of these, brick 
columns are built, which pass through the ceiling into 
the ‘fourth-year’ physical labora- 
tory, which occupies the room above. 
The other one reaches a height of 
three feet, and forms a solid founda- 
tion for the support of a heliostat, 
microscope, spectroscope, or other 
instrument. A and B are the two 
dark rooms, entirely separated from 
one another by a partition, and by 
a wooden frame containing the gas- 
jet G, which is partially surrounded 
on three sides by sheets of Carbutt’s 
ruby paper. S, S, S, are soapstone 
sinks, the two former of which are 
supplied with vacuum pipes for the 
purpose of accelerating filtration. 
T, T, T, represent tables, the one in 
the window being used for printing 
purposes, while the others are to sup- 
port photographic apparatus and ac- 
cessories. Gas will be introduced 
into the dark rooms over the sinks for 
lighting when they are not in photo- 
graphic use. It will also be supplied at the small 
square table in the larger dark room for heating pur- 
poses, such as boiling emulsions. C' is a case of 
shelves and drawers to contain books, paper, and ap- 
paratus. J# is a series of shelves for the storage of 
plates and chemicals. M is.a square wooden box 
resting on the pier, but connecting by an aperture 
measuring ten inches by twelve with the interior of 
the larger darkroom. This is to contain a microscope 
for researches in photomicrography, the light coming 
from the heliostat through a small hole in the box. 
The image is thence projected upon a screen placed 
inside the dark room, where the operator can examine 
it at his leisure. This screen is supported upon the 
focusing table R, which rolls upon a track, and may 
be placed at any distance less than three metres (ten 
feet) from the aperture at M. The dark room is 
thus converted into a large camera, inside of which 
the operator stands and exposes his plate, while he 
may at the same time be developing another one pre- 
SCIENCE. 
81 
viously taken. - The greatest efficiency, convenience, 
and economy of time are thus combined by this 
arrangement. 
Both dark rooms are constantly ventilated by a 
system of double walls, with openings at the ceiling 
and floor, whilst the draught of the lamp G is utilized 
to increase the circulation. The light thus becomes 
a source of health, instead of vitiating the atmos- 
phere, as is the case in most dark rooms. The room 
A is provided with double doors, so that the operator 
may leave the room at any time during an exposure, 
without the slightest fear that even the most sensitive 
plate could possibly be fogged by a chance ray of stray 
light. This arrangement, though convenient at all 
times, will be particularly so when working with long 
exposures of two or three hours in length; and, 
indeed, it is only by some such arrangement that 
these exposures become possible. Besides the aper- 
ture at M, a smaller one six inches square is made 
through the wall of the dark room. This is intended 
VM ou Vp__V7, 
PLAN OF PHOTOGRAPHIC LABORATORY. 
for spectroscopic and astronomical work. Either 
window may be closed by a sliding shutter when the 
other is in use. 
Between the brick columns of the pier P is placed 
a shelf, on which will be kept a large carboy contain- 
ing a saturated solution of potassium oxalate, from 
which the developer bottles may constantly be replen- 
ished by means of a siphon permanently attached. 
We thus avoid the trouble of continually making up 
fresh solutions, and at the same time do not require 
to have the developer bottles inconveniently large. 
The hyposulphite-of-soda and sulphate-of-iron solu- 
tions will be similarly provided for, the latter being 
covered with a thin film of oil to prevent oxidation 
from the air. 
The routine work of the department will be ar- 
ranged somewhat as follows. Only those students at 
the institute taking the courses in mechanical and 
electrical engineering, architecture, chemistry, natu- 
ral history, physics, and the general courses, will 
