A SIMPLE PHOTOGRAPHIC SPECTROMETER. 
Epwin Morrison. 
Photographic spectrometers of several different types can be purchased 
from instrument makers. Attachments to convert ordinary prism spectro- 
meters into photographic spectrometers can also be found upon the market. 
It is the purpose of this article to describe a method of constructing a simple 
photographic attachment for a prism spectrometer that can be constructed at 
slight expense in any well equipped laboratory. 
Figure one shows a diagram of the camera attachment. The dimensions 
have to do with the one I have constructed, and would need to be modified 
to meet the conditions of available material. That is, the length and diam- 
gees ae 
eter of the camera tube is determined by the focal length and diameter of the 
objective lense used. The figure is largely self explanatory. The section of 
the tube from C to B is constructed from a piece of wood 3x8x7 inches. A 
hole is bored lengthwise through this piece. From C to E this hole is 2 inches 
in diameter, and in order to shut out the stray light from around the focusing 
tube the remainder of the distance from E to B is 134 inches. A brass tube 
T, 2 inches in diameter is carefully fitted into the hole in this piece so that 
it can be slipped freely inward or outward for focusing purposes. At the 
outer end of this tube a 1%4-inch, 28 inches focal length, achromatic lense L 
is mounted. The tube from B to A is a tapering box, 2! inches square at 
B and 4 inches square at A. This section is constructed from 3s-inch lumber, 
the joints being carefully glued and reénforced by screws to make the box: 
