A photometer is arranged in such manner that the screen and the lamp tested are stationary, the standard lamp being adjusted in distance to effect a balance. If the standard is moved by means of a band running over a wheel conveniently near the screen this wheel will revolve through an angle proportional to the distance the standard is moved.
Proceedings of the Iowa Academy of Science
©1928 Iowa Academy of Science, Inc.
Spinney, L. B.
Proceedings of the Iowa Academy of Science, 35(1), 254-255.
Available at: https://scholarworks.uni.edu/pias/vol35/iss1/55