Serial D-282. Phototube housing and lamp housing directly attached to main unit. Attached by cord is undistinguished light gray metal box (power supply regulator?) Mfg. National Technical Laboratories, South Pasadena, CA.
Spectrophotometer, quartz, Model DU
Serial no. 29649. With phototube housing and lamp housing directly attached. Connected by cord to power supply; cord is frayed. Mfg. National Technical Laboratories.