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Psyche 
[September-December 
ment. The basic principle is the superposition of images from two 
lens systems, one from the moving specimen and one from an 
oscillographic trace, on the same film frame as it passes the lens 
openings. The insects were placed in a water-cooled cage (Fig. 2) 
against the observation window within a double-walled audiometric 
room (Industrial Acoustics Corporation). The camera (HYCAM, 
Red Lake Laboratories) was positioned outside the room on the 
opposite side of the window. An Angenieux 12:120 mm zoom lens 
faced the insects and was equipped with a 1 -diopter enlarging lens. 
The ultra-high-speed 16 mm camera is capable of speeds up to 
11,000 16 mm pictures per second, but only 800 pps was used in 
the present study. An 8-sided revolving prism coupled with a 1/2.5 
shutter is driven by the film advance mechanism. The prism and 
shutter are in the light path of the front lens only, and this system 
imposes a minimum aperture of F 4.2 on the objective. The rear 
lens (Pentax, F. 1.8, automatic) which faces the oscilloscope is 
inserted into the through- the- lens viewing aperture in the camera 
back. A two-way prism directs the oscillographic image through the 
back of the film onto the emulsion. (Film with minimum anti- 
halation backing is desirable, q. v.) 
The Tektronix 502-A oscilloscope (CRO) has a dual-beam 
cathode-ray tube (CRT) with a phosphor coating (P 11) which 
has the least persistence, greatest resolution and greatest photo- 
sensitivity ratio for the film speeds used. The trace is viewed on 
the CRT as a standing wave with only vertical amplification, and 
the advancing film, moving horizontally in the same direction as a 
normal oscillotrace, acts as that in a kymograph camera. It is 
possible to burn the CRT phosphor when the screen is on full 
intensity, therefore full intensity is used only for the few seconds 
of filming. The calibrating grid should be removed from the screen 
for filming. A light-tight sleeve connects the oscillo-lens and the 
CRT. Beam orientation and focus are important. The upper trace 
should be inverted so that the normal positive peaks of both traces 
point to the center of the screen (therefore, the film track) — espe- 
cially if one wishes to have the traces at the sides of the finished 
film rather than superimposed over the specimen. A timing trace 
of 1600 Hz (later calibrated at 1560 Hz in the pictures here) was 
produced by a Precision model E-310 signal generator using the 
square-wave mode, its 0.5 cm displacement was a calibration for 
the amplitude of the other trace. 
The acoustic signals were received by a Sennheiser 404 directional 
condenser microphone situated directly behind the grid in the water- 
