would produce a stronger signal from the photomultiplier tube, which would result in faster servo response, The tachometer feedback circuit also warranted component changes to eliminate feedback voltage. Optimum operation resulted with the ''feedback pot'' in the fully counter-clockwise (off) position. The light source strength was also critical item. The best operation resulted with a General Electric 300 watt PH/300 TIOP-120 volt projection lamp which had a lifetime of only 30 operating hours, The red-light (GE-328) indicator on the microswitch push button of the densitometer did not operate satisfactorily, due to the red bulb's lifetime of from only two to three days, The Mosely servo-voltmeter performed excellently, requiring only occasional cleaning and oiling. The correct reference voltage was obtained with an Eveready No. E502 mercury-type battery, The Mosely curve follower also performed excellently. The X-axis potentiometer had to be swabbed out with carbon tetrachloride every other day. The correct X-axis reference voltage was obtained with a Mallory RM-12R mercury-type battery. 2.4.12 PRAM-5 The Jordan aerial survey instruments, PRAM-5, did not function properly and were deadlined at the start of the Operation. Considerable circuit checking and recalibration was performed to no avail, ll