What are these gauges on the Comet 4's engine-gauge panel (between the captain's and first officer's instruments, above the throttle levers), marked "POWER LOSS INDICATOR", for? (Sorry for the blurry image.)
(Image cropped and annotated by me; original by Geni at Wikimedia Commons)
I'm assuming they're engine gauges of some sort, since there're four of them and they're located immediately below the engine RPM and EGT gauges (and above the throttle levers); could they be for monitoring engine performance during hot-and-high takeoffs?
They are apparently not present in the Comet 1, which instead has engine oil temperature/pressure gauges in this area (see pages 59-60 of this PDF, marked as pages 58-59).