Through The Overcast: The Weather and the Art of Instrument Flying, by Assen Jordanoff F9F Cougar Hydrostatic fuel quantity indicators are

Hydrostatic fuel quantity indicators are readily identifiable by the pump knob at their base

The dial and rim show the impact of sun exposure

and rather heavy

The case screws are missing and the case can be readily removed to view the gyro inside

The book is in good condition given its age

Through The Overcast: The Weather and the Art of Instrument Flying, by Assen Jordanoff F9F Cougar Hydrostatic fuel quantity indicators areThrough the Overcast, originally published in 1938 (this edition 1943). This 356 page book covers all that was known and deemed important at the time regarding flight by instruments. The book is in good condition given its age.