I completed my RN apprentiship in 1957 and recall during the Instruments phase that it was explained that a civil accident had occurred when the 10000 ft needle was hidden behind the 1000 ft needle.
The solution was to place a circular ring on the 10000 ft needle that could be seen when the needles overlapped, which became standard on RN aircraft.
I believe the Scimitar was the first FAA aircraft to have the cross hatch window in the altimeter.