“instrument of the week”: comparing compasses

by on Apr.03, 2011, under General

Interesting to compare different compasses made in the 40’s and 50’s. With Ralf’s latest piece of his collection, we can compare three different cases and plexi dome shapes.

The flexible lugs are an eye catcher on the first (and probably the oldest) compass. Remarkable are the solid lugs and the black painted case of the 2nd compass, which has the same construction on the bottom of the case (6 screws going into the plexi dome) as the version with flexible lugs (see side view on the 2nd photo). Click here for more details.

Both small compasses have a short bearing line which is drilled horizontal into the dome (see top view on the 1st photo). The big compass made in the 1950’s has a longer bearing line across the entire dome. The position of the screw to open the plexi dome for filling it up with fluid is is at 3’o’clock position (90°), while on the smaller compasses the position of the screws is different (at 225° on the flexible lug version and at 45° on the small version with solid lugs).

The compass rose on all three compasses is divided into 22.5° sections, commonly used in seafaring circles. Note also the different shape (hight) of the plexi domes on the small compasses.

[photos by Ralf Ehlers]

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