1920's SPERRY Angle of Sight instrument Brooklyn, NY #7573

1920's SPERRY Angle of Sight instrument Brooklyn, NY Marked #7473. This is a device that combines the functions of a prismatic aiming compass with that of a clinometer / abney level. When stood upright the clinometer can be disengaged allowing vertical angles to be measured on the white scale.

When the sights are also released a vertical angle can be sighted as with the service pattern clinometer. The clinometer scale can be locked for convenient reading.

If the large visor is raised the compass card is also unlocked. To read the compass, the clinometer card must be rotated out of the way by holding the device upside down. This will show the green compass card which can be read using the prism. The instrument was tagged a USN engineer tool that it was a military instrument. Not very familiar with this instrument and just did my research online to get all this information so I apologize if anything is inaccurate.

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