Tripod mount for USBS model D aircraft sextant

This is a mount for a US Bureau of Standards Type D aircraft sextant. It may be attached to a tripod, monopod, or other base. This device offers a more stable measurement than hand held, giving a noticable improvement in accuracy. The sextant drops into the mount from the top, and there is provision for a locking device so that the instrument cannot fall out of the mount if it is overturned. This mount was designed to fit my sextant, and may or may not fit other examples of the type D sextant.