A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Bill Morris
Date: 2016 Feb 3, 20:18 -0800
I am pretty sure that the instrument is a dip meter. There is a dip meter for sale on e-bay at the moment: http://www.ebay.com/itm/221947240119?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT.
It has a certifcate and log book rated 1953. I think it is probably earlier than the one described here: https://sextantbook.com/?s=russian+naval+dip