NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Math principle of Soviet dipmeter, correction
From: Alexandre Eremenko
Date: 2012 Apr 25, 23:23 -0400
From: Alexandre Eremenko
Date: 2012 Apr 25, 23:23 -0400
In my previous message on this subject I said that "a US stadimeter, which is apparently based on the same principle as the Soviet dipmeter." The stadimeter I am talking about is called the Schick stadimeter. There is one like this in the Mystic Seaport Museum. Now I have it and see that this is not so. It has no telescope, but simply an extremely small pinhole. In front of the pinhole there are two horizontal bars, one fixed and one moving up and down. The moving one is moved by a cam which is on the axis of the wheel with a scale. That's all:-) The disadvantages are a) small accuracy (limited by the size of the pinhole), and b) poor performance when there is not enough light. A similarly-looking Soviet range finder seems to be of the same construction as the dipmeter (where the main part are two lenses, positive and negative which move parallel to each other), http://www.ebay.com/itm/370604452555?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649#ht_2471wt_1163 but the price tag on it is close to a good metal sextant, and I am reluctant to pay so much as I have no real use of it. And I don't need it to verify whether I am right or not: A very complete Russian manual is posted with it, and it shows that the device works like the Soviet dipmeter. So in principle it must have the performance of the best sextant-type stadimeters, or better. Alex.