Meta name="viewport" content="width=device-width, initial-scale=1.0">. This offer is for a new in the original package, Stadia Circular Slide Rule Computer. Made by the C-Thru Ruler Company, Hartford Connecticut. The circular slide rule works like this.The base, just outside the disc, has a logarithmic scale that represents readings in feet of a stadia rod used with a transit telescope. The edge of the disc has two scales of functions of angles. Applying the first scale multiplies the stadia reading by 1/2 sin 2A, where A is the vertical angle of the transit telescope. This multiplication gives the difference in elevation of the transit and the stadia rod, in feet.
The second scale multiplies the stadia reading by the square of cos A, to find the horizontal distance of the rod in feet. A very accurate and easy to use slide rule! Also a neat memorabilia item.The item "New Stadia Computer Circular Slide Rule+original pack. USA C Thru Ruler Comp" is in sale since Thursday, August 3, 2017. This item is in the category "Collectibles\Science & Medicine (1930-Now)\Engineering\Slide Rules".
The seller is "buckeye445" and is located in Columbus, Ohio. This item can be shipped worldwide.