For Sale – 1933 – #764 — of only 2500 made. Dempster RotaRule Circular Slide Rule, Model AA #764. One of the top collectable circular slide rules. He started with a original metal prototype of five feet in diameter, in his Bekery CA basement. This circular slide rule is old with some wear and is 5 in diameter. It rotates fine and has smooth action. The brake release is loose and needs adjustment. Some red letter color on the far outside handle faded to missing. The black ink color on the serial #764 is gone but indentation is visable and clear. All other red and black markings are clearly readable. Production #764 of 2500. Produed between 1928 – 1948. There is no optional magnifier stand combination for this piece. The leather case has one strap end with the stiching missing, see photos. The 46 page Directions manual is stapled binding and is loose with multiple pages loose from the staples. The pages are yellowed due to age and a rip on page 39. Overall condition is ok and lettering very readable. The white, 4 page, folded pamphlet is almost completely apart into four pages and pages are yellowed. All writing and pictures are clear and readable. History: Highly regarded during WWII RotaRules were used by the Military in various applications, including gunnery calculations. One known example: a RotaRule was carried across Omaha Beach during the Normandy Invasion in 1945 by a young Gunnery Officer. This was because the Dempster Circular Slide Rule was so easy and in such high demand. I say no more since serious collectors already know the significance of this beautiful instrument. What a Historic Piece for the Serious Collector or Museum!!! . For investment, nostalgia or better- Bragging Rights. There are Few Known Pieces. Thank you for your time and please read the articles on John R. Dempster if you don’t know of this great man, his outstanding work, dedication and brilliance to all in the United Sates of America. I mostly sell vintage & pre-owned items. I try to thoroughly describe all flaws. Please view all photos. The item may have or not have been in a smokers home, or a home with pets. I try to provide the best customer service possible. The item “1933 Model AA #764 only 2500 made John R Dempster RotaRule Circular Slide Rule” is in sale since Tuesday, May 14, 2019. This item is in the category “Collectibles\Science & Medicine (1930-Now)\Engineering\Slide Rules”. The seller is “dpbeachaau” and is located in Las Animas, Colorado. This item can be shipped to United States.
- Country/Region of Manufacture: United States