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Binocular List #251: 31 March 2003
Subject: Hastings Brashear Binocular
From: "Steve Stayton" <sstayton@___ink.net>
The Hastings-Brashear Roof Prism binocular that was acquired on ebay recently is really fascinating and was new to binocular historians and collectors as far as I know until this one turned up. I will be posting a detailed description and pictures of it as found and disassembled on my website (under construction as they say) in the future as my time allows. It is a very early example of a roof prism binocular and the first one that I know of using this particular type of prism arrangement. Here are some links to some low resolution pictures:
Hastings-Brashear Binocular http://www.lightmechanics.com/HB1/HB_Binoc2.jpg
Prism Assembly: http://www.lightmechanics.com/HB1/HB_Prism2.jpg
The build and finish of the binocular is consistent with quality commercial binoculars of the time but it would seem to me that this binocular is a prototype built to evaluate the usefulness of the Hastings erecting prism. The binocular is constructed in a form more typical of 19th century non-prismatic twin telescopes than that of the new Zeiss type prism binoculars of the day. It may well have been one of a kind or one of a limited production prototype build. Maybe it was a modified twin telescope body with the prism and new imaging optics replacing the original erecting lens system but I don't recognize the particular model as one I have seen before. If anyone knows of a similar binocular body without prisms please let us know.
John Brashear (1840-1920) was a famous American telescope maker and optician known for his high quality of workmanship. For some info on Brashear see: http://johnbrashear.tripod.com/
The ebay seller told me that the binocular was purchased at a flea market in Pittsburgh so it is possible that it spent its first 100 or so years close to its presumed origin at the John A. Brashear Co. works in Pittsburgh.
It is well known that John A. Brashear Co. built production quantities of lenses and porro prisms for the Warner and Swasey binoculars starting in 1899. (ref: W.R. Warner, The How and Why of the Porro Prism Field-Glass, Transactions of the ASME No.926, December 1901) The porro prisms used in the W&S required much less accurate face angles than the roof prism type of the Hastings. The level of precision required to fabricate the roof prism in the Hastings prism would be an obstacle in making the design cost effective for the commercial market.
The Hastings-Brashear binocular is engraved with a patent date of July 20, 1897. The patent (US Patent 586,708 titled "Erecting Prism" dated July 20, 1897) is awarded to Charles S. Hastings (well known American optical scientist of Hastings Triplet fame) and no mention is made of Brashear in the Patent. Charles Hastings was employeed by Brashear to "calculate the curves of lenses" (as they called optical design back in those days) starting in 1887.
Hastings 1897 Roof Prism Patent: