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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Centerless Sextant
From: George Huxtable
Date: 2008 Jun 14, 16:37 +0100
From: George Huxtable
Date: 2008 Jun 14, 16:37 +0100
d walden asked Anyone have information about: http://mobius.mysticseaport.org/detail.php?t=objects&type=browse&f=maker&s=Hughes%2C+H.+%26+Son&record=2 Micrometer quintant made by H. Hughes & Son, London INSTRUMENTS - QUINTANTS Micrometer quintant Hughes, H. & Son Micrometer quintant, brass frame, brass fittings, wooden handle. Stamped on front of frame: "Registered Trade Mark/ (rising sun over the water)/ Husun/ Gt Britain". Centerless sextant. Unusual and unsuccessful variation of common sextant manufactured by H. Hughes & Son. An attempt to lessen the weight and bulk to give the operator and easier celestial navigation instrument to hold steady. Measuring to 136�. 1953.3561 =========================== and Gary LaPook added- I don't have any information about it but we had the opportunity to see it at Mystic on June 6th. ============================= Comment from George- What an interesting device! Thanks to d walden for bringing it to our attention. I've never seen such a thing, or even heard of one, until now. There isn't one in Peter Ifland's "Taking the Stars". It's frustrating that the description and the picture from the Mystic website are so uninformative. Is more detailed information available elsewhere, I wonder? Calling it a "quintant" is somewhat overstating the matter. Formally, it's still a sextant, not a quintant until it reaches 144�, and this only reaches 136�. And even if the scale reaches that far, without trying it, it's hard to be sure that any instrument remains functional up to the limit of its scale, as often the field of view shrinks to an unusably narrow slot before reaching that point. The one picture is so muddy and small (even when expanded) that I can't work out what's going on, and where the optical path is, and even which way should be up. Can anyone else do better, or recall it from a visit to Mystic? Often, quintants were produced, not for navigating, but for nautical surveyors and hydrographers to measure horizontal angles. In which case, they would be sold without shades, and sometimes without a telescope; just a peep. Is that the case with this one? Is that why its handle is at such an odd-seeming angle? It's not surprising that the design failed to catch on. Presumably, without a centre-pin, the design must have relied on the machining of the rail, or rails, or grooves of the arc, and the wheels or rollers or balls that ran along it, to define the angle. That must have been extremely demanding in precision, if the device was to rival the precision of a normal sextant, and I find it hard to believe that it could ever have done so. Perhaps that was the reason for its short life. Willem M�rzer-Bruyns, now-retired director of the Amsterdam Scheepvaartsmuseum, has recently spent some time on a research fellowship at Greenwich, renewing their catalogue of navigational instruments, which has been badly needed, and I hope his new volume will be published soon. Then, I understand, he plans to do something similar for the Mystic museum, and again, that seems to be much in need of doing. He is very careful and methodical, and knows a lot about his subject. According to Willem, Mystic holds the World's largest collection of octants, and the third largest of sextants, after Greenwich and Mariners' Museum. George. contact George Huxtable at george@huxtable.u-net.com or at +44 1865 820222 (from UK, 01865 820222) or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK. --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---