NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Trombone Kamal Prototype
From: George Huxtable
Date: 2009 Jun 6, 00:20 +0100
From: George Huxtable
Date: 2009 Jun 6, 00:20 +0100
About calibrating a cross-staff: I have this little scene in my mind of how a cross-staff maker might ply his trade. The erstwhile navigator enters, saying that he wishes to buy. The proprietor fetches one of his stock out of the window. All these stock items have been made with the staff a bit extra-long. "Stand exactly at this spot, the navigator is told, and with this instrument held by your eye, tell me the angle you make it between yonder horse-trough in the yard, and the baker's chimneytop across the alley." and a moment later- "twenty two degrees and fortytwo minutes, you say? I'll soon fix that". He takes it into his workshop, and knowing that the angle should be 23� 15', can work out exactly how much to remove from the end of the staff to bring the reading up to scratch. The mariner is asked to try again, and presuming that his reading is now the correct one, money changes hands, and both parties are happy, with the instrument now tailored to suit his own skull dimensions.. This is a scene that could be repeated over many years, as long as nobody shifted the horse-trough. That's just imagination. I have no idea whether that's the way it was done, but it's possible. George. contact George Huxtable, at george@hux.me.uk 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 -~----------~----~----~----~------~----~------~--~---