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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Sextant frames
From: James N Wilson
Date: 2009 May 22, 20:15 -0700
From: James N Wilson
Date: 2009 May 22, 20:15 -0700
A bit far fetched from the effects of thermal expansion on sextant frames, but some years ago I took a look at the reality of the phrase, "Freeze the balls off a brass monkey." Historically, the brass monkey was what supported the local store of cannonballs. I think that the assertion was that in extreme cold, the cannonballs would shrink enough to fall off the supporting monkey. Here's what I found: The difference in the coefficient of thermal expansion between brass and iron is 6x10-6. Applying that to a 4 inch diameter cannonball (and a similar sized hole in the monkey) times a 100 degree F temperature change equals .0024" on the back of my envelope. I can't imagine that such a minuscule change would affect the static stability of a cannonball on the monkey. Sorry to throw cold water on a colorful phrase. Jim Wilson ____________________________________________________________ Compete with the big boys. Click here to find products to benefit your business. --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---
