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From: Joel Jacobs (no email)
Date: Fri May 07 2004 - 15:53:41 EDT
Brooke,
That's an interesting item. I've never seen one like it before.
I note the compass card at the bottom of the device, and the ruler-like
upright scale. So here's a guess.
When a ship assumes a list as a result of being out of trim, or in the case
of a sailing vessel when it is heeled over underway, a different source of
deviation is introduced due to the compass ridding at an angle from
horizontal.
I submitt that this device is used to measure this type of heeling compass
error by simultaneously measuring the change in compass heading induced by
the list, while at the same time measuring the amount of list that produced
this change. There are certain compensating heeling magnets that hang in a
tube directly beneath the compass card to adjust for this error.
See Article 607 and the following, starting on page 88, of Bowditch. Mine is
the 1995 Edition.
Joel Jacobs
----- Original Message -----
From: Brooke Clarke
To:
Sent: Friday, May 07, 2004 1:00 PM
Subject: What is a "Rare Brass List Compass& Clinometer,Deflector"
Hi:
How is this used?
eBay item 3721631458
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=37967&item=3721631458
Thanks,
Brooke Clarke, N6GCE
http://www.PRC68.com
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