NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Pocket sextant
From: Dan Allen
Date: 2005 Dec 12, 08:06 -0700
From: Dan Allen
Date: 2005 Dec 12, 08:06 -0700
I own two such sextants but I have not used them enough to know about
their errors. I'll have to do some testing sometime...
Dan
-----Original Message-----
From: Navigation Mailing List [mailto:NAVIGATION-L@LISTSERV.WEBKAHUNA.COM]On Behalf Of Jim Hickey
Sent: Monday, December 12, 2005 7:59 AM
To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM
Subject: Pocket sextant
From: Navigation Mailing List [mailto:NAVIGATION-L@LISTSERV.WEBKAHUNA.COM]On Behalf Of Jim Hickey
Sent: Monday, December 12, 2005 7:59 AM
To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM
Subject: Pocket sextant
A number of years ago I purchased out of curiosity a small craft sextant by Francis Barker & Son. When
received
the instrument appeared in excellent condition and well
made.
I was interested in seeing just how well it performed in comparison to my
good full sized brass sextant.
The small sextant as one would expect was difficult to use with the
tiny mirrors but results could be consistently obtained within +/- about 1'
under ideal conditions. In an absolute sense, the instrument performed as
advertised.
What I did discover was that this sextant has an error in it through the
entire arc of about 3' per 10 degrees on the arc. No perceivably perpindicularity error. No optics to contend with. I
simply made a small table that I keep with the instrument.
Has anyone on this forum used one of these sextants? Has anyone had a
similar experience? Maybe my expectations were too high but I was surprised by
the systematic error I discovered.
Cheers,
Jim