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Re: SNO-T Manual, Heath Brochure CLEANING SEXTANTS

From: Joel Jacobs (no email)
Date: Fri Aug 06 2004 - 08:15:09 EDT

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    Lee,

    Thanks much for pointing me at the other site.

    I am sorry to be a bother again, but I still have a problem. The CHO-T link results in a 404 Error. Since I was able to read the Heath manual, I doubt my pdf system's at fault.

    IMO, the Heath manual is full of worthwhile material, including mounting a stop watch on a sextant. It does a very good job in discussing scopes. The manual states the clear portion of the horizon glass is an advantage since it reflects back the other half of the image which is lost if the horizon mirror only has a silvered side. Remember the lengthy exchange of this topic started by Jim Thompson. I couldn't find a date on the manual, can you confirm where you obtained the 1936 date you mentioned?

    However, the manual is light on the topic of taking care of a sextant. This is surprising since they talk about a very special mirror, "Sea Safe" with a laminated cover glass and notched sealed and glued edges to make it water proof, and then only superficially discuss the care and feeding of standard mirrors. So lets get back to sextant cleaning and the use of water to rid the instrument of salt for a movement. Surprisingly, this went unmentioned in the Heath manual. For those interested, I suggest reading Article 1610 of Bowditch, and also the extensive discussion by Bruce Bauer in the "Sextant Handbook". Bauer goes so far as suggesting placing the sextant in a bucket of fresh water if it was splashed with seawater. That's a measure that sounds pretty extreme.

    Thanks Lee,

    Joel Jacobs
      ----- Original Message -----
      From: Lee Martin
      To:
      Sent: Thursday, August 05, 2004 10:46 PM
      Subject: SNO-T Manual, Heath Brochure

      Joel apparently had trouble with downloading the SNO-T manual from Gerard's site, others found it worked fine. There is an alternative site for download at www.pcug.org.au/~martin/Sextants/ . Also on that page is a 1936 Heath and Co brochure on the care and maintenance of sextants, with particular reference to Heath sextants.

      Lee Martin

  • Next message: George Huxtable: "Derek Howse's book "Nevil Maskelyne, the seaman's astronomer""



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