NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Chuck Varney
Date: 2023 Apr 22, 11:35 -0700
Frank Reed,
You wrote, in reference to my statement that the Smithsonian had wrongly attributed introduction of the index arm spirit level to William Harkness:
"Well, in fairness to the Smithsonian folks, it seems that one of the advertisements also refers to this as "Prof. Harness' Pattern". I wonder what was going on there... Did Harkness independently suggest the idea? Or did he invent some small enhancement that briefly came to be associated with the original invention? This is small-time historical trivia, but it I admit I'm curious. :)"
I tend to think the Smithsonian folks drew an incorrect conclusion of origin from the words that Harkness used in the document they referenced ("Report of Professor William Harkness, U.S.N.," in B. F. Sands, ed., Reports on Observations of the Total Eclipse of the Sun, August 7, 1869 (Washington, D.C., 1870), p.30.on the Smithsonian).
Specifically, in a list of instruments employed, Harkness wrote on page 30:
"A Sextant, made by Stackpole & Brother, of New York, from my own designs, marked No. 937, of six inches radius, divided on platina, and reading to ten seconds, having a telescope of 5.32 inches focus and 0.89 inch clear aperture, provided with eye-pieces magnifying respectively 2.75, 5.66, and 8.88 diameters. Attached to the index bar is a finding-level, which proved a very great convenience and saved much time and trouble."
Yes, he used a sextant made to his specifications by Stackpole & Brother. The fact that he referred to its having a 'finding-level' attached to the index bar without defining what a finding-level was, or how it was used, suggests to me that it was something previously known in the astronomical community, and not something originating with his 1869 sextant design.
The above-cited Harkness report is one of many in a document titled "Reports on Observations of the Total Eclipse of the Sun, August, 7, 1869", which may be viewed, and downloaded, from:
https://books.google.com/books/about/Reports_on_Observations_of_the_Total_Ecl.html?id=x03nAAAAMAAJ
Chuck V.
