NavList:

First some background - I am an armchair enthusiast. I have never used celnav professionally or recreationally. In the early 1970s I developed an interest in celnav and purchase a few books, including those by Blackburne and Cloudy Weather Johnson. I have since purchased other books including Norie and the Amiralty Manuals of navigation. A few days ago in a secondhand bookshop I found a copy of AP3270. I did not buy it but  will probably return and add it to my collection.

In about 1972 I purchased a vernier sextant from a retired ancient mariner. Unfortunately I did not ask him the questions I would now like to ask. I estimate that he would have been at sea in the 1930s or even 1920s.  A note in the box indicates that three times in 1973 I measured the index error.

For the past 44 years the sextant has sat in a cupboard. It survived a burglary. The burglar forced open the case (the key was in the lock)  but fortunately was more interested in CDs. About 20 years ago I took it to an expert for appraisal. She measured a horizontal angle and said that it was badly out of adjustment.

Now retired I have decided to resume this interest.

The sextant is a vernier. There is no certificate or any documentation. The maker's name is Whyle Thomson & Co Glasgow. There are no other markings on it. I believe that a brass tube with female theades at each end is missing because there is a lens with male threads each end that does not fit anywhere. Both the telescopes are inverting. My  guess is that  the the stray lens converts the telescopes to erect. The box has morticed joints so I am guessing it is original.

Now my questions:

I have googled Whyle Thomson but cannot find any reference to this company. What is the history of this company?

What is the likely age of the sextant?

Is my theory about the missing tube correct?

Is restoration realistic (I may not be able to afford it but that is another issue)?

I have attached a photo.

Thanks in anticipation of replies.

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