NavList:

Frank,

I know that discusion initially was about the end of the 19. century and the beginning of the 20. century, but David’s question somehow made me to look at the problem in a wider time frame.

You wrote:

“Don't get me wrong: it's fine if you're just describing your own estimation of how they might have gone about it. But we should distinguish that from "history"”.

No, it is not my estimation. David mentioned lunars in context with chronometer rating. This made me think of this aspect, because I remembered that I had read something about this somewere. At first I couldn’t remember, but than I finally remembered at least one historic sorce: this concept was described in the book of D. Thomson, where his super compact method of clearing lunars was described. I found the book and, indeed, under the methods of rating chronometers, there was a method of rating (not checking, but RATING!) chronometers by lunar distances (suplemented with an example). This book was reprinted many times in 19. century. Why there was such a strange thing as rating by lunars included in the book? My speculation is: this was typical comercial edition and the author wanted to show, how valuable his tables could be, if they can serve even for rating chronometers.

I mentioned Chauvene only to ilustrate that even such a armchair math profesor limited his expectations of chronometer checking by lunars to 20 seconds of time. This value was reprinted in Bowditch editions even in the begining of 20. century. However I have quite neutral attitude to him, contrary to you : )

The purpose of my post was to show that seemingly stupid composition of the  words “rating chronometer by lunars” has some historic meaning. And I will repeat: I don’t believe that rating by lunars was a popular method, but at the same time I have no rights to claim that no one has even tried to do that.    

Of course, the concept “checking chronometers by lunars” is more comon, confirmed by documentary evidence.

Modris Fersters