Bob
A few days ago I wrote in an internet forum for the first time. (I joined ‘cloudynights’ to respond in a thread, and yesterday ‘birdforum’ to comment in a thread.) I posted the following (this same text, now copied here) in my first thread, on a different subject (after I had posted my responses in that subject). It now seems to me that this might possibly deserve a thread of its own.
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Could someone please tell me: What is the origin of the word "by" for the x in [magn.]x[obj.diam.], e.g. "eight by forty", which is so widely used? Unable to find the etymology (even after much searching on the internet), I would guess it originates in measuring areas, as in 8 ft x 12 ft -> a side of 8 feet lying by a side of 12 feet -> "eight by twelve". (Note there are two guesses: the reason for the use of the word for x there, and the word being transferred to optics because of the x.)
As this seems illogical to me, I have always used the word "times" for the x, e.g. "eight times forty", "an eight-times binocular", etc. Frank comments on this word will also be appreciated!
It is simple, and you have got it. Just think of the power of the optic times the size
of the objective in millimeters. Example 8x42, means "8" power with a 42 mm sized
objective lens.
So that's it! I get it now! It's like getting hit upside the head by a 2 x 4!
Bob