Talk:Peter Barlow (mathematician)

Birthdate
Why does the article say "Only the month and year of Barlow's birth in Norwich have been recorded for posterity" while the Infobox gives a date? Radagast3 (talk) 13:05, 11 April 2009 (UTC)
 * both were wrong and have now been corrected. Radagast3 (talk) 09:50, 4 July 2009 (UTC)

"Barlow Lens"
I rewrote this part to reflect the fact that none of us really knows what we're talking about here. The sources cited are unfortunately very vague. Here's what we do know: --BjKa (talk) 13:22, 10 January 2013 (UTC)
 * Barlow did not invent the achromatic lens (Dollond didn't either, but he held a patent for it at the time)
 * Any "achromatic lens" is not the same as what is understood today as a Barlow lens. Specifically: The main use for achromatic telescope lenses is in the objective, which is positive/converging, while a Barlow lens or teleconverter is an negative/diverging lens which is placed additionally between the objective and the focal plane.

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Last reprinting of Barlow's tables
I'm reluctant to make changes to the article as I'm not completely sure about what standards are expected but "These tables were regularly reprinted until 1965,[2] when computers rendered them obsolete." stuck me as incorrect as I knew I'd bought a copy well after that and computers were not that commonly available. I have a "Science Paperbacks" edition published by Chapman and Hall Ltd. My copy says "First published as a Science Paperback 1965" adding "Reprinted 1969, 1971" which matches the postcard from the bookseller I bought it from in 1974. The SBN is shown as "412 20110 0".

Graham Rule (talk) 03:25, 19 March 2022 (UTC)


 * Since this is sourced information, the "standard expected" is to provide a better source. You cannot simply change it to something the source does not say.  I agree that computers did not render tables obsolete in 1965.  In fact the source says something a little more nuanced; "it was reprinted many times, the last being in 1965 when it had been all but superseded by the calculator and computer."   Computers existed in 1965, but were hardly accessible by the average design office unless in a large company.  One could get tables printed out, but ti required writing a program in Fortran, having it typed on to punched cards (in those days engineers just didn't do typing themselves), sending it away to wherever the mainframe lived and waiting for a stack of paper to be returned from the line printer.  That just wasn't the way everyday calculations were done.  Slide rules and tables were the order of the day.  Portable electronic calculators were just coming in around this time.  The first company I worked for in 1969 had a HP reverse Polish handheld calculator in the design office.  But you couldn't hold it in your hand because it was screwed down to the desk to stop anyone walking off with it.  That's what a rarity they were.
 * On the last published date, it is easily shown that editions existed after 1965. There is 1975, 1977.  But those are primary sources, and we really need a secondary source saying these tables were still in general use on those dates.  To show how difficult it is to rely on primary sources, there is this edition with a claimed publication date of 2010.  This is a digital reprint edition from Nabu Press, an imprint of BiblioBazaar who specialise in historical reprints.  You can buy it, but that doesn't mean that anyone is actually using it for real. SpinningSpark 13:54, 19 March 2022 (UTC)