Re: 1638 Letter from Oughtred to Allen

Andreas Poschinger

Hi Tom,

Am 14.06.2021 um 10:49 schrieb Tom and Lu Wetmore via
Forster's "The Circles of Proportion and Horizontal Instrument, Both
Invented and the uses of both written in Latin by Mr. W. O. [William
Oughtred], Translated into English and set forth for he publique by
William Forster"
Yes I know it, because it is the only book about Oughtreds dialrule, at
least which really got published, isn't it? But actually it is Oughtreds
book and Forster is the translator only. I'd say that under normal
circumstances the official author of this book would be Oughtred and if
Oughtred would be a nice guy there would be somewhere acknowledgements
for Forster for having translated this book. So that Forster is now the
author actually makes it even suspicious for me - at least I do not
regard it as independent source.

Of course, somebody is lying or has a least a strong and strange
alternative truth, but I'd not say that this is necessarily Delamain.
You may remember where Delamain describes his meeting with Oughtred
before he published the Grammelogia respectively donated the prototype
to the king, and this description reads for me quite objective and
trustable, though of course it is a defense against Oughtred's accuse
that Delamain did not have more than two circles of logarithmic lines
yet (which actually is the very point of a sliderule!). Oughtred however
did - according to Delamain, and I believe him here - not tell anything
about his (Oughtreds) sliderule or instrument. So the only possibility
for me to stay within alternatives thruths and not accusing for mere
lies and given that at that time nobody (but maybe Delamain) could
define a sliderule yet, the most likely for me is that Forster saw the
Dialrule including manual and maybe even some linear sticks, but these
alone actually are no sliderules yet. They get a sliderule when you know
how to use them as sliderule but this is described by Delamain only. And
even if there was something linear, then we do not know at all how it
may have looked like. The only source is the letter to Allen, several ys
after Delamains sliderule and Oughtreds dialrule, and I agree with you,
that it is difficult to say by beyond 90% what it really is about. So
far I remember one yr. back we came to the point that we were even
uncertain whether this drawing really fits the text or whether there
came in some Wingate or whatever stuff, I remember it was confusing.

Indeed, given that Delamain clearly published a sliderule in shape and
use, while we do not know any details from an Oughtred sliderule -
neither shape nor use (not his dialrule!), and given that Delamain
published first (even if very hasty either to not miss the kings
birthday, and/or even to fear that Oughtred may steal his sliderule idea
e.g. by "industrial spying" at Allen), in my opinion it is an unfairness
and even nogo to not acknowledge his merits about sliderule development
placed at a very prominent position in the timeline.

There are of course open questions: One point e.g., why the Grammelogia
evolved quite slowly starting with the basic logarithmic lines only. One
explanation is that he first needed to steal new ideas from Oughtred or
other people again, another may be simply that Delamain was not wealthy
enough so that he could afford new scales only when having money. Of
course this would be somehow embarrasing, so that Delamain would not
have written it. Nevertheless the grammelogia always seemed to have its
huge diameter of two feet (!). So this tells me that Delamain most
likely had at least a clear vision and most likely even a paper model
for what to use the space, even if there were only two logarithmic lines
in the beginning (plus the line of 100000 equal parts which should have
costed already quite a money...).

Best regards


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