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As always, your knowledge and scholarship is to be admired!
One thought I have, upon reading your message, is that we tend to think most early “slide rule” development was in England, with movement to France in the early 19th century. Lambert shows the is not really correct.
I do hope you will update your paper — and it would be wonderful if more reproductions could be made.
On Jun 14, 2021, at 3:15 AM, Karl Kleine <firstname.lastname@example.org> wrote:
Lambert wrote a book in 1761, second edition 1772, "Beschreibung und Gebrauch
der logarithmischen Rechenstäbe..." (description and use of logarithmic calculating rods...)
and had them made by Brander in Augsburg. I made replicas and presented both the
paper and the replicas at the IM2006 in Greifswald. Lambert wanted maximum
precision with rods still usable, so he proposed a length of 5 feet. I built two pairs
with 4 feet scales (my practical limit for manufacturing them); I donated one pair to the
computing museum of Greifswald university and still have the second pair.
These are square rods, a logarithmic scale of two cylces, a linear scale (log of the first one),
a sin and a tan scale.
Brander made Lambert's rods. One is known to still exist, but unfortunately only one of a pair.
It's in the Deutsches Museum and came there in a package of a lot of other instruments.
The documentation is inconclusive with respect to the second rod, if only one came to the
museum or if the second one got lost in the turmoil of WWII. I did not know that when I built
my replicas, and so I followed Lambert's idealistic view of practically achievable precision with
the help of a professional large scale precision plotter. I will have to redo the whole thing with
the knowledge of today of Brander's rods, and I have to rewrite the paper, which was in German,
So, yes, there were slide rules in the form of two independent rods. As there was a request for
a second printing / edition ten years after the first, it looks like there was a need and a market
for them in the second half of the 18th century in Germany. And yes, it looks like Brander also
made shorter versions of them (there are notes to multiples of feets for their length, which
also points to the issue of usual lengths of slide rules, which occured earlier in this forum).
PS: Whenever I wrote foot / feet above, that refers to an "Ulmer Fuß", which was 29.7 cm.
PS2: I tried to attach a picture of my rods, but that failed. Will send it to you personally, Dean.
Prof. Karl Kleine - c/o Ernst-Abbe-Hochschule Jena, Germany - email@example.com
Von: firstname.lastname@example.org <email@example.com> im Auftrag von Edward Dean Butler <firstname.lastname@example.org>
Gesendet: Montag, 14. Juni 2021 03:18
Betreff: Re: [sliderule] 1638 Letter from Oughtred to Allen
With regard to early slide rules that are only two “sticks” that slide one against the other: does anyone know of such slide rules in museums or private collections?
....... rest deleted .............. kl