Charvoz - Roos SR-113 SuperTrig

The SR-113 SuperTrig slide rule was manufactured in the United States initially by the Roos Company in the early 1940's, and since 1945, after a fusion with Charvoz Inc., by the Charvoz-Roos Corporation until 1953, year this corporation was sold.

Fabricated with mahogany coated with white plastic, all plastic cursor and held also with plastic braces. This model was also commercialized under the brand Post 1462 Du[plex.

It's 19 scales, made the SR-113 appropriate for professional engineering work. The scales on this rule are: LL0, LL00, A [ B, K, L, C ] LL3, LL2, LL1 on the front face, and T, DF [ CF, CIF, CI, C ] D, S, T on the back face..

This model was also produce with metallic braces after 1945, according with the copyright date of the specimen displayed on page ISRM Charvoz-Ross page.

During the SR-113 production years Charvoz-Roos fabricated unbranded rules with not known purposes, the specimen in this collection is one of those without brand, model or serial number, only the Made in USA label, so it is not possible to state with precision when it was fabricated, but observing the models in the ISRM Charvoz-Roos, and Frederick Post pages, this model may be fabricated in the early 1940's, presumably to replace foreign imports of slide rules during WWII.

Here is the User Manual for the Post 1462 (Charvoz-Roos SR-113)

Click on the next links to see professional panoramic pictures of the SR-109:

c1941 Model:

https://www.sliderulemuseum.com/MiscUSA/S449_Roos_SR-109.jpg

c1950 Unbranded model with metallic braces

https://www.sliderulemuseum.com/MiscUSA/Charvoz-Roos_SR-109_DonatedByBruceEVanDeuson.jpg

SR-109 (1947) with metallic braces:

https://www.sliderulemuseum.com/MiscUSA/Charvoz-Roos_SR-109_DavidHecht-030.jpg

c1950 Model:

https://www.sliderulemuseum.com/MiscUSA/S397_Charvoz-Roos_SR-109.jpg

Click on the next links to see professional panoramic pictures of the SR-109:

https://www.sliderulemuseum.com/MiscUSA/P101_Chavroz-Roos_SR108_PlasticEnds.jpg

c1946 branded model with metallic braces

https://www.sliderulemuseum.com/MiscUSA/Compass_SR-108_DustinEMorrisCollection_GiftOfNancyMorris.jpg

Model No. 1442 branded Frederick Post, fabricated prior WWII

https://www.sliderulemuseum.com/Post/Post_1442_Dual_10in-5in_SlideRule.jpg

References:

• Tina's American Slide Rules: http://tinas-sliderules.me.uk/Slide%20Rules/AmericanSlideRules.html

• Slide Rule Museum. The Roos Company. The Charvoz-Roos Corporation: https://www.sliderulemuseum.com/CharvozRoos.htm

• University of Toronto. Scientific Instruments Collection. https://utsic.utoronto.ca/wpm_instrument/charvoz-roos-duplex-slide-rule-model-sr-109/

• Roos, Paul - Hume, Ted: Slide Rules of the Frederick Post Company. Journal of the Oughtred Society, Vol.9 No.2 Fall 2000. http://www.oughtred.org/jos/articles/V09.2_p37-46.pdf