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The Hemmi 154 was manufactured in Japan by Sun Hemmi Slide Rule MFG, Co, LTD. This rule was fabricated from a large-diameter variety of bamboo grown in Kagoshima Prefecture on the island of Kyushu, coated on all sides (except the ends) with white celluloid, and held together with metal posts. The 154 duplex model was only fabricated 21.5 inches long ( 20-inches long scales), and it is one of the models Hemmi created specifically for electrical engineering, along with models No. 255 (12.5 in), No. 275 (21.5 in) and No. 153 (12.5 in).
According with the User Manual., the model 154 was designed for use of the expert electrical engineer and provides different arrangement scales and graduations from models No. 255 and No. 275. Especially purpose of this slide rule lies in the simplification of calculation for vector and hyperbolic funciton relating to the calculation for theory of electricity or power transmission line.
This is the only Hemmi model with a scale P', addtional to the scales P and Q used to find the absolute value or lenght of a vector x + iy, present in model No. 153.
Unlike the other electric engerinering models created by Hemmi, model No. 154 was equiped with two cursors, the most common configuration, but also was equiped with four cursors.
The scales on model 154 are: Front: Sx, Tx, Tθ [Th, Sh, Sh, C] D, L, X, and Back: DF, P', P [ Q, CF, CI, Sθ°] A, D, K.
The specimen in this collection was manufactured in August 1957.
Here is a ISRM scan of the User Manual for this rule:
M90_HemmiBambooSlideRuleDuplex_1951.pdfClick on the next link to see professional panoramic pictures of the 154 model.
Click on the next link to see professional panoramic pictures of the 154 model.
Four Cursors Model
https://www.sliderulemuseum.com/Hemmi/Hemmi_154_4Cursors_SRC50741.jpg
Two Cursors Model
https://www.sliderulemuseum.com/Hemmi/Hemmi_154_50cm_ElectricalEngineersDuplex_1926.jpg
References.
Ross, Paul: A Comprehensive Hemmi lide Rule Catalog. Journal of the Oughtred Society. Vol. 12, No.1, Fall 2003 https://osgalleries.org/journal/pdf_files/12.1/V12.1P41.pdf
Ross, Paul: Hemmi Slide Rule Catalogue Raisonné: Part 1: http://srtco.us/HemmiCatalogueRaisonne/Index.htm
Ross, Paul: Hemmi Slide Rule Catalogue Raisonné: Part 2: http://srtco.us/HemmiCat2/Index.htm
Robinson, Bill: Hyperbolic Slide Rule Archive. https://osgalleries.org/hyperbolic/index.html
Robinson, William K: LISTING OF ALL KNOWN SLIDE RULES WITH HYPERBOLIC SCALES, www.oughtred.org/jos/robinson-hyperbolics-dec06.html
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