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The Hyperbolic 159 was produced in Japan by the Ricoh Ltd company since the mid 1960's until the early 1970's. Fabricated with bamboo laminated with white plastic where scales were engraved, metallic braces and all plastic cursor, this 26-scales rule was designed for the expert electrical engineers to simplify calculating problems involving the various electrical phenomena.
The scales on the Hyperbolic 159 are: LL1, LL2, LL3, A [ B, BI, K, CI, C ] D, LL3, LL2, LL1 on the front face, and Sh1 , Sh2 , P2 , P1 [ Q, Sr, Sθ, Th, C ] D, T2, T1, L on the back face. The front face standard scales allow to perform regular mathematical operations, and experiential-logarithm problems. On the back face there are the scales specific for the engineering work:
Sh1 , Sh2 : these scales allow to find (on D-scale) the Hyperbolic Sine value for arguments between 0.1 - 0.9 and 0.9 - 3.0 respectively
P2 , P1 , Q: these scales allow to compute the length z of a vector given its components x, y, or found one the components given the vector's length, in the same way the scales C-D are used to multiply and divide.
Sr, Sθ: Scales to give the value (on Q-scale) of trigonometric functions Sine and Cosine, for arguments in radians and degrees, respectively. Used also for conversion radians-degrees.
Th: this scale allow to find (on D-scale) the Hyperbolic Tangent value for arguments between 0.1 - 3.0
T2, T1: These scales allows to find the value of the Tangent function (on D-scale) for the argument given in radians between 0.1 - 1.48.
According with the serial number engraved on the edge of this specimen and the reference tables in the ISRM WEBpage, this rule was fabricated in 1965; and commercialized with a selling price of $16.95 USD (about $129.00 USD in 2020):
The next operations could be solved with a precision of two - three decimals
SlideRulePractice-3.pdfHere is the scan of the User Manual for this model, courtesy of the ISRM. This English version is not very good but is the only I found:
Ricoh_159_Instructions_ScanByBillRobinson.pdfReferences:
Ross, Paul: Relay/Ricoh Slide Rules: Journal of the Oughtred Society 9-No.2 pp 64-65, 2000
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
Smith Hughes, Richard: Watch your Ps and Qs -The Pythagorean Scales- Are They Worth the Effort? Journal of the Oughtred Society, Vol 15, No.2, 2006. https://osgalleries.org/journal/pdf_files/15.2/V15.2P50.pdf
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