Dating hemmi slide rule, collections search
This is a circular slide rule first created in the s for aircraft pilots to help with dead reckoning. T1, T2, S2, S1.
Ah well, that's progress for you. Specialized slide rules were invented for various forms of engineering, business and banking.
Carrier Ductuler (Bamboo), 196
The belt clip is still intact, though. Charles Bruning is Dates that a design was registered or patented only suggests an approximate year a model may have been first produced, as the model may have been distributed a year or more before issuance patent pending.
These were sold under their own name Sun as well as redistributed for a large number of other companies, most notably roma vittoriosa latino dating Frederick Post Co. On the outer edge of dating faber-castell slide rules rule is a decimal feet scale.
Another drawback of circular slide rules is that less-important scales are closer to the center, and have lower precisions.
Post Slide Rules
Bottom edge of rule carries non-linear scales 9 and Versor, and Printed in red along the center of the face of the center slide is an inverted logarithmic scale "CI", with values descending from 10 to 1. Circular slide rules to estimate ovulation dates and fertility are known as wheel calculators.
The other side bears a Post logo in red, which has largely been rubbed away. Although a bit too small to really be all that useful in everyday life, this rule probably attracts more attention in my collection than any other!
There are several tables of formulas on the back.
Front of rule upper picture implements the Hazen and Williams formula; rear lower picture implements the Manning System. Special thanks to D. Clearly not the greatest design, which presumably explains why all the major slide rule manufacturers abandoned it for a modified cursor design by the late 30's.
The other giveaway is the Geotec name and new numbering numbering format. The red Post logo and the serial number appear on the right front of the slide.
Quality Control - HEMMI SLIDE RULE CO., LTD.
It has total of 24 scales. They may not actually exist.
Dating this particular specimen is especially difficult, as this model is only listed in the three earliest Hughes Owens catalogs, and doesn't exactly match any of the illustrations.
Dating faber-castell slide rules - Complete with two part trademark green hardboard case.
Sun Hemmi Slide Rules Hemmi was the largest manufacturer of slide rules, and is estimated to have sold some 15 million rules over its lifetime. Interestingly, the trig sine scale on this model goes from 6 up to 90 degrees, compared to 1 to 75 on the older version the trig scales are also upside down on this one, compared to the other.
Boone; the rule carries no date code.
Although the date codes were prominently engraved and paint-filled in the early years, from the late 's onward they can be hard to spot as they are only lightly engraved in small letters, often near an edge.
In Edmund Gunter of Oxford developed a calculating device with a single logarithmic scale; with additional measuring tools it could be used to multiply and divide. The Bruning boys work for another blueprint company.
This rule is quite rare; I am indebted to Wataru Tsuchihira for the picture and information.
Giovanni Breda's Slide Rule Collection
A most unusual find, and clearly my oldest Hughes Owens rule to date. This brought greater accuracy to the mass production of their slide rules and they began exporting to the US [Post], Canada [Hughes-Owens] and Europe. Face of rule carries eight full-length non-linear scales labeled simply 1 - 8.
Frankly, I must say that I prefer the quality of the older leather cases! I'm going to keep my eyes open for more 's to add to my collection One eight-inch premium circular rule had a inch spiral log-log scale.
The pictured calculator is marked "Hemmi Versor Makepeace, who in started the B. Unlike some other makers, their plastic rules were as good in terms of craftsmanship and appearance as their bamboo body rules, and were often very complex designs.
All Japanese language except name "Pressmate" on box and some labels like " shear strength " on rule. Scales are often "split" to get higher accuracy. Hydraulic Flow Rule Another hydraulic flow rule from Hemmi.
Eric's Hemmi Slide Rules
Circular slide rules also eliminate "off-scale" calculations, because the scales were designed to "wrap around"; they never have to be reoriented when results are near 1.
Interestingly, the instruction manual has both the Hughes Owens name and Geotec logo shown on the cover. The back of the center slide is also printed with three scales.
A challenge to members to share their treasures with members of their communities. The rule is labelled "Made in Japan," fixing it either to pre or post I've also obtained the Hughes Owens versions of the hard-cover Versalog instruction books, both the first and second Canadian editions shown above.
The beveled edge of the slide rule base above the top slide is printed with a scale in centimeters, graduated into tenths.