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RELAY/RICOH GALLERY 5

Here's a slide rule from the collection of Mr. Steve Kay, fellow slide rule enthusiast and also a collector of Relay/Ricoh rules. This represents his biggest, in my estimation, discovery so far.
    We see here in his own photos a slide rule, obviously a Relay/Ricoh, re-labelled by the TOBE-DEUTSCHMANN, an electronics manufacturer. This company was huge supplier of electronics parts to the U.S. military during World War two. ( at top right, a scan sent by Mr. Kay of a capacitor made by the same company.)
    Apparently at some point they decided to procure a few slide rules to sell or give away, and so we have this rule here. This is the latest brand to be discovered, and was totally unknown to me until Mr. Kay corresponded with me about it. Exceedingly rare would be an understatement.
    Above, the rule with it's gray drawer box, actually not an uncommon box style for certain re-badged types of R/R rules. At left, the leather case. (The set decodes to 1959, btw.) The manual seen is a standard R/R manual, re-named in typical fashion.

...at left, a "ripped" scan from an ad in an auction, which shows an ad for the TOBE corporation, apearing in a magazine during WW2. The exact history of this company is unclear to me, requiring further research, and we don't presently know if they sold any other R/R types.

This slide rule, from my own collection, goes along with the one on Gallery page 4, the Lietz "Occupied Japan" rule. This is a Relay 403, with a magnifying cursor (not shown here) marked for sale by Charvoz-Roos. Note the clearly visible "Made in Occupied Japan." Again, this dates the manufacture of the rule to after 1945 and before 1952. No date code, but again evidence that this company not only existed prior to when we thought it might, but also that they were already importing to the U.S. before we thought. This is another one of the slide rules which seems to cloud the Nikkei-Relay relationship.

Here we have the Lafayette F-686, otherwise an unaltered R/R 157 electronics rule. These are very large and powerful rules, with an impressive scale set, but while they are known for this size and power, one thing that is almost never mentioned is this: they may possess the smallest, shortest scale EVER PUT ON ANY SLIDE RULE OF ANY SIZE. Don't think so? Look at the scan at left, at the little tiny red scale attatched to the end of the C scale on the slide of this F-686, and note that it is labelled LL1'.

What's up with this scale? Isn't it just a scale over-range extension? Nope. It's pretty clever actually, and totally, completely unique. Here's what Relay themselves had to say about it! The following is all excerpted from the 1959 RELAY DUPLEX SLIDE RULES instruction manual.
    In the front of the manual, going through the available scales on their rules, they say the LL'1 scale is "...used with C and D scales. This LL'1 scale is deviced by us to substitute LL1 and LL0 scales." (sic). I will here point out that 1. their spelling isn't reel good, and 2. in the manual, they refer to the scale as LL'1, but on the rule itself it looks more like LL1'. Oh well.
     On page 15 we begin the usage of this unique scale. " As a extension of the C scale there is a very short scale at the right end of the C scale marked from 1 to 1.1 in red. This minute scale called LL'1 is invented in our laboratory to substitute the several lower LL scales in calculation of ln x, x to the y power, and e to the x power, etc. " I won't give all the instructions, but from what I'll give users will see that this thing really works. In fact, it's a pretty darn good way to save some space to use for other scales, and I'll point out that that is exactly what they did on the 157.
     "Natural logarithms: ( ln x ) when x is nearly equal to 1, its natural logarithm is approximately equal to x-1. But using LL'1 scale we can obtain its value more precisely. The procedure is: A. opposite (x-1) on D, set the hairline. B. Opposite the hairline, set x on LL'1. C. Opposite right index of C, read answer on D.
Example: ln 1.05 = 0.0488. In ordinary slide rule we use the LL1 and D scales, and read the result on the LL1 scale. A. Opposite .05 on D, set 1.05 on LL'1. B. Opposite right index of C, read 0.0488 on D."
     "Computation of x to the y power. Using the LL'1 scale, we can compute the form x^y without LL1 and LL0 scales. Example 1. 1.06^2.68 = 1.169. In ordinary slide rule we use the LL1 and CI scales, and read the answer on the LL2 scale. A. Opposite .06 on D, set 1.06 on LL'1. B. Opposite 2.68 on C, read 1.169 on LL2.     Example 2. 1.008^14.8 = 1.125. Without the ordinary LL0 scale this computation can be done.       A. Opposite .008 on D, set 1.008 on LL'1. B. Opposite 14.8 on C, read 1.125 on LL2."

    Additional examples are given for fractional powers, and powers of e using this little scale. The 157 already has an impressive scale layout, as it was intended for electronic engineers. About the 157, Relay said it was designed for the Expert Electrical Engineer, and was made to handle all normal computations, and all vectorial and hyperbolic computations/functions too. And, without this tiny little LL'1 scale, there wouldn't have been room for all the specialized scales in addition to a good selection of "normal" scales. An impressive and capable rule, and partly due to one tiny little overlooked scale!