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RELAY/RICOH ARCHIVE

PAGE FOUR

    Below we present the last page of the RELAY DUPLEX SLIDE RULES manual, from 6/1959, a listing of the types available at the time. This manual came with a 1959 date coded RELAY 150 slide rule. Just look at all the types we never see here in the U.S.!! A few observations follow. 35 rule types are listed.
     We can clearly see the numbering system, with the first digit in each model number telling us the rule length. Note also that the duplex rules all have "5" as the second digit, with the first telling us the length as in the simplex and mannheim types. As the manual states elsewhere, many of the duplex rules have log-log scales. Note production of 4,5,6,8,and 10 inch rules!!
    The manual, written for use with duplex types, specifically mentions the 651,100,150,157,450,550,650,and 652 rules in the text. NOT mentioned are the 151,152,153, and the 158. Since all the rules in the manual have their trig scales divided in degrees/min/sec format, (as did the 150 it came with) and a manual has been seen copyright 1959 for the " Log-log deci-trig deluxe", we think that initially there was a separate manual for the 151. A slightly earlier manual makes no distinction as being for only duplex rules, unlike the above mantioned manual, and covers basically all rules with deg/min trig format. That is, all the above listed rules PLUS others.
     A manual has also been seen from 1962, used for the 151,153,252, and 551 rules. If we assume the 252 was the re-numbered or replaced 152, and the "pocket 151" model 551 had been added, we might have an explanation that makes sense. These 4 rules all used DECIMAL divided trig scales. We would then have one manual for the duplex types with decimal trig scales, another for the deg/min/sec trig format rules, and then perhaps a third general purpose manual for the simplex and/or mannheim types ( one such manual came with my RICOH 550, and covers the ELECTRO and DARMSTADT types as well.).
    ( It should be noted that a few skipped model numbers, such as the 154, are known to exist. Whether or not they existed at the time of this manual is unclear. Perhaps they were unused numbers, or weren't sold in English speaking countries.It is also known that some models existed outside the U.S. NOT in this numbering scheme at all. )
     Anyways, here it is for your perusal. Keep in mind, we see very few of any of these here. We had roughly 8 distributors of 151's, 6 of 150's, 4 of 551's, and 4 of 157's, and a smattering of the smaller models. By far these 4 types listed are the most common. But look at Relay's line up! Lots of advanced types! And look, waaay down there at the bottom, plastic slide rules by Relay! (more on this to come!!) Also, be sure to compare this to our recently found 1957 catalog. It may just put a wrinkle or two in the progression above!