## 8.3 The Original 4083

In the summer of 2020 while looking for vector slide rules online, I performed a search for the number 4083. I knew that the models 4083-3 (10 in. long) and 4083-5 (20 in. long) made by Keuffel and Esser were vector rules and while I had a 4083-3 in the Collection, I was interested in what the market looked like for the long-scale version. In my search, up popped a link to a slide rule for sale – and it was a long-scale model! It was being sold on a less-popular site and and the few low-resolution pictures did not emphasize the scales on the rule. It did not appear to be a vector rule, however – more of a Mannheim type. But, for $19, why not buy it? It’s probably worth at least twice that! When it arrived, I found that it was indeed a K&E and it did indeed have the model number 4083 stamped on it. And it was certainly old. The slide rule was fairly dirty, and the leather case that came with it was stiff and falling apart inside and missing its flap. But the cursor was good, and after a quick cleaning with Windex and a bit of careful scrubbing, the rule itself was in great condition for its apparent age. But, many questions remained, and new questions emerged. Why is this slide rule labeled 4083, without any dash or “length” number attached? I immediately checked on the ISRM web site, and there was no picture nor any mention of such a model. Searches at the Sphere Research Corporation site, and a couple of other sites that I tried, gave the same result. I sent a message out to the person from whom I bought the slide rule, and asked if she had any knowledge of the history of the item I had purchased. Here is Sally G.’s reply to me: “That belonged to my grandfather. He was born in 1897 in Griffin, Ga. He ran cotton mills in several states through his career. I have no idea how he used it. I am thrilled that you have it and will enjoy it. I have spent quarantine going through my parents things. My goal has been to find good homes for them. Mom died at 95 with Alzheimer’s. The proceeds from your purchase will be donated to the Alzheimer’s Association. Thank you so much for reaching out.” $$~$$  K&E 4083, c. 1916 One of the best resources for information on K&E slide rules is Clark McCoy’s web site which contains immense documentation on K&E including scans of original catalogs. The first vector slide rule – the 4093-3 – was introduced by K&E in the late 1920’s. Their next-generation model – the 4083-3 – became available in 1939. But our rule is clearly from before 1922, as it does not have a serial number stamped onto it, which, according to the site, K&E began to provide starting that year. Also, the edges of duplex slide rules became laminated starting in 1922, and our rule has a bare edge. We also know that the K&E slide rules began using all-glass cursors in 1915, which this rule has. And the cursor blocks were metal in 1915, but were replaced with celluloid blocks starting in 1916 which this rule has. The McCoy site also has K&E catalogs for the years 1916 and 1921. The 4083 is not mentioned in the 1921 catalog, but it is listed as a 16-inch duplex in the 1916 catalog, selling for$12.00, a fairly high price for that time. But, sixteen inches? I had never bothered to measure it – I had assumed that what I had in my possession was a standard 20-inch rule. But now many months after the purchase I finally measured the distance between the 1 and the 10 on the C scale, and low and behold it was 16 inches! The McCoy site shows an image of a model 4083T, which is a 16-inch rule that includes trigonometric scales, but there is no image for the 4083. The scales on the model in my possession are:

front: A [ B C ] D
back: A [ BI CI ] D

The 16-inch rules were evidently retired by 1921, as was the 4083 model number. This allowed for the number to be re-used when the updated vector rules were introduced nearly 20 years later. All of this is consistent with Sally’s email, and indicates to me that if Sally’s grandfather came into possession of this slide rule in 1916-1920, say, then he would have been in his early 20’s at the time as he started out in his business ventures. Of course, he could have picked it up a few years later as a “used” slide rule, or it may have sat on the shelf in a store for awhile. But in any case, the story and its dates hang together. I’m thrilled to have a piece of history as well as a fairly rare K&E 4083 in the collection.