Sellers' Corner Walter Shawlee 2, Kelowna, BC, Canada The Slide Rule Universe Millions of rules are still made today, with thousands of variations….. While most slide rule collectors focus on traditionally constructed, solid slide rules (made of wood, plastic or aluminum), in real life, that group of rules represents one of the smallest pools of slide rules ever in production. Perhaps a million rules were made by Hemmi/Post and K+E apiece in their entire production history and a similar amount by major European manufacturers, but annual production today of slide charts or “Perrygrafs” (rules made from cardboard or plastic film) is still running around 6 million rules annually. This dwarfs conventional slide rule production. Plus, their continued production has already outlasted conventional rules by almost 40 years. Slide Charts or Perrygrafs (named after the US company, Perrygraf, a major manufacturer) generally have a specific task to perform, such as metric unit conversion, profit calculation, air duct sizing, safe driving alcohol thresholds, concrete volume, and so on. They are slide rules in every way, some extremely sophisticated both mathematically and visually, but with limited application. They were also used by many manufacturers as specifying tools, and could give answers not only in mathematical terms, but in specific zener diode part numbers, valve sizes, optimum lamp types, and so forth. In this way, they not only solved the theoretical problem, but the practical design one at the same time. The entire article and several images are available by downloading the zip file here. Walter walter2 “at” sphere.bc.ca The Slide Rule Universe Slide Charts Really Useful Boxes Ron Knapp, Rancho Murieta, CA An interesting name, to say the least, and a self-descriptive name, as they are very useful. I had looked for years trying to find the 'perfect' (for me) slide rule storage box. Mostly, I wanted something that could hold the larger full-size 12-inch slide rules in their cases. I also wanted something which wasn't too deep, as I didn't want to stack the slide rules too high. Previously I had used Rubbermaid boxes, which worked, but I had to put the shorter rules in the bottom before the longer rules would fit. A few years back, I was fortunate enough to come across some Really Useful Boxes at Staples. I purchased several and they worked perfectly! Made in the United Kingdom, this was the beginning of their marketing in the United States. So, these first batches were "bonus" boxes. The larger box had smaller boxes inside of it, but the price was the same as if you were just purchasing the one larger box. Each time I visited Staples, I would take a look to see what they had. I guess they weren't selling fast enough, and the price dropped. This happened a couple of times until they were only about $4. Needless to say, I picked up all that was left from several stores. The boxes are perfect for me in several ways. The various sizes (listed in terms of liters) come in handy, as slide rules come in different sizes. Besides being nice fits, they also stack nicely. I have a stack of 16 of the 9L boxes right now, but have gone higher with no problems. There is now a full line of the different size boxes available in the U.S., and my next purchase will be one of the longer boxes to store my 20-inch and longer slide rules. I mentioned my satisfaction of the boxes to my friend, Russ Weaver in the U.K., and wondered if he had used them since they originated there. He hadn't, but upon looking into them, he purchased enough to house the majority of his slide rule collection. In his own words: The stack houses virtually all my collection though I could do with a couple more boxes to spread things around a bit.The only slide rule which isn't in the boxes is my Pilot Balloon Rule, which at 66cm is just too long to fit in the largest box. I started with the shallow 4l boxes but soon found that the deeper 9l size is a better choice. They are an ideal length for standard size rules, even those in cases or boxes (mostly) fit comfortably. The small 1l size is great for pocket rules and small circulars. The large 50l beast swallows up 20inch rules, large circulars and any other odds and ends that don't fit in the smaller boxes. If I have a criticism of the Really Useful Boxes it is that the blue swing clips used to retain the lids could do with gripping a little tighter. I've found that it is all too easy to knock off when moving boxes around. I agree with comment on the clips. (The company does make an extra strong box, but I don't know if that means the lids are extra tight or not.) As can be seen from his pictures, he prefers the clear boxes. That way he can see the contents through the sides, which is a nice feature. I actually like the different colors that are available. (When I purchased my boxes, there were only three colors available, clear, blue, and purple.) I have applied labels so several in order to have quicker access to the box that I'm searching for. Editor's Note: How do you store your slide rules? We would love to hear and see what you have come up with. Editor's Note 2: Do you display some or all of your collection? We would love to see pictures. Tales of Discovery Ron Knapp, Rancho Murieta, California Where is the strangest place where you found a slide rule? I once came across a K&E 4083-3 slide rule at a thrift shop in the display case for kitchen knives. (I had found several other slide rules over time at this same store, only they were all in the Bric-a-Brac section.) Perhaps the employee thought it might be dangerous? But, when cases were also known as sheaths or scabbards, then I guess that isn't too much of a stretch. Editor's Note: Do you have any tales of discovery in a strange location? How about any amazing finds? Please email to us with your story. St. Francis and Slide Rules? Ron Knapp, Rancho Murieta, California Sometimes it is the "extras" that come with a slide rule which bring a surprise. One of the Pickett slide rules that I came across had a little (~3.5 by 2.25 inch) calendar for the year 1966 and marked "Pickett SLIDE RULES" on the front. Nothing strange there, but on the back is the Prayer of St. Francis. Something that you don't see often, if ever, on company printed material these days. Editor's Note: Have you come across anything that seemed out of the ordinary? Please email to us with your story.