Sketchy calculation
As a bit of weekend fun, here's something called a Rechenstift - German for "calculating pen" - by the venerable Hamburg firm of Dennert & Pape, erstwhile inventors of the…
Fan scales
A recent discussion with Peter Hopp of Slide Rules fame, prompted by an item in the latest UKSRC Newsletter, finally encouraged me to photograph some of my fan scales. This type of…
Thornton on folding pocket rules
I recently took a gamble on a job lot of plastic slide rules and other oddments on account of a blurry pocket rule in one corner of the photo. Superficially…