Faber-Castell novoduplex slide rule (Vale LA1)

Before there was anything like a pocket calculator all scientists and engineers used slide rules or logbooks, but it was an absolutely fantastic piece of equipment that permitted you to perform amazingly complex mathematical calculations. There was a time I could perform calculations accurate to four decimal points faster than my grandkids with scientific pocket calculators. It requires no batteries. Because of my age, however, even though I can perform many mental arithmetic calculations, and need no calculator for most common needs such calculating VAT, I no longer need this amazing piece of equipment. It comes with a case, and and instruction leaflet.