by Philip Davis (1961). Picked up this delightful little introduction to arithmetic and scientific computing from a used bookstore. Written when “computers” meant “people trained to carry out, by long-hand, long chains of numerical computations”, the author, a famed mathematician talks breathlessly about “gigantic electronic brains”. Does a great job of explaining why inverting rank n matrices involves very large and very small numbers and that the heat equation at rest essentially implies that the steady-state temperature is the average of the temperature in its neighborhood.