Over at , Samuel has bought a new slide rule. He spent most of 10 August wandering in and out of the engraver’s, watching with fascination as the new plates for the slide rule were being prepared, and on 11 August it was finished for the princely sum of fourteen shillings. Samuel can’t resist his new toy: “I late to my office, and cannot forbear admiring and consulting my new rule, and so home to supper and to bed.”

We tend to forget that Pepys was a real geek. The slide rule is of course the seventeenth-century equivalent of the computer. By 1664, about the same time has elapsed since the first slide rules were produced (in the early 1630s) as has passed for us since the launch of the personal computer in 1977. But Pepys is in part a coder as well; he spent much of the previous summer (1663) commissioning his own design for a slide rule, and then playing with it.

(This is the man who would go on to publish Newton’s Principia.)