Christmas table settings customarily include a pretty Christmas cracker next to each plate, to be pulled apart with a SNAP! with a fellow diner before the meal begins. From each torn cracker tube falls a colourful paper hat, a motto, joke or riddle, and a miniature knick-knack, usually inexpensive. This ritual is all thanks to Londoner Thomas Smith (1823-69), who had a talent for making wedding cake decorations, plus a certain business acumen.

Remarkably, Smith was employed in a bakery from age 7. He set up his own wedding cake shop as a teenager and on a visit to Paris was intrigued to see bonbons wrapped individually in a twist of tissue paper. He began selling these in his shop and soon added a tiny love verse inside each wrapper. Looking for a way to add a surprise element, Smith then invented the cracker, removing the sweets and adding little gifts instead.

Faced with competition from a foreign manufacturer who stole his idea, Smith quickly produced a variety of designs and crowded out the market. After he died, his sons took over and Walter (1854-1923), the youngest, was particularly proactive and creative in boosting sales for Tom Smith & Co., which still exists today.

(Images LtoR: Smith by Jack 1956 at Wikimedia Commons / CC BY-SA 4.0, crackers by freshfoodvillage at Wikimedia Commons CC BY 3.0)

When a football commentator uses the term “a slide rule pass”, what is meant is that the ball was kicked with great accuracy, sometimes through a narrow gap, to a running team-mate’s feet. Even though electronic calculators superseded the slide rule in the 1970s, its great importance in mathematics over the previous 350 years has thereby left at least one cultural imprint.

In fact, the engineering feats behind the Industrial Revolution, including James Watt’s steam engine, would have been impossible without this tool to achieve solutions to complex equations quickly. A succession of at least ten Britons devised and developed it, so that by the mid-1800s there were 40 different versions of the slide rule, including a spiral one. Thereafter, other countries, and plastic, took it on.

Notable among the Britons are John Napier (1550-1617), who invented logarithms and Napier’s Bones in 1617, followed by Edmund Gunter (1581-1626) who invented logarithmic scales for use with calipers in 1620. The big name is William Oughtred (1574-1660) with his invention of a circular slide rule with two scales c.1622 and one for calculating excise duty on ale, wine and spirits in 1633. Other scales were gradually added and other uses applied, including Henry Coggeshall’s (1623-90) slide rule specifically for carpenters in 1677.

(Image of slide rule in use in 1966: U.S. Department of Agriculture Forest Service at picryl.com / Public domain)