Ian Stewart*

The catapult that Archimedes built, the gambling-houses that Des- cartes frequented in his dissolute youth, the field where Galois fought his duel, the bridge where Hamilton carved quaternions--not all of these monuments to mathematical history survive today, but the mathematician on vacation can still find many reminders of our sub- ject's glorious and inglorious past: statues, plaques, graves, the card where the famous conjecture was made, the desk where the famous ini-

rials are scratched, birthplaces, houses, memorials. Does your home- town have a mathematical tourist attraction? Have you encountered a mathematical sight on your travels? If so, we inviteyou to submit to this column a picture, a description of its mathematical significance, and either a map or directions so that others may follow in your tracks. Please send all submissions to the Mathematical Tourist Editor, Ian Stewart.

The Cornish Caveman Mathematician H.P. Williams

The southwest edge of Bodmin Moor in Cornwall is wild and remote. It is Iess visited than other parts of the moor, as it is away from the major road through Cornwall. Nev- ertheless, it is an interesting and romantic area. There

Figure I

*Column Editor's address: Mathematics Institute, University of Warwick, Coventry, CV4 7AL England.

are the Hurlers, two prehistoric stone circles. It was near here, on Twelve Mens Moor, thatJem Merlyn, the amiabIe rogue of Daphne du Maurier's Jamaica Inn, lived. There is also the Cheesewring, one of the most spectacular of the granite tots.

Less known is that here, over 250 years ago, a recluse mathematician named Daniel Gumb lived in a cave (see Ref. 1). Daniel Gumb was a stonemason, born in 1703 in the parish of Linkinhorne about 4 miles away. He was introverted, and although both his father and grandfa- ther were illiterate, Daniel was well read and acquired a considerable knowledge of mathematics and astronomy. He sometimes worked in the quarry, now long disused, beneath the Cheesewring. When he married the second of his three wives in 1735, he decided to make his home here. It is not known if this was to avoid the council tax or simply a reflection of his reclusive nature and an oppor- tunity to observe the stars at night. He found a large slab of granite and dug out a 12-foot-deep cave beneath it. Here he lived with his wife, and eventually his children also, through the wind, rain, hail, and snow of Cornish winters on the exposed moor. Whether he continued to live here through his third marriage does not seem to be known.

On the granite stone entrance to the cave he carved "D Gumb 1735." Mathematical diagrams were carved on other pieces of granite which made up the cave. In the middle of the last century the now-deserted cave was damaged by an extension of the quarry, but part of it was moved to a site nearby. The entrance, with its inscription, remains, together with the large granite roof. On the roof is a diagram reported as a "very ingenious method of proving the Theorem of Pythagoras (Euclid 147)"[2]. It is illustrated in Figure 1.

Continued on p. 64

34 THE MATHEMATICAL INTELLIGENCER VOL. 17, NO. 1 ~ 1995 Springer-Verlag New York