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 cafd where the famous conjecture was made, the desk where the famous ini-

Ian Stewart*

tials 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.

Snel l ius's Memoria l Stone Dirk Huylebrouck

Snellius's memorial stone inside the church.

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

Aarsthertogstraat 42 8400 Oostende Belgium

A visit to the Peter Church at the Dutch city of Leyden turns out to be interesting for two reasons: the presence of a memoria l stone in honor of Willebrord Snellius (1580- 1626), and the absence of Ludolph van Ceulen's (1540- 1610) tombstone, generally known to be engraved with 35 digits of 7:. They worked at about the same period at the University of Leyden, but when still alive they al- ready did not do things the same way. As Petr Beckmann stated it in his A History of 7r (The Golem Press, 1977),

There is all the difference in the world between Ludolph's digit hunting and Snellius's numerical test. Snellius had found a new method and checked its quality by calculating the decimal digits of ~r; Ludolph's evaluation to 35 decimal digits by a method known for 1900 years was no more than a stunt.

In Leyden, a visitor cannot miss the Peter Church; but what is called the "Sint-Pieterskerkhof" or "Peter 's cemetery" is not a graveyard, but the name of a little road next to the church. In fact, the dead were buried inside the church, the size of their tombstone being pro- portional to the money their family was prepared to in- vest. As space inside the church was not unlimited, it happened that several years after someone died, other investors disturbed his rest. Sometimes the unfor tunate 's stone a n d / o r mortal remains were moved elsewhere. This is wha t probably happened to van Ceulen (further evidence of this story does exist).

Not only Snellius's computat ional but also his funeral method was of a better quality: instead of having just a tombstone on the floor, a memoria l plaque was fixed to the church wall. It is still there, and quite easy to find: his name and two Latin words referring to mathematics are clearly visible.

5 8 THE MATHEMATICAL INTELLIGENCER VOL. 17, NO. 4 �9 1995 Springer-Verlag New York

T h e church as s e e n f rom "Peter's cemetery."

THE MATHEMATICAL INTELLIGENCER VOL. 17, NO. 4, 1995 59

Van Ceulen's Tombstone Dirk Huylebrouck

Ludolph van Ceulen, professor of mathematics at the University of Leyden, died in 1610 and was buried in the Peter Church at Leyden (the Netherlands). His tomb- stone is generally known to be engraved with 35 digits of 7r.

However, in A History of Tr (The Golem Press, 1977), Petr Beckmann quotes the historian J. Tropfke to the effect that "the last three digits [of the 35 Van Ceulen computed] were engraved in his tombstone in the Peter Church at Leyden. This seems to invalidate vague refer- ences by other historians, according to which all 35 dig- its were engraved in his tombstone, but that the stone has been lost." A transcript of the tombstone text out of Humanitds Scientifiques-- Vols. 331,332, 333 by Serge Minois is copied in Le Petit Archim~de, numdro Spdcial 7r. This suggests the memorial would have survived any- way.

There is some confusion about van Ceulen's biogra- phy. His year of birth does not seem to be known exactly: some references mention 1539, others 1540. His name is written Ludolph(ff) van C(K)eulen, and he is even called differently, Ludolph a Collen, in an original Latin text by

his contemporary Adrien M6tius. Van Collen is read on the front page of a book by the mathematician himself! The exact number of digits he computed seems to be a problem too (34, 35, or even 3 more?).

A visit to the Documentary Center of the City (ask for the Gemeentearchief, it is a few minutes walk from the church) can clear some doubts. The Center contains cer- tificates of where, when, and how someone was buried. Catalogs and transcripts of tombstone texts are available. Item 320 (see outline below) is found under the disap- pointing heading Inscriptions Of Tombstones And Memori- als That Are No Longer Present. It is not the original text, says a footnote: the real epitaph was in the local Dutch language (which is different from the official Dutch lan- guage). The above Latin translation was found in Les Ddices de Leide, p. 67, this reference indicates. Appar-

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ently, it must have been a French book, and that may be why it was translated (but why then into Latin and not into French?).

A tour at the site, the Peter Church, does not reveal much, except under the guidance of Mr. R. M. Th. E. Oomes, a retired mathematics teacher. He did archeolog- ical research to find out what happened to van Ceulen's tombstone. During the restoration of the church, the whole floor was literally rooted up as can be seen on the photograph, and Mr. Oomes was called in for help.

No decimals were excavated: the stone must have been moved or destroyed during the second half of the 19th

century. A French army man wrote that he had seen the stone at that time, but a few years later the well-known mathematician Bierens-De Haen (responsible for many formulas in M. Abramowitz and I. A. Stegun's Handbook of Mathematical Functions) no longer mentions it. Why did he not at least note the tombstone's disappearance?

It is nevertheless possible to retrieve the location where the tombstone should have been. Our guide thinks he can prove that stone 106 would still cover the mortal remains of Ludolph van Ceulen. The author of the present paper was proud to find it finally (picture!), but it is just an ordinary stone with the number 106 notched in it.

The disappointed visitor can compensate his disillu- sion by leaving the church area through a little road called the Klokstraat. At the end of the street, to the left, coming from the church, one walks along the area (the houses have been rebuilt) where van Ceulen would have computed, during the best part of his life and until death prevented him, 34 decimals of ~r.

Let us hope many mathematicians visit the site, so that van Ceulen's zeal may be recognized one day. Snellius and a professor in theology, both contemporaries of van Ceulen, do have nice memorial stones inside the church, so why not our digit hunter? If you plan to visit the site and need a qualified guide, contact Mr. R. M. Th. E. Oomes, van den Brandelerkade 23, N1-2313 GW Leyden.

Aarsthertogstraat 42 8400 Oostende Belgium

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