320 Dr. Moll on the Invention of Telescopes. 



source from which information is generally derived, is a passage 

 in Descartes's Dioptrics*, in which he attributes the invention 

 to a citizen of Alkmar, called James Metiiis. Both the versions 

 of Borel and Descartes are usually given in books written on 

 this part of natural philosophy, and very recently they were 

 repeated in the very excellent account of the life of Galileo 

 published in England, and in the still more recent and capital 

 work of Professor Littrow on Dioptrics. 



The real name of this Metius, of whom Descartes speaks, 

 and who is also mentioned by Huygens, was Jacob Adriaansz. 

 His father Adriaan Anthonisz was a man of considerable know- 

 ledge for his time; he possessed a great influence, and took a 

 principal part in the struggle with Spain. In consequence, he 

 was banished by the Duke of Alva, and his property confis- 

 cated. He contributed very essentially to the glorious defence 

 of his native town against the Spaniards in 1592. He was 

 created afterwards inspector of fortifications, and many towns 

 were fortified on his plans. As a mathematician he is cele- 

 brated for his expression of the ratio of the diameter and cir- 

 cumference of the circle, by the numbers 113 and 355. At 

 that time Ludolf van Ceulen had not given his celebrated num- 

 ber, and the ratio of Archimedes, of 7 and 22, was in general 

 use. The numbers of Anthonisz have the merit of being easily 

 kept in memory, and of being as accurate as almost any pur- 

 pose requires. If no logarithms are used, it is easier to calcu- 

 late than Ludolf's number. 



There is another problem remaining of this Anthonisz, which 

 shows his ability as a mathematician : it is recorded in one of 

 the writings of his son Adrian, and Delambre notices it in his 

 history of astronomy, The problem was solved by Nicholas 

 des Muliers of Bruges, then professor of mathematics in Gro- 

 ningen. 



All the four sons of Adriaan Anthonisz were mathematicians 

 like their father. The eldest, Dirk or Theodore, was an engi- 

 neer and surveyor in the service of the States. He sailed in 



Pierre Borel was a native of Chartres, and author of several other books : 

 he died 1689. A copy of this very rare tract has been recently added to 

 the library of the Royal Institution. It contains a portrait of Lippershey. 

 * Cartesii Dioptrica, p. 49. 



