300 Mr. J. W. L. Glaisher on some new Facts in 



cate his books. By the help of Dr. Johnston_, Bishop of London, 

 he was, however, enabled to prevent the seizure and procure a 

 licence to sell the books he had in stock. The King^s printers 

 then offered to procure him his licence as of old, if he would 

 buy from them copies of two books which they had printed at 

 Laud^s request. This he did, and obtained a licence for two 

 years, with the hope of its being then renewed ; but the civil 

 war broke out at the end of that time, and he accordingly left- 

 London and went to Paris. There he got on very w^ell for some 

 time and published several books (most of them theological) of 

 which he has given the titles, believing that he had a right to do 

 so. His success made him enemies, and, after a prosecution, all 

 his books were confiscated. He appealed to the Court of the 

 Parliament, but was advised by his friends to accept a com- 

 promise, whereby he was allowed to retain his books, but agreed 

 to leave the city and not return within a year; as it was a pri- 

 vilege of the Paris booksellers that foreigners should only come 

 there once a year to sell their books. He then went to the 

 Hague to spend the remainder of his days; and as far as his 

 conduct there is concerned, he appeals to his friends. From this 

 account it seems that Vlacq was born about 1600 ; and he was cer- 

 tainly alive in 1655. One is almost inclined to pardon Milton 

 his abwse, seeing that thereby we are made acquainted with what 

 would otherwise probably have always remained a mystery. 



Montucla says that in 1628 Vlacq published, besides the 

 Arithmetica, a French translation of it [Arithmetique Logarith- 

 metrique &c.) ; and Murhard gives the title, but not as having 

 seen the book. I always used to think there was a mistake, as 

 I could find no place in which the work, though often spoken 

 of, was described as having been seen by the writer. The ex- 

 istence of the book, however, is beyond question, as there is a 

 copy in the British Museum. Vlacq is even more modest in 

 the French than in the Latin edition, as the only occurrence of 

 his name on the titJepage is in the following sentence: — "La 

 description est traduit du Latin en Fran9ois, la premiere Table 

 augmentee, & la seconde composee par Adriaen Vlacq."*^ The 

 Introduction is translated into French; and the first Table has 

 the titlepage, Table logarithmetrique j^our les nomhres depuis 

 rUnite jusqu'a 100000. In the Penny (and English) Cyclo- 

 paedia and 2\so in i\iQ Biogrophie Universelle (1863), accounts are 

 given of Vlacq ; but they are very meagre and inaccurate. In 

 Rees^s Cyclopaedia he is erroneously described as '• a Flemish 

 mathematician of Ghent,^^ and in the same v/ork (under Briggs) 

 as " of Targou, in Holland.''^ In most cyclopaedias &c. (including 

 Hutton's 'Mathematical Dictionary' and Phillips^s ^Dictionary of 

 Biography^) his name does not appear at all, though much space 



