378 Mr. J. W. L. Glaisher on Early Logarithmic 



esse cogebar, ut exemplaria excusa distribuerem ; istaq ; de 

 occasione primum in Galliam, deinde etiam in Angliam profec- 

 tus sum, ubi me rem meam bene acturum putabam * J (Joannis 



Miltoni Defensio secunda Hag. Com. 1654. Typographus 



pro se-ipso) . These words, taken literally, imply that Ylacq was 

 not connected with the bookselling trade until he began to print 

 the Arithmetical which must have been subsequently to 1626; but 

 I do not think that great importance is to be attached to their 

 exact meaning, as Vlacq here, as in the Arithmetical ignores his 

 early work performed in conjunction with De Decker ; and as we 

 know that the Arithmetica itself was also printed by Ramma- 

 seyn. Thus most likely either Vlacq had nothing to do with 

 printing or bookselling till after the publication of this work in 

 1628, or he was connected with the trade in some way or other 

 through Rammaseyn from the date of his (or De Decker's) 

 earliest logarithmic work in 1626. The latter view is that 

 adopted by Prof, de Haan, and is very likely correct ; but the 

 simple meaning of Vlacq' s own words agrees better, I think, 

 with the former. It is proper to state here that a list of names 

 (with dates and places) of editors of logarithmic tables appended 

 to a tract of Prof, de Haan's, " lets over Logarithmentafels ** *, 

 contains that of De Decker (Gouda, 1626) ; but this is, as far as 

 I know, the only place in which any allusion is made to the 

 work. It should also be added that the above paper on De 

 Decker's works was written by Prof, de Haan before he had 

 seen my second communication, " Supplementary Remarks, &c." 

 (Phil. Mag. Dec. Suppl. 1872), which accounts for the partial re- 

 capitulation of the translation of a portion of the preface of the 

 Erste Deel van de Nieuwe Telkonst. In regard to the life of 

 Vlacq, Mr. W. Barrett Davis drew my attention to the following 

 petition, printed in the Calendar of State Papers, Domestic 

 Series, 1637 :— 



" Petition of Richard Whitacres to the same [Archbishop 

 Laud]. One Hooganhuysen, a Dutchman, being heretofore 

 complained of in the High Commission for importing books 

 printed beyond the seas, was bound not to bring in any more. 

 One Vlack has kept up the same agency, and sold books in his 

 stead, and is lurking here, observing what is most useful and 

 vendible, and causes it forthwith to be printed abroad. Peti- 

 tioner having lately brought from Frankfort mart to Rotterdam 

 four great vats of books to the value of £500, Hooganhuysen, 



* Amsterdam, 1862, reprinted from the Verslagen en Mededeelingen der 

 Koninklijke Akademie van Wetenschappen, Afdeeling Natuurkunde, Deel 

 xiv. This pamphlet, which I had not met with till Prof, de Haan recently 

 sent me a copy, contains far the most complete list of writers on logarithms 

 or publishers of logarithmic tables that I know of. 



