532 PHILOSOPHICAL TRANSACTIONS. [anNO 1681-2. 



j 



Answer to the foregoing Observations. By Dr. Pell. An. 1639. Dec. 2. Ibid. 



p. 137. 

 If 1 understand you right, learned Sir, you approve of all I have said, except 

 that you think I require a larger apparatus than is necessary. It is your opinion, 

 that not all the mathematical books and instruments should be collected, which 

 I contend for, but the best of them only be selected. This opinion I should 

 not oppose, if it were generally agreed on, among such a multitude of authors, 

 which are the best, or which should have the preference before all others ; and 

 if I had this only in view, that something of labour and expence might be saved 

 to the studious in these arts. But since it was my object to obtain the most 

 perfect foundation for the whole scope of the mathematics, I ought not to de- 

 lineate any other scheme than that might completely answer such a design. The 

 principal part, I apprehend, of a project must consist in such a universal library 

 as I have described. That being the case, I ought not to despise any attempt, 

 much less to condemn any one unexamined, that may throw in his mite, and 

 endeavour to promote this undertaking. And if I may give my judgment, the 

 most trivial writing, or mathematical instrument, ought to be preserved, one 

 copy at least, even for its errors, in some certain accessible place in every coun- 

 try. For we perceive many things that have been ingeniously invented, in the 

 ruder instruments of former ages, that are now not only worthy of observing, 

 but even of being imitated ; as some writers of a lower class may give very good 

 hints, and assist the invention of those of a happier genius ; for we can often 

 point at an excellence, which we cannot arrive at ourselves. We perceive many 

 lemmata that have been well demonstrated by this kind of writers; yet, because 

 of some one fundamental fallacy, their whole superstructure has come to the 

 ground. If you think that many ought to be rejected, as well for their trifling 

 and verbosity, as for error and false conclusions; you should consider how dif- 

 ferent are the notions and taste of mankind, and without estimating the judg- 

 ment of others by the measure of your own sagacity. For there are some per- 

 sons who can understand nothing, unless repeated to them a hundred times, 

 and that almost in the same words : so that those tautologies are well adapted 

 to such persons. And because we must always begin with the more knowii 

 things; and the same things being not equally known to all; we must therefore 

 make very different beginnings. So that you can scarcely find one learner, but 

 he may be assisted by a rude instrument, or an unskilful author : hence then 

 he wh"o undertakes the office of a mathematical monitor, ought not to be un- 

 acquainted even with these. So that the complete collection of books, before- 

 mentioned, seems to me to be quite necessary. 



