2 DISCOVERY OF TELESCOPES. 



can be fairly inferred from some well-known passages of 

 Seneca, Pliny, and Pisidas* that the ancients were 

 acquainted with the power of glasses to magnify objects, 

 or to make remote objects appear near ; or, whether 

 Roger Bacon and the monks of his time advanced farther 

 than the construction of spectacles, are questions to 

 which, however interesting they may be, we need not 

 here devote any time. It suffices for my present pur- 

 pose to remark that both telescopes and microscopes were 

 unknown to the philosophers of the sixteenth century ; 

 and that a fortunate occurrence led to their invention, 

 and to the grand and rapid extension given, in conse- 

 quence, to the physical sciences. Borelli informs us, in 

 a treatise composed not so long after the circumstance 

 as to render his authority doubtful, that the children of 

 Zachariah Jansen, a spectacle-maker of Middleburgh, 

 amusing themselves in their father's shop, placed by 

 chance a convex and a concave lens in such a manner 

 that on looking through them at the weathercock of the 

 church, it seemed to them nearer and much larger than 

 usual. The father was called to witness this, and 

 immediately fixing the glasses upon a board, that their 

 relative position might be rendered permanent, he pre- 

 sented either those or others similarly arranged to his 

 patron, Prince Maurice. The first telescope after these, 

 which he made, was in the year 1590, and it did not 

 exceed sixteen inches in length. No sooner was this 

 remarkable discovery announced than Galileo, Kepler, 

 and other philosophers, bent the whole force of their 

 genius to the improvement and employment of so useful 

 an apparatus; and since that epoch, theoretical and 

 practical men have vied with each other in improving 

 its construction and extending its powers. The posses- 



