ORIGIN A\D HISTORY 



(4) One lens is used which has one spher- 

 ical and one hyperboloid surface. 



(5) Two hyperboloid glasses are used, 

 one convex and one concave, as described 

 also by Descartes. 



Caspar Schott (1608-1666) wrote Magia 

 Universalis Naturae et Artis with a chapter: 

 "Microscopes and Their Wonderful Power 

 in Revealing the Constitution of Natural 

 Objects" which appeared in 1657. In this 

 book the author gives a classification of 

 microscopes of his day: 



(1) A short tube with a fiat glass at one 

 end and a glass sphere at the other end. 

 The object had to be put inside of the tube 

 on the flat glass. 



(2) A glass vase into which small objects 

 are put at the bottom and the neck of which 

 is closed with a crystalline lens of a spheri- 

 cal shape. 



Other examples for microscopes are given 

 which repeat what Kircher had listed pre- 

 viously. 



Peter Borelius made in 1655 a contribu- 

 tion to microscopy of historical importance 

 in his book De Vero Telescopii Inventore. 

 He collected important evidence concerning 

 the inventors of the microscope which is 

 used in the foregoing text. He also gave a 

 classification of the microscopes of his time: 



(1) Two glasses are put at the ends of a 

 small tube. One is convex with spherical 

 surfaces and the other is plane and carries 

 the object. When this was a fly "enlarged 

 to the size of an elephant", the instrument 

 was called "conspicilium muscarium", or 

 fly glass. But it would be "conspicilium 

 pulicarium" or flea glass when the object 

 was a flea enlarged "to the size of a camel", 

 much to the enjoyment of the observer. 



(2) One single spherule was mounted at 

 the end of a tube. At the other end would be 

 a small glass box containing sundry tiny 

 objects. 



(3) Two convex lenses were used with 

 much superior properties. 



(4) Several coaxial tube parts were 



mounted in such a way that the whole could 

 be lengthened and shortened. It would 

 contain three or four different lenses. 



Borelius mentioned also the names of some 

 of the more important opticians of his time 

 and described the manufacture of their in- 

 struments, including the grinding and polish- 

 ing of lenses. 



In another part of his book Borelius gave 

 a record of microscopical observations in- 

 tended to be a guide to those who "wished 

 to study the Majesty of Cod in minute cre- 

 ation and an offering of respect to the worthy 

 citizens of Middelburg among whom the 

 microscope had been invented." Listed are 

 milk, blood, vinegar, two kinds of lice, fleas, 

 six kinds of worms, spider eyes and eggs, 

 pimples, ants, moss, ferns, caterpillars, but- 

 terflies and other objects up to one hundred 

 exactly. 



The attitude of Borelius demonstrated in 

 his work and the details both of his instru- 

 ments and observations classify him more 

 as an amateur of optics; he was a physician 

 at the court of Louis XIV. 



Several other writers in the 17th century 

 were delighting in listing the innumerable 

 objects of the new world invisible to the 

 naked eye. Among them was Robert Hooke, 

 who gave a list of some 60 microscopical 

 observations in his J\Iicrographia, written in 

 Enghsh and pubhshed in 1665. This book is 

 remarkable because it also contains a de- 

 tailed description of his compound micro- 

 scope which had two convex lenses and, 

 what would be called later, a field lens which 

 he had learned to use with advantage for 

 some observations. He also built a special 

 illuminator in order to get brighter images of 

 his objects. He complained about the un- 

 avoidable smallness of the objective lens 

 which will not "admit a sufficient number of 

 Rayes to magnifie the Object beyond a 

 determinate bigness." He mounted on a 

 stand an oil lamp, then in the proper dis- 

 tance, "a pretty large Clobe of Class fiU'd 

 with exceeding clear Brine," and a convex 



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