THE MICROSCOPE. 



scopes, left by that famous man at his death to the Royal 

 Society as a legacy, each instrument has a double convex 

 lens, and not a sphere or globule." 



An account of these microscopes was drawn up by Baker, 

 in 1740, and published in the Philosophical Transactions for 

 that year. Fig. 2 is a front view of the instrument, 

 and fig. 3 a back view, both being of the exact size of the 

 original: a, fig. 2, represents a flat plate of silver, which is ri- 

 vetted to fig. 3 by rivets, b b b; between these plates a small 

 double convex lens is let into the socket, and a hole drilled 

 in each plate for the eye to look through the lens at c ; a 

 limb of silver, d, is fasteiied to the plate, a, by a screw, e, this 

 has another piece of silver joined to it at right angles, f, fig. 3, 

 through this a long fine-threaded screw, g, runs, which turns in 

 and raises or lowers the stage, h, whereon is fastened a pin, i, 

 for the object to be attached to ; this pin can be turned about 

 by the little handle, k, and the stage itself is adjusted to or 

 from the lens by the screw, I, which passes through the stage 

 in a horizontal position, and when the screw is turned, the 

 stage is forced from or brought nearer to the lens at c. 



" All the parts of these microscopes," says Baker, " are of 

 silver, and fashioned by Mr. Leeuwenhoek's own hand, and 

 the glasses, which are excellent, were all ground and set by 

 himself, each instrument being devoted to one or two objects 

 only, and could be applied to nothing else. This method 

 induced him to make a microscope with a glass adapted to 

 almost every object, till he had got some hundreds of them. 

 The highest magnifying power was 160 diameters, and the 

 lowest 40." 



About this time, the end of the 17th century. Sir Isaac 

 Newton was in the zenith of his glory; having discovered, in 

 1672, the theory of light and colours, he was led to the im- 

 provement of the telescope, by substituting mirrors for lenses, 

 and he commences his memorable paper in the Philosophical 

 Transactions with these words: — "When I had found that 

 light consists of rays differently refrangible, I left off my 

 glass works, for I saw that the perfection of telescopes was 

 hitherto limited not so much for want of glasses truly figured, 



