THE MICROSCOPE: CHAKLES SINGER 57 



(8) Francesco Mauroiico (1494-1575) was perhaps the first after 

 Roger Bacon to attempt a mathematical analysis of the optics of 

 the lens. He is thus the predecessor of Kepler. His work, rhotismi 

 de lumine et umbra, was printed at Venice in 1575. 



(9) Leonard Dujyes (died 1571 ?) was the first to whom can be 

 definitely attributed the construction of a bilenticular system. The 

 evidence for this statement rests on the following passage in a work 

 by his son, Thomas JJigges (died 1595): — 



" Marueylouse are the conclusions that may be perfourmed by 

 glasses concaue and conuex of circulare and parabolicall fourmes, 

 using for multijolication of beames sometime the ayde of glasses 

 transparent, which by fraction should unite or dissipate the images 

 or figures presented by the reflection of other. By these kinds of 

 glasses or rather frames of them, placed in due angles, ye may not 

 only set out the proportion of an whole region, you represent before 

 your eye the lively image of euery towne, village, etc., and that 

 in as little or great space or place as ye will prescribe, but also 

 augment and dilate any parcell thereof, so that whereas at the 

 firste apparance an whole towne shall present it selfe so small and 

 compacte together that ye shall not discerne any dijBference of streates, 

 ye may by applycation of glasses in due proportion cause any 

 peculiare house or roume thereof dilate, and shew it selfe in as 

 ample fourme as the whole towne first appeared, so that ye shall 

 discerne any trifle or reade any letter lying there open, especially 

 if the Sonne beames may come unto it, as playnly as if you wer 

 corporally present, although it be distante from you as farre as eye 

 can discrye. But of these conclusions I minde not here more to 

 intreate, hauing at large in a volume by it selfe opened the miracu- 

 lous effectes of perspective glasses." Digges's system appears to 

 have been combined in some manner with a camera ohscura. Un- 

 fortunately, his further description of it was never published. The 

 work of Thomas Digges in which this passage occurs is entitled A 

 Geometrical Practise named Pantometria, and was printed in London 

 in 1571. 



(10) Gianhattista della Porta (1540-1615) is the first to whom 

 can be attributed the actual combination of lenses in the form of 

 a microscope. This statement rests on the evidence of the following 

 passages in his Magia naturalis: — " Concave lenses enable one to see 

 far off more clearly, while convex ones make near objects more 

 discernible." He was apparently myopic, for he goes on to say 

 that '' with a concave lens you see things afar smaller but plainer, 

 with a convex lens you see them larger but less distinct. If, how- 

 ever, you know how to combine the two sorts properly, you will 

 see near and far both large and clear." In later years, when the 

 microscope became a recognised instrument, much larger claims 

 were made by and for Porta, but there is no real evidence that 

 he made any effective practical application of his idea. The Magia 

 naturalis was first printed at Naples in 1558, but the passages in 

 question do not occur in it, nor in any edition of the w^ork that 

 appeared before that of 1588. 



{\l\ Zach arias, son of Jan, and known as Jansen (1580-16?), 

 of Middelburg, is usually regarded as the first who actually con- 

 structed a microscope. His first attempt was the result of an 



