MICROSCOPIC OBJECTS. 25 



aim was magnifying power, not penetration, — not a word 

 was said of the latter. At Cambridge, laborious analy- 

 tical investigations were made on the best construction of 

 the eye-piece. So far, however, were these eminent 

 mathematicians from the right course, that even after 

 effective achromatic object-glasses were executed, they 

 gave the optician an elaborate paper for constructing in 

 a simple manner a microscope that, as a whole, should 

 be achromatic ; the only objection to which construction 

 was, that by it no penetrating power of any amount 

 could be obtained. Hence in a short time this construc- 

 tion was abandoned, and that of the achromatic object- 

 glasses vdth larger angular aperture, combined with a 

 modification of the Huyghenian eye-piece, is now per- 

 manently established. 



To enumerate the various apphcations of the microscope 

 to science is unnecessary in this work, as the subsequent 

 chapters will show. One use, however, may be mentioned, 

 as, a priori, it would not have been expected, namely, its 

 value to the geologist. It has been well said by Mr. 

 Witham, in his work on Fossil Vegetables, that the 

 ancient fossils of our earth are its " medals, recording 

 changes which it has undergone, and placing before our 

 eyes innumerable specimens of nature's early productions. 

 The study of the wonders of creative power," he con- 

 tinues, "so profusely scattered wherever we cast our eyes, 

 is calculated to improve the tone of public feeling, by 

 turning into channels of useful inquiry the natural 



