THE MICROSCOPE, 



INTRODUCTION. 



No one who attentively examines the progress of any depart- 

 ment of Science, save such as are (like Mathematics or Meta- 

 physics) of a purely abstract character, can fail to perceive how 

 much it is dependent upon the perfection of its instruments. 

 There are few instances, in fact, in which the invention of a new 

 instrument, or the improvement of an old one, has not given a 

 fresh stimulus to investigation ; even where it has done no more 

 than afford that degree of precision to the results of inquiries 

 already in progress, which alone could enable them to be made 

 available as data for philosophical reasoning. But there are 

 many cases in which such inventions or improvements have 

 opened out entirely new paths of scientific research, leading to 

 fertile fields of investigation whose very existence had been pre- 

 viously unknown, to rich mines of discovery whose treasures had 

 lain uncared for because entirely unsuspected. A few examples 

 of this general truth may not be inappropriate, by way of pre- 

 face to the brief notice which it is intended to give in the present 

 Introduction, of the most important epochs in the history, as 

 well of the Microscope itself, as of its application to the purposes 

 of scientific research. 



Thus in taking a retrospective survey of the history of Astro- 

 nomy, we find that every great advance in our knowledge of the 

 Celestial Universe, has been preceded by improvements, either 

 in those instruments for measuring space and time, by which the 

 places of the Heavenly Bodies are determined, the rate of their 

 movements estimated, and a basis for the computation of their 

 distances ascertained ; or, again, in the. telescope, by which our 

 power of sight is so wonderfully augmented, that we are enabled, 

 when gazing through it into the unfathomable depths of space, 

 to take cognizance of world beyond world and system beyond 

 system, whose remoteness cannot be expressed by any form of 

 words that shall convey a distinct idea to the mind, and to bring 

 the members of our own group within such visual proximity to 



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