THE MICROSCOPE. 



TRANSLATED FROM " AUS DER NATUR, ETC.," LEIPZIG, 1858, FOR THE SMITHSONIAN 

 INSTITUTION, BY C. A. ALEXANDER. 



It may be generally observed that those to whom the performance 

 of a scientific instrument is not known through its proper use, are 

 disposed partly to overrate, arid again, in some other respects, to 

 conceive too low an estimate of its effects ; and this is no where more 

 clearly seen than in regard to the microscope. Nor have we to seek 

 far for the reason. The operations of the microscope have not been 

 made known to the great public through the results of scientific re- 

 search alone; while the costliness, and still more the difficult handling 

 of the instrument have prevented it from becoming, like the mag- 

 net, and the electrical machine, a familiar means of "pleasant and 

 instructive" amusement, by which it might have found its way into 

 wider circles. So much the greater, however, has been its use, and 

 often misuse, by itinerating showmen, whose interest it was to exag- 

 gerate to the utmost the marvel and strangeness of the object by which 

 spectators were to be attracted. Numerous are the fallacies which 

 have been thus scattered abroad. It may not be out of place, then, to 

 attempt to convey more accurate views of an instrument to which de- 

 scriptive natural science is indebted for the most important of its 

 advances in modern times. 



Microscopes, or, in the widest sense, the apparatus by which objects 

 but slightly removed are made to appear larger than they really are, 

 and the observer is enabled to inspect parts of them which are other- 

 wise undiscernible, are of great antiquity. Archa3ologists are now 

 agreed, however eloquently Lessing may have maintained the opposite 

 opinion, that the ancients were in possession of magnifying glasses, 

 without the help of which it would have been impossible that the ex- 

 quisite work of their engraved stones could have been executed. In- 

 deed, the wonder would be if it had been otherwise. Daily observa- 

 tion must have evinced to them, as it does to us, that transparent 

 bodies with curved surfaces magnify objects which are viewed through 

 them. 



The physical laws on which this phenomenon depends are so well 

 known, that we shall only briefly indicate them. Kays of light which 

 pass from one transparent body into another of different density, from 

 air for instance into glass, undergo a deflection from their original 

 course, and are bent or refracted. Those proceeding from a remote 

 object in parallel lines will, at the point of contact with a transparent 

 body bounded by spherical surfaces, (a lens,) be bent in such a manner 



