Microscopical Essays. 



5 



and obfcure, appear larger and clearer through a glafs bubble 

 filled with water." Thofe who wilh to fee further evidence con- 

 cerning the knowledge of the ancients in optics, may confult 

 Smith's Optics, Dr. Prieftley's Hiftory of Light and Colours, 

 the Appendix to an Effay on the firft Principles of Natural 

 Philofophy by the Rev. Mr. Jones, Dr. Rogers's DifTertation on 

 the Knowledge of the Ancients, and Mr. Du ten's Enquiry into 

 the- Origin of the Difcoveries attributed to the moderns. 



The hiftory of the microfcope, like that of nations and arts,, 

 has had it's brilliant periods, in which it has fhone with uncom- 

 mon fplendor, and been cultivated with extraordinary ardour ; 

 thefe have been fucceeded by intervals marked with no difco- 

 very, and in which the fcience feemed to fade away, or at leaft 

 lie dormant, till fome favorable circumftance, the difcovery of 

 a new object, or tome new improvement in the inftruments 

 of obfervation, awakened the attention of the curious, and ani- 

 mated their refearches. Thus, foon after the invention of the 

 microfcope, the field it prefented to obfervation was cultivated by 

 men of the firfl rank in fcience, who enriched almoft every branch 

 of natural hiftory, by the difcoveries they made with this in- 

 ftrument : there is indeed fcarce any object fo inconfiderable, 

 that it has not fomethmg to invite the curious eye to examine 

 it ; nor is there any, which, when properly examined, will not. 

 amply repay the trouble of inveltigation. 



I {hall firft fpeak of the single microscope, not only as it is 

 the molt fimple, but becaufe, as we have already obferved, it was 

 invented and ufed long before the double or compound micro- 

 fcope. When the lenfes of the Angle microfcope are very con- 

 vex. 



