Curiosities of Science. 39 



rude " language of chimes ;" or sound, in place of electricity, 

 might have passed along the metallic path, and appealed to 

 the ear in place of the eye. For the printing-press and the 

 typographic art might have been found a substitute, however 

 poor, in the lithographic process ; and knowledge might have 

 been widely diffused by the photographic printing powers of 

 the sun, or even artificial light. But without the telescope and 

 the microscope, the human eye would have struggled in vain to 

 study the worlds beyond our own, and the elaborate structures 

 of the organic and inorganic creation could never have been 

 revealed. North- British Review, No. 50. 



INVENTION OF THE MICROSCOPE. 



The earliest magnifying lens of which we have any know- 

 ledge was one rudely made of rock-crystal, which Mr. Layard 

 found, among a number of glass bowls, in the north-west palace 

 of Nimroud ; but no similar lens has been found or described 

 to induce us to believe that, the microscope, either single or 

 compound, was invented and used as an instrument previous 

 to the commencement of the seventeenth century. In the 

 beginning of the first century, however, Seneca alludes to the 

 magnifying power of a glass globe filled with water ; but as he 

 only states that it made small and indistinct letters appear 

 larger and more distinct, we cannot consider such a casual re- 

 mark as the invention of the single microscope, though it might 

 have led the observer to try the effect of smaller globes, and 

 thus obtain magnifying powers sufficient to discover pheno- 

 mena otherwise invisible. 



Lenses of glass were undoubtedly in existence at the time 

 of Pliny ; but at that period, and for many centuries after- 

 wards, they appear to have been used only as burning or as 

 reading glasses ; and no attempt seems to have been made to 

 form them of so small a size as to entitle them to be regarded 

 even as the precursors of the single microscope. North- British 

 Review, No. 50. 



The rock-crystal leiis found at Nineveh was examined by Sir David 

 Brewster. It was not entirely circular in its aperture. Its general form 

 was that of a plano-convex lens, the plane side having been formed of one 

 of the original faces of the six-sided crystal quartz, as Sir David ascer- 

 tained by its action on polarised light: this was badly polished and 

 scratched. The convex face of the lens had not been ground in a dish- 

 shaped, tool, in the manner in which lenses are now formed, but was 

 shaped on a lapidary's wheel, or in some such manner. Hence it was 

 unequally thick ; but its extreme thickness was T 3 s ths of an inch, its 

 focal length being 4 inches. It had twelve remains of cavities, which 

 had originally contained liquids or condensed gases. Sir David has 

 assigned reasons why this could not be looked upon as an ornament, but 

 a true optical lens. In the same ruins were found, some decomposed 

 glass. 



