Chap. 3-] Extreme Mimitenefs of certain Particles, ij 



times greater than in its fluid form *. A particle 

 of light has been eftimated, on apparently a well 



conducted calculation, at c 



30,83 i, 230, 1 28,000 of a 



grain f- 



We fhall indeed .ceafe to wor-der at fuch a calcu- 

 lation, when we confider that by means of this fluid 

 the unparalleled wonders of the microfcopic world are 

 made cognizable to our fenfes. The fcarf-fkin of the 

 human body is faid to be compofed of minute fcales 

 refembling thofe of fifties, two hundred of which may 

 be covered by a grain of fand ; under thefe fcales there 

 lie concealed a number of pores, or excretory duels, 

 through which the perfpirable matter is fuppofed to 

 ifiue, and one hundred and twenty of fuch pores in. a 

 direct line extend to only one tenth of an inch. If 

 fuch therefore is the organization of the human body, 

 what fhall we think of the organized parts of thofe 

 animals which are themfelves one thoufand times too 

 imall to affed the human eye without the aid of art ? 

 Animalcule, however, have been diicove^ed nearly 

 one hundred times fmaller than thefe, many thoufands 

 of which may dance upon the point of a fine needle < 

 indeed Lewenhoek calculates that one thoufand mil* 

 lion of fuch animalcula: as are difcover.ed in common 

 water would not equal in magnitude a grain of com- 



* This fac"l may at any time be proved by an eafy experiments 

 Take a common flafe, and let it ,be exaftly weighed ; fill it with 

 water, and then let it be weighed again after the water is emp- 

 tied, there \vill necefi'arily be a little moifture adhering to the 

 iides ; put the flafk before a fire to evaporate the moifture, and 

 when the whole of the water difappears, cloife the flafe, "vr.d 

 weigh it again, and you will then have the weight, and conis- 

 quently the bulk of vapour, compared with that of water. 



f Botidoin on Light. Memoirs of the American Acad. Vol. I. 

 p. 198. 



mon 



