oculis nudis diftinguuntur, & adeo exigute fuperfrciei 
ut radii luminis, licet exiliffimi, fenfibilem habeant ad 
ipfani fuperficiem ratlonem, quod in lentibus, aut 
globis majoribus non evenit. Ideoque has omnes 
cautiones quas adhibendae funt plufquam par erat 
forfan expofui ; ufus enim quae neceffariae tantum 
funt facile edocebit. 
HE firfl obfervatlon was made July a'’, 1761, 
with Wilfon’s frngle microfcope, conftrudted 
for a perpendicular infpe6lion, with a mirror beneath 
it for rededlng the light. The inftrument was placed 
on a table near to a South window, but the fun’s 
rays were not refledled on the objedt j it being Father di 
Torre’s opinion, that the ordinary day-light would 
Ihew the globules in a more natural ftate. A fmafl 
drop of blood was included between two talks, and 
was changed during the obfervatlon, in order to give 
the appearance all the advantage that might arife 
from the accidental htuatlon of the globules between 
the talks, and alfo to renew their motion; for al- 
though the blood viewed in this manner is not in a 
O ^ 
ftate of circulation, yet, either from the vacuum 
formed between the talks, the attradion of their 
furfaces, or fome other caufe, the ferum is feldom in 
a quiet flate on its being firft included between them, 
and the globules that float in it move for fome time 
An Account of fome microfcopic Obferuations on the 
human Blood. 
m 
