Of Microscopes in General . 3 
of Microfcopes, is not in me to determine: 
the Honour lias been given by fome to 
Dr ebb el, & Dutchman-, by others to Fon¬ 
tana, a Neapolitan and by others frill to 
different People. The firft Appearance of 
them however was about the Year 1621 i 
fince when they have been improving down 
to the prefent Time. 
As my Defire is, to make People fenfible 
of the Pleafure and Information the Micro- 
fcope can afford, and inftrudt them how to 
manage and underfland it, rather than how 
to make it, I fhall take up none of their 
Time with the Manner of melting, grind¬ 
ing, polifhing, or fetting of Glaffes a Work 
very few of my Readers will ever trouble 
themfelves about. But, inftead thereof, I 
fhall endeavour, with all the Brevity and 
Clearnefs I am able, to explain the Effects 
of Glaffes on the Sight, and lead them gra¬ 
dually into the Nature, Ufes, and magnify¬ 
ing Powers of Microfcopes. 
When ObjeCts are feen through a perfectly 
flat Glafs, the Rays of Light pafs through 
it, from them to the Eye, in a flrait Direc¬ 
tion, and parallel to each other ; and confe- 
quently the GbjeCf s appear very little either 
diminifhed or enlarged, or nearer or farther 
off, than to the naked Eye. But if the 
Glafs they are feen through has any Degree 
of Convexity, the Rays of Light are direct¬ 
ed from the Circumference towards the 
B 2 Center, 
