[ 5*7 3 
Room. The End of the brafs Tube without the 
Shutter has a convex Lens, to colled the Rays, and 
bring them to a Focus ; and on the End within the 
Room, Wilforis Pocket-Microfcope is fcrewed, with 
the Objed to be examined applied to it in a Slider. 
The Sun’s Rays being direded by the Looking-glafs 
through the Tube upon the Objed, the Image or 
Pidure of the Objed is thrown diftindly and beauti- 
fully upon a Screen of white Paper, and may be 
magnified beyond the Imagination of thofe who have 
not feen it." — I allifted lately in making fome Expe- 
riments with Dr. Alexander Stuart , by means of 
this Inftrument, and a particular Apparatus contrived, 
by him, for viewing the Circulation of the Blood in 
Frogs , Mice , &c. and had the Pleafure of beholding 
the Veins and Arteries in the Mefentery of a Frog 
magnified to near Two Inches Diameter, with the 
Globules of the Blood rolling through them as large 
almoft as Fepper-corns . We examined alfo the 
Strudure of the Mufcles of the Abdomen , which 
were prodigioufly magnified, and exhibited a mod 
delightful Pidure. Bur, as the Dodor intends him- 
felf to communicate to you an Account of thefe 
Experiments, I will not anticipate your Pleafure. 
The Microfcope for opake Objeds remedies the 
Inconvenience of having the dark Side of an Objed 
next the Eye : For by means of a concave Speculum 
of Silver, highly polifhed, in whofe Centre a mag- 
nifying Lens is placed, the Objed is fo ftrongly illu- 
minated, that it may be examined with all ima- 
ginable Eafe and Pleafure. A convenient Appa- 
ratus of this kind, with Four different Specula, and 
Magnifiers of different Powers, has lately been brought 
t@< 
