134 Of viewing the Current 
applied between the Tube and the Magni¬ 
fier whereby the Sun’s Rays reflected from 
the Looking-glafs, through the Tube, upon 
the Objed, pafs on through the Magnifier* 
and exhibit upon the Screen an Image of the 
Objed mod: prodigioufly enlarged. This, I 
hope, may give fome Idea of our Inftrument: 
and now I come to the Application. 
Our Objed was a Frog , whofe Limbs 
being extended and fattened on the Frame, 
we opened the Skin of the Belly from near 
the Anus to the Throat ; then giving it a 
little Snip fideways both at the Top and 
Bottom, by flicking a Fijh-Hook in each 
Corner of the Skin, it was eafily flretched 
out before the Microfcope , and prefented on 
the Screen a moil beautiful Pidure of the 
Veins and Arteries in the Skin, with the 
Blood circulating through them. In the 
Arteries we could plainly perceive the Blood 
flopping, and as it were receding a little, at 
each Dilation of the Heart, and then im¬ 
mediately rufhing forwards again at each 
Contradion ; whilft in the Veins it rolled 
on in a continual Current with inexpreffible 
Rapidity *. 
After confidering this as long as we 
thought needful, we opened the Abdomen , 
* When the Arteries were magnified very much, byre- 
moving the Screen to a copfiderable Diftance, the alternate 
Expanfion and Contraction of their Sides were very vifible 
and remarkable. 
