x S Of the Circulation of the Blood.. 
The description of a new apparatus for con¬ 
fining frogs, mice, bats, or' any other crea¬ 
tures of the like fize, particularly adapted 
to the variable and improved foiar micro- 
Scopes. 
T HIS apparatus conflfb of a fquare frame of brafs 
A) B, C, D, fig 46. which may be taken to pieces 
at pleafure. It is held together at the corners, by the 
four pillars F, F, F, F, which alfo fupport the frame. 
At the lower end of the two pillars which fupport the 
corners C and D of the frame, is fixed a fteel bar G H, 
having one of its ends made fall to one of the pillars at 
G, and the other end fcrewed to the oppofite pillar by 
the nut H: on this, fquare bar is fitted a Aiding focket 
I K, to which are fixed the ftems for placing k to the- 
microfcope. 
When a frog is to be diftedted, tie a firing to each of 
Its four legs j firft having firained firings thro’ fome of the 
principal holes of the frame, eroding each other, as in 
the figure is reprefented by the fmall letters a b, c d, e f, 
g h, i k, 1 m, which form a kind of lattice, or couch, 
whereon to extend the frog. Then firft put the two 
firings which are tied about his arms, through two holes, 
the neareft to the corners A, C, and there fix them wjth 
two pegs made of fur, as at n and o, in the figure. The 
reafon why I diredt his two fore legs or arms to be fa¬ 
ttened firft is, becaufe you may with eafe hold his hind 
legs in your hand, till the fore legs are pegged down 
faft; whereas if you attempt to fix the hind legs firft, 
the creature will give fuch fprings and ftarts, as will not 
only tire himfelf, and thereby prevent him from being 
able 
