[ 6 77 ] 
to the Back of E [or to H in Fig. 2.] and this Fold 
turned round, till E comes to the Back-fide of B. as in 
Fig. 3. and the Seam formed by the Edges B F and 
E F may be palled together, only the inner Fold on 
the Right Side muft be pufhed back from the outer 
circular one, fo as to form a Partition, as at G. in 
Fig. 4. and 3. by which means Two Cavities will be 
formed, that on the Right Side the Partition in this 
Form the other, on the Left Side, almoft cir- 
cular, thus, 0 > as in Fig. 4. the Outfide of the fir ft 
confifting but of one ft ngle Fold, the Outfide of the 
latter confifting of a double Fold, and the Partition 
being but of one Fold : Thus the firft Cavity reprefents 
the Right Ventricle of the Heart, the other the Left 
Ventricle, and the Partition G the Septum , as in Fig. 
4. [All thefe Particulars are diftin&ly exprefled in 
Fig. 2. which is to be cut off from Fig. 1. 3. and 4. 
and is to be folded upon the Line BE)) fo that the 
Letters EE and FI H come exaftly Back to Back, 
and that the Line EF and HF tally precifely ; pafte 
this Paper thus folded together Back to Back, then 
cut off the white Paper to the Rim of the Circle, 
and cut out a Piece at the Centre to F, and you will 
by this means have a femicircular Piece of Paper, 
with all the Lines reprefented on both Sides tallying 
to each other, as above deferibed at Fig. 1. But as it 
was very difficult to print on each Side of the fame 
Paper, fo as to make the Lines tally, I thought it 
better to have this Figure printed in a whole Circle, 
that fo fuch, as would be at the. Pains, might cut it off, 
pafte it, and fold it, and thus, as it were, form a 
Model of an Heart. In this Figure likewife I ordered 
the Engraver to diftnguifh the feveral Surfaces of the 
mufcular Coats, by Lines and Dots, in fuch man- 
T 1 1 1 ner 
