t 4^ 3 
•Fig. to. Demonftrat verticalem tumoris fedionem, 
A, G, H, Flexuofa tumoris cavitas, ex foramine A, 
Fig. 9. oblique in ejufdem corpus defcendens, quaa 
in centro in duas minores cavitates H 1 , H K , 
dirimitur. 
I K, Alia major in fundo tumoris cavitas, per quam 
ad ptasfatas minores patet adieus. In hoc tumoris 
cavo modicum ofFendimus ichoris, qui folo contadu 
argenteum perfpicillum denigravit. 
M My Interna & farcomatofa tumoris fubftantia. 
X. A Letter front James Jurin, M. D 
F. R. S. Coll. Med. Lond. to Martin 
Folkes, Ffq\ Prefident of the Royal So- 
ciety, concerning the ASlion of Springs. 
SIR , 
Pre/ented April if NEED not inform a Perfon Fo well 
' 2 1744 A acquainted with all the Branches of 
Mathematical Philofophy as yourfelf, that the Theory 
of Springs not only is of great Ufe in the more 
curious Parts of Mechanics, as the Strudure of 
Watches, &c. but may give Light to many Opera- 
tions of Nature, there being few Subftances but 
what are endued with fomc Degree of Elaftici'ty ; 
and particularly the Bodies of Animals, and of Vege- 
tables likewife, being known to confift, in a great 
meafure, if not wholly, of Organs ftrongly elaftic. 
For which Reafon it is not to be wondered at, that 
this Theory has engaged the Thoughts of feveral 
eminent 
