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AutomaU^ Cloch ami Watches^ vphiljl its Motion is performed 
like that of other Mufcles^ the Blood doing the Office of a Pon- 
dus. 
This Explication, being but a Simile without a diftindi 
application to particulars, is befide fo very (hort, that I can 
at beft but give a conjefture at the meaning, which if I 
miftake, 1 ftiall deferve to be excufed, and expeftto be bet- 
ter informed. 
By the Blood's doing the Office of a Ponduf, I fuppofe 
he means, that the Blood contributes in the fame manner 
to the Motion of the Heart, as the Weights do to rhat of 
the Pendulum of a Clock- If fo, the Blood, according to 
jiim, muft be the Inftrumcnt of Conjlri^ion ^ and Dilatation 
muft be the Natural State, or Spontaneous Motion, to which 
it wou*d, when under no Violence, return 5 the contrary 
of which, I prefume, will appear e're I have done. 
But if he means, that the Blood in its reflux, by gravi- 
tating on the Auricles and Ventricles^ dilates and expands 
'em, afting therein as a Counterpoife to its contraftion as a 
Mufcle, I cou'd wifti his defign had not bound him up to 
fo narrow a compaO, and that he had given us an explica- 
tion at large of fo abftrufe and fo important a Phenomenon. 
Becaufe the Specifick Gravity of the Blood feems to me a 
caufe by no means alone adequate to the effeft, which it is 
here fuppos'd to produce. 
For, if the Blood ads only as a 'weight by meer gravitati- 
on^ then that part of it only which defcends from the Parts 
above the Heart can be employed' in that aftion. This at 
the largeft computation can't amount to five pound weight, 
and muft, according to the computation of Borellus^ force 
a Machine,that is able to overcome a refiftance of 135,000/, 
I leave every -man to deduft what he (hall upon examinati- 
OH find reafenably to bededuded, and yet (hall reft fecure, 
that it is not to be effeded in the leaft with fo fmall a 
Weight. 
But 
