PHYSICAL anp LITERARY. | 439 
that the pulfe is quicker when we fit or ftand 
than when we lye; and that the action of 
the mufcles of voluntary motion, not only 
promotes the return of the blood to the 
heart, but determines it thither, with much 
greater force than ufual. In fleep therefore, 
~where the horizontal pofture of the body,* 
the quiefcence of the voluntary mufcles, and 
compofure of the mind, all concur to render 
the return of the venous blood to the heart, 
more equable and flow, the contraction of 
this mufcle muft be renewed at greater inter- 
vals, and with more regularity, than when 
we are awake, and the circulation is quicken- 
ed or difturbed by fome, or all, of the above- 
mentioned caufes. But, if no farther cir- 
cum{tance, tending to retard the hearts mo- | 
tion, were found in fleep, the pulfe fhould 
be equally flow and full in a waking perfen 
lying at reft in a horizontal pofture, and 
whofe mind is compofed, as in the fame per- 
fon in time of fleep; which, however, does 
not feem to be entirely the cafe: for tho’ the 
difference may be fmall, and there may be 
many caufes which may render it difficult, by 
obfervation, to determine that difference with 
any degree of certainty; yet the remarkable 
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flownefs 
