( 2*5* ) 
the circulation of a large quantity of fluggilh Blood, a 
great ftrength is abfolutely requifite to propel the Blood 
through una&ive Velfels to the extremities of the Body, 
and back again. No doubt this is more eafily done in 
Men of a low ftature (as old Boyles was) which I am apt 
to think was a qualification of old Age. The fecond v/as 
the largenefs of their Chefts, and goodnefs of their 1 
Lungs, by which the Air had its full effort upon every 
Particle of the Blood, in rendringit florid and attenuating 
it , that it might eafily move through the contracted 
Channels of an old Body. 
Few have the happinefs of fuch a Heart and Lungs, 
yet moft men with to live long 5 nor was it eafy for 
Phyficians to give Rules for preventing the ill confe- 
quences of extream old Age, whilft the effefts of a long 
Circulation of the Blood were unknown ^ of which we 
can be certain only by Diffeftions of old perfons, and 
thcfe are not numerous enough to ground any thing cer- 
tain upon : But if after Obfervations (hall confirm the 
Remarks that have been now made, no doubt the Indi- 
cation will be to preferve (itch a foftnefs in all the Fibres, 
that they may eafily yield to the preflure of the Blood, 
and by their Elafticity reftore themfelves to their former 
ftate, giving thereby a new impetus to the Blood. 
IX. The 
