1 0 6 UcBmaJlatics. 
the Air, which k in fuch great Qiiantides 
infpired into them. It has long been the 
Subjeft of Enquiry of manyj to find of what 
ufe it is in Refpiration, which tho* it may 
in fome Refpeds be known, yet it muft be 
cotifefled that we are ftill much in the dark 
about it. 
37. As the Air in ordinary Infpirations and 
Expirations, pafles freely and eafily too and 
fro with fmall Velocity, fo it cannot have any 
confiderable Effed on the Blood by any im. 
pulfive Force : Nor yet by any additional Gra- 
vity arifing from the Form of the Lungs, which 
Gravity, upon a Calculation that the Sum of 
all the Areas of the Veficles is equal to a hun. 
dred and fifty two fquarc Feet, has by Dr. 
James Keil been cftimated to be equal to 
50443 Pounds Weight, there being a mani- 
fefi: Miftake in the Argument. For fuppofe 
a cubic Foot of any folid or fluid Matter, to 
be divided into an hundred Lamina or Plates 
each of thefe Plates when fpread abroad will 
be prefled with the whole Weight of the At- 
mofphere *, and when laid on each ocher in 
the Form of a cubic Foot, they will then alfo 
each of them fuflain the fame Weight of the 
Atmofpherei befides that in this Poficion, all 
except 
