( 9 * ) 
flute, as it always is when we are in Bed, the comprefs’d 
Cartilages will, by their natural elaftick Power, begin 
gradually to enlarge themfelves, till they recover the 
lame expanded State they enjoyed before they were 
forced to give Way, and yield to the incumbent Pref- 
fure ; and fo confequently it will produce a confidera- 
ble Alteration in a Perfon’s Stature, agreeable to the 
determined Times mentioned in the preceding Letter. 
For if we only confider, that the before-mentioned 
compreftive Power will leften the thicknefs of all the 
Cartilages, in proportion to the Quantity of Matter 
they contain ; and that there are ufually reckoned about 
twenty four in Number, it will be no difficult Matter 
for us to apprehend, that their natural Expanfion be- 
ing recovered by our cuftomary Repofe, the Aggregate 
of the whole of the Expanfions may amount to 
about an Inch. Now if the Alteration be fo con- 
fiderable as this, occafioned only by the bare incum- 
bent Weight of the fuperiour Parts of the Body, with- 
out any additional Force applied to comprefs the Car- 
tilages yet clofer, how much more may we reafonably 
imagine it would be, were the Experiment tried on 
fuch Perfons, whofe ufual Employment it is to carry 
heavy Burthens. I have only this one Particular far- 
ther to obferve upon this Head, which is, that this 
Alteration is not to be expected to be the fame in aged 
Perfons as in thofe that are younger, becaufe the Car- 
tilages, as we advance in Years, gradually grow har- 
der and harder, till many of them arrive to the foli- 
dity of a Bone; that is, by Degrees they lofe their 
Spring or expanfive Power, and at length continue in 
a comprefs’d State of Reft. And this is without doubt 
one principal Caufe, why old People not only feem to 
have loft lomewhat of their former Height, but are 
actually fhorter. 
III. A 
