( i6i ) 
Strength of Light in the Objed encreafed in Pro* 
portion to the Square of the Length. 
At the End of the Treatife is fub joined a Letter 
from the Reverend Father Melchior a Briga, die. to 
the Author, giving an Account of fome former Attempts 
to difeover the Revolution of this Planet round its Ax- 
is, by Mr. CaJJini.^ De la Hire^ die, confifting chief- 
ly of an Extrad of a Letter from Mr. Cafftnt to Mr. 
Petit, jrmtedi in the Journal des Sfavans, i66y\ 
TEom. ii. Edit, MntJK Fhe zd and 3d Figures which 
are referred to in this Letter, are inverted by. the En- 
graver, who copied them from the Original. 
yil. Oh/erVations on a Treatife wrote by Monf 
Helvecius of Paris, defined to prove that the 
Lungs do 7iot divide and ex/pand the IBlood, hut 
that on the contrary, they cool and condenfe it. 
IBy R Nicholls, M S. frd. AnaU Oxon 
F. (2^. S. 
T H E Matter in Queftion between the Author and 
Slgnior Michellotti is, whether the Lungs cool 
and condenfe the Blood, according to the Opinion of the 
Antients, orwhether they mix, attenuate, and of Confe- 
quence expand it, according to the Syfl;em of Dr. 
Pitcairn. 
Zz 
The 
