( ) 
are not equally denfe in all their Parts, and Glafs Balls 
break after two or three ftrokes ; I caufed Balls to be 
nicely turned of Steel, and made as hard (as the Work- 
men call it) that is, as elaftick as polTible, and the 
Weights of ithem were precifely as .follows : Two 
Balls of twelve Ounces Troy each, one of fix Oun^ 
ces, one of three, one of two, and one of Eight-pen- 
ny-weight. Then making Pendulums of thele Balls, 
and hanging them upon the Machine contrived by 
Mariotte for the Congrefs of Bodies, and lately im- 
proved by Dr. Grave fande % I meafured 5'y \ Inches 
between the Center of Sufpenfion and the Center of 
Gravity of the Balls, and then every Degree of the Cir- 
cle they defcribed in their Ofcillation was one Inch, 
and the Degrees being marked upon a line of Chords 
on a Brafs Ruler above the Balls, by their Strings iuc- 
celTively covering the crofs Lines of DiviBon, the 
Degrees that the Balls fell from, and thole to which 
they rofe, were very difcernable to an Eye placed at a 
convenient Diftance. 
EXPERIMENT VII. 
I took the two Balls it, and removing each from 
the lowed: Point of their equal and refpecStive Circles, 
up to 4 Inches, or 4 Degrees, I let them fall lb that 
they met at bottom, and were both relle(d:ed again to 
4 j the Place from whence they fell. 
EXPERIMENT VIII. 
Every thing elfe being as before, inllead of one of 
the Balls it, I took the Ball 6, then letting 6 go from 
» Introd. No. 170. Vol.' i. 
8 Degrees, 
