( 6i 9 ) 
the Darts in Figure ) and pufhes back the Light fo as 
to refled: it when the Vibration is contrary to its 
Dired:ion, but brings it down to be refracted when 
the Vibration confpires with the faid Motion. See 
a further Account of this in Sir Ifaac NewtonV 
Of ticks , Book II. Part 3. Propofition 12. 
The Perfons prefent at the Experiments above- 
mentioned, tried them as well as myfelf, and be- 
ing fatisfied with the Succefs of them, allowed me 
to mention it, and make ufe of their Names in this- 
Account. 
Of Royal Society, 
Sir Hans Sloane y Prefident. 
Dr. Scheutzer . 
Mr. Grey. 
Mr. Georges. 
Mr. Hu good. 
Other Gentlemen. 
** - A w * . ; 1 * » f 
Colonel Sfotfwood. 
Mr. Haily. 
Mr. Graham. 
Mr. He wet. 
Foreigners. 
The Abbot Lercari , a Nobleman of Genoa> Cou- 
fin to Cardinal Lercari. 
The Abbot Cuzzoni. 
The Abbot Roll's^ and his Brother. 
Ilf. The 
