Motion  by  Impatf  and  Gravity.  379 
confiderations  appear  to  have  the  lead;  tendency  to  pro- 
mote fo  ufeful  an  end,  in  the  opinion  of  that  Society  to 
whofe  learned  and  zealous  endeavours  we  owe  the  very 
firfl:  important  difcoveries  in  the  year  1668,  concerning 
the  collifions  of  bodies. 
Vol.  LXVIII.  C c c 
