t 344  3 
XVII.  Reflexions  on  the  Communication  of  Motion  by  bn- 
paX  and  Gravity.  By  the  Rev.  Ifaac  Milner,  M.  A. 
Bellow  of  Queen’s  College,  Cambridge.  Communicated 
by  Anthony  Shepherd,  D.  D.  F.  R.  S . and  Plumian 
Profeflor  at  Cambridge, 
Read  Feb.  26>r'T"^  HE  theory  of  moving  bodies  was  little 
*“■  underftood  by  the  philofophers  who 
lived  in  the  fixteenth  century.  They  obferved,  that  a 
body,  once  put  into  motion,  continued  to  move  for  fome 
time  after  the  force  was  impreffed ; but  they  argued  very 
ftrangely  from  this  ordinary  phenomenon.  Far  from 
confidering  the  air  as  a refilling  medium ; they  fuppofed 
with  aristotle  and  the  ancients,  that  it  was  the  perpe- 
tual influx  of  the  parts  of  the  atmofphere  which  con- 
tinued to  urge  the  body  forward  and  preferve  its  motion. 
When  a body  is  projected  in  any  direction  inclined  to  the 
horizon,  the  gravity  of  its  parts  is  always  obferved  to 
bend  the  direction  of  its  motion  into  a curve  line ; and 
becaufe  this  gravity  remains  invariably  the  fame,  what- 
ever the  force  of  projection  be,  in  very  fwift  motions,  the 
figure  defcribed  may  approach  very  nearly  to  a right  line. 
This 
