SEC. 11.] OF NATURAL PHILOSOPHY. 263 A, together with — drawn into a. will be the moment of 1, that is, nothing. A Therefore the moment of -r, or of A — ', is -r— . And generally since A .A T- into An is I, the moment of —drawn into An together with — into A n A. A n naA" — ! will be nothing. And, therefore, the moment of -r- or A — n A will be— £T^~7- Q-E.D. V . t . ' i CASE 5. And since A2 into A2 is A, the moment of A1 drawn into 2 A2 will be a (by Case 3) ; and, therefore, the moment of A7 will be n~r~r or ^A-j £#A — £. And, generally, putting A~^ equal to B, then Am will be equal to Bn, and therefore maAm — ! equal to nbBn — ' , and ma A — ' equal to ?tbB — ', or tib A — ^ 5 an