282 RELATION OF DECREMENTS, &C. 



X 



but the Abbe Haiiy's symbol would be (D2 O F3), 

 and would be understood to imply that the compound 

 molecules abstracted in the production of the new 

 plane, consisted of smaller compound ones, each of 

 these being three molecules in height, and two in 

 breadth, repeated twice on the edge D, and three 

 times on the edge F. 



From this exposition of the difference between the 

 two symbols, it will be readily perceived that if in 

 the Abbe Haiiy's symbol, we substitute for the letter 

 denoting the angle on which the decrement is con- 

 ceived to take place, that which denotes the edge 

 upon which the angle of the new plane may be said 

 to rest, and place the number used by him to express 

 the decrement in height, which is in this case the 

 denominator of his fraction, after it as its proper 

 index ; and if we multiply at the same time his other 

 indices by the number he uses to express the decre- 

 ment in breadth, which is in this case the numerator 

 of his fraction, the new symbol will be similar in 

 character to those which are contained in this volume. 



This method of converting the form of the one 

 symbol into that of the other, may be considered 

 general, and by reversing the process, the symbols 

 given in the preceding pages, may be converted into 

 the form of those which he has used. 



