Sir B. C. Broclie on the 



[May 18, 



event is an event which is not so regarded. Thus, for exaraple, take the 

 Rvstem of the four events : — 



(1) cCv -\-aK^oj =aio -\-a^i:~t', 



(2) aV'v + tt^'C'w =a(t) -\-a^K^y, 



(3) a^K^v-\-a^K^co =a(o +aVj^, 



(4) a'y -\-S a^K'(i) = 3 au) -\- a^K^)'. 



The event 4 is a compound event, being the aggregate of the events 

 1,2, 3; whereas the events 1, 2, 3 are in that system simple events, 

 being incapable of such a construction. 



Section III. On tlie causes of events. — The cause of an event is 

 given when the operations are defined by the agency of which the event 

 occurs. Bef. If in any chemical event the change in the arrangement 

 of the symbols, by which the composition of the units of matter before and 

 after the event respectively is symbolized, be of such a nature that where 

 in the arrangement before the event the symbol appears the symbol 

 a appears after the event, and where a appears before appears after, 

 so that the two arrangements differ in this respect and this respect alone, 

 then the event occurs by the substitution of a for .v, which is the " cause" 

 of the event. Hence the same event may arise from more than one 

 cause. Thus, for example, the event 



occurs by the substitution of a for and of h for y, for these symbols 

 satisfy the condition given in the above definition. 

 It is similarly shown that the event 



A.vi/z + Aahz + Aai/c + A.vLc — Axyc -j- Acibc + Aayz + Accht 

 occiu's by the substitution of a for cv, h for y, z for c ; and, further, that if 

 the equation to any chemical event be of the form A (.v — a) (y — b) (z-c) 

 (v — d) (iu — e).,.=0, that event occurs by the substitutions of a for .r, h 

 for y, c for z, d for v, 'a for iv .... 



If in these substitutions any symbol, say 'a'=l, the event occurs by 

 the transference of the simple weight thus sjanbohzed. 



The following event occurs in three ways by the substitution of | for 

 X, the hydride of propyl, being constant, 



the equation being of the form 



, aV(x-?)»=0. 



Similarly the event 



ci'/cx^ •\- 3a"fcx = 3a"K"x^ + a'K 

 is an event occurriug in three ways by the transference of x, the equation 

 being of the form 



I submit the follo\rag equation to the consideration of the reader, 



