149 



X = V (y + z + yz) 

 y = o 



X = vz. 



The immediate verbal interpretation of the first of which is, 

 that the cases in which Xis true (x) are found by taking (=) 

 the aggregate of all the cases in which Y and Z are separately 

 and simultaneously true {y + z + yz), and selecting from this 

 aggregate according to some law of election (y), the nature of 

 which is not defined in the proposition. 



Mr. Graves added, that he had the satisfaction of learning 

 that his suggestion, with respect to the mathematical expres- 

 sion of hypothetical propositions, had met with Mr, Boole's 

 approval. In fact that gentleman had himself contemplated 

 making the change here proposed, in pursuance of a like hint 

 thrown out by Mr. Graves in the case of Categoricals. 



Rev. Dr. Todd read the following extract from a letter 

 addressed to Dr. Apjohn, from Robert R. Cornwall, Esq., of 

 Killucan : 



" In digging round a rock in one of my fields, for the 

 purpose of having it blasted, four very old graves were found ; 

 the bodies had evidently no coffins, but were surrounded on 

 three sides by common, rough, flat stones, set upright on the 

 edge. The rock answered for the headstone. The graves 

 were but three feet long, twenty-two inches wide, and little 

 more than two feet from the bottom of the grave to the grass. 

 The bones very much decayed and broken ; the top of one 

 skull, and the face of another, were all that I could get in any 

 way sound." 



The President read the following communication from 

 Mr. Stewart Blacker, upon an cxtraor<linary Rainbow ob- 

 served by him on the 7th of March in the north of Ireland : 



