ON THE TYPES OF COMPOUND STATEMENT. 81 



Brahe^s ' Mechanica/ which he immediately began to print 

 at Hamburg, whilst he remained at Ranzovius's, and that 

 there may not have been time to have it engraved ; or, may 

 be, it was too self-glorious. 



The residence of Ranzovius, half a mile from Hamburg, 

 existed till ten or fifteen years ago, when it was pulled down, 

 and a full-length portrait of Brahe disappeared, representing 

 him with an astronomical instrument in one hand. 



Dr. C. exhibited a photograph from his picture, taken 

 by an able photographer, Mr. White, Crescent, Salford. 



Note. — In the description of Brahe's dress there is a se- 

 rious omission, viz. that he is represented in a cloak with 

 a high collar. Further particulars respecting this picture 

 will be found in 'Nature,^ October ii, 1877. 



XIT. On the Types of Com/pound Statement involving four 

 Classes. By Professor W. K. Clifford, M.A., F.R.S. 

 Communicated by Professor W. S. Jevons, M.A., 

 F.R.S. 



Read January 9th, 1877. 



Professor Stanley Jevons has enumerated* the types of 

 compound statement involving three classes, among which 

 the premises of a syllogism appear as a type of fourfold 

 statement. He propounded at the same time the corre- 

 sponding problem of enumeration for four classes, which is 

 solved in the present communication. The reader is re- 

 ferred to the paper or the book just mentioned for further 



* ' Proceedings of the Manchester Philosophical Society ' vol. vi. pp. 65-68, 

 and 'Memoirs,' Third Series, vol. v. pp. 119-130. 'The Principles of 

 Science,' vol. i. pp. 154. -164. 



SER. III. VOL, VI. G 



