286 



Monday, 20(h January. 

 Ricrht Hon. Lord GREENOCK, V. P. in the Chair. 



The followdng communications were read : — 

 1. On General Differentiation. Part II. By Professor Kelland. 



" In the preceding memoir on this subject, the author had confined 

 himself to the fundamental operations leading to the differential 

 co-efficients of various functions. In the present paper, he offers 

 an illustration of the entrance of such coefficients into the analysis 

 of physical and geometrical problems. Having first established a 

 general theorm, connecting finite integrals of a certain form with 

 fractional and negative differentials, the author adapts it to repre- 

 sent the integrals actually occurring in several problems. By this 

 means he wishes to shew that the theory of General Differential 

 Coefficients will at some future period become a powerful mstru- 

 ment in the hands of analysts, by furnishing them with results com- 

 prehended under general forms, and thus opening another section 

 of the science of comprehensive memory." 



2. On the Means employed to prevent Forgeries of Bank 

 Notes, Bills of Exchange, Cheques, &c. By Dr Traill. 



« The author prefaced his remarks by a short history of Bills of 

 Exchange, and other kinds of paper currency; in which he pointed 

 out the economy and convenience of a well reguMed paper circulation. 



" The means usually employed to diminish the facilities to for- 

 gery are — 



« 1. Colouring the paper, or the pulp of which it is manufactured, 

 by various vegetable and mineral substances, either singly or com- 

 bined. The best attempts of this sort have been imitated by a 

 clever hand and a pencil. 



" 2. Certain water-marks in the paper of the note or bill, as that 

 employed by the Bank of England. A good imitation of this would 

 perhaps require the connivance of a paper-maker; but successful 

 imitations of tvater-marks have been made by gum and a pencil, 

 or by pale tints of China ink to imitate a worn note. 



'« 3. Printing notes in different colours, from two or more wooden 

 blocks, increases the difficulty of forging ; instances of this were 

 given in the coarse Excise paper stamp, and in the more elegant 

 L.l note formerly issued by the Bank of Ireland. 



