1814.] discovered in the College Lihrary of Edinlurgh. 35S 



on the lid is a table of addition, the figure in the intersection of a 

 line and a columii, being equal to the figure at the head of the 

 column, plus the figure at the left extremity of the line. 



C, D, E, F, is the body of the box ; G, H, I, K, L, M, are six 

 slits, under each of which, in the thickness of the box, which is 

 about half an inch, a cylinder is placed, which may be turned 

 round its axis by a handle, g, /?, i, k, I, m; on each of these cylin-: 

 ders is pasted the table N, 0, P, Q, which is a inultiplication table 



disposed in the manner of Napier's rods, the line N P being 

 parallel to the axis of the cylinder V to the slit. If the solution 

 of the above example from Tartaglia be required, turn tlie handle / 

 till the column which has 4 at top appears through the slit, turn k 

 till the column 5 appears, I till 6, and rn till 7 is seen, then write 

 out the line 3 of these four columns, write out the line 2, and the 

 line 6, and we have the figures disposed as in the example : upon 

 adding them diagonally, the product is obtained. 



R, S, T, U, is the lamina for the extraction of the cube root, as 

 described in the Rabdologia. 



Article V. 



E^my on the Cause of Chemical Proportions, and on some Cir-' 

 cumstances relating to them: togethtr uith a short and easy 

 Method of expressing them. By Jacob Berzelius, M.D. 

 F.R.S. Professor of Chemistry at Stockholm. 



{Concluded from p. 255.) 



14. Platinvm (Pt). — I have already in a preceding memoir given 

 an account of my experiments to determine the capacity of satura- 

 tion of this metal. Several metals, particularly rhodium, platinum, 



Vol. III. N" V. Z 



