70 



sequence to derogate from the character ascribed to the general 

 motion of the water throughout the strait. 



A reference is made to the erroneous opinions which have 

 hitherto been entertained with respect to the motion of the streams 

 of our channels ; and the author concludes his paper by explaining 

 his views as to the manner in which the turn of the stream is ren- 

 dered simultaneous by the rapid rise of the combined wave in the 

 centre of the strait, and expresses a hope that he has satisfactorily 

 shown from the observations, that throughout the English Channel 

 and North Sea the movement of the stream may safely be referred to 

 a common standard. This, it is considered, will be of great import- 

 ance to navigation ; as thus the seaman's progress through these 

 moving waters will be freed from the numerous and perplexing re- 

 ferences he was before obliged to make, and which too often — and, 

 it is to be feared, in many instances too fatally — caused the tides to 

 be wholly disregarded. All uncertainty as to the effect of the stream 

 will henceforward, it is expected, be obviated by a simple reference 

 to a tide table. 



The paper, which is accompanied by numerous plans and charts, 

 forms a practical illustration of the tidal streams of straits, under 

 the influence of a combined wave. 



May 22, 1851. 

 The EARL OF ROSSE, President, in the Chair. 



Edward Schunck, Esq. was admitted into the Society. 



Mr. James Smith gave notice, that at the next meeting of the 

 Society he would propose His Grace the Duke of Argyll for imme- 

 diate ballot, to which as a peer of the realm His Grace is entitled. 



The following papers were read :— 



1. "Additional Observations on the Diffusion of Liquids." By 

 Thomas Graham, Esq, F.R.S.,F.C.S. &c. Received March 27, 1851. 



The experiments detailed in this paper were conducted with the 

 same apparatus and in the same manner as those described in the 

 author's two former papers on this subject. The diffusion was gene- 

 rally made from four different proportions of each solution, so as to 

 exhibit pretty fully the character of the salt in reference to this 

 property. The salts operated upon were of two bases only, potash 

 and soda, but the acids were considerably varied, so as to include the 

 hydrates, carbonates, sulphates, sulphites, hyposulphites, sulphovi- 

 nates, oxalates, acetates and tartrates of these bases. 



The times chosen for the corresponding potash and soda salts, 

 with the view of obtaining equal diffusions, v/ere always in the pro- 

 portion of 1*4142 to 1-7320, that is, as the square root of 2 to the 

 square root of 3. Eight cells were diffused of the 1 and 2 per cent, 

 solutions, and four cells of the 4 and 8 per cent, solutions. The 

 salts were always taken anhydrous, . 



