Royal Society. 227 



The experiments of the author, of which an account ^s^giv€n in this 

 paper, were made with a glass tube, about an inch in diameter, one 

 end being drawn out into a slender tube of the interior diameter of 

 one eighth of an inch, and having a piece of bladder tied over the 

 other end. When this Endosmometer, as it has been called, is by means 

 of a small funnel introduced into the narrow end filled with alcohol, 

 and immersed in water, the water penetrates through the blad- 

 der, and the spirit rises rapidly in the narrow stem. The author 

 found on trial that this action was apparently not affected by a pow- 

 erful current of voltaic electricity passed through the bladder, by in- 

 troducing positive and negative wires on both sides of it. On sub- 

 stituting a strong solution of sulphate of zinc for the alcohol, the same 

 negative result was obtained. 



The author considers the action of the animal membrane to be the 

 consequence of its strong attraction for water, an attraction to which 

 it owes its hygrometric properties : while, on the other hand, the 

 membrane has no attraction for alcohol, which has itself a powerful 

 attraction for water. The water, therefore, finds its way easily through 

 the membrane, and uniting with the alcohol, is carried oft' by it, and 

 diffused through the liquid, making room for the other portions that 

 successively come over. Whalebone and quills have similar hygro- 

 metric properties, and may be substituted for membranes with the 

 same efiect. All substances readily soluble in water give rise to the 

 phenomena of endosmose, on the same principle as alcohol, such as 

 gum, sugar, and salts. The phaenomenon bears a striking resem- 

 blance to the rise of the sap in the capillary vessels of plants, both 

 being probably dependent on the same principle ; the filamentous 

 texture of the roots performing the function of the membrane, and 

 the contained sap that of the attractive fluiJ; by the agency of which 

 the external moisture of the earth is imbibed and raised into the 

 interior of the plant. 



June 16. — A paper was read, " On the Tides in the Port of 

 London." By J. W. Lubbock, Esq., V.P., and Treas. R.S. 



This paper contains a discussion of observations of the tides 

 made at the London Docks, and registered in various Tables, showing 

 the time and height of high water, not only at different periods of 

 the moon's age, but also for the different months of the year, for 

 every minute of the moon's parallax, and for every three degrees of 

 lier declination. The tables themselves were registered by Mr. 

 Dessiou of the Admiralty ; but the arrangement of the tables and 

 the methods employed are due to the author. The tides in the river 

 Thames are extremely regular; and as the rise is considerable, the 

 observations on them are easily made. Those at the London Docks 

 present an uninterrupted series from the opening of the Docks in 

 180t to the present time ; which is more extensive than any extant, 

 with the exception only of that made at Brest by order of the French 

 (Joverninent. Some observations are also given of the tides made du- 

 ring one year at the Eiist India Docks, under the superintendence 

 of Captain Eastfield, and which were imdertaken at the suggestion 

 of the author, and made with extreme care. 



2 G 2 Tlie 



