290 British Association for the Advancement of Science. 



dulum for alteration in time. The edge of the cap belonging to 

 the cistern is graduated, which subdivides the threads of the 

 screw on the cistern, it being turned round for alteration in time. 

 There is an aperture on the top of the jar, which allows of mer- 

 cury being added or removed without unscrewing the cap of the 

 cistern. This aperture is closed by a screw, which, as well as 

 that on the cap, has a leathern collar to render the joints perfectly 

 air-tight. 



Prof. Whewell made a '^ Hepoi^t 07i the Discussions of Tides, 

 performed under his direction, by means of the grant of money 

 made for the purpose by the Association." Prof. W. remarked, 

 that he had adopted the method of curves, first systematically 

 employed by Sir J. Herschel, which consists in laying down a 

 number of points expressing the results of individual observa- 

 tions, and then getting rid of the irregularities which these in- 

 volve, by drawing, not a line joining the points, which would be 

 a broken line, but by striking with a bold but firm hand, a line 

 among the points, so as to come as near as possible to the whole 

 assemblage of them. In this manner the heights and lunitidal 

 intervals were laid down as ordinates, and curves were drawn. 

 This method of curves depends upon the fact, that the eye gene- 

 ralizes the relations of space more rapidly and surely than the in- 

 tellect can generalize phenomena in any other way. 



Mr. Russell, of Edinburgh, brought up the '■[Report of the 

 Committee (consisting of Sir John Robison and himself) on 

 Waves." This report was a continuation of that of last year, 

 recently published. These researches are of great value and in- 

 terest, but it is scarcely possible to condense the account. We 

 give merely some remarks on the best forms for ships. One part 

 of his subject was the relation which the translation-wave bore 

 to the phenomena of resistance of fluids. He had previously as- 

 certained that the displacement of a fluid by a vessel took place, 

 not in the body of the current, but solely by the generation 

 of waves. Now, the manner in which they were generated ap- 

 peared to throw light upon the subject of the resistance of fluids ; 

 because they wished to have exactly the same transference for 

 particles of matter which was required for transference of waves. 

 They wished to remove the particles of fluid from a state of rest, 

 and admit the vessel to pass through, and then allow them to re- 

 turn to their formei: places, just as in the wave the particles were 



