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 c aay has a ravens cater, to render the joints poriay 
air-tight. 
Prof. Whewell made af impor on. the Discussions of ‘Tides, 
performed under his direction, by means of the grant of money 
made for the purpose by the shiniOciddicink? 4 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 (cousisting. 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 former places, hens the wave the pee 
