112 REPORT—1843. 
tide was in this case only to be explained by the method he had adopted, 
which removed the difficulties in which the subject had formerly been 
involved. 
He then proceeded to explain the mode of discussion which had beenadopted. 
It was the semi-diurnal inequality, so accurately examined by Mr. Whewell, 
which enabled us to decide on the ages of two tides. If the two tides which 
appeared together presented opposite inequalities both in time and in height, 
regularly alternating, varying with the moon's declination, disappearing with 
it and reappearing with it, and following it regularly without regard to other 
simultaneous changes of a different period, then it becomes plain that no 
other inference could be drawn than that he had mentioned; and when 
further, he had proceeded to treat these tides as compounded of two success- 
ive tides, one due to a transit 12"24™ later than the other, and had used for 
this purpose two simple river tides superimposed at a distance in time cor- 
responding to that at which the northern and southern tides could enter the 
Frith, he had obtained a close representation of the double tides of the 
Frith of Forth; when these two methods of examination ended in the same 
conclusion, he conceived that it had attained a very high degree ef pro- 
bability. 
By means of these observations tide tables had been formed which were 
designed to afford a more accurate means of predicting the local tides of the 
east coast of Scotland than any we now possessed. 
The author of the report took occasion to express the deep regret with 
which he appeared as the only representative of this Committee, having been 
deprived of the valuable services of his coadjutor by the lamented death of 
Sir John Robison, a zealous promoter of science and a valuable member of 
the British Association. 

Notice of a Report of the Committee on the Form of Ships. 
By Joun Scorr Russe, Esq. 
Tuis report was voluminous, containing the reductions of a large number 
of experiments, and about 20,000 observations, made on more than 100 
vessels of different forms, accurate drawings of all of which, on a large 
working scale, were laid on the table. It is the hope of the Committee that 
this report may be published in order to give the public all the benefit 
which accurate knowledge on this point was likely to convey. The present 
abstract does not therefore enter fully into the details of their voluminous 
results, but is confined to a general account of the objects which this Com- 
mittee had in view, the methods of inquiry which they had adopted, and a 
few of the more general conclusions to which they had been conducted. 
It had long been the reproach of science that so little had been done to 
enable the practical man to proceed with certainty in his attempts to improve 
the speed of ships. There were some points in which science had done all 
that can be desired. The immersion of a ship, her trim, her centre of buoy- 
ancy, her stability, can all be determined with accuracy beforehand, and the 
scientific naval constructor can proceed with certainty upon fixed scientific 
principles. It is otherwise with the speed and resistance of a ship. In 
nothing does calculation more completely fail than in the attempt to deter- 
mine beforehand the speed of a ship constructed on given lines, or to show 
how a form may be so altered as to render it faster than before. To ealeu- 
late the resistance opposed by the water to the passage of a ship through it, 
and to find that form which at a given velocity will pass through the water 
with least resistance, and of course with the smallest expenditure of power; 
