TRANSACTIONS OF THE SECTIONS. 133 
On the Construction of Sea Walls and Embankments. 
By Joun Scotr Russert, F.RSE. 
Mr. Russell, from his various researches on the formation of waves, 
and the methods of increasing or diminishing their velocity, had come 
to the conclusion that the best form of sea walls and embankments for 
breaking the waves gradually is a parabolic curve, with the convexity 
upwards. 
On the Duty of the Cornish Engines. By Mr. Joun Taytor, 
F.RS., §¢. 
Mr. John Taylor gave some explanation respecting the methods of 
ascertaining the duty of Cornish engines. He confirmed the state- 
ment that one engine had performed 125 millions; but as this experi- 
ment only lasted 26 hours, he agreed with Mr. Henwood in consider- 
ing that much importance was not to be attached to this trial. He 
considered the method adopted as a perfectly fair one for ascertaining 
the comparative duties of engines; but it was never asserted that the 
quantity of water was actually delivered at the adit. The quantity of 
coals consumed was also another very good test of the duty done, 
and an examination into the account-books of the different mines con- 
firmed the reports of the duty done. 
On Preventing the Dangers from Collision, and from Fire in Vessels. 
By Mr. WinLiams. 
The method now proposed consists in dividing the vessel into 
several compartments, by division bulk-heads, built up completely 
through the vessel, similar to the plan which has been adopted in the 
iron steamers. Thus, should any aperture be made by collision, the 
water would not extend through the whole vessel, as in the case of 
the Apollo, but would be confined to the compartment in which the 
injury takes place. In case of fire, the compartments in which the 
fire existed might be filled with water without any danger to the rest 
of the vessel; these bulk-heads would also prevent the existence of 
any strong current of air throughout the vessel. 
Experiments on the Equilibrium of the Arch. By Professor 
Mosetry, King’s College, London. 
The results of experiments on the equilibrium of the arch, laid by 
Professor Moseley before the Section, confirm the theoretical conclu- 
sions at which he had already arrived, in papers read before the Cam- 
bridge Philosophical Society. In flat arches, the breadth of whose 
voussoirs are the same, the thrust is found to be as the square of the 
span, and altogether independent of the depths of the voussoirs. In 
circular arches, the ratio of the depth of whose voussoirs to their radii 
