TRANSACTIONS OF THE SECTIONS. 199 
‘obtuse angles rounded off, so that a ship or steamer can pass from the river into the 
basin, and take up her berth without warping, or any such annoyance and delay. 
Similarly, on leaving, a vessel, when once her head is round, can pass out without 
slacking speed, and therefore without risk of being carried by the current against the 
pier-heads. The diagram represents a succession of basins formed according to the 
proposed method, and, if desirable, at different periods to meet the exigencies of the 
port, yet-in such a manner that there is easy communication between each quay and 
the main road leading into the city or the traffic depots. These quays are, from 
the obtuse angles at which they intersect, well adapted for tramways, which may 
branch off a trunk line laid along the main road. 
When additional port accommodation is thus obtained the result cannot but be 
beneficial to the river, since these basins will act as reservoirs, increasing the volume 
of water which passes through the channel, and thus aiding by its source in maintain- 
ing the river at its proper depth. 
S>——— 
On Machinery for Laying Submarine Telegraph Cables. 
By Professor W. THomson. 
On Superheated Steam. By J. WeTHERHEAD, United States. 
APPENDIX. ; 
On the proposed Ship Canal through the Isthmus of Suez. 
By Dr. Hopexin. 
Although the difficulty at one time supposed to exist in the difference of level 
between the Mediterranean and Red Seas is now no longer urged, there are other 
_ physical difficulties which are of at least equal importance. The canal must not only 
_ be made, but must also be maintained in a serviceable condition. Now, it is well 
known that on the Mediterranean side the sea is not only shallow and sandy, but that 
its depth is subject to constant variation from the moving character of the sand-banks. 
It might almost be presumed, @ priori, that the same causes which prevent any of the 
mouths of the Nile from serving as an available ingress or egress for vessels navigating 
_ the Nile, would produce and maintain an effectual obstacle to vessels passing in either 
_ direction between the Mediterranean Sea and an artificial canal. I had an oppor- 
_ tunity of witnessing a strong confirmation of this inference in proceeding from Alex- 
andria to Jaffa. Although we kept out at sea to the distance of some miles, the 
eaptain of the steam-boat, which was a much smaller vessel than would be required 
for Indian or Australian commerce, thought it needful, in broad daylight, to be 
frequently using the sounding-line as a security against stranding his vessel. The 
force of this objection is so far admitted by the advocates of the canal as to induce 
them to allow that it will be necessary to construct piers advancing some miles into 
the sea, and that at their mouth, and in the channel between them, it will be requisite 
to keep dredging vessels constantly employed to preserve a practicable passage. 
It will, perhaps, be asked in what the difficulties consist? The general facts may be 
safely stated to be—first, a certain amount of elevated land to be cut through; secondly, 
and considerably lower than either sea, where very substantial embankments must be 
jhrown up to prevent the neighbouring country from being submerged. Throughout 
is tract, and probably along the greater portion of the line, a very careful and ex- 
“pensive process of puddling will be absolutely necessary to enable the canal to hold 
water. 
