826 



STEAM. 



SUEZ CANAL. 



Mr. Isherwood as a witness on the opposite 

 side. The jury gave their verdict for a savirfg 

 of 34 per cent, produced by the Sickles cut-off. 

 The positions taken by Mr. Isherwood in his 

 book are as follows : 



The causes of the great discrepancy found to exist in 

 steam engines using steam with different measures of 

 expansion between the economy as promised by the 

 law of Marriotte and as realized experimentally, may 

 be summed up as follows, premising that the same in- 

 itial and back pressures are supposed to be employed 

 in the cylinder, namely : 



1st. The law of the expansion of steam is not rigor- 

 ously that of Murriotte, even when condensation is 

 prevented by superheating ; the pressure decreases in 

 a higher ratio than the volume increases. 



2d. The condensation of steam in the cylinder due 

 to the production of power. 



3d. The condensation of steam in the cylinder due 

 to superheating the back pressure vapor as a gas. 



4th. The condensation of steam iu the cylinder due 

 to its expansion per se. 



5th. The condensation of steam iu the cylinder due 

 to external radiation. 



6th. The condensation of steam in the cylinder due 

 to the re-evaporation of water deposited on its internal 

 surface. 



7th. The loss of dynamic effect in the cylinder clear- 

 ance and steam -passage. 



8th. The influence of the back pressure in the cylin- 

 der resisting the stroke of the piston. 



9th. The influence of the pressure required to work 

 the engine per se. 



10th. The difference of dynamic effect due to an 

 equal weight of steam used at the average cylinder 

 pressure and at the boiler pressure. 



To which Mr. Dickerson replies : 



Now, each and all of these statements are either 

 false or do not affect the economy of expansion any 

 more than the economy of non-expansion. 



1st. The first one is false. Expanded steam increases 

 its pressure not diminishes it^in a higher ratio than 

 the volume increases; and this is the discovery of 

 Regnanlt. 



2d. The second one is false, no such condensation 

 occurs ; but if it did, there would be no difference of 

 practical consequence between expansion and non- 

 expansion. 



3d. The third one is of itself immaterial, and not ad- 

 verse to expansion. 



4th. The steam does not condense by expansion in 

 an engine, as Regnault shows. 



5th. The loss by external radiation from the cylin- 

 der is too insignificant to mention, but Isherwood says 

 of it that " the radiation from the exterior surface of 

 the cylinder and the condensation by the interior sur- 

 faces will be about the same," whether expansion or 

 non-expansion is used. 



6th. No such effect is produced no "water is de- 

 posited on the interior surface of the cylinder," and 

 of course none is re-evaporated 



7th. The total loss of power by clearance is perfectly 

 calculable, but is less with expansion than without it, 

 although it is a greater percentage of the total power 

 with expansion than without it. 



8th and th. The answer is that the back pressure 

 and friction are just like all other resistances which 

 oppose the steam in its effort to drive down the piston 

 just such resistance as the friction of the boat going 

 through the water, or of the mill-stone which grinds 

 the grain and by whatever means any of these resist- 

 ances are overcome with less steam than otherwise 

 would be needed, by that same means all of these re- 

 sistances are overcome more economically. 



But " back pressure" is diminished by increasing 

 expansion that is to say, a lower " vacuum" is pro- 

 duced by cutting off short than by following full stroke 

 and therefore, in respect to this item, there is a re- 



duction of resistance to be overcome, effected by the 

 very act of economizing the means by which it is 

 to be overcome. 



10th. I trust I shall not be considered intensely ig- 

 norant when I confess that I don't understand what 

 this means either philologically or scientifically con- 

 sidered. 



SUEZ, CANAL OF. The project of a ship 

 canal across the Isthmus of Suez, for which M. 

 de Lesseps, a Frenchman, has received the con- 

 cession from the Pasha of Egypt, is not only 

 of the utmost importance for the commercial 

 world, but has, of late, also led to some politi- 

 cal complications. According to the plan of 

 M. de Lesseps a canal was to be dug, ninety 

 miles long, three hundred and thirty feet wide 

 at the water line, and sloping at the sides down, 

 to the bottom, which was to be twenty feet be- 

 low low-water level in the Mediterranean. A 

 eluice-lock, three hundred and thirty feet long, 

 by seventy wide, was to be formed at each end ? 

 and by taking advantage of the rise of the tides 

 at Suez, it was expected, or hoped, that an ad- 

 ditional depth of three or four feet might be 

 obtained. The more formidable portions of 

 the, work would be two artificial harbors, ne- 

 cessary to be constructed at the ends of the 

 canal; seeing that no ship could enter it from 

 the sea except through a harbor protected at 

 all times from sands and shoals. At Suez, the 

 piers would have to be carried out to the length 

 of three miles, in order to inclose a harbor 

 deep enough for such a purpose, and would 

 have to pass through shifting sand ; but still 

 the stone to construct them is near at hand, and 

 the difficulties are only such as engineers are 

 accustomed to deal with. At the Mediterra- 

 nean end of the canal, however, near Tyneh or 

 Pelusium, the indispensable harbor would be 

 much more difficult of construction, and much 

 more costly. The Nile annually pours out 

 thirteen million cubic yards of sand and mud 

 into the Mediterranean, beside" that which is 

 deposited on the land of the Delta, or Lower 

 Egypt. These thirty million cubic yards are 

 borne by a current directly toward the shore 

 of the Mediterranean near the region of Tyneh, 

 making the sea at that spot shallower and shal- 

 lower every year, full of shifting mud banks and 

 sand banks. The English, in general, showed 

 a great opposition to the plan, and the French 

 naturally attributed this to political reasons. 

 After seven years of discussion, the matter was 

 taken up, in 1855, somewhat in an internation- 

 al spirit. The nations that would be most bene- 

 fited commercially by the opening of a canal 

 across the isthmus France, England, Austria, 

 Prussia, and Holland were invited by the 

 pasha to send out a joint commission of civil 

 engineers, to test the plans of Lesseps and Tala- 

 bot, and to report upon the feasibility of the 

 whole project. After they had made their re- 

 port, a larger commission, appointed by the 

 pasha, devoted the greater part of 1856 to a 

 consideration of the matter. The commission 

 came to the conclusion that a canal, differing 

 in certain points from Lesseps' plan, could be 



