TRANSACTIONS OF THE SECTIONS. Ill 



ferred. This arrangement is found by experiments to have the best effect for steering 

 and propelling, although this new form of vessel admits of many variations of adapt- 

 ing the ordinary propeller or other propellers to it ; for example, the common pad- 

 dle-wheel may be placed on the sides of the vessel in the usual way, or the common 

 screw propeller may be placed between the framework, or sailing vessels may be 

 constructed on this principle. The advantages of the duplex rudder and screw pro- 

 peller may be considered under three heads : first, as regards the two rudders ; se- 

 cond, the two propellers ; and third, the construction of the vessel. To explain the 

 advantages fully of having two rudders to a vessel instead of one, it will be necessary 

 to refer to what has actually taken place practically on a model, as I have not 

 been able to make any experiments on a larger scale up to this time. The duplex 

 rudder has the power of turning the vessel about in the extremely short space of less 

 than once and a half of her own length, with the helm put hard over on starting, 

 and going full speed all the time till the circle has been completed. A single rudder 

 of the same size placed in a line with the midship keel on the same model, and pro- 

 pelled in the usual way with a screw propeller in the dead wood, will not turn a 

 vessel about in less than four and a half times her own length under similar circum- 

 stances. This fact shows the infinitely superior power and command there is over 

 a vessel at all times with the duplex rudder in comparison with that in general use, 

 and consequently that accidents by collision would be in a great measure prevented, 

 and the general safety of steam-vessels better secured by its adoption. Moreover, 

 as either of the rudders on the duplex principle can be used to steer with singly, it 

 is evident that, in the event of damaging either one or the other, the vessel would 

 be still under command, and therefore safe from immediate danger, when a vessel 

 fitted with a single rudder would be in a perilous position. 



A proposed Railway Communication from the Atlantic to the Pacific in the 

 Territories of British North America. By Alexander Doull, CE. 



The author prefaced his notice of the railway by a general view of the great public 

 questions which its construction involved, and remarked on the nature of Mr. Whit- 

 ney's project for the construction of a railway from Lake Michigan to the Pacific, 

 through the territory of the United States, which has deservedly attracted considerable 

 attention in England. 



The recent introduction of railways, and the application of steam power to navi- 

 gation, has very much altered, and will no doubt still further alter, the sj^stems of 

 travelling, and consequently the great leading feature of the day is the perfecting of 

 expeditious and cheap modes of travelling; and as there ever will exist a physical 

 impossibility of travelling as expeditiously, as comfortably, and as safely on the waters 

 of the ocean as on land, every effort will no doubt be made to shorten the distance 

 by sea, and to accommodate the land communication to the new arrangement. 



Halifax in Nova Scotia will therefore possess considerable advantages over New 

 York, in the United States, as the Atlantic terminus of a railway communication 

 across the continent of America, inasmuch as a line drawn from Cape Clear in Ire- 

 land to New York, would pass very close to Halifax ; and thus the whole of the 

 coasting distance of the sea passage from Halifax to New York would be saved. 



From Halifax to Quebec the line would follow the course selected by Major Ro- 

 binson of the Royal Engineers, and from Quebec it would be directed, as nearly as 

 circumstances would permit, to the northern extremity of Lake Superior, crossing 

 the Ottawa at the most convenient point below Lake Temiscaming. 



From Lake Superior the line would pass to the north of the Lake of the Woods, 

 •which portion of its route would pass through a rich mineral and agricultural di- 

 strict. Continuing through a very favourable country to the important Red River 

 settlement, and along the extended prairies south of the river Assiniboine, which por- 

 tion of the line for a considerable distance would pass nearly along the water-shed of 

 the country, there would be no bridges of any importance to construct; continuing 

 from Brandon House to Red-deer River, still keeping near the water-shed of the 

 country, and passing through a district where coal is found to crop out in the banks 

 of the rivers, and consequently easily worked. 



The passage of the Rocky Mountains is doubtless a point of considerable import- 



