MECHANICS AND USEFUL ARTS. 37 



tending from the top side of the keel to the deck. The depth to which the 

 sliding keel can be lowered, is of course limited by the depth of the main 

 keel ; being somewhat less, but its length being nearly that of the main keel, 

 a sufficient area is presented to prevent that motion of the vessel technically 

 termed " flatting off," which would otherwise take place under a side wind. 

 The old fashioned sliding keel is objectionable, as the "well" or opening in 

 which it slides runs fore and aft of the vessel, for one-fourth or one-third of 

 her length, and requires the deck beams and frames for that length to be cut 

 entirely through, thereby much diminishing the strength of the hull. Mr. 

 Maskel's plan requires no such sacrifice ; nothing is cut through ; but the 

 hull is built in the usual way, except the recess in the main keel. For vessels 

 navigating the shallow rivers and bays of our Southern coast it must prove 

 valuable, particularly in the cotton districts, where the largest vessels of 

 deep draught, unable to come in, are loaded by means of lighters. The plan 

 is favorably reported on by a commission of United States Naval officers, 

 and is approved by some of the most eminent naval architects of the country. 



NOVEL STEAM VESSEL. 



There is now in the course of construction, in London, a small steamship^ 

 built of iron upon a new principle, which the builders believe will accomplish an 

 average speed of from twenty-five to thirty miles an hour. The invention, for 

 which a patent has been obtained, is intended to be applied to special transit 

 vessels only, and is not suitable to river steamers, or other vessels intended 

 to be used Avhere the water is shallow or the channels uncertain. Should the 

 expectations of the builders be realized, a vessel built and fitted in the manner 

 proposed can make the voyage from Liverpool to New York in five days, or 

 from Liverpool to Melbourne in forty days. The novelty of the invention 

 consists for the most part in constructing the vessel so that the centre of 

 gravity is placed below the water line. This is effected by constructing a 

 chamber called a " well " all along the bottom of the vessel, in which the 

 machinery, coals and stores can be deposited. As it is not proposed that the 

 vessel shall carry cargo, the centre of gravity will thus become a suspended 

 instead of a supported body ; and it is believed that this peculiar formation 

 will materially decrease the area of resistance to the water. The sides of 

 the vessel rise perpendicularly from the well ; and although the appearance 

 of the vessel at present is anything but graceful, the patentee is of opinion 

 that her form is constructed so as to secure the greatest amount of speed 

 compatible with safety. 



The improvements proposed to be carried out may be shortly described 

 area as follows : 1. Vessels built according to this plan show a decrease in the 

 of resistance to the water full thirty-five per cent, when measured against any 

 other vessel of the same breadth of beam and draught of water, thus insur- 

 ing greater speed. 2. They have a better disposition of the centre of grav- 

 ity, a consequent increase in stability, and a decrease in the amount of oscil- 

 lation, enabling them when required to carry a larger quantity of canvas 

 than other vessels of the same size. 3. The engines are so constructed as 

 to effect economy in space and weight, causing also a saving of coals equal 



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