HISTORY OF MARINE ARCHITECTURE.

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■unanswerable manner. Practice and experience, combined with theory, renderthe investigation of a science as complete as human ability is capable of carryingit; and the happy combination of the three points silence at once the breath, notonly of scepticism, but even of cavil. It is manifestly the inventor’s opinion,that the quick passage of a ship through the water docs not so materially dependupon the form and contour, that is to say, whether it is sharp or full bowed, asit does on the depth which the vessel is immersed in water. Frequent experi-ments have so established the fact, that not the smallest doubt can be entertained,but that the lower the immersion is made in the water, the stronger and moredifficult is it to divide. In order to ascertain this, instead of experiments madewith different figures of the same weight, it has been strongly recommended thatthey should be made on figures of different forms sunk to different depths;the result of many, already tried, have been so clear, that they have not admittedof a doubt, and these trials gave birth to the ingenious invention alluded to.Captain Schanck states very properly, that in the case of a fiigate drawing seven-teen feet water, and another frigate of the same burthen drawing only eleven feet,the last will have a body of six feet less fluid to divide, opposing only one, two,or three keels, as may be found necessary, to make her hold a good wind, whilethe first has six feet perpendicular depth of her hull depressed, being about onethird of her real size. It follows, therefore, she has a body of water to displace, andforce herself through, equal to the difference between eleven and seventeen ; whenit is considered, in addition to this, that the resistance of the fluid rapidly encrease3in proportion to the depth it is acted against, the disparity is almost incredibly en-creased. North-country built vessels, or those in the coal-trade, are a strongproof of this observation. These in general, draw one-third less water,than any other of British construction ; yet, when employed as transports, theyare generally found to sail as fast as any others ; and, when going before thewind in ballast, or half loaded, frequently beat the ships belonging the RoyalNavy. When however they are close hauled on a wind, they will drop to lee-ward ; but, were they furnished with sliding keels, there is no doubt but that theywould have the advantage over all other English vessels. The Dutch, whobestow little pains in making their trading vessels sail, are nevertheless not totallyunfortunate in this respect; for when they are light, they sail fast before the wind,owing to their small draught of water. They have also other vessels built almosttotally flat, such as pilot boats, yagers for carrying the first herrings to marketfrom Shetland, and pleasure yachts All these have lee-boards, by the assistanceof which they sail as fast as the generality of those which navigate the Northern

Seas;