2. In the second place, seeing that much greater strength of parts is required to overcome the increased resistance, it is equally evident that this high speed and power thus require a larger outlay in every point of the prime construction of the vessel and engines by which the speed is to be attained. The hull's heavier timbers cost a higher price according to size than the direct proportion of size indicates. Large and choice timbers are difficult to get, and costly. The hull must also be strengthened to a large extra extent by heavy iron strapping and bracing, which, unlike the rest, cost in the ratio of the material used. So with the engines. The shaft, which weighs twice as much, does not cost only twice as much, but frequently three or four or five times as much. This arises not from the weight of the metal, as is evident; but from the difficulty of forging pieces that are so large. The persons engaged in the forging and finishing of the immense shafts, cranks, pistons, etc., used in our first class steamers, frequently consider that the last and largest piece is the _chef d'oeuvre_ of the art, and that it will never be transcended, even if equalled again. They have expended all of their skill and ingenuity in the task, and have not succeeded sometimes until they have forged two or three new pieces. When a great work of this kind is done, it may be discovered in the turning, polishing, and fitting up, that it has at last a flaw, and that it will not do for the service intended. As a matter of course, it must be thrown aside and a new piece forged. This was but recently the case with one of the shafts of the "Leviathan," in England. So with the shafts of the new Collins' steamer "Adriatic." They were forged in Reading, Pennsylvania, and in addition to their enormous prime cost had to incur that of shipment from the interior of Pennsylvania to the city of New-York. In all such cases the prime cost increases immensely, and to an extent that would hardly be credited by those not practically familiar with the subject.