The question as to the best form for vessels, is one which has long excited much attention in this and foreign countries. Many attempts have been made to determine, both by mathematical deduction and by experiments, the amount of the resistance of water to bodies of different forms, and the form of least resistance. But, since the application of steam to the purpose of navigation, the question becomes still more interesting; as, from the great expense of steam compared with wind, as a propelling power for vessels, and the space occupied by the machinery, which tends greatly to limit the room that can be allotted for fuel, and, consequently, the time which steamers can keep at sea, it becomes of the utmost importance to economise the power, by reducing the resistance as far as possible. The question also admits of nearer approaches to accuracy in the solution in the case of steamers than in that of sailing vessels, as experiments may be conducted so as to assimilate more to practice in the former case, than in the latter.

The propulsive action of steam is likewise more direct than that of wind, and its force more constant and easily computed than that of the wind, which is constantly varying, and cannot be accurately estimated.