358 Analysis of Scientific Books and Memoirs. 



But we must hasten to the last branch of this interesting anj copious 

 paper on the Application of Steam to the purposes of Navigation, — an ap- 

 plication unquestionably destined to impart a new character to naval war- 

 fare. In a calm, a steam-ship, as the author properly remarks, must pos- 

 sess a decided superiority over an opponent navigated by sails ; and hence 

 battles that formerly remained undecided on account of the wind, would, 

 had the power of steam then been known, have been entirely accomplish- 

 ed. Coasts, rivers, and harbours also, that were considered as secure by 

 the old plan, will, by this new application of vapour, be assailed and de- 

 fended by it. The system of warfare will thus be entirely altered, and 

 perhaps the steam-gun will aid the work of human destruction. A modi- 

 fication of its energies, as our author beautifully observes, will, however, 

 assist the milder and more beneficent purposes of commerce, and direct 

 the steps of civilization into regions now debased by gloom and superstition. 

 Thus it is that art as well as nature tends to an equilibrium in all its 

 operations. If the application of steam to the purposes of war seems like- 

 ly to increase the sum of human calamity, so will the sum of human hap- 

 piness be augmented by the impulse it will communicate to the whole 

 social system. 



We are exceedingly glad to see that the author of the paper unequivo- 

 cally admits Jonathan Hull as the first inventor of the steam-boat, and 

 that to Great Britain the invention is due both in theory and practice. 

 He does full justice, however, to the merits of Mr Fulton. 



Some of our readers perhaps remember, that our neighbours, the French, 

 anxious to know every thing respecting the construction of steam- vessels, 

 sent Marestier to North America to report on the steam navigation of 

 that country. Much of the important matter of that report is brought 

 before us in the article under consideration. Copious tables of the length, 

 breadth, and draught of water of the American steam-boats are given ; the 

 positions also of their paddle-wheels ; the relation between the dimensions 

 of a vessel and the power of its engine ; the comparative proportions and 

 velocities of steam-boats ; the resistance of their hulls ; the equivalent ac- 

 tion of the paddles on the water, and the steam on the piston ; the effects 

 of friction, &c., for the able disquisitions on which we must refer to the 

 article. Marestier's rule, however, for finding the velocity of a steam-boat, 

 may not be unacceptable to our readers in this age of steam. 



The velocity of a steam-boat may be found by extracting the cube root of 

 the product of the following- quantities : The altitude of the column of vier- 

 cury the steam will support, the square of the diameter of the piston^ the 

 length of its stroke, and the number of times it is raised in a minute^ and 

 dividing the result by the cube root of the product of the breadth of the ves- 

 sel into its draught of water, the final result being multiplied by the constant 

 coefficient 2.53. The application of this rule to nine of the American 

 steamers gave an error of less than ^Lth of the actual value. 



Marestier objects to the method commonly employed of estimating the 

 power of a steam-engine by the number of horses. His rule is: Multiply 

 the height of the column of mercury the steam tvill support by the square of 

 the diameter of the cylinder, and. the mean velocity of the piston ; sixty-six 



