1760.

Jan. 5,1769.

1774.

1776,

14 STEAM NAVIGATION.

Jlearned that thirty years before a Scotchman proposed to make aship sail with gunpowder, but that thirty barrels of gunpowder hadscarce forwarded the ship ten miles.

On the 5th of January, 1769, James WarTrT obtained a patent forimprovements in the steam engine, one of which, namely, the“ fourth,”was for causing the steam to act above the piston, as well as belowit, and which engine is called the“ double impulse,” or“ doubleacting engine.” This improvement in all cylinder engines is herementioned in consequence of its having been the first step by whichthe steam engine was rendered capable of being successfully used topropel a vessel; which great improvement was applied to the firstpractically propelled steam boat, as will be hereafter shown, and isstill used in the present system of steam navigation.

In this year the Comte de Auxiron induced a number of indi-viduals to associate for the purpose of enabling him(the Marquis)to carry his plan into execution. An experiment was tried on theSeine, near Paris, but the boat moved so slowly and irregularly thatthe company abandoned the scheme.

In the same year, Perier, a French engineer, who had witnessedAuzxiron’s experiment, made a trial on a boat with a steam engine ofabout one horse power, which had been laying about his shop."Thisengine was attached to two wheels, one on each side the vessel, witha contrivance to give them a rotary motion: the boat moved slowly,and the project was abandoned.*

In 1776 an ingenious American, Mr. D. Bushnell, invented asub-marine vessel, or diving machine, by which, when under water,“he could row upward or downward, or continue at any particulardepth, with an oar placed near the top of the vessel, formed upon theprinciple of the screw, the axis of the var entering the vessel, so thatby turning the oar one way he raised the vessel, and by turning it

the other way he depressed it.”"The means by which he propelled

* Stuart, vol. i. p. 282. Scott Russell, p. 238.