The Paris correspondent of tho Boatoo Travahr sends the followiug account of the new in7ention by a Frenchman of a gas engine, which ia now exoiting oonsiderable attention iu tke Franoh metropolis "I believo the machina reoontly Inven ted by Mr. Denois, (a gentleman quite well known by h:s galvano-plantio oopies of alto-relievo soulpture and engraviug) I mean his gas engine, whioh he looks upon a3 destined to tako tho plaae o? the steara ongine in a great many placas where a motive power ís requirad, oocupies tho ohtef share of the Acudemy's attention at this present moment, This gas engine is a good djal like the steam ongine in its extornal appearanoe; There is tho same cyliuder with its piston, the same fly wheel. eocentrio and süde box, but no boiler and no furnaoe. It has a gas nieter aud a very small reduo tivo apparatus. There is a tuba leading from the gas meters, and ooaductors leading from the eleotrioal apparatus to the cvlinder, or rather to the organa of distribution which immediately preoede tho cylinder. When the gas enters the slide box it is mixed with a largo proportion of ordinary air, introduoed first on ona and then on tho othsr side of the piston, and whero it moets an eleotrio spark which fires it; the moment this takes plaoe the aperture through which the gas euters is closed, so that the combustión takes place in aswiled ohamber and determines in the mixed gas and air force of expansión which acts immediately upon the surfaco of the piston. "The motiou of the slide box and olectrio distributor is so arranged that the moments of introducción, inflamation atid expulsión took plaoe in succoasion. and at proper times. W hen the piston has its motion in one direotion the same phases of the introdution and combustión of tho gaseous mixture take plaoe at the other extremity of the oylinder. You sos t utilizes and transforms into labor a portion - but ouly a portion- of tho heat produced by the combustión of the gas, which is fchfl ordinary gas used for lighting tho streats, When the combustión takos place the heat, which is suddnly disengagüd by an explosión oouiaiued in a rigid ohamber, is eommunieated to all the olastio fluid in the cbarnber, which fluid is the motivo power which iets upon tho surface of tho piston, and if its expansión oould bo carriod further, a!l tho hoat would disappear iu the chamber, a.id tho trausforraation would be completo. Uufortunately, before this refrigeratioa takes plaoe the fluid has lost its excess of elastic force, and it is necessary to force it to retain a high temperature to euablo it to escape iuto tho atmosphere, and wliioh high temperatura it ostrón away with it, thereby oausing an inevitabl loss to the maohine. "The porfection of thia macliino consists in this, that all the heat produood by the combustión is rcally brought into play, which is very far from taking place in the steam engino; but, as in all machines, only a sraall portion of the heat devcloped is used, the greater pnrt csoapca all attempt to transform it iuto motive power. Thia machine is thirty per cent. more ecouomioal thau the stea.n-engine, and it only costs $'2ÖJ, and cn ba usod wherever gas is used. I cali the attentiou of your mechanics to it, if they ever stand in nood of ; small motiva power. - It is cheap, it isconveuient, and it is freo from danger." jLsg" "G'od morning, Patrick," said a goiiilouian to hia Irish laboror. "rlippory this morning." "Slipper? - and be jabera, it is nothinz elae, jour honor. - Upon my word, and I slid down tLr 8 ÜK es without setting up eet!"