Recent Inventions

it is said thíit a hrm in Liondon ia now oonstruoting the inost economical steam entines in tho world. For their mili engiiies these manufacturara guarantoo a eonsumption of less tlrm two pounds of coal horse power por hour, nud they claim that in Dino instances thesa engiues Í7i praètice havo brought tho figuro as low as ono pound of ooal per huis.; power per hour. To realize tho importonee of this improvement, it must be eonsidered that ordinary stcam engin 19, in ïnany oases, burn as mueh as ten pounds of coal por horso power per hour. Tliis is cominon when tlio boiler admits of the erapoxbtion of only six pounds of water for o very pound of ooal. When engines aro suppliod with theCornish boilers, so colobratod liy their oconomy - sinco they ovajjorate twelve lounds of water for every pound of coal per horse power per hour ; and the reduetion of this amount to tln-ee, or even two and ii half pounds lias tlius far been considerêd soraething extruordiuary, the best result in faot to be praotioably obt vined. ïhatthere is, ho wever, still room for improvement, is evident frorn tho theoryof the meohanioal equivalent ot' heat, The best ongines, in place of obtaining as Ik retofore only ouc-tonth or onc-twentieth of tho thoorotic.il equivalent of the heat consumcd, aro reported to have roached noarly one-fifch, whieh, according to the Tcchnoloyirt, is a wonderful advance. Most engiiioi'rs are agres l on the main features of tho most economical steam engines. Thoy are proportionally large boilers, with large heating surfaces, and proper grates ; heating of thu food water in the condenser; high pressure in eonnection with proper eut-oft' arrangoments, so as to utilizo the expansión ; careful protection front loss of heat by radiation ; and abovo all things, intelligent and faithf'ul enginoors and liremen. Many uiodorately good boilers and engines lose all claim to reasonable economy by impropor troatment in uring. Some intorosting experimenta on the freozing of water wore made by M. Boussingault duriug the rigors of last winter; a redort of which he has rccontly communicatod to tho French Academy. It is, of course, knownth.it watetin freezing tonds to dilato with vory considerable forco, cqual to that which would be necssaary to apply to ice to ríiduce its volume eight por cent. M. Boussingault proposed tb decide by oxpcriineitt whether, in opposing to the dilation of water a suffiBiont foroe, freezing could be prevented at a very low temperature. For this purposo ho took a cast steel cylinder eigliteen inches long and ono an one-eighth inch diamotor, and in this waa drilïed a bolo of one-half inch diameter arid 9 1-2 inches deep. The end of this tube could be hernielieally closcd by a serow-joint. It was cooled down to a temperature of 39.29 degrees Fahrenhoit, and fllled with distilled water of the same temperature. It was then hermetically closed, after a small fragment of steel had boen introduced. Tho apparatus was then exposed to the following temperaturas: 8.60,10.50,15.80 and 11.20 degreos bolow zero - :md at cach trial it was possiblo to teil by the movement of tho steel fragment that tho water was unfrozen. The water froze in.stantly when the pressurj was removod. These experimenta were áflorward repeated with procisely tho samo result. Improvoments in tho manufacturo of ■teel are constantly making in Oreat Brit.vin, whore its uso has boon extended more rapidly than in the United States. It is but a short time since manufacturera were unable to guarantee steel plate of greater thiokness than one-fourth of an inch ; but good plute can now be obtained of any thieknesj tliat can ordinarily be uso:l in either boüur-making or shipbuilding, and a steel containing from 0.3 to 0.5 per cent cast is probably beforo many years destined tosupersede wrought iron alniost entir-.'lv. Such a stool has all the ni-illeability of wrought iron, combined with very much highor absolute tonacity and restlience. lts introduction, therefore, rcnlsrs many construetions practicable that were quite otherwise with wrought iron. It is asserted that orie cause of tho sucoess of Biïtish steeltnakers, according to tho Bcssemer plan, is the invariable employment of a professional ohemüt at the works, who analyzea earefullj all stock receivod and all grades of product. Frequently he makes a set of analyses metal of vanous stages of manufacture, and thua keeps a useful check upon all employés, from purchasing agents to tho workinen in the rolling mili. A ehemical test thns conduoted determines the value of allmaterials before use or purchaso, and well as to wh ther a crackod rail is faulty in the ch aructerofthe metal, or from carelessness at tho rolls. An improvemont in globular spark arresters - the invention of a gentleman in Matanzas, Cuba - isamong therecent mechanical novdties announced. The spark reoeiver, in this c.isc, is of globular forra, and placed in relation to tho chimnoy so that the sparks shall bo dischargod the rein, while, at the samo timo, there will be a sutficient opening bctween the top or discharge end of the chimnoy, and the receiver for the discharge of the smoko and uncondensed steam into open air. - This improvement may be appued to the top of a ourvedchimney so as to discharge the sparks laterally ; but the samo or similar resuitmay bepredueed with a roceivor ourviag Over the ohimney. The receiver is plaoed 011 tho top of the fannel, and si :ured by bands or olampa to the ohimney. To the bottpm of the tunnel isattaohed atabe, or oinderflue, bywhich tho sparks and oindora are conducted into the ash pit, or into a receptado containiug water for extinguishing the sparks. Whcre the spark arrester is aplied to the smoke-steck of a steamboal the sparks may be discharged direotly into tho water.