The annexed engravings are views of Sef-Feeding Machinery for Furnaces, by MonsMoufarine, an engineer of Paris, and a de-scription of which first appeared in the on-don Artizan." In the instance "before us, the revovinggrate is appied to a boier, having two gene-rators beow the she, which is generayused on the continent of Europe, and is wecacuated for high pressures.Figure 1 is a front eevation ; figure 2 is aongitudina section ; and figure 3 is a trans-verse section. The fire bars, a, form a circu-ar grate, and their ends rest on a cast-ironring attached to a wrought-iron funne, b.—The weight of the grate is sustained by armswithin the ring, having a centre boss, c, whichcarries a brass bush, and revoves upon thefixed spinde, d. This spinde is hoow forits entire ength, and a sma jet of steam is ad-mitted through it by means of a pipe, e, com-municating with the boier. This jet ofsteam, which, if the bearing be propery fit-ted, wi be but sma in amount, Eerves to u-bricate the bearing and keep it cear fromdust. The bottom of the funne has a cyin-drica form, and is kept in position by cast-iron arms and a boss, moving on the uprightspinde, d. The bottom of the spinde is car-ried by a frame, g, a of these parts being soarranged as to offer as itte obstruction aspossibe to the passage of the air through thefunne to the bars. In order to prevent theeakage of air round the funne, a ring is at-tached to it, which revoves in a channe fi-ed with sand, as at h ; motion is given to thegrate by means of a pair of beve whees, asat i, connected by a strap and fast and oosepueys to any convenient prime mover.To faciitate the remova and renewa ofany of the parts, a cast-iron pate, k k, isboted on the front of the brick-work. Theiront o the furnace is boted to this, so thatby oosing a few bots it can be removed andaccess obtained to the interior. Ordinaryfire doors, as m m, serve to fire by, beforesteam is got up and the engine started ; whenthat is effected, the feeding apparatus isthrown in gear.The feeding apparatus consists of a conicaI grooved roer, o, revoving in a coa hopperp, and driven by the whees and gearing,*'.The suppy of coa is adjusted by means ofthe sider, s, moved by a screw to give thedue amount of opening. The connectionsbetween the hopper and the fire may be en-tirey shut off, by means of the damper, t.The roer, by its revoution, breaks the coato an uniform size, if it be too arge, and itsconica form distributes it equay over thesurface of the grate, the greater diameter ofthe cone feeding the coa faster on that partof the grate which, being nearer the circum-rence, revoves at the greatest veocity.The form o the funne beow the fire-barsis found to distribute the air advantageousyover the fire, whist the perfection of thecombustion is such that a considerabe sa-ving over hand-firing is obtained, there beingony a ew ashes in the ash-pit."It has aways been an object with us topresent as much usefu information as wecoud obtain reating to the use and combus-tion ot fue for steam and other purposes ;hence we have presented the above. Sef-feeding furnaces, if the machinery is not tooexpensive and cumbersome, are desirabe.A short time ago w received a pamphetfrom Prof. Horsford, of Cambridge, Mass.,containing a report of Messrs. R. Jones, Jr.,and Chares S. Homer, Jr., of the awrencesScientific Schoo, on experiments made at theNeponsit Mis, Canton, Mass., on Baker's pa-tent furnace, and the od pan. The boierswere pain cyindrica ones. It was found byan experiment of 48 hours 25 minutes dura-tion, that the boiers connected with Barker'sfurnace evaporated 22,601 bs. of water with2.462 bs. ot coa, or 9?79 bs. of water by Jpound oi coa. In the od furnaces in an ex-periment of 48 hours duration, 23,030 bs. ofwater were evaporated with 3,646 bs. ofcoa, or 6'317 bs. of water by one of coa—agreat difference.We beieve that great improvements wiyet be made in boier furnaces or economi-zing fue. At the present moment, with thevery best in use, as much as 25 per cent, isost. , This is a arge amount, but yet it issma compared with that of some furnaces.