9j8

THEORY AND PRACTICE OF ENGINEERING.

Book II.

Fig. 133$.

Verzy's Steam-engine whose Motion is continuous. —Let cdef bea section perpendicular to the axis o, of a cylinder whose heightis equal to the distance mn, which separates it from anothercylinder ghikql , which penetrates the first in such a manner thatthey have the same axis, and that the surface of the latter adjustsitself exactly to the upper and lower edges of the first; therewill be between the two cylinders a circular channel whosehorizontal section will be mgdhknpqmg, and the height equalto the plane pq , which is attached to the external cylinder,the continuity of which it interrupts: the bases of the innercylinder are closed by plates of metal, making a small rebate : atthe crowns of the outer cylinder they are below the axis o ,so that the inner cylinder may freely turn round its axis,supposing the outer one fixed: in the curved surface of the

inner cylinder two openings are made diametrically opposite to each other, equal in heightand in breadth to those of the circular canal; two angular valves are opened which turn ontheir axis, and tend to close these openings as well as the canal, by means of two spiralsprings which are in the upper part of the axis, and whose elastic force may be increased ordiminished at pleasure; the axes extend beyond the upper base, and have each a handlewhose positions are projected in the directions, g,m,k,n ; the curved surface of the outercylinder is pierced by two circular holes, one where the tube a abuts, which conducts thesteam, and the other communicating with the condenser by means of the tube h : supposethen the steam enters at a, the plane pq opposes its passage, whilst the two sides of theangular valve present the same surface to the steam, consequently it does not change itssituation, and its edge will lean on that of the inner cylinder with all the force of the springgrs ; and this cylinder will turn in the direction of abc. Before me arrives at the hole b,which communicates with the injector, the handle at k will meet the obstacle o, at which isa small bar fixed to the upper crown of the great cylinder ; this forces the angular valvet kn to turn inwards; thus going without difficulty past the fixed plane pq, in such amanner that when it shall have taken up its first position mr will have passed the hole b,and the vacuum will he formed, the inner cylinder having made only a half revolution :the action of the steam will continue to communicate a continuous motion of rotation tothe axis o, which may be applied to any required use.

Universal Windmill. — This machine has for its object theimmediate transformation of the rectilinear motion of thewind to circular, and is more curious than useful. Let acegbe the equator of a sphere whose radius is kl, and kpep thevertical projection of the meridian, which cuts the equator inthe diameter ke. In the upper part of the plane of the equator *draw the two diameters ae,cg, perpendicular to each other;and in the lower part of the same plane the two other diametersdh,bf, which form angles of 45° with the preceding: in theupper part of the plane of the equator are constructed fourcurves formed by the surfaces of cones whose summits are ate,g,a, and c, and whose bases are oppositely curved; whichresults from the intersection of the surface of the sphere withthe right cylinders, which cut the equator in the curves l,e,f&c., tangential to the lines lg,hl, al,ll, See., and through thecorresponding parts of the surfaces of the two meridians eg, ae,and of the equator. In the lower part of the plane of theequator are also placed four curves constructed according tothe same principles; the summits of the cones are at dl, hb: cthe curves l, g, h are traced by geometrical principles, viz. fromthe summit g of the triangle Igh, the line EM is drawn tothe middle of its base; at M is elevated a perpendicular Meequal Me: the circle le'f drawn tangential at f and l tothe two sides pZ, kl of the isosceles triangle Igh : from eachpoint N of the line If, two lines were drawn, one parallel toME', which is terminated at v! in the arc of the circle; andthe other N n equal to the first, and parallel to M E, which githe line LeF, required to be drawn.

Fig.1339

Fig. 1340.

es a point n belonging to

It must be observed that, in consequence of the very small angle at which the sail of thevertical windmill is inclined to the direction of its motion, which generally is not more than20°, and of which angle the sine, which represents the force to give motion to the sails,scarcely exceeds one-third of the radius, much of the power of the wind is lost: oa this ac-count horizontal sails were introduced, under the notion that more power could be acquired;numerous contrivances for this purpose are contained in the Repertory of Arts.