ROSE-ENGINE. 



lathe and the common lathe is, that in the former the centre 

 of the circle, in which the work revolves, is not a itatiomry 

 point, but a flight motion is given to the centre whilft the 

 work is revolving upon it, the tool being all the while 

 ilationary ; the furface of the figure which it forms will be, 

 of courfe, out of round, ;'. c. it will deviate from the circular 

 figure as much, and as often, as the motion is given to the 

 centre. 



The art of turning curiofities in wood or ivory, is one of 

 thofe which is bell adapted, of any of the mechanic arts, 

 as an amufement for perfons who either have leifure to apply 

 to fuch fubjefts, or who require relaxation from mental 

 ftudies : it has long been a favourite purfuit of many gentle- 

 men, and the machines they employ are very ingenioufly con- 

 ftrucled. The curious in this art reckon two points of per- 

 fection in their works, one where the extreme delicacy, or 

 elegance, of the objecl renders it admirable, and the other is 

 confidered from the difficulties of the execution ; the former 

 may be judged by all perfons polfeifed of good tafte, but to 

 judge of the latter requires fome knowledge of the art, or, at 

 leaft, fo far as to know that the lathe will form only fuch arti- 

 cles as are perfectly circular, all the parts having a common 

 axis ; therefore the fpecimens of turning are to be more or 

 lefs efteemed, in proportion as they are more oppofed to the 

 circular figure. This .art was more cultivated a hundred 

 years ago than at prefent, and more curious fpecimens were 

 then produced, fuch as hollow balls of ivory, containing 

 many excentric figures, formed within each other, all being 

 cut from the fame folid piece, and every one beautifully 

 ornamented upon the furface, although only fmall holes 

 were left through them to gain accefs to the interior ones : 

 this was carried fo far as to form twelve balls of ivory one 

 within the other. A great colle&ion of curiofities of this 

 kind will be found in a French work entitled " Recueil d'Ou- 

 vragesCurieux dansle Cabinet deM. Grollier deServir," 4to. 

 Lyons, 1719. This contains drawings of fome very curious 

 articles ; but although the art is not fo generally pradtifed 

 at the prefent day as formerly, the machines which are now 

 invented are vaitly fuperior, and, with the lame attention, 

 would doubtlefs admit of the curiofities being equally ex- 

 tended. Mefl'rs. Holtzapffel and Deyerlien, of Cockfpur- 

 ftreet, London, have made many improvements in the conflruc- 

 tion of rofe engines, which they execute, as well as all other tools, 

 for ornamental turning, in the mod finifhed It vie. We have ob- 

 tained drawingsof one of thefe, feeP/rt/cIII. Engines, in which 

 fig, 6. is an elevation in front of the machine. AABB is 

 the wooden frame ; D, the large foot-wheel, tc give motion 

 to the mandrel, or fpindle, T T, by the band and pulley F. 

 The work is fixed in a chuck I, at the extremity of the 

 mandrel ; and the tool is held by the flide-relt K, which, 

 though it has the means of moving the tool a fmall quantity, 

 to adjuft it to the radius of the role, or figure intended to 

 be cut, ft i 11 it will firmly retain the pofition in which it is 

 placed. The upper part, A, of the frame of the machine 

 is made of mahogany, but has within it a caff. iron frame, 

 conlilting of two bars, or bearers, which being placed pa- 

 rallel, and at a fmall diltance afunder, leave a groove or 

 opening between them, in the fame manner as the cheeks of 

 any other lathe, for the reception of the tenon, at the 

 lower end of the back puppet (lhewn by the dotted lines) L, 

 which is ufed to fupport the end cf a long piece of work ; 

 though this is feldom ufed, becaufe the work can only 

 be turned circular, when the back centre fupports it. All 

 work which is to be figure-turned mult be held in a chuck, 

 fcrewed on to the end of the mandrel T ; becaufe it is only 

 the mandrel which is moveable, to give thofe deviations 

 from the circular figure, which are neceiiary to form the 



figured work. Fortius purpofe, the two ftandards, G and 

 H, which fupport the mandrel, are not firmly fixed to the 

 bed, A, of the machine, as in other turning-lathes; but 

 they defcend between the cheeks or caft-iron bed, almoft as 

 low as the bottom of the mahogany bed A, and have there 

 an axis P (dotted), which is parallel to the mandrel, and 

 fupported on pivots at its ends ; thefe pivots being received 

 in pieces of caft-iron, defcending from the checks, and 

 ftrengthened by the iron bar, Q, extended between them. 

 The two ftandards, G, H, are formed of one piece, and 

 have a ftrong bracing of iron between them, in addition to 

 the axis P ; but this cannot be feen in the figure, becaufe it 

 is concealed between the cheeks of the bed O. The ofcil- 

 lating motion is given to the mandrel by means of metal 

 rofettes M : thefe are wheels, fixed upon the mandrel, each 

 having its periphery indented and curved with a waving 

 line, as fhewn at M, fig. 7. The rofettes are afted upon by 

 a fmall roller, placed at the end of a piece n, which is fup- 

 ported by a triangular bar m, fixed parallel to the mandrel, 

 upon the upper ends ot curved arms, as (hewn in both 

 figures. Now it is evident that when the mandrel revolves, 

 the eminences and depreflions of the rofette, applying them- 

 felves to the roller of the piece n, which is Ilationary, will 

 caufe a vibrating or oicillating motion of the mandrel, and 

 the frame, G H, which contains it. A ftrong fpring is 

 placed within the cavity of the bed A, and applied to the 

 frame of the mandrel ; fo that it inclines the latter always 

 towards the central or vertical pofition, that is, the pofition. 

 when the line of the mandrel is produced, would pafs ex- 

 actly through the point of the (crew of the back puppet L ; 

 therefore, when the protuberant or waved parts of the 

 rofette caufes the mandrel to depart from this fituation, the 

 fpring will be bent, and ready to force it back, the inflant 

 the curvature of the rolette will permit. The fpring is 

 (lightly curved, and placed in the fpace between the infides 

 of the iron cheeks of the bed and the frame of the mandrel, 

 fo that the middle of the curved part acts thereupon, and 

 the two ends bear againft the inlide of the frame, to give 

 the re-arllion. Seventeen different rofettes are placed upon 

 the mandrel, as fhewn in a duller at M, each being of a 

 different pattern. Several are of the kind fhewn in Jig. 7, 

 that is, fcolloped out with waves or concave depreflions, 

 but differing in the number of waves from 12, as in the 

 figure, to 144, which will, therefore, be very minute. 

 The focket for the piece n can be fixed, by its clamp fcrew, 

 upon any part of the triangular bar m, to bring it oppofite 

 any one of the rolettes which is required to be ufed. Other 

 rofettes, inftead of having waves or concave depreflions, as 

 (hewn in Jg. 7, have convex protuberances. In either cafe, 

 when the pattern is very fine, the roller upon the end of the 

 bearing-piece, n, cannot be admitted, becaufe its curvature 

 would not be fufficiently rapid to fuffer it to fall into the 

 depreflions. In thefe cafes, therefore, the end of the 

 piece « is ufed for the contact, being rounded, and well 

 hardened and polifhed, to diminilh as much as poflible the 

 friflion of the rofette revolving, whilft in contadt with it. 



The Hide -reft, which fupports the tool, is next to be de- 

 fcribed : the manner in which it applies to a piece of work, 

 when fixed in a chuck at the end of the mandrel, is fhewn in 

 Jig. 6, whilfl^jj. 1 1 and 12 are on a larger fcale to defcribe 

 it minutely. The reft can be fattened at any part of the bed, 

 by the lower part of the foot, which is fupported on the bed, 

 A, of the lathe, and is divided with a dove-tailed groove in 

 the under fide, to receive the head of a fcrew-bolt, going down 

 through the lathe-bed, and fixing it at any place by a thumb- 

 nut, as fhewn at k, Jig. 6 ; the groove in the foot is for tliv 

 purpofe of allowing the reft to be moved to and from the 



cenl 



