ROSE-ENGINE. 



nately in contrary direftions : thus, after eight, twelve, or 

 any other number of rings have been drawn, by gradually fhift- 

 ing them each time, as before defcribcd. By reverfingthe 

 fhifting movement to the oppofite direction, a total change 

 will be produced ; and continuing in this manner for eight 

 or twelve more circles, the rofettes are again to be advanced 

 in the firlt-mentioned direction, and continued for eight or 

 twelve. This method produces a curious effeft, and admits 

 of much variety in the patterns. 



After having drawn a waved line, the rofette may be ad- 

 vanced half a divifion, and then another line drawn, without 

 altering the (lide-reft. By this means, the two waved lines 

 will interfcft each other, and make a number of loops like 

 a chain of beads. A number of concentric lines of this fort, 

 drawn upon a circle, is very handfome. 



We have now {hewn the principal diftinftions of the 

 patterns which can be defcribed upon a flat furface ; but it 

 is evident, that from the number of the rofettes, a very nu- 

 merous fuit of curious combinations can be made. An ellip- 

 tical and an excentric chuck are adapted to this machine, 

 to fcrew on at T : a new field is thus opened, which is fo 

 cxtenfive as to exercife conftantly the tafte and fancy of the 

 operator, in producing new combinations, and renders the 

 machine a fource of the moil interelling amufement. The 

 elliptical and excentric chucks, when applied to a common 

 lathe, will form a great many interefting patterns, but are 

 vailly more extenfive with the rofe engine. Their conftruc- 

 tion will be defcribed under Turning. It is fufficient here 

 to fay, that by the elliptical chuck, the waved lines may be 

 drawn in ellipfes, inflead of circles ; and by the excentric, 

 ■feveral fmall waved circles, or ellipfes, can be arranged 

 round the circumference of a larger circle, and their inter- 

 feftions produce a very pretty effeft. 



Another fpecies of rofe-turning is performed upon the 

 furface of a cylinder, globe, or cone ; whereas that which 

 we have delcribed is only upon the flat furface of a circular 

 piece, or end of the cylinder. To ornament the furface of 

 the cylinder, the (lide-reft is turned round one-fourth of a 

 circle, as before defcribed, for forming the cylinder ; fo 

 that the long Aider becomes parallel to the mandrel. In 

 this way the whole furface of the cylinder may be waved ; 

 but great care muft be taken to advance the tool very gra- 

 dually, becaufe it will not cut fo readily as when turning 

 circular work. By dividing the length of the cylinder into 

 fmall equal portions, and by fhifting the rofettes every time 

 one of thefe is finifhed, the waves may be made to follow 

 each other in a fpiral direction round the cylinder ; or, by 

 a proper rofette ufed in this manner, very elegant patterns 

 of balket-work may be formed. 



There is another movement of the rofe lathe, which we 

 have not yet defcribed : this is called the pumping. It is 

 principally ufed for defcribing waved lines upon the furface 

 of a cylinder ; that is, the furface is left cylindrical, but 

 the lines are waved in the direftion of the length of the cy- 

 linder, or alternately towards its ends. This is effected by 

 making the mandrel move end-ways in its bearings : for 

 which purpofe, the necks upon which it turns are made ex- 

 actly cylindrical, and fitted very correftly to flcel collars, 

 which are fixed into the ftandards, G, H. It has there- 

 fore, liberty to Hide end-ways in its collars, when the 

 pumping motion is required. This is given by rofettes 

 waved upon the edge or fide, and afting againft the fide of 

 a piece of ftecl, fuch as n, Jig. 7. A ipring, pt fig- 6, is 

 fixed at the end of the frame, and afts againll iliu moulder 

 of the mandrel, to force it end-ways, and keep the rofette 

 always in contact with the piece of ft eel. The rofettes, M, 

 are cut in a waved manner upon their fides, as well as upon 



their circumferences ; and thus a variety of pumping ro- 

 fettes are obtained. By this means, curious waving line» 

 may be drawn round a cylinder ; or, if the motions firil 

 defcribed are ufed in combination with the pumping, the 

 furface of the cylinder may be waved, at the fame time that 

 waved lines are drawn upon it. In this cafe, the two ro- 

 fettes employed muft have the fame number of waves. 

 When the pumping motion is ufed upon face or flat 

 work, fuch as is (hewn in Jig. 6, it produces very agreeable 

 effects, by rendering the waves of the line, which the tool 

 cuts, alternately deeper and fhallower, fo as to give fine 

 and ftrong ftrokes alternately, in the manner of fine writing : 

 or, if the tool is not fet fo deep, they will only be cut on 

 one fide of the wave, and diminifhing gradually, will not be 

 feen on the other, and thus produce a number of new 

 patterns ; as the waved lines will confift of detached ftrokes, 

 cut fine at each end, and deep in the middle. 



Many patterns may be cut very expeditioufiy in the rofe 

 engine by means of fcrew tools : thefe tools are formed like 

 a broad chiffel, but the edge is cut with notches, fo as to 

 prefent a number of points inftead of one continued edge. 

 Thefe points are very exaftly equidiftant, being intended to 

 cut fcrews ; and therefore the teeth are of the proper figure 

 to form the threads thereof. By a tool of this kind fix or 

 eight lines may be cut at one operation, inftead of the trouble 

 of altering the flide-reft, and cutting each feparately ; and 

 there will be a greater certainty of cutting them all to the 

 fame depth, and exaftly equidiftant. The mode of cutting 

 fcrews by this tool is called cutting flying, and is thus per- 

 formed in the rofe, or in any common lathe, without a (lide- 

 reft. The intended fcrew being turned cylindrical, the points 

 of the tool are applied to its furface, fo that they will cut, 

 and the tool is regularly advanced up towards the mandrel as 

 it turns round : its teeth will, therefore, inftead of defcribing 

 circles, trace the fpirals of a fcrew on the work ; and if the 

 advancement is timed fo exaftly that in one revolution the 

 tool is advanced the exaft quantity of a fpace between two 

 adjacent teeth, then the fecond tooth will, at the end of a 

 revolution, fall into the fpiral cut by the firft tooth, and one 

 complete fpiral being thus obtained, it guides the whole tool, 

 by means of the fecond tooth, regularly along, the firft 

 tooth continuing to cut the fpiral forwards till a third tooth 

 lays hold, then a fourth, and fo on, till the required length 

 of a fcrew is cut. The trace of a fcrew being thus made, the 

 tool is prclled deeper, till the threads are fully formed, the 

 turner taking care, every time, that the end-tooth of the 

 tool gets to the end of the fcrew, to difengage it, and draw 

 it back, for as it could not advance any further than the 

 (houlder, it would fpoil all the threads by cutting them to 

 circular rings. 



This method requires great habit and dexterity to give the 

 motion io exaftly that it will caufe the teeth to fall properly 

 into the fpirals cut by their predeceflbrs, and that without 

 any fudden advance at the place, for the fcrew would then 

 be what is called drunken, that is, its threads would be 

 more inclined at one part of its revolution than at another, and 

 fuch a fcrew can never be fitted exaftly with its fellow. The 

 habit of cutting ferews accurately with tin- lcrcw.toul, can 

 only be acquired by praftice and experience, the only pre- 

 caution which is taken being to get the lathe-wheel into a 

 regular motion, and at fuch a rate as has been found, by ex- 

 perience, will be proper for the fize of the thread intended to 

 be cut. The role engine before us has 1 very complete appa- 

 ratus for cutting fcrews, which defervea .1 particular deferip- 

 tion. A tube is fitted on the end of the mandrel at 0, its 

 circumference being cut with a fpiral, or fcrew-thtcad of the 

 degree of finenefs required : this ii oiled the regulator fcrew. 

 4 D 2 H is 



