Disposition of the piece to be embroidered

—We have already stated that the pincers which hold the needles always present themselves opposite to the same point, and that in consequence they would continually pa backwards and forwards through the same hole, but the piece is displaced with sufficient precision to bring opposite the tips progre ively of the needles, every point upon which they are to work a design, such as a flower. IMG:4147767755307473660_illo0431.jpg:Embroidering machine Fig. 371 enlarged (465 kB) Explanation of Figure The piece is strained perpendicularly upon a large rectangular frame, whose four sides are visible in fig. 371. ; namely the two vertical sides at F F , and the two horizontal sides, the upper and lower at F ′ F ′′. We see also in the figure two long wooden rollers G and G , whose ends, mounted with iron studs, are supported upon the sides F of the frame, so as to turn freely. These form a system of beams upon which the piece destined to receive the embroidery, is wound and kept vertically stretched to a proper degree, for each of these beams bears upon its end a small ratchet wheel g , g ; the teeth of one of them being inclined in the opposite direction to those of the other. Besides this system of lower beams, there is another of two upper beams, which is however but imperfectly seen in the figure, on account of the interference of other parts in this view of the machine. One of these systems presents the web to the inferior needles, and the other to the upper needles. As the two beams are not in the same vertical plane, the plane of the web would be presented obliquely to the needles were it not for a straight bar of iron, round whose edge the cloth pa es, and which renders it vertical. The piece is kept in tension cro wise by small bra templets, to which the strings g′ ′ are attached, and by which it is pulled towards the sides of the frame F . It remains to shew by what ingenious means this frame may be shifted in every po ible direction. M. Heilmann has employed for this purpose the pantograph which draughtsmen use for reducing or enlarging their plans in determinate proportions. b b′ f b′ ′ ( fig. 371. ) represents a parallelogram of which the four angles b , b′ , f , b′ ′ , are jointed in such a way that they may become very acute or very obtuse at pleasure, while the sides of course continue of the same length; the sides b , b′ and b , b′ ′ are prolonged, the one to the point d , and the other to the point c , and these points c and d , are chosen under the condition that in one of the positions of the parallelogram, the line c d which joins them pa es through the point f ; this condition may be fulfilled in an infinite number of manners, since the position of the parallelogram remaining the same, we see that if we wished to shift the point d further from the point b′ , it would be sufficient to bring the point c near enough to b′ ′ , or vice vers a ; but when we have once fixed upon the distance b′ d , it is evident that the distance b′ ′ c is its nece ary consequence. Now the principle upon which the construction of the pantograph rests is this; it is sufficient that the three points d , f , and c be in a straight line, in one only of the positions of the parallelogram, in order that they shall remain always in a straight line in every position which can po ibly be given to it. We see in the figure that the side b c , has a handle B ′′ with which the workman puts the machine in action. To obtain more precision and solidity in work, the sides of the pantograph are joined, so that the middle of their thickne lies exactly in the vertical plane of the piece of goods, and that the axes of the joints are truly perpendicular to this plane, in which consequently all the displacements are effected. We arrive at this result by making fast to the superior great cro bar D ′′ an elbow piece d 2 , having a suitable projection, and to which is adapted in its turn the piece d′ , which receives in a socket the extremity of the side b , d ; this piece d′ is made fast to d′ ′ by a bolt, but it carries an oblong hole, and before screwing up the nut, we make the piece advance or recede, till the fulcrum point comes exactly into the plane of the web. This condition being fulfilled, we have merely to attach the frame to the angle f of the parallelogram, which is done by means of the piece F ′′. It is now obvious that if the embroiderer takes the handle B ′′ in his hand and makes the pantograph move in any direction whatever, the point f will describe a figure similar to the figure described by the point c , and six times smaller, but the point f cannot move without the frame, and whatever is upon it moving also. Thus, in the movement of the pantograph, every point of the web describes a figure equal to that described by the point f , and consequently similar to that described by the point c , but six times smaller; the embroidered object being produced upon the cloth in the position of that of the pattern. It is sufficient therefore to give the embroidering operative who holds the handle B ′′, a design six times greater than that to be executed by the machine, and to afford him at the same time a sure and easy means of tracing over with the point c , all the outlines of the pattern. For this purpose he adapts to c , perpendicularly to the plane of the parallelogram, a small style terminated by a point C ′, and he fixes the pattern upon a vertical tablet E , parallel to the plane of the stuff and the parallelogram, and distant from it only by the length of the style c C ′′; this tablet is carried by the iron rod c′ , which is secured to a cast iron foot E ′, serving also for other purposes, as we shall presently see. The frame loaded with its beams and its cloth forms a pretty heavy ma , and as it must not swerve from its plane, it needs to be lightened in order that the operative may cause the point of the pantograph to pa along the tablet without straining or uncertainty in its movements. M. Heilmann has accomplished these objects in the following way. A cord e attached to the side b c of the pantograph pa es over a return pulley, and carries at its extremity, a weight which may be graduated at pleasure; this weight equipoises the pantograph, and tends slightly to raise the frame. The lower side of the frame carries two rods H and H , each attached by two arms h h , a little bent to the left; both of these are engaged in the grooves of a pulley. Through this mechanism a pre ure can be exercised upon the frame from below upwards, which may be regulated at pleasure, and without preventing the frame from moving in all directions, it hinders it from deviating from the primitive plane to which the pantograph was adjusted. The length of the rods H ought to be equal to the amount of the lateral movement of the frame. Two guides i i carried by two legs of cast iron, present vertical slits in which the lower part of the frame F ′ is engaged.