BRITISH  PATENT  1.971 - 1857

1.971  John Henry Johnson, of 47, Lincoln's Inn Fields, in the County of                     Middlesex and of 166, Buchanan Street, in the City of Glasgow, North               Britain, Gentlemen, for an invention for improvements in sewing                       machines. A communication from J. E. A. Gibbs, of Virginia, U.S.A.                 According to one arrangement it is proposed to produce a single thread,             chain, or tambour stitch, by means of a needle and revolving hook, each             loop of the stitch being twisted half a revolution after it has been drawn             through its predecessor, by which means a firmer and more                               secure chain stitch is obtained than has hitherto been accomplished by               sewing machines of this class. The needle is jointed to the vibrating                   needle arm, which is actuated by a cam. The shaft which carries the                   needle cam is fitted or formed into a hook at its front end, such hook                 being of a peculiar construction. It is gradually increased in thickness                 from its point, which enters the needle loop towards its shank or shaft               and is concavely shaped at the part where the needle loop is in contact               with it, for the purpose of not drawing more thread than is                               requisite. After the loop has thus been drawn open, it will slip off the                 hook and lodge in an angular recess which the book forms with the                   shaft. This is effected while the hook revolves from a horizontal to a                   vertical downward position, such motion giving a twist to the loop                     through the aid or a spur or cast off on the back of the hook.This cast               off is so arranged, in relation to the hook and angular recess, that the               loop is spread for the nose of the hook to pass through it on taking a                 fresh loop from the needle. At this moment the hook has two loops                   engaged with it, the fresh loop at the joint or nose and the preceding                 loop, which now bears against the convex part or the hook.The further               motion of the hook will allow the latter loop to slip off entirely from the             flook, which loop is drawn tight by the opening or spreading of the new             loop. Motion is imparted to the machine by drawing the cloth, which is               to be sewn through it by hand.The cloth is pressed up the roughened                 periphery of a revolving wheel which carries a spur wheel gearing into a             pinion on a second shaft. This second shaft carries a conical drum,                     which imparts motion by means of a strap or belt to a second conical                 drum, the shaft of which carries a spur wheel gearing into a pinion on               the cam or hook shaft.The strap or belt is adjusted along the conical                 drums, so as to vary the relative speeds of the shaft which works the                 actual sewing mechanism and the feed shaft and consequently                         regulates the size of stitch, since, if the cloth is drawn through the                     machine faster or slower in relation to the movements of the needle and             hook, it follows that a greater or less length of cloth will be drawn along             between each stitch.The joint in the head of the needle is to enable the             needle to play laterally and thus admit of the cloth being moved even               when the needle is still in it. Modifications of the foregoing                               arrangements are included in the invention.     

            Letters Patent sealed.                                                  July 15, 1857