(372) As has been previously stated, the most essential point in the successful construction of a ring frame is the preservation of the exact concentricity of the spindle and ring. If this is destroyed a very detrimental effect is produced, and it does not need to be pointed out that where there are two bearings to a spindle each of which is attached to a different rail, the difficulty of preserving a correct vertical alignment is very great. For these reasons the introduction of the Rabbeth spindle into this country by Messrs. Howard and Bullough about the year 1874 led to its wide adoption, and the practical supercession of the Sawyer, and gave a great impetus to this system of spinning. The principle of the Rabbeth is that of the Sawyer so far as the position of the upper bearing is concerned, but it has the further merit of being entirely self-contained. The latter feature was not new in the annals of British invention, but it was never thoroughly worked out nor made a success in this country until the firm just named took up the Rabbeth spindle. Students who desire to take up the history of this subject, can refer to a patent granted to William Wright in 1836, and also to one obtained by David Cheetham in 1857. The Rabbeth is entirely self-contained, its construction being that illustrated in section in Fig. 191. The spindle =B= revolves in a case or bolster =C= made of cast iron, which acts as a bearing for the spindle both at its upper and lower portions. The bolster is formed with a flange, as shown, and is accurately turned and bored all over. It has its shank screwed with a fine thread, so that when passed through the hole in the spindle rail, it can be firmly fixed in position by the nut shown. As the underside of the flange is quite square with the hole in the bolster, it follows that the spindle rail being planed on the top, the bolster case =C= will be in a perfectly vertical position. The spindle =B= is borne by a bronze bush at =C=, and by the footstep at =F=, the case being recessed so as to form a chamber containing such a quantity of oil that the necessity for lubrication more than once in six months is obviated. Fitting on the spindle is a sleeve with a warve or grooved pulley at its lower end as shown at =E=, the sleeve being bored with a conical hole and being tightly pressed on the spindle. The driving band passes round the warve and thus rotates the sleeve and consequently the spindle. A brass cup =D= is placed on the lower part of the sleeve, into which the foot of the bobbin is pushed, the upper part fitting the spindle as shown at =A=. In this way the bobbin is positively driven, and the pull of the band being low down, the spindle can be run at a high speed with great steadiness. The sleeve is prevented from lifting by the hook =G=, which is carried in a small specially balanced frame suitably pivoted so as to allow of the sleeve being removed easily when required. This device is a patented one of Messrs. Howard and Bullough’s, and is one of the best for the purpose. Various modifications of the Rabbeth spindle have been made, including the Dobson-Marsh, which provides for a readier means of oiling by taking off a cap at the lower end of the spindle and thus allowing the dirty oil to run away, this necessitating pumping out in the Rabbeth. In all essential features the Rabbeth may be taken as the best type of self-contained spindle, in which the spindle proper is sustained by rigid bearings, and one of its chief merits is that it can be readily adjusted so as to be quite true with the ring. As a matter of fact this was practically the only advance noticeable in the Rabbeth over its predecessors, and was not perceived even by its inventor until after spindles made under his first patent had been working some time.