FLAX 



447 



at present known, and which promises to become general, is that where the necessity 

 to have a top to the bobbin is avoided. It will bo seen from the diagram (fig 977), 



977 



978 



that the yarn is compelled to rub the top of the bobbin, and the friction thereby 

 created quickly causes it to become rough ; and therefore it has a tendency to catch 

 and break the thread. The desirableness, therefore, of having a clear course for the 

 yarn was evident, and this improvement that we are about to explain produces the 

 ''effect by employing what is called a coping motion, which, like that used in mule- 

 spinning, preserves the layers of thread upon the bobbin ever in a pointed or conical 

 state, and therefore self-supporting without the aid of the wooden end of the bobbin. 

 See COTTON SPINNING. 



The arrangement of the rollers for holding and drawing the slivers or rovings, as 

 well as the plates and rollers for aiding to retain the twist of the rovings, in order to 

 render their elongation more equable when to be drawn dry and spun upon the older 

 methods, will be seen in Jiff. 978. 



A (fig. 978), roving bobbin ; B, back or holding roller ; c, carrying roller ; d, flat 

 plate with a slightly curved face ; the carrying roller and plate are so placed as to 

 cause a degree of friction to the roving when passing over them, so as to retain the 

 twist, and thus act as the pins in the ' gill frames ; ' e, tin conductor for contracting 

 the roving at the moment of being drawn ; /, metal roller ; g, wooden roller pressed 

 against the drawing roller in order to pinch the roving ; h, lever and weight. When 

 it is intended to wet the yarn previously to twisting, the trough i is used, in which is 

 water, which is supplied to the roller g by the capillary attraction of a piece of cloth 

 immersed therein, and bearing against the roller by lever Jc. 



The machines for ' wet ' spinning are of a very different construction and appear- 

 ance ; as the close proximity of the holding and drawing rollers prevents the inter- 

 vention of holding rollers or friction bars, while the force requisite to draw the rovings 

 at the short reaches used, varying from 2 to 4 inches, requires each pair to be 

 deeply and accurately fluted into one another. The water used is heated, in order 

 by the expulsion of the fixed air more rapidly and completely to saturate the rovings 

 while passing through it. The following drawings and description will be sufficient 

 to give an accurate idea of the principle of these machines, which are generally 20 to 



