Page:Encyclopædia Britannica, Ninth Edition, v. 6.djvu/528

49(5 COTTON the vibration of the spindle (caused by the flyer being placed on the top of it, with nothing to keep it steady), whereby it is prevented from being driven with advantage beyond a certain limited speed. To remedy this, Danforth introduced into his throstle a stationary spindle, on the top of which he fixed an inverted conical cup. In this improved throstle the bobbin revolves on the spindle with great rapidity, and by a transverse motion is raised and depressed so as to be, when at the highest point, entirely within the cup, and when at the lowest entirely below it. The edge of the cup, passing thus along the whole length of the bobbin, builds the yarn equally on every part while it is receiving the necessary twist, and gives also the drag required to wind the yarn upon the bobbin. Danforth s improvement gives a great increase of quantity, but the waste it causes is such as to form, in the opinion of many spinners, an insuperable objection to its use, though as regards the stronger material of worsted it is still exten sively used. The throstle frame is now exclusively used for the production of warps. In the most approved machines of this kind the spindles make 5500 revolutions a minute, each spindle producing twenty-seven hanks per week of 5G hours when spinning 32 s. The Dauforth frame is now entirely out of use except for worsted. The ring and traveller frame is also an American in vention. It was introduced into England under the name of the " Niagara Throstle " by Sharp, Stewart, & Co., but found very little favour amongst English cotton spinners. In America, however, it is very extensively used, and owing to some important recent improvements it is beginning again to attract attention in England. Its peculiarities are that instead of a flyer on the top of the spindle there is a small steel traveller working in a ring placed in a third rail, commonly called the rin^ rail and FIG. 12. Throstle. passing over the bobbin, which moves up and down the full length of the bobbin ; the twist is given by the revolu tion of the spindle, the drag or winding of the thread on the bobbin (fixed to the spindle and carried round with it) being effected by the friction of the traveller in its revolu tions round the ring. The travellers are of varying weights and sizes to suit the different counts of yarn. The spindles generally make about GOOO to 7000 revolutions per minute. Messrs John Elce & Co. claim to have introduced an improvement in the throstle, in which two tin cylinders are employed instead of one for driving the spindles, whereby a longer band is obtained, and a saving of friction and power is said to be effected. The MULE (fig. 13). Probably no inventive con tribution has been offered to the cotton trade more important than the mule. Samuel Crompton of Bolton completed in 1775 his invention of the "mule jenny," in contriving which he had been engaged for several years. But this machine, possessing great merit and advantages, did not come into general use, nor was its value known, until after the expiration of Arkwright s patent, the spinner till then being confined to the rove prepared for common jenny spinning, which was unsuitable to the mule jenny. After the spinner was allowed to make use of Arkwright s fine process of preparation, by his patent being cancelled, the power of this machine became known ; and its intro duction forms an important era in the history of the cotton manufacture. Being fitted to supply those counts or " grists " and qualities of yarn which the other machines could not produce, it enabled the manufacturer to enter upon fabrics which otherwise it would have been in vain to attempt. Warps of the finest quality are spun upon the

mule ; while on the throstle yarn of a finer grist than No.