46 COTTON 



of India ; the amount of cotton produced by a day's 

 work with it is not more than about five pounds. 



It is evident that the cotton industry could not 

 have made gre%t progress, unless such slow and tedious 

 processes of ginning had been replaced by a more* 

 rapid and less laborious method. This problem was 

 solved by the invention of the saw-gin by Eli Whitney, 

 which was patented in Washington in 1794. 



The saw-gin consists essentially of a series of 

 notched, circular, thin steel discs or " saws " which 

 are fixed on a cylinder. The cylinder revolves in a 

 box, one side of which consists of a grating of steel 

 bars between which the saws rotate. The saws 

 project from J to f inch beyond the grating, and 

 grip the fibre as the seed-cotton is fed on to them. 

 As the saws revolve, they pull the cotton off the 

 seed and draw it into the box with them whilst the 

 seeds remain behind, the openings being too narrow 

 to admit them. Immediately beneath the cylinder 

 carrying the saws is a rapidly revolving brush which 

 takes off the lint from the teeth of the saw as it enters 

 the box ; a blast of air then carries the cotton into the 

 condenser at the rear of the gin. 



There are two kinds of gins in use at the present 

 day, namely, roller-gins and the saw-gin described 

 above. The latter can effect the separation of the lint 

 more rapidly than the former, but is more liable to 

 injure or break the fibres. In the case of the smooth- 

 seeded kinds of cotton, the lint is easily detached, 

 whereas in the fuzzy-seeded varieties, the fibre is 

 very firmly attached to the seed, and considerable 

 force is required to remove it. For these reasons, 

 saw-gins are used for the shorter and fuzzy-seeded 

 varieties such as the American Upland kinds, whilst 

 the longer, finer and smooth-seeded cottons, such as 

 Sea Island and Egyptian, are ginned by means of 

 roller-gins. 



Roller-gins are of two kinds. One of these is con- 

 structed on the principle of the old Indian " churka " 

 gin and consists essentially of two rollers, which 

 rotate in opposite directions. The cotton is drawn 

 between the rollers, whilst the seed is held back by 



