370 SOUTHERN FIELD CROPS 



separated by rollers from the lint. This general type of 

 gin has been in use in India for centuries. 



The saw gin, employed to gin short-staple cotton, is a 

 modern machine, which has been second to no other agri- 

 cultural invention in its effects on the world's wealth, 

 commerce, and comfort. The saw gin has made possible 

 the South's greatest industry, cotton culture, and has 

 supplied with fleecy food the textile industries of all manu- 

 facturing nations. It was invented by Whitney and 

 Holmes abput 1792. Before that time a laborer with his 

 fingers separated about one pound of lint cotton per day. 



A single gin of average size accomplishes the work of about 

 4000 such laborers. Within one hundred years after its inven- 

 tion the saw gin made possible a four-hundred-fold increase in 

 the cotton crop of the United States. 



The saw gin is also used in ginning long-staple upland cotton ; 

 but to do this without injury to the staple, the usual speed of 

 the saws should be greatly decreased. 



When long-staple upland is ginned, care should first be taken 

 to remove from the gin the roll of cotton left by the preceding 

 bale of short-staple ; for the mixing of even a little of this with 

 long-staple cotton greatly lowers the selling value of the latter. 

 This is because the spinning machinery in any one mill is arranged 

 for a fiber of a definite length ; the admixture of fibers of widely 

 different lengths results in loss to .the spinner, either by fibers 

 wasted or by the making of thread of undesirable quality. 



344. Care of baled cotton. Since cotton does not 

 readily absorb large amounts of moisture, farmers and 

 warehousemen often leave bales of cotton exposed for 

 weeks or months to the weather (Fig. 161). This results 

 in darkening and weakening the fibers in the outer layers, 

 and consequently in a decreased selling value. Cotton 



