108 THE WEALTH OF THE SEA 



dark outer rim or edge. These shells come principally 

 from Egypt, Bombay, Panama, La Paz, and Costa 

 Rica. Black shells are shipped from Tahiti, the 

 Gambler Islands, and many other islands of the 

 South Pacific. 



The manufacture of mother-of-pearl buttons is 

 a rather modern industry, for it had its beginning in 

 Austria only about two centuries ago, the material 

 used being shells from the Red Sea. The industry has 

 grown rapidly, however, until now it is the most 

 important button industry. It is well established in 

 the United States, France, England, Germany, Aus- 

 tria, Japan, Italy, and Spain. 



In the larger button factories, the shells are first 

 classified according to species and quality. Then 

 they are soaked in water for a week or more in barrels 

 or tanks, thus softening the shells so that they may be 

 cut more readily. Blank disks, of the size of the but- 

 tons desired, are then cut by means of a lathe fitted 

 with a tubular saw having a ratchet handle for grad- 

 ually forcing the rougher shell against the rapidly 

 rotating saw. The blanks are classified according to 

 their thickness by a machine and are then cleaned 

 by churning with water and pumice-stone or sand 

 in slowly revolving barrels. The cleaned blanks are 

 then ground on an emery wheel to remove the horny 

 backs and reduce the blanks to uniform thickness. 

 After grinding, the blanks are softened by soaking 

 in water and are then ready for the finishing machine. 

 This machine is a marvel of ingenuity, for it rounds 

 the edges, carves out the center in the desired pat- 

 tern to make the face of the button, and drills the 



