7O BULLETIN OF THE BUREAU OF FISHERIES. 
Most of these processes have become obsolete in the United States with the devel- 
opment of modern machinery. It is, indeed, to the automatic machinery that the 
industry owes its present relative importance. The old process of sawing remains prac- 
tically unchanged, but the grinding, facing, and drilling, the principal features of button 
making, are accomplished by automatic machinery. For the three processes either 
two or three machines are used; in some cases a grinder attachment to the double auto- 
matic makes it possible to combine the entire process in one machine. 
The sorting, or grading, of the buttons requires nice judgment and must still re- 
main a hand process; but recently a machine has been introduced for the attachment 
of buttons to the cards. 
Not only the departures in the mechanical equipment but the improved efficiency 
of labor and better shop management are combining to increase the output and to 
promote economy of production with better quality and uniformity of product. These, 
and such other present-day features as the utilization of waste materials and the intro- 
duction of sanitary devices, will undoubtedly be more generally and effectively applied 
in the future. 
PROCESSES OF MANUFACTURE. 
The description of the general process of button making as given below is essen- 
tially that of the average modern plant, although in each factory characteristic modifi- 
cations of method are encountered. 
PREPARATION OF SHELLS. 
STORAGE.—When the mussel shells are received by barge or freight car, they are 
hauled to large covered or exposed storage bins at the factories, to be kept until ready 
for use. A rough sorting is often done at this stage, so that each bin will contain shells 
of a relatively uniform size and quality. There is no apparent deterioration of the 
quality of shells if protected from the weather. If not so protected, they are liable in 
time to lose the luster and become lifeless or chalky. The exterior of the shell is most 
readily affected once the horny covering is worn or scaled off. For this reason shells 
which have been long exposed on the banks or “‘dead” shells from the rivers are consid- 
ered undesirable. 
CLASSIFYING—When the shells are taken from the bins for use, they are first 
sorted by hand according to species or quality of material, if this has not previously 
been done, and are then classified as to size. The latter process is accomplished by 
a machine called a classifier, which, though larger, is similar in principle to the classi- 
fier used for blanks (Pl. XX XVIII, fig. 1). The shells are put into a large hopper, from 
which automatically they are fed slowly onto an endless belt leading to the classifier, which 
consists, primarily, of two hollow metal rollers about 6 inches in diameter and 8 feet 
in length. By falling between the two rollers the shells are to be separated, roughly, 
into four or five grades, according to size and thickness. To this end the rollers are 
set with an incline and are not quite parallel with each other, being more widely sepa- 
rated at the lower ends. As they revolve outwardly the shells slip, or roll down the 
incline to a point where the opening between the rollers permits them to fall into one 
of a series of buckets placed below. The smaller and thinner shells are found in the 
buckets nearest the head. 
