FRESH-WATER MUSSELS AND MUSSEL INDUSTRIES. 77 
arises from the fact that the outside, after having been backed, is flat and true, while 
the inner face may have a natural unevenness. The blank on its back or flat side 
thus rests more securely in the chucks of the finishing machine and, when finished, 
both sides are in such true form as desired. 
Assuming each chuck to be properly filled in turn, a machine might finish from 33 
to 72 buttons per minute, according to the speed given it. Ordinarily the capacity 
varies from 100 to 190 gross per day. In the days of handwork the output of a single 
operator in shaping was about 20 gross per day, and the buttons had then to be passed 
to the driller, who could turn out about 50 gross per day. The cost of a double auto- 
matic machine in r914 was about $1,300, with about $300 additional for the feeding 
attachment, but a machine would probably cost $2,500 in 1919. The operators are 
usually women, who were paid, in 1914, 1 to 2 cents per gross and earned $7 to $11 
per week. In 1919 the rate of pay and earnings are 33% per cent higher. 
The automatic machine has revolutionized the industry of button manufacture 
from fresh-water shells. It makes possible not only a far greater yield, but a better 
uniformity of product than was ever possible with handwork. Something is yet to 
be desired in the way of lessening the amount of breakage of blanks in process of manu- 
facture, but the machine is being continually improved and perfected. 
PoLisHinc.—From the machine the buttons are taken to the churns, where they 
are tumbled, or churned, with water and pumice to clean them, take off the rough edges, 
and make them ready for receiving the final polish (Pl. XXXV, fig. 1 and Pl. XL, fig. 1). 
The polishing is also a tumbling process, in which, however, sulphuric or other 
acid is used in conjunction with steam. After the buttons are dried in shakers with 
sawdust (Pl. XXXV, fig. 4), they are placed with dry sawdust and washing powder 
in a combined tumbler and shaker. This process removes any trace of limy deposit 
and gives the final luster. Finally the buttons are conveyed in buckets or boxes to the 
sorting room. 
Sortinc.—A very important feature of a button factory is the sorting room, for 
the qualitiesand grades can not be sold if mixed indiscriminately. The classifying accord- 
ing to sizes and thicknesses has already been accomplished in the blank stage, but the 
grading according to freedom from defects of manufacture or from natural shell stains 
and with respect to color, luster, and iridescence must be accomplished by the hands 
and eyes of skilful sorters. Girls are always employed for this work on account of 
their superior deftness, or quickness of selection, and the most expert sorters can 
separate the buttons into 12 grades with extreme rapidity. They are provided 
with a well-lighted room and work seated in rows at long tables before windows (Pl. 
XL, fig. 2). The buttons are handled individually and thrown into series of boxes or 
drawers arranged about the operator; from 85 to 200 gross of buttons may be sorted 
in a day, so that sorters might earn, in 1914, from $5.25 to $12 per week, on the basis 
of pay at one cent a gross. In 1919, sorters are apparently earning from $10 to $19 
per week on a sliding scale wage of 0.6 to 1.15 cents per short gross according to the 
number of grades (from 2 to 12) sorted. 
The number of grades varies with the several establishments, but it would not be 
practicable to enumerate them. Some factories make a specialty of iridescents or 
shiny-backs, as they were originally called. The iridescents are made from the hinder 
portion of the niggerhead, pimple-back, and related shells. If a niggerhead shell is 
110307°—21——6 
