74 BUI^I^ETIN OP mn BUREAU OF FISHERIES. 



SPBcies AND Sizes OP Shjsll That May bjs Adapted for Different Lines of Buttons. 



Coxnjnon name. 



Species. 



Lines of buttons. 



Small 



Medium 



Large 



shells. 



shells. 



shells. 



Lines. 



Lines. 



Lines. 



14-18 



14-22 



14-30 



14-16 



14-20 



14-24 



14-20 



14-20 



14-20 



14-20 



14-20 



14-20 



14-20 



14-24 



14-40 



14-20 



14-24 



14-30 



14-16 



14-20 



14-24 



14-16 



14-20 



14-24 



14-16 



14-20 



14-20 



Remarks. 



Mucket 



Yellow sand-shell 



Slough sand-shell 

 Fat mucket 



Washboard 



Three-ridge 



Niggerhead 



Maple-leaf 



Pimple-back 



Lampsilis ligamentina. . 

 Lampsihs anodontoides 



Lampsilis fallaciosa .... 

 LampsiUs luteola 



Quadrula heros 



Quadrula imdulata 



Quadrula ebenus 



Quadrula lachrymosa . . 

 Quadrula pustulosa 



This species usually ex- 

 ported for novelty 

 work. 



Good shell only in cer- 

 tain regions. 



Often much waste on 

 account of spotting. 



These species yield a 

 proportion of irides- 

 cents. 



Tips are cut from all of the above-named shells. Take, for example, large washboard 

 shells )delding 14-40 line blanks. The shells are first taken to the 40-line cutte r, who cuts 

 out all the 40-Hne blanks that are of the proper thickness with a true face (PI. XlylV). 

 They are then taken to another cutter, who cuts out all the 24-line blanks that are avail- 

 able. Finally, they are passed to the tipper, who cuts the remainder of the available 

 material into 14 and 16 line tips. These tip blanks when run through the blank classifier 

 may turn out a good per cent of blanks that are classed as butts, meaning by this that 

 they are thick enough to make into any style of button; the tips are usually so thin that 

 they must be finished with a machined face that requires the least material to be taken 

 from it. 



At first glance the process of cutting might appear a very simple one, yet it is properly 

 an operation requiring much skill on the part of the laborer and the wisest type of 

 management. A fuller discussion of the significance of the cutting room in the proper 

 utilization of shells is given on pages 82-87. 



FINISHING PROCESSES. 



Preparing the Blanks. — Before going to the finishing machines the blanks are 

 usually passed through four intermediate processes. 



The blank classifier is essentially similar to the shell classifier on a smaller scale 

 and need not be described in detail (PI. XXXVIII, fig. i) ; by falling between rollers the 

 blanks are separated into different lots according to thicknesses (PI. XXX VI I, fig. 2). 



They are then placed in tumblers, consisting of heavy and slowly revolving barrels 

 of iron or wood (PI. XXXV, fig. 2). In these the blanks are churned with water and 

 pumice stone to clean them and remove the rough edges, making them easier to handle 

 and more workable. Lye is sometimes used in connection with the pumice stone. As a 

 cheaper abrasive of more rapid action, fine sand may be used with the pumice stone. 



The blanks are now ready for the grinder, a machine fitted with an emery wheel 

 which grinds away the homy backs and reduces the blanks to a uniform thickness (PI. 

 XXXV, fig. 5). These machines are operated by girls, who place the blanks face down 

 upon moving belts 3 or 4 inches wide, while the belts convey the blanks underneath 

 the emery wheels. These machines, as well as all others that require it, are generally 

 connected by suction tubes with blowers for removing the dust that would otherwise 



