There is given below a table that will repay careful examination as
illustrating the wastefulness of using the small shells. While the
figures must be understood to be only approximate, they are based upon
careful weights and counts of a number of shells from several
localities. The shells were all "niggerheads" and were all obtained
after shipment to factories.
The first two columns show the limits of size for each lot used, the
greatest diameter being the basis of measurement.
The third column shows the approximate number of pairs of shells
composing a ton, the unit of purchase; multiplying this number by 2
would give the number of single shells per ton.
In the fourth column there is given, in the case of the critical sizes,
the number of 18-line blanks readily taken from a single shell (which
is one-half the number yielded by a pair of shells, or an individual
mussel).
The fifth column indicates the number of gross of blanks, by
computation, yielded by a ton of shells. This computation is based upon
the cutting of 18-line blanks (not the larger 20-line blanks that have
been taken from some of the larger shells in the illustration). Some of
these shells are cut excessively close to the tips, on account of
taking too many larger line blanks. It must be understood that
different sized shells are adapted for different lines of buttons. The
data herein is for comparative purposes only.
TABLE OF SIZES, WEIGHTS, AND BUTTON PRODUCTION FOR NIGGERHEAD SHELLS
(APPROXIMATE FIGURES).
+-------------------+----------+-----------+-------------+---------------+
| Longest dimension.| Number of| 18-line | Quantity | |
+-------------------+ mussels | blanks | of blanks | Refer to |
|Greater Less | per ton. | per single| per ton. | illustration. |
| than-- than-- | | shell. | | |
+-------------------+----------+-----------+-------------+---------------+
| Inches. Inches. | | | Gross. | Plate I-- |
| | | | | |
| ¾ 1 | 174,000 | | | 1st row. |
| 1 1¼ | 110,000 | | | 2nd row. |
| 1¼ 1½ | 55,000 | | | 3rd row. |
| 1½ 1¾ | 33,000 | 2 | 917 | 4th row. |
| 1¾ 2 | 26,000 | 3 | 1,008 | 5th row. |
| 2 2¼ | 20,000 | 4 | 1,111 | 6th row. |
| 2¼ 2½ | 15,000 | 5 | 1,042 | 7th row. |
| 2½ 2¾ | 10,500 | 6 | 875 | 8th row. |
| | | | } | { |
| 2¾ 3 | 8,500 | [B]7-8 | }Gradually | {Plate II-- |
| 3 3½ | 6,200 | [B]10 | }diminishing| {1st row. |
| 3½ 4 | 4,000 | [B]12 | }to less | {2nd row. |
| 4 | 3,200 | [B]14 | }than | {3rd row. |
| | | | }650 per | {4th row. |
| | | | }ton. | { |
+-------------------+----------+-----------+-------------+---------------+
[B] At the time of making this table only a few of the larger-sized
shells were available, so the estimates of blanks are less accurate.
It may be seen from the table that a marketable ton of niggerheads
could be composed of the shells of 3,200 or of 33,000 mussels,
according as the shells were 4 inches in length or only 1½ inches.
As a matter of fact, no marketed ton is ever composed of mussels of an
exactly uniform size; furthermore, the extremely large niggerhead
shells are very rare and generally not very desirable on account of
inferior quality and disproportionate waste. A ton of shells from a
region of depletion will also include a number of the smallest and not
strictly marketable shells.
Now, let us take a concrete illustration: Several counts of mussels
gathered by shellers in the white River near Clarendon, Ark., were made
in October, 1913; from these an average was taken that fairly
represents the catches being made at that time in that region. It was
found that 60 per cent by number of the shells taken were of a size
less than 2 inches in greatest dimension; also that a ton of shells
comprised 20,500 pairs, of which 12,300 were less than 2 inches. Now,
it is evident that if these smaller shells were returned to the bed we
would be depleting the bed less than one-half as fast as at present.
This would be the substantial advantage that such a size limit would
have to the mussel beds; and any advantage to the mussel beds is an
ultimate advantage to the fishermen, manufacturers, and all others in
any way dependent upon the perpetuation of the mussels. Under the
working of a 2-inch size limit, 60 shells out of every 100 then being
taken on the niggerhead beds of that vicinity would have been thrown
back. This seems to be asking a good deal, but not so much as at first
appears, for the undersized shells constitute only 38 per cent of the
weight or selling value of the shells taken.
On the other hand, both sheller and manufacturer would be saved the
trouble of handling over and over again an unnecessarily large number
of shells. A ton of shells (from the same locality) comprising only
those above 2 inches in greatest dimension would contain about 13,000
pairs, or 37 per cent less than the number now found in a ton (20,500),
while these shells, the smallest ones being eliminated, would produce
at least 10 per cent more buttons of corresponding sizes.