This edifice, which is one of the best of its class, is situated at the
foot of Fifty-fourth street, on the East river, in the city of New York.
It is hexagonal in form, and rises to the hight of one hundred and
seventy-five feet; being sixty feet in diameter at the base, and
gradually growing smaller as it rises toward the top. It forms a most
striking object of interest; and is remarked by the multitudes who pass
by it going up and down the sound, to and from New York. When we
consider the small size of the article to the manufacture of which this
lofty structure is devoted, the means appear greatly out of proportion
with the result. Formerly in casting shot, the apparatus was merely a
plate of copper, in the hollow of which were punched a number of holes.
This was placed a few feet above a kettle of water, into which the
melted lead descended, after passing through the holes in the plate. But
in falling so short a distance, and being so suddenly cooled and
hardened, the shot did not acquire a perfectly globular form, a
desideratum which is now attained by means of shot-towers. In the tower
of Mr. McCullough, the largest shot falls from the summit of the tower
to the bottom of a well twenty-five feet below the surface of the earth,
making the descent one hundred and seventy-five feet. The size of the
shot is determined by the size of the holes through which it passes. The
furnaces for melting the lead are situated near the top of the tower;
three or four tuns of shot are manufactured per day. This method of
casting shot was invented by Mr. Watt, the celebrated engineer, in
consequence, it is said, of a dream. He tried the experiment from the
tower of the church of St. Mary, Radcliffe, and finding it very
successful, obtained a patent, which he afterward sold for ten thousand
pounds. There are now several shot-towers in the vicinity of London, and
different parts of the world; but none more worthy of notice than the
one of which we are now speaking. An iron staircase ascends from the
base to the summit of the tower. Arsenic is mingled with the lead in
proportion of forty pounds to one tun. In casting, the metal is poured
through a tube, but descends through the open space of the tower in a
continual stream of silvery drops. As the weight of the lead prevents it
from scattering or being blown about like water-drops, the workmen pass
to and fro, without danger, close by this fiery cascade. The shot is of
different sizes, from number one, swan shot, to number twelve, dust
shot. Mr. James McCullough has brought the art of the manufacture of the
shot to perfection. Certain portions of his factory are kept entirely
secret; and the shot manufactured in New York are not surpassed in the
world. The cause of most of the imperfections in the manufacture of lead
shot, is the too rapid cooling of the spherules by their being dropped
too hot into the water, whereby their surfaces form a solid crust, while
the interior remains fluid, and in its subsequent concretion shrinks so
as to produce the irregularities of the shot. The patent shot-towers
originally constructed in England, obviate this evil, by exposing the
fused spherules, after they pass through the cullender, to a large body
of air during their descent into the water-tub placed on the ground. The
greatest erection of this kind is probably at Villach, in Carinthia,
being two hundred and forty Vienna, or two hundred and forty-nine
English feet high. The following is the process. Melt a tun of soft
lead, and sprinkle round the sides of the iron pot about two shovelfuls
of wood ashes, taking care to leave the center clear. Then put into the
middle about forty pounds of arsenic, to form a rich alloy with the
lead. Cover the pot with an iron lid, and lute the joints quickly with
loam or mortar, to confine the arsenical vapors, keeping up a moderate
fire to maintain the mixture fluid for three or four hours; after which,
skim carefully, and run the alloy into ingots or pigs. The composition
thus made is in proportion of one pig to one thousand pounds of melted
lead. Two or three tons are usually melted at once in large
establishments. A crust of oxyd of a white spongy nature, sometimes
called cream by the workmen, covers the surface of the lead, which is of
use to coat over the bottom of the cullender. The cullenders are hollow
hemispheres of sheet-iron, about ten inches in diameter, perforated with
holes perfectly round and free from burs. These must be of a uniform
size in each cullender; but, of course, a series of different
cullenders, with sorted holes for every different size of lead shot,
must be prepared. The operation is always carried on with three
cullenders at a time, which are supported upon projecting grates of a
kind of chafing-dish made of sheet-iron, somewhat like a triangle. This
chafing-dish should be placed immediately above the fall; while at the
bottom there must be a tub half-filled with water, for receiving the
granulated lead. The cullenders are not in contact, but must be parted
by burning charcoal, in order to keep the lead constantly at the proper
temperature, and to prevent its solidifying in the filter. The hight
from which the particles should be let fall, varies likewise with the
size of the shot; as the congelation is the more rapid, the smaller they
are. The workman then puts the filter stuff into the cullender, pressing
it well against the sides; he next gently pours lead into it with an
iron ladle. The center of the cullender being less hot, affords larger
shot than the sides. Occasionally, also, the three cullenders employed
together, may have holes of different sizes; the shot will then be of
different magnitudes. These are separated by square sieves of different
fineness, and after passing through other minute processes, are ready
for sale and use.