104 Progress in Science. [January, 
ordnance, and varying from 2 to 5 inches in diameter, into which the explosive 
material is placed. By preference, Mr. Bessemer recommends the use in each 
chamber of a number of separate charges of powder, separated from each 
other by diaphragms having a fuze for communicating the ignition, or else 
parted by a thin layer of meal powder. The quantities of powder in these 
charges increases at every succeeding discharge of the series,and the intervals 
of time between the discharges diminish, so as to keep time with the increasing 
velocity of the projectile, and thus keep up the pressure in its rear nearly 
uniform throughout its entire movement from the breech to the muzzle of the 
gun. By this means, it is expected that a projectile may be thrown whose 
weight may be measured by tons, which clearly could not be effected under the 
present method of gun construction. 
Torpedoes.—At page 292 of our last volume, we gave a brief account of 
torpedoes adopted by the English Government. The Harvey torpedo has 
since then fully maintained the high opinion we then expressed regarding it, 
and it would appear to be the one finally adopted for purposes of attack. 
The Germans, also, have recently introduced a similar offensive weapon in 
their fleet, and three boats are stated to be now under construction in 
Deyrient’s Dockyard at Dantzic, the destination of which is to place torpedoes 
under, and thus to destroy an enemy’s ship. These boats are built almost 
entirely of iron, and, being about 60 feet long and only 6 or 7 feet broad, they 
have nearly the form of a fish. The deck is not flat, but round, so as to be*but 
little exposed to damage from an enemy’s shot; and, while employed in active 
operations, no one will be visible on board. These boats will be steered from 
the bows; and on the deck, above the rudder, there is a slight elevation to 
allow the steersman to stand on his feet, and a small opening, about an inch 
wide, to serve him as a look out. As they are intended to operate close to an 
enemy’s vessel, the armour will be as thick as is consistent with high speed. 
The most curious part of the invention, perhaps, is, that these tiny screw- 
steamers use petroleum as fuel, which is contained in a number of iron 
receptacles in the stern, of sufficient thickness to be impervious to projectiles. 
The chimney is so small that it can scarcely in any case be hit. The hold for 
the torpedoes is in the middle of the boat, as well as the quarters of the 
crews. 
Pulverised Fuel—Many devices have from time to time’ been put forward 
with the view of utilising small coal. Amengst others, may be noticed that of 
pulverising it and burning it as a jet, mixed with air. In the year 1831, one 
J. S. Dawes took out a patent in this country for applying pulverised fuel to 
the blast-furnace through the tuyeres; it, however, proved unsuccessful, 
owing, doubtless, to the fact that the agency of fuel in the blast-furnace is 
chemical as well as physical. In 1846 a patent was taken out by one 
Desboissiers for pulverising fuel and blowing the dust into the furnace, but 
though the conception involved some correct ideas, the machinery was totally 
impracticable. In 1854 Mouchel suggested the injection cf powdered fuel and 
ores, either separately or together, upon a hearth or inclined plane of a cast- 
iron box, heated by waste heat from other furnaces. Mushet proposed, in 
1856, to use pulverised coal, carried by a blast into a reverberatory furnace to 
produce the oxidation of the iron. More recently still, Crampton has taken 
up the subje@, and achieved tolerable success in the combustion of powdered 
coal for locomotive and other steam purposes. The plan, however, which 
appears hitherto to have beenattended with the greatest success, is one by 
Messrs. Whelpley and Storer, of Boston, at whose establishment pulverised 
coal is applied to metallurgical and other purposes. A description of this 
method has recently been given by Lieutenant C. E. Dutton, U. S. Ordnance 
Corps, in a paper read before the Franklin Institute, from which the following 
particulars have been taken. One great improvement in Messrs. Whelpley 
and Storer’s process is, that the pulverising and blowing of the fine coal into 
the furnace is effeéted by one and the same machine. ‘Conceive an 
ordinary blowing-fan with the following modifications.” We are now quoting 
from Lieutenant Dutton’s paper. ‘ The box is about 18 inches in diameter, and 
about the same length. Instead of opening at both ends, one end is tight 
