214 REPORT—1858. 
must be capable of perfect regulation down to an infinitesimally slow speed, and 
without impairing its certainty of action at thatslow speed. Hence it cannot depend 
upon momentum to pass the dead points at the top and bottom of the stroke, as in a 
steam engine; and for simplicity it must only consist of one cylinder. It must also 
be absolutely independent of attention or lubrication, and be always ready for use. 
The author, after detailing the results of a number of experiments, described an 
engine which he illustrated with drawings. For some time the engine continued to 
work perfectly; but afterwards difficulty was experienced in lubricating the valve upon 
its face, this requiring attention varying from once per month to once in three or 
six months. Various metals were tried relatively for the valve and face; but all after 
a time squeezed out the lubricating material from between them, and cut into each 
other. Glass was tried with no better success. Lastly, a lignum vite valve was 
put in: this stood every test, and, though taking a little more power to drive when 
originally put in, it was found to need no lubrication of any kind, the water acting 
in the place of it. 
The peculiarities of the engine as it now stands are—Ist. A machine giving out a 
reciprocating motion by the pressure of a non-elastic fluid, and capable of being re- 
gulated to the lowest possible speed without the possibility of failing at the return 
stroke, that return stroke depending upon a movement completed by the previous 
stroke. 2nd. The adaptability of this machine to work under any pressure of the 
afore-named non-elastic fluid, entirely free from the shocks usually attending such 
machines from the necessity of suddenly changing the direction of the moving column, 
which may be changed as slowly as requisite, by retarding the valve, or diminishing 
the outlet. 3rd. The entire independence of attention or lubrication. 
The organ of the Leeds Town Hall is blown by five of these engines. They are 
calculated to be able to supply 50 cubic feet of air per second, at a pressure equal to 
a column of water of 6 inches, and when working at full speed to develope a power 
equal to about 8 horses, as calculated by Watt’s rule. 
On the Application of Combustible Compounds to be used in War. 
By Joun MaAckInTosH. . 
This paper relates to the use of coal-tar, naphtha, or other hydro-carbons, alone or in 
combination with other materials, to be used as an agent in attack and defence; also 
to the application of hydro-carbons mixed with gunpowder, and brought to a plastic 
state by means of Indian rubber or other gums, and fibrous materials, introduced into 
shells and other missiles ; also in filling shells with coal-tar, naphtha containing po- 
tassium, for igniting when used injwater, and in filling shells with coal-tar, naphtha 
mixed with phosphorus and bisulphuret of carbon, with bursting powder sufficient to 
open the shells. 
To attack fortresses from seaward, the author would generate an artificial dense 
and dark fog, capable of being prolonged at pleasure, in front of the batteries to be 
attacked, which would render them untenable, enabling the attacking vessels to 
approach and destroy the works unmolested by any hostile fire. 
The diaphragm shells filled with naphtha, phosphorus, and bisulphuret of carbon, 
may be used with great effect against cavalry and troops, as the bursting of the shell 
scatters the contents in all directions. ; : 
When a shell containing the combustible material bursts in earthworks, the earth, 
being porous and incombustible, prevents the combustion from spreading rapidly, 
but allows the black vapour to ooze out gradually, causing most serious annoyance 
to the enemy, who are unable to extinguish the suffocating fog, and are hindered 
from carrying on their operations. 
It may be brought to bear with most satisfactory results against an enemy en- 
camped in tents. 
On Constructing and Laying Telegraph Cables. 
By Joun MackinTosu. 
In the ordinary process of expressing the gutta percha through dies in a fluid state, 
the covered wire, as it issues from the die, is caused to pass into a long trough con- 
taining water, for the purpose of setting it, but great difficulty is found in causing 
the perfect union of the different coatings, which renders the insulation liable to 
