SCIENTIFIC SUMMARY. 
437 
Select Committee, with very satisfactory results. The principle of the in- 
vention is that the whole momentum of the recoil of the gun should he 
absorbed in lifting a heavy balance weight, the gun itself at the same time 
descending in a cycloidal curve under protection of the parapet. Having 
descended, the gun is held by a self-acting pawl until it is loaded, by gun- 
ners perfectly protected from fire, and the work stored up in the balance 
weight during the recoil is then sufiicient to raise it to the firing position, 
above the parapet, its ascent being regulated by a friction break. The ex- 
posure of the gunners when the guns are placed en harhette on the ordinary 
system, and the weakening of the parapets when pierced by embrasures, are 
thus equally avoided, and the labour of training the gun is at the same time 
reduced to a minimum. Captain Moncrieif has further devised optical 
means by which the aiming of the piece may he effected without the expo- 
sure of a man to hostile fire. 
Hailways for Steep Inclines . — Amongst the modes of obtaining increased 
grip or adhesion to enable steam power to he employed on steep inclines, it 
has been suggested that the wheels of the locomotive or traction engine 
should be allowed to run on a road formed in the ordinary manner,, whilst 
the wheels of the waggons only run on the rails. The tractive force neces- 
sary to draw a given load on rails is thirteen times less than on common 
roads, and conversely the adhesion or grip of a given engine on a common 
road must be about thirteen times greater than on rails. M. Larmangat has 
submitted a plan based on this principle to the French Emperor. It is not 
impossible that, in cases where the expense of a more perfect system would 
preclude its adoption, this simple expedient of a composite road may be 
useful. 
Liquid Fuel . — In reference to a note on this subject Mr. C. J. Richardson 
addresses the following explanation : — You favour me in your late number 
in noticing. Captain Selwyn’s lecture on liquid fuel, to state that I have 
formed a theory “ that the water or steam introduced with the liquid fuel, 
and which seems necessary with its successful use, is decomposed, and the 
heat of the combustion of the hydrogen added to that of the liquid hydro- 
carbon;” and you add, “it is difficult to conceive that an additional heating 
effect can be gained in this way.” Will you please permit me to explain ? 
I do not hold any such notion as you describe. All liquid hydrocarbons 
when burnt in a furnace require such a large amount of oxygen that it is 
not possible by the usual way of admitting air to supply it, and hence there 
is an enormous amount of carbon in the form of soot and smoke. Now, by 
introducing a little steam into the furnace and decomposing it — and the hot 
fiery liquid fuel does this readily — the oxygen water-vapour immediately 
attaches itself to the escaping carbon, or soot, or smoke of the liquid fuel, 
great heat evolves, the fire clears, and there is no smoke. The hydrogen of 
the water escapes as it likes, it is sure to act well, but it is the oxygen that 
does the work. Thus, although the combustion of the water gases may 
give no heat themselves, they serve to use up or make the liquid fuel give 
all the heat it is capable of, I lb. of it vaporising 18 to 19 lbs. of water 
according to my process, as returned by the Government Engineers. A^ou 
often see a locomotive sending forth a dense column of black smoke, and 
by the side of it an equally dense column of white steam. If the latter 
