444 
the steam pressures at each part of the stroke, assuming in both 
cases the same initial steam pressure of 60 Ibs, per square inch 
above the atmospheric pressure, and the same load upon the 
engine. They show that in the latter case the same amount of 
work is accomplished by filling the cylinder roughly speaking up 
to one-third part of the length as in the other by filling it entirely. 
Here we have then an easy and feasible plan of saving two-thirds 
of the fuel used in working an ordinary high-pressure engine, 
and yet probably the greater number of the engines now actually 
at work are of the wasteful type. Nor are the indications of 
theory in this case (or in any other when properly interpreted) dis- 
proved by practice ; on the contrary, an ordinary non-expansive 
non-condensing engine requires commonly a consumption of 
from 10 to 12 Ibs. per horse-power per hour, whereas a good ex- 
pansive and condensing engine accomplishes the same amount of 
work with 2 Ibs. of coal per hour, the reason for the still greater 
economy being, that the cylinder of the good engine is properly 
protected by means of a steam-jacket and lagging against loss by 
condensation within the working ‘cylinder, and that more care is 
generally bestowed upon the boiler and the parts of the engine, 
to ensure their proper working condition, 
A striking illustration of what can be accomplished by way of 
accuracy in a short space of time was brought to light by the 
Institute of Mechanical Engineers, over which at present I have 
the honour to preside. In holding their annual general meeting 
in Liverpool in 1863, they instituted a careful inquiry into the 
consumption by the best engines in the Atlantic Steam Service, 
and the result showed that it fell in no case below 4% lbs. per 
indicated horse power per hour. Last year they again assembled 
with the same object in view in Liverpool, and Mr. Bramwell 
produced a table showing that the average consumption by 17 
good examples of compound expansive engines did not exceed 
2} lbs. per indicated horse power per hour, Mr. E. A. Cowper 
has proved a consumption not exceeding 14 lbs. per indicated 
horse power per hour in a compound marine engine constructed 
with an intermediate superheating vessel, in accordance with his 
plans, nor are we likely to stop long at this point of comparative 
perfection, for in the early portion of my address I have endea- 
voured to prove that the theoretical perfection would only be 
‘attained if an indicated horse power was produced with — ths, of 
pure carbon, or say 4 lb. of ordinary steam coal. 
Here then we have two distinct margins to work upon, the one 
up to the limit of say 2 lbs. per horse power per hour, which has 
been practically reached in some and may be reached in all cases, 
and the other up to the theoretical limit of 1b. per horse power 
per hour which can never be absolutely reached, but which in- 
yentive power may and will enable us to approach ! 
Domestic Consumption—The wastefulness of the domestic 
hearth and kitchen fire is self-evident. Here only the 
heat radiated from the fire itself is utilised, and the com- 
bustion is generally extremely imperfect, because the iron 
back and excessive supply of cold airs, check combustion 
before it is half completed, We know that we can heat 
a room much more economically by means of a German 
stove, but to this it may be very properly objected that it is 
cheerless, because we do not see the fire or feel its drying effect 
on our damp clothing ; it does not provide, moreover, in a suffi- 
cient degree for ventilation, and makes the room feel stuffy. 
These are, in my opinion, very potent objections, and economy 
would not be worth having if it could only be obtained at the 
expense of health and comfort. But there isat least one grate 
that combines an increased amount of comfort with reasonable 
economy, and which, although accessible to all, is as yet very 
little used. I refer to Captain Galton’s ‘‘ Ventilating Fireplace,” 
of which you observe a diagram upon the wall. This fireplace 
does not differ in external appearance from an ordinary grate, 
exceptthat it has a higher brick back, which is perforated at 
about mid-height to admit warmed air into the fire to burn a 
large proportion of the smoke which is usually sent up the 
chimney unburnt, for no better purpose than to poison the atmo- 
sphere we have to breathe. " 
The chief novelty and merit of Captain Galton’s fireplace 
consists, however, in providing a chamber at the back of the 
grate, into which air passes directly from without, becomes 
moderately heated (to 4° Fah.), and, rising in a separate flue, 
is injected into the room under the ceiling with a force due to 
the heated ascending flue. A plenum of pressure is thus estal- 
lished within the room whereby indraughts through doors gad 
NATURE 
[ Sept. 25, 1873 ' 
ae" 9 
windows are avoided, and the air is continually renewed by — 
passing away through the fireplace chimney as usual. Thus the — 
cheerfulness of an open fire, the comfort of a room filled with — 
fresh but moderately warmed air, and great economy of fuel, are — 
happily combined with unquestionable efficiency and simplicity ; — 
and yet the grate is little used, although it has been fully de- 
scribed in papers communicated by Captain Galton, and in an 
elaborate report made by General Morin, le Directeur du Con- 
servatoire des Arts et Metiers of Paris, which has also appeared 
in the English language. 
The slowness with which this unquestionable improvement 
finds practical application is due, in my opinion, to two cireum- 
stances,—the one is, that Captain Galton did not patent his 
improvement, which makes it nobody’s business to force it into 
use, and the other may be found in the circumstance that houses 
are, to a great extent, built only to be sold and not to be lived 
in. A builder thinks it a good speculation to construct a score 
of houses after a cheap design, in order to sell them, if possible, — 
before completion, and the purchaser immediately puts up the 
standard bill of ‘* Desirable Residences to Let.” You naturally — 
would think that in taking such a house you had only to furnish 
it to your own mind, and be in the enjoyment of all reasonable 
creature comfort from the moment you enter the same. This 
fond hope is destined, however, to cruel disappointment; the 
first evening you turn on the gas, you find that although the - 
pipes are there, the gas prefers to pass out by the joints into the 
room instead of by the burners ; the water in like manner takes 
its road through the ceiling, bringing down with it a patch of 
plaster on to yourcarpet. But worst of all, the fire-grates (of a 
size irrespective, probably, of the size of the room), absolutely © 
refuse to avail themselves of the chimney flues preferring to 
send the volumes of smoke into the room. Plumbers and 
chimney doctors are now put into requisition, pulling up floors, 
dirtying carpets, and putting up gaunt-looking chimney-pots ; 
the grates themselves have to be altered again and again, until 
by slow degrees the house becomes habitable in a degree, although 
you row only become fully aware of innumerable drawbacks of 
the arrangements adopted. Nevertheless, the house has been an 
excellent one to sell, and the builder adopts the same pattern for 
another block or two in an increasing neighbourhood. Why 
should this builder adopt Captain Galton’s fireplace? It will 
not cost him much, it is true, and it will save the tenant a great 
deal in his annual coal bill, not to speak of the comfort it would 
give him and his family; but nobody demands it of him, it 
would give him some trouble to arrange his details and subcon- 
tracts, which are all settled beforehand, and so he goes on build- 
ing and selling houses in the usual routine way. Nor will this 
state of things be altered until the dwellers in houses will take the 
matter in hand, and absolutely refuse to put up with builders’ 
ways, or, what is still better, get builders who will put up house 
in their way. This is done to some extent by building societies, 
but there is as yet too much of the old leaven left in the trade, 
and the question itself too little understood. ‘ 
Consumption in Smelting Operations —We now come to 
the third branch of consumption, the smelting or metal- 
lurgical furnace, which consumes about 40,000,000 of the 120 
millions of the fuel produced. Here also is great room for 
improvement, the actual fuel consumed in heating a ton of 
iron up to the welding point or of melting a ton of steel is more 
in excess of the theoretical quantity required for these purposes 
than is the case with regard to the production of steam powe 
and to domestic consumption. Taking the specific heat of iron 
at ‘114 and the welding heat at 2,700° F, it would require 
2,700 x ‘144—307 heat units to heat 1b. of iron. A pound of 
pure carbon developes 14,500 heat units, a pound of common 
coal 12,000, and therefore one ton of coal should bring 39 tons of 
iron up to the welding point. In an ordinary re-heating furnace 
aton of coal heats only 13 ton of iron, and therefore produces 
only ¢srd part of the maximum theoretical effect. In melting 
one ton of steel in pots 2% tons of coke are consumed, and taking 
the melting point of steel at 3,600° F. the specific heat at *119 it 
takes ‘119 x 3,600=428 heat units to melt a pound of steel, and 
taking the heat producing power of common coke also at 12,000 
units, one ton of coke ought to be able to melt 28 tons of steel. 
The Sheffield pot steel melting furnace therefore only utilises 
ysth part of the theoretical heat developed in the combustion. 
Here therefore is a very wide margin for improvement, to which 
I have specially devoted my attention for many years, and not 
without the attainment of useful results, Ihave since the yea 
