a” 
308 
fecting the theory of the motion of the moon, it is 
necessary that a considerable number of auxiliary 
observations should be made. These, it is proposed, 
should be made at the Natal observatory with the 
greater facility, as all the lengthy mathematical 
analysis necessary for their reduction has already 
been executed by Mr. Neison himself. The princi- 
pal subjects already taken up at the observatory are 
the following : — 
1°. The determination of the exact amount of the 
parallactic inequality in the motion of the moon by 
means of observations of the position of a crater near 
the centre of the lunar surface. 
2°. The determination of the exact diameter of 
the moon by observations of pairs of points near the 
limb. 
3°. The effect of irradiation and its variations upon 
the apparent semi-diameter of the moon. 
4°. The systematic variation in the apparent place 
of the moon produced by the irregularities on its limb. 
o°. The real libration of the moon by a method 
independent of the errors caused by abnormal varia- 
tions in the apparent semi-diameter of the moon. 
The first investigation is in continuation of the 
one already commenced at the Arkley observatory, 
England, and will be carried out with the additional 
co-operation of the observatory of Strasburg, Ger- 
many. Arrangements are being made to obtain the 
co-operation of the Cape and other observatories in 
the investigation of other of the above subjects. 
ECONOMY OF FUEL IN IRON-MANU- 
FACTURE. 
As the price of iron falls, every item in the cost of its 
production is more and more carefully scrutinized, — 
the quality of the ore, the cost of transportation, the 
labor used at the various steps in the process, the ac- 
cessories and mechanical appliances, the rapidity of 
working, the quantity of fuel to the ton of pig-iron 
produced, and the cost of the fuel. Of all these, the 
cost and quantity of fuel used are, perhaps, receiving 
the largest share of attention from the iron-men just 
at present. 
One coal-saving device is the Gjers soaking-pit. 
Formerly the huge ingots of steel from the Bessemer 
converter were allowed to cool, and were again heated 
before rolling them into steel rails. The efforts to 
roll them while still hot failed, owing to the fact that 
the core might still remain fluid while the outside 
shell of the ingot was cooling even below the rolling- 
heat. The Gjers soaking-pit is a hole in the ground, 
walled with bricks, in which the ingot of steel is 
placed until it has uniformly cooled to the rolling-heat, 
thus saving the reheating-furnace. Itis claimed that 
the Gjers soaking-pit saves sixty-seven tons of coal 
to a hundred tons of rails, Again: at the South Chi- 
cago works the pig-iron is run directly from the blast- 
furnace into the Bessemer converter; while the usual 
practice in most works has been, and still is, to allow 
the pig-iron to cool, and to melt it again in a special 
furnace for the Bessemer converter. 
SCIENCE. 
oe 
[Vou. IIL, No. 
The above processes save in the quantity of fuel;. 
while, on the other hand, a large saving in the cost 
of fuel is looked for in the improved methods of. 
coking and in the recovery of the valuable by-prod- 
ucts. It seems quite generally admitted, that a good 
system of coking, which will save the tar-oils and the 
ammonia, will pay all the coking-expenses. 
The great national economy will be better under- 
stood from figures. In the year 1880, in the United 
States, 2,752,000 tons of coke were produced from 
4,360,000 tons of coal by the old-fashioned beehive 
oven. Two years ago the figures for Great Britain 
were 7,000,000 to 8,000,000 tons of coke from nearly 
13,000,000 tons of coal by beehive ovens. This quan- 
tity of coke could have been produced by the Simon- 
Carvés system of coke-ovens from 10,000,000 tons of 
coal; effecting a saving of 3,000,000 tons, and also a 
saving of the coal-tar and ammonia by-products. 
The beehive oven, which takes its name from its 
form, is a low, square chamber with dome-shaped 
top; has. an opening for escape of gases at the top, 
and a door in the side through which to admit the 
air, to charge the coal, and to discharge the coke. 
The burning is regulated by opening and closing the 
side-door, and all the gases go to waste at the top. 
The Simon-Carves system of ovens consists of a row 
of chambers side by side, with combustion-flues in 
the parting-walls and under the floors. The waste- 
gases are burnt in these flues, and liberate heat 
enough to distil the gases of the coal. These gases, 
before entering the combustion-flues, are passed 
through condensing-apparatus, where the tar and am- 
monia by-products are saved. The two ovens, there- 
fore, work upon totally different principles. The 
beehive cokes by slow combustion, sacrificing a por- 
tion of the coal by the door, as well as the by-prod- 
ucts: the Carves simply distils. The beehive saves 
60% to 65 % of the coalas coke: the Carvés saves 75%. 
The beehive oven produces a very fine coke, in long, 
columnar, hard, silvery, porous masses: the Carves 
gives a dark, dense, heavy coke. And it is here that 
the iron-master hesitates; for he likes the silvery, 
porous beehive coke for making iron, and does not 
yet accept the dense, heavy coke of the Carves oven. 
Jameson has invented an oven which is known by 
his name, and which is essentially a beehive oven, 
with a suction-pipe entering at the bottom instead of 
the roof-outlet for gases. The products of combus- 
tion are drawn by an artificial draught through the 
pipe; and, after being carried through apparatus for 
the condensation of the by-products, this gas is avail- 
able for any purpose. The actual yield from a ton of 
coal has been estimated to be: sulphate of ammonia, 
10 pounds; oils, 8 gallons; gas, 12,000 cubic feet; 
coke, 67% to 69%. The tar from this oven is lighter 
than water (specific gravity, .960), and consists mostly 
of. oils, boiling between 250° and 300° C., of little value 
as burning-oils, and of. secondary value as lubricants. 
Paraffine is present, and both toluine and xyline in 
small quantities, but no benzine. A portion of the oils 
breaks up into phenols, which, so far as investigated, © 
give colors of little stability. Neither naphthaline 
nor anthracine is present, both valuable as sources 
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