February 2, 1917.

THE COLLIERY GUARDIAN.

227

ends, where it engages with the brackets or lugs on the
bottom corners of the yoke, and is flattened out to
II in. x 3 in. in the centre and to within 3 in. of the
ends, where a collar is shrunk on to the turned portion.

The brackets or lugs on the bottom corners of the
yoke which act as bearings for the axle to turn in, are
made out of 1 in. X 6 in. mild steel set at right angles
on edge, carried through the. 6 in. the width of the yoke
with a lug turned over to catch the other edge. These
brackets are then riveted to the yoke.

The entire weight of the skip is carried on the yoke,
and only when the skip is in the act of dumping does
any weight come on the axle.

The tipple is constructed of angle irons riveted to
4 in. plates, which plates are bolted to the head frame
on each side of the shaft at a point for discharge.

The general construction is such that the skip can
he installed in short time. It does away with any extra
rail in the shaft to hold the skip from tilting while in
motion. It helps prevention of accidents in the shaft
due to upsetting.

On account of the advantages already mentioned, it
should meet with a ready demand where companies are
installing hoisting plant.—Canadian Mining Journal.

THE FILTRATION OF AIR.

The filtration of air is more generally associated with
the mechanical ventilation of buildings, and certainly
constitutes a very important factor in the successful
operation of plant of this character; but it also has a
very real commercial value in other branches of the
industrial world, and there are many other ways in
which it is profitably employed. One of the most
important applications is for cooling turbo-generators.
These machines are small in size in proportion to their
output, and have consequently a limited space wherein

Fig. 1.—Sirocco Air Washer, with side plate removed.

only comparatively small air channels can be embodied
for the dispersion of the heat. Since the introduction
of mechanically ventilated generators it has been found
that the use of unfiltered air has a deteriorating effect
on the insulation, owing to the presence of dirt and
dust particles in the atmosphere, which were gradually
deposited on the windings, causing local overheating
and eventual breakdown of the insulation. The
hammering action also of many thousands of minute
dust particles impinging on the end windings wears
away the varnish and insulation fabric, with the result
that when the machine in such a condition cools down
in an atmosphere of ordinary humidity, the end windings
rapidly absorb moisture, causing serious and unexpected
“ burn outs.” The importance of filtraton is still more
evident when the large amount of air- required for
ventilating large turbo-generators is taken into account.
For instance, a moderately large generator would use
20,000 cu. ft. of air per minute, which means a
total of 28,800,000 cu. ft. per day of 24 hours. As
a rough approximation, it may be assumed that one
hundred-millionth of the volume of the air in the
vicinity of power plants consists of dust, dirt, and other
foreign particles. This would mean that 87 cu. ft. of
dust would be blown into the machine during a year of
300 working days. Whilst, of course, a part of this
dirt will pass directly through the machine, a portion
will be deposited in the air passages by the air swirls
and eddies. Such deposits of dirt-become a considerable
handicap to ventilation, as the quantity of air is
decreased by the partial closing of the ventilating
passages, and the cooling effect of the air is greatly
diminished owing to the fact that the air cannot come
directly in contact with the heat-radiating surfaces.

The above advantages of filtered air apply also in
the case of forced or pipe-ventilated motors working in
a dusty atmosphere. However well they may be pro-
tected, the presence of grit and dust in the atmosphere
has a destructive effect, not only on the windings, but
also on the bearings. By using purified air the dusty
atmosphere is kept out of the motor, thereby prolonging
its life and and allowing it to operate under the most
ideal conditions, irrespective of its surroundings.

Filtered air is also valuable in the case of air com-
pressors, as the admission of gritty and dusty air plays
havoc with the valves and cylinders, causing trouble
and expense, and resulting sometimes in a serious break-
down. Particularly is this the case when the compressor
is installed on a colliery where the atmosphere contains
a large proportion of coal dust.

The types of air filters generally in use may be
broadly divided into two classes, dry and wet; the
former may consist of cloth of fibre screens; whilst, in
the wet type filters, the purification is obtained by
passing the air current through a fine water spray.
The dry filter takes up more space than a wet one, and,
where cloth screens are used, there is also the risk of
fire, due to spontaneous combustion. Furthermore, in
the dry type the maximum quantity of air passes
through when the filter is clean, gradually lessening as
the cloth becomes choked up, and thereby setting up
more resistance to the free flow of the air. These filters
also require to be cleaned frequently, which can usually
only be accomplished when the machine is out of action.

In the wet type of filter, as just explained, the air is
thoroughly washed by passing the air current through
a chamber filled with a very fine mist, which causes the
bulk of the solid matter suspended in the air to be
precipitated down into the tank at the base of the
machine. The air after leaving the spray chamber
encounters a battery of scrubber plates on which any
dust or dirt remaining in the air is deposited, and then
passes on to a series of eliminator plates, by means of
which it is buffeted from side to side, depositing during
this process any free moisture upon the eliminators,
and leaving the washer in a thoroughly clean and
cooled stage with no trace of free moisture. Fig. 1
shows a “ Sirocco” air washer, made by Davidson and
Company Limited, of Belfast, with the side plate
removed to expose the spray chamber and the series of
scrubber and eliminator plates (fig. 2). In this filter
the resistance to the air current is constant, thus
allowing'the same volume to pass all the time, and as
the resistance is low, less fan power is required to pass
a given volume of air than in the case of a dry filter.

Fig. 2.—Scrubber and Eliminator Plates-

It is also easily cleaned while in operation. The water
consumption is very low, as it is re-circulated by means
of a pump passing through two sets of filters, so as to
prevent any dirt choking the spray nozzles. This washer-
will remove 98 per cent, of solid matter from an impure
atmosphere, and will deliver the air entirely free from
moisture and in a cooled state.

Coal Contract Litigation.—In the King’s Bench Division on
January 26, Mr. Justice Sankey delivered his reserved judg-
ment in the case of Lambert Brothers, Cardiff, against
Watts, Wafts and Company, Cardiff, in which (as reported
in our issue of January 19) the plaintiffs claimed damages
for breach by them of a contract, by which the defendants
sold to the plaintiffs 3,700 tons of Powell Duffryn coals for
shipment between February 20 and March 15, 1916, at
Cardiff, Penarth, Barry, or Newport, at 30s. per ton. The
substantial defence set up was that the ship nominated was
the “ Costanza,” and as the plaintiffs failed to send her, they
(defendants) were under no obligation to load another vessel.
Mr. Justice Sankey decided that the extension of time that
the defendants gave was only for the “ Costanza,” and as
the ship was not ready, the defendants were not obliged to
load another. He gave the defendants judgment, with
costs.

Coal Trucks and Railway Companies.—In the City of
London Court on January 26, before Judge Atherley-Jones,
an action, which was said to be a test case, was brought by
the Great Eastern Railway Company against Gardner, Locket
and Hinton Limited, 3, Fenchurch-avenue, E.C., to recover
Sil for siding rent on coal trucks incurred by them. Plain-
tiffs’ case was that the charge sued for was made for the
accommodation of the defendants’ trucks in the sidings of
the plaintiff company at Devoushire-street. It was made
under the plaintiff company’s Act of Parliament. Defendants
had allowed coal to remain in wagons for over 30 days in
some instances. Plaintiffs were charging at the rate of 6d.
per wagon per day for the time which the defendants had
taken up unreasonably. That, of course, was done after
advice notes were given to the defendants. The defendants
claimed that they had been prevented from having delivery
of coal in the ordinary course, and now the railway company
was endeavouring to charge a siding rent. This they con-
tended was unreasonable in the circumstances. The hearing
was adjourned until February 7.

THE DONCASTER RESCUE STATION.

Through the courtesy of the committee controlling
the establishment, a representative of this journal
recently had an opportunity of inspecting the new
rescue station which has been established, and is now
in full working order, at Wheatley, Doncaster, to serve
the new collieries in South Yorkshire, including the
Bentley, Brodsworth, Bullcroft, Yorkshire Main, A skern,
Rossington and Hatfield pits.

The building, which involved an expenditure of
between £3,000 and £4,000, is situated at the junction
of Went worth-road and Wheatley-lane, and is built
upon a site three-quarters of an acre in extent. It is a
substantial structure of red brick, with white stone
dressings, and was erected by Messrs. Thornton and
Son, of Rotherham, to the designs of Major J. E.
Knight, architect, of the same town. It is partly one
storey and partly two storeys high, the latter portion
comprising a house for the superintendent and a com-
mittee room. The observation hall, on the ground
floor, measures 55 ft. by 26 ft., and enables observation
to be made of the experiments carried out in the
adjoining fume gallery, entrance to which can be
obtained by several doors. The gallery itself is
8 ft. 6 in. wide, and is admirably adapted for practice
in every phase of rescue work. The committee room
is 22 ft. 6 in. by 19 ft., the apparatus room and
workshop 20 ft. by 15 ft., and the waiting room 16 ft.
by 12 ft. 6 in. There are a series of six baths, foot and
shower, for the use of the rescue teams in training,
fitted with cold, tepid and hot water, and every con-
venience in the way of dressing rooms, lavatory
accommodation, &c., is provided.

A tour of the station shows that it has been erected
on the most modern and up-to-dat-r principles, and is
splendidly equipped in every respect. In the main hall
stands a 20-h.p. Studebaker motor car, ready for use at a
moment’s notice in case of call. This car is specially
constructed for the conveyance of rescue apparatus
from the station to the spot where its use is required.
It also carries a small reviving apparatus and ambulance
box. The station was built and completed some time
before being used, and it was not until July 1915 that
the serious training of rescue teams commenced. So
far just under 100 miners have been passed out as
efficiently trained in the duties of rescue work. The
men are trained in teams of six, and put in 14 practices
of three or four hours each, two hours actual work being
with the rescue apparatus. Those who successfully

' complete the course are granted a certificate of efficiency.
The management of each pit select their own men. who
' are then subjected to a thorough medical examination;
. and very few fail to complete the course. The men are
given such tasks as would fall to then- share in actual
i rescue work, while the gallery is filled with poisonous
■ gases and heated to a high temperature. Just now
training at the Doncaster station is taking place four
days per week, but five days is not an unusual circum-
. stance. At the time of our representative’s visit a
Bentley team was in training, the fourth from that
colliery.

Very great care has been taken in the selection of
. apparatus, and it was only after exhaustive tests and
- experiments that the particular make in use was agreed
upon. It will be remembered that the Doncaster Coal
Owners Committee commissioned Dr. J. S. Haldane,
M. D., F.R.S., to report on self contained rescue apparatus
for use in irrespirable atmospheres, and placed the whole
of their staff and laboratories at his disposal. After
prolonged investigation he reported the Proto to be the
simplest of all, and as, upon the whole, the best for the
equipment of the Doncaster Rescue Station. Conse-
quently the Rescue Station Committee adopted this
apparatus, with which the miners of the district are at
present being trained, and which appears to answer its
purpose admirably. ,

Among the minor appliances is a bird cage, designed
by Dr. Haldane, for canaries used for air-testing
purposes. This cage measures about 9 in. by 5 in., and is
capable of being closed immediately the bird drops from
its perch owing to the effects of foul air, whereupon the
oxygen can be turned on from a small attached cylinder
to revive the bird. Oxygen for the rescue apparatus is
received at the station in cylinders holding 100 cu. ft.,
and is transferred into the smaller cylinders by an
electrically-driven oxygen pump. The apparatus is
thoroughly washed and cleansed after use, and
mouthpieces are properly disinfected. There is
accumulator capable of charging 35 batteries for
lamps used in connection with the wo'k; and
station is heated by hot-air radiators. The fumes

the

the
the
fer-
tile practice gallery are generated in a slow combustion
stove, and are withdrawn from the gallery by means of
a powerful electric fan. The station is fitted with an
ergometer, and, in fact, with every appliance likely to be
of practical utility in the work. It is connected with
the various collieries by telephone, and is under the
direction of Mr. Donald Macaskill, who for 15 years was
a member of the London Fire Brigade.

French Maximum Coal Prices.—The Minister of Public
Works has issued a Decree increasing the pithead prices of
coals from the St. Etienne basin, from January -21, by 1 fr.
per ton (see Colliery Guardian, August 18, 1915, p. 307).
This measure has been adopted in accordance with the recom-
mendation of the Central Committee of Coal Prices and
Freights, to compensate the coal owners for the advance in
miners’ wages, in the same way as wais recently done in the
Pars-de-Calais district. The coal owners in the Loire
Department have, in fact, just agreed to pay their under-
ground and surface workers an extra 30c. per day, the wages
of young persons under 13 years being advanced by 10c. At
the same time, the premium paid to workers who have not
been absent a single day has been increased by 5 fr. per
month.