1196

THE COLLIERY GUARDIAN.

June 6, 1913.

workings under pressure. It holds the world’s record
for horizontal boring of 702 ft. A feature of the device
is comprised in the iron wedges inserted after the pre-
liminary boring has been made, these serving to give
a gas and water-tight joint, which may be tested by
means of a special pump before boring proceeds. In
operation the drill point, boring rod, and hydro pump
are propelled forward by the feed screw M, and at the
same time water is forced through the boring rods and
out through holes in the drill point, so as to force out
the debris. The presence of gas or water is immediately
shown on the gauge. As the boring extends, the pump
is detached and further lengths of boring tube inserted.
A spring valve in the drill point prevents any escape of
water or gas through the boring rods. When these
elements are discovered, the drill point may be with-
drawn and the gas and water led or piped off. Mr.
Burnside also makes a long hole apparatus for use in
dry holes, and he shows besides a collection of deep
boring tools for proving faults, &c., and a reversible
rock-drilling machine with regulating feed and ball
bearings, the feed screw working on 32 threads through
a solid nut. On this stall there is exhibited, in
addition, one of Pow and Burnside’s eye-guards for pit
ponies.

JOHN DAVIS AND SON (DERBY) LIMITED.

This exhibit, as may be expected, is of special
interest. It contains instruments and apparatus of
special feature for the safer working of mines, which
come under the scope of the Coal Mines Acts and
Electricity in Mines Rules, and comply with the rules.

Beginning with surveying instruments, attention may
be called to a new design of transit entitled cable-word
“ Excellence.” This is claimed to be the last word in
theodolite construction, and certainly it appears so.
Davis’s Hedley dials, also shown, are too well known to
need elaboration. The late Mr. Bennett H. Brough,
Assoc.R.S.M., F.G.S., in his treatise on mine surveying,
described the Davis’s Hedley dial as “ the best instru-
ment for colliery use.” Various types of joints and
legs, are supplied with these instruments. The dumpy
levels exhibited cover a range which meets all the

Davts Clinometer.

requirements of surveyors. They are supplied with or
without compass. The Davis clinometer, with improve-
ments by Prof. H. Louis, is an excellent portable
instrument for field work, combined with the features
of a German hanging dial. There is a good range of
surveying aneroids which are designed for the purpose
of readily ascertaining variations, levels, &c., and from
their extreme sensitiveness are found of considerable
utility in mining and surveying work. In anemometers
there are several instruments of the “ Biram ” type, of
which Messrs. John Davis and Son (Derby) Limited,
were the original manufacturers for the inventor, Mr.
Benjamin Biram. Their latest instrument, however, is
the “ Davis-Biram,” which is constructed on the prin-
ciple of Biram’s revolving fan, but offers several advan-
tages over its predecessors. The air enters, as usual,
from the back of the instrument, and instead of passing
in a straight line through the protecting ring, is
deflected outwards, by a cone, through port-holes.
Experiments have proved that, if held 18 in. from the
body, there is no hindrance to the free current of air,
and that the accuracy of the readings is not interfered
with. The instrument is provided with a handle through
which a plunger passes, so that the operator can hold
the anemometer and connect or disconnect the revolving
fan from the train of wheels with one hand. For the
purpose of measuring air in various parts of a large
roadway, an extension rod may be provided, 3 ft. long,
which forms a walking stick. A zero-setting attach-
ment is provided, by means of which all the pointers
may be set to zero promptly. The “ Davis-Biram ”
anemometer is rapidly replacing the ordinary form of
Biram. and some colliery companies are turning out
their existing instruments and replacing with the “ Davis-
Biram.”

The “Davis Lyall” air speed indicator is intended
for special work, such as fan testing, blast and aeroplane
work, &c. It gives instantly the present actual velocity
and requires no watch to time the readings. Its general
appearance is similar to that of the “ Davis-Biram ”
anemometer above described. A shutter is provided,

which, if applied (i.e. closed to its extent), then the
readings of the scale must be multiplied by 2. This
shutter is applied when a greater velocity occurs than
the scale indicates. Davis’s pit water-gauge and self-
registering water gauge are other instruments to be
seen on the stand. The latter is an ingenious apparatus,
which is practically non-stoppable. The clockwork
driving the drum, arid the mechanism being separate.

The subject of hygrometers is of especial interest at
the present time. Messrs. Davis show several forms.
Two of these are for stationary use and the other is
their portable form. A self-recording hygrometer is
also exhibited. Both the mercurial and aneroid types
of barometers are shown; also portable thermometers
for pit use. Turning next to miners’ safety lamps, it
may be mentioned that all the miners’ safety lamps and
glasses supplied by Messrs. John Davis and Son (Derby)
Limited will comply with the Home Office requirements.
Lamps for the working miner and for the official are
shown. These are fitted with various deviations such
as electric ignition attachment, magnetic lock, &c.
The officials’ lamps are fitted with devices for detecting
firedamp—viz., the Cunynghame-Cadman and the
Briggs’ loop. Davis’s deputy lamp is a favourite
throughout the mining world. Other types of gas-
testing lamps for officials’ use are, Mr. A. H. Stokes’s
lamp, the Gray type lamp, the Beard-Mackie indicator,
&c. For lighting the pit bottom or roads, we noticed
a “ Porch ” lamp which gives an excellent light.

The “ Davis-Baxter ” gas-testing chamber exhibited
appears to be a very reliable apparatus. The observa-
tion chamber is accessible from all sides, and the
percentage can be varied by simply turning certain
taps.

There is also a good show of the Gray-Sussman
electric miners’ safety lamp. This lamp is the only one
which has stood the test of time in this country, and is
being largely adopted. It was a prize-winner in the
recent competition organised by the Home Office, and
it has been approved in accordance with the Coal
Mines Act, 1911. Amongst the accessories for use in
connection with miners’ lamps, there is a revolving lead
rivet-moulding machine, which will cast 90 rivets at one

Rivet-moulding Machine.

(John Davis and Son (Derby) Limited).

“ Davis-Fryar ” Mechano-Electric
Signalling System.

casting, every few minutes, and is found to be an
excellent machine in practice. A very substantial and
well constructed stand for miners’ safety lamps is also
exhibited.

No. 15 of the Special Rules for the Installation and
Use of Electricity in Mines, now in force, requires that
signalling apparatus shall be so constructed and worked
that there shall be no open sparking ; consequently the

Duplex Compressor, with Short Belt Drive.
(Ingersoll-Rand Company).

system of carrying two bare wires side by side along
haulage roads, whereby the signal is transmitted by
connecting such wires by hand, has to give way. The
“ Davis-Fryar ” mechano-electric signalling system
meets the requirements of the rule, and it is claimed
that this system is considerably less costly than that of
installing flame-proof push buttons, and is more efficient
owing to the fact that a signal can be transmitted from

any part of the haulage plane, whereas push buttons are
fixed only at intervals. It has been found by experiment
that one contact box will operate 200 yards (i.e., 100
yards right and left). Davis’s mining bell complies with
the Special Rules, being damp, dust and flame proof.

The “ Davis-Brown ” pit-prop drawer calls for special
mention. This tool is readily set and will draw a prop,
or other load to be moved, any distance up to 13 ft.
without being reset. Mention may also be made of a
new prop-setting appliance.

The “ Davis-Derby ” pocket form magneto exploders
are very robust machines. They have cast aluminium
cases, which prevent the gearing getting damaged from
outside pressure, and in this respect show a decided
advantage over sheet metal cases. They are made for
firing various numbers of shots.

LEECH, GOODALL AND CO.,

Messrs. Leech, Goodall and Co., of Hunslet,
exhibit a working model showing a complete screening
plant. This model includes the small trucks going
through the tipplers and delivering on to the screens
and picking belts, and afterwards delivering, by
means of lowering arms, into the railway trucks run-
ning on lines underneath. In addition, there were
photographs of several plants erected by the firm,
including headgears and screening plants, &c., for the
Harton Coal Company, South Shields, Micklefield Coal
and Lime Company Limited, near Leeds, Langley Park
Colliery Company, Langley Park, North Biddick
Colliery, co. Durham, the Askem Coal and Iron Com-
pany, Askern, &c.

INGERSOLL-RAND COMPANY.

This firm make a speciality of air-compressing plant
and rock drilling machinery. In the former category is
a small size “Imperial” air compressor, with duplex
compound cylinders and intercooler between the stages,
short belt drive and unloaders. The frames are totally
enclosed, but every part is accessible whilst running. A
special feature is the system of lubrication, which is
automatic, the crank discs delivering oil by means of
wiper pans to the main bearings, eccentrics, &c. The

overflow is returned to the crank chambers to be used
again. In the short belt drive a floating idler pulley is
interposed between the motor and compressor pulleys
to take up the slack. The compressor is driven by a
Lancashire Dynamo Company’s motor, and controlled
by a Brookhurst starter. We noticed also several sizes
of a new type 12-vertical compressor, adapted for cases
where small volumes of compressed-air are used. These
are of the single-stage, single-acting, enclosed type, and
their principal feature is their rugged construction.
The company make a portable outfit, comprising one of
these “ Imperial 12 ” compressors, with short belt drive,
the compressor, motor and all accessories being mounted
on the air receiver, which forms the body of the truck.

On the stand are the various types of rock drills made
by the firm, including the latest type of air-feed
hammer drills and the “ jackhammer ” drill, with butter-
fly valve. This drill belongs to the type which rotates
the steel automatically while striking. The butterfly
valve consists of two wings and a central stem on which
it oscillates. One wing controls the supply to each end
of the cylinder, the other wing controlling the exhaust
from the alternating ends. As the two wings are of the
same area, the pressure holding the supply wing on its
seat is equalled by the pressure tending to force the
exhaust wing off its seat, thus making a balanced valve
which requires very little pressure to shift it. The valve
closes the ports by advancing to the seat, and the valve
chest is arranged to carry the throttle valve. The air-
feed telescopic hammer drills include three distinct

types—viz., those having a valve motion identical
with the “Jackhammer”; the “Crown” valve drills,
which have a valve motion entirely separate from the
piston or hammer movement, the valve being of the
air-thrown type; and the “ Imperial ” valveless drills, in
which the admission and exhaust of air is controlled by
the movement of the piston itself, the latter covering or
uncovering various air ports in its travel. The Temple-