AN HOUR AT ALL SAINTS' WORKS
DERBY
(JOHN DAVIS &
SON).
the suggestion
of the Local Committee of the Federated Institution of Mining Engineers, which
was appointed to arrange the business for the Annual Meeting to be held at
Derby in February, 1893, the proprietors of All Saints' Works were invited to
throw them open for inspection. It was with some diffidence that the firm
consented, for although they fully appreciated the compliment paid, they felt
that while the mere exhibition of plant and apparatus used in mines might
savour of a trade advertisement, such portions of the manufactures as could be
witnessed in the short space of time available might leave the members very
little wiser; the production of such apparatus being slow, and not resembling
the Hindoo conjuring trick where spectators at one sitting can witness the
growth of an adult tree from the seed.
At the request
of the Local Committee, the following notes have been compiled, showing what
the visitors may expect to see should they find themselves at Derby with an
hour or so hanging on their hands.
The firm, which,
perhaps, is best known as manufacterers of mining and surveying instruments,
has, during the last few years, so developed its operations in electricity that
it has been found necessary to divide the management into two distinct
branches, under the departments classed A and B; the former (A) being the
production on the old lines, and the latter (B) being the installation of
electric light and power plants with their collateral electrical accessories,
and of telephones and electric signals.
Taking the points of interest in the various rooms, which,
for the convenience of the visitors have been numbered:‑
Room 1 contains lathes which have mostly been
specially constructed for the production of miners' safety lamps. Here may be
noted the ease and precision with which the various screw threads of a safety
lamp may be cut. Standards in steel being worked to in all cases, uniformity of
size, and the interchangeability of parts are ensured throughout. This
improved screw‑cutting tackle is employed for all apparatus manufactured
at All Saints' Works, and for some few years the various parts, especially
those of miners' dials and levels (which instruments will be more fully
demonstrated in Room 2), have been made to standard sizes, and are, therefore,
interchangeable.
In this room has
recently been constructed some improved apparatus for naval signalling,
invented by Lieut. INGLEFIELD, R.N. An order has been executed this year for
the German Navy, and Messrs. JOHN DAVIS & SON have received the gratifying
intelligence that it is the intention of Prince HENRY of PRUSSIA to adopt the
same throughout the whole German Navy; and this same apparatus is to be used
throughout the British Navy.
Mercier's Mining Bell.
A new form of ringing key is now being manufactured,
designed by Mr. M. Mercier, and also an electric signal bell. The special
feature in both bell and key is protection against damp and dust of pits and
all exposed situations; the contacts are enclosed in gas‑tight chambers,
so that any fear of igniting gas in a fiery mine is eliminated.
An improved form of insulator is
also exhibited which is designed by Messrs. MORGAN and JAMES chiefly for
colliery planes where it is desired to carry the wires side by side so that a
signal may be transmitted from any point in the plane. The insulator has two
transverse grooves which keep the wires at a proper distance apart. It is
intended to run the upper wire taut, and the lower loose, to avoid contact
between the insulators.
While on the
subject of electric signalling it will not be out of place to call attention to
a demonstration of the manner of connecting up signal wires so that they can be
used for speaking by telephone. In the engine room is fixed a telephone and
automatic switch, which cuts out the bell and battery when the telephone is in
use; at the distant end of the plane, or any desired point, the second
instrument is fixed, and in addition to this, or in place of it, portable
telephones can be carried in the pockets of the Deputies and hooked on to the
wires at any point. A special signal must of course be arranged when the
telephone is to be used. Though the above system works well, it is best to run
one separate wire for the telephones, the earth wire being common to both
signals and telephones.
Room 2 is chiefly devoted to the manufacture of
scientific instruments other than electric, but here electricity plays an
important part in the production of finely divided and figured faces or dials
for such articles as Anemometers. The process of reproduction by electrotyping
of the faces for these instruments may be witnessed throughout. First, the
plate engraved by the machine to be seen in Room 3. This forms‑the
inverted copy or matrix‑then upon this is deposited the patrix, from
which further copies of the matrix are produced. Next comes the process of
waxing the lines and figures, and then the silvering process.
In this room are
constructed Magneto machines for shot firing and blasting on the " High
Tension " and Low Tension " principles, and also batteries for the
latter method, the battery being much lighter and cheaper than a Magneto
exploder of the same power.
As most of the
members are probably aware, the high tension fuse (which has been in general
use until recently), is fired by a spark jumping across two points in the fuse.
The low tension, which is the more reliable of the two, has only recently come
into use. It consists of a bridge of fine platinum wire between the two leading
wires; this bridge is heated by the current from the battery and thus fires the
fuse. One of the chief advantages of the low tension fuse is, that it can be
tested before use and a defective fuse detected. Mining bells and signalling
apparatus of various forms are also constructed in this room.
The Hedley Dial
will be familiar to most of the members, the firm having been actively engaged
in their manufacture for over half a
century; but as finality or perfection is never arrived at, and as it is
always endeavoured to produce the batch in hand something better than the last,
some points of novelty and improvement may be observed. As the boundaries of a
coal mine are more nearly approached the demand for more accurate instruments
increases, and year by year the Hedley Dial claims closer relationship to the
Theodolite. Thus, in the latest improved form, the Hoffman Patent joint has a
centering movement, self contained, and clamped by the same set of screws. The
limbs of this dial have been recently remodelled to give greater rigidity, and
at the same time weigh less than the pattern of its predecessor.
Aluminium is now
extensively employed in the construction of surveying instruments, particularly
for large foreign properties.
This wonderful
metal combines strength with extreme lightness. The transit Theodolite, now
nearing completion, is constructed wholly of aluminium, contains many points of
novelty, and weighs only 15lb. 2 oz. complete with its legs, against 29½lb. for
the same instrument in brass.
Dumpy Levels
with an improved beam, Clinometers in aluminium, and Biram's Anemometer, so
well known, may be seen in course of construction, but the Self‑timing
Anemometer, although it has found its, way to most parts of the mining
world, may not be so familiar.
Briefly
describing its action and construction, it will be seen that the fan, after
revolving freely and taking up a velocity due to the current of air, is engaged
in winding up a spring similar to the mainspring of a watch.
This spring
carries a hand over a graduated dial, which shows the current of air in feet
per second. To calibrate this anemometer, a special form of testing apparatus
has been constructed, and to ensure accuracy each instrument is separately
calibrated throughout the whole of its range.
In ROOM 4
may be seen the machine for testing anemometers on the Biram principle,
illustrated above. The modus operandi consists in the passing of the
instrument through still air at various velocities, while the machine for
calibrating the Self‑timing Anemometer, by placing it in the same current
of air as a Biram Anemometer, may be seen in action; the various velocities
being obtained by a partial vacuum caused by a steam jet.
In Room 3,
the manufacture of safety lamp‑ gauzes is extensively carried on with a
small staff of workpeople by the aid of machine tools. Here may be seen the
various processes from cutting the blanks from the roll to a finished and well‑knit
gauze, passing through the hands of the operatives sixteen times before
completion. A most useful and ingenious machine is at work engraving and
dividing the faces of dials, which work was hitherto executed by hand. A
specially interesting feature of this machine is that it is driven by an
electric motor
which takes its
current from the Electric Station (to be shortly noticed more
fully and the
required variation in speed is obtained by switching in more or less
resistance, readily adjusted by turning the small handle as exhibited.
In Room 4
are stored the various parts of bonneted miners' safety lamps, and, in passing,
the practical value of reducing the manufacture to standard sizes may be
remarked, the shells of the lamps being interchangeable and all internal parts
being constructed to fit these shells. Lamps of all types, whether Marsauts,
bonneted Mueselers, bonneted Clannys, or any other of their modifications, can
be rapidly put together and consigned to their destination.
Here may be mentioned
the safety lamp cleaning machine shown in Room 5. This is the invention of Mr.
WOLSTENHOLM, of the Bestwood Coal and Iron Company. It has several advantages
over other machines of‑the‑kind. Arrangements are made‑for
unscrewing the ring holding the glass and gauze, for cleaning and polishing all
parts of the lamp, and for screwing the ring up again into position. An
eccentric imparts an oscillating movement to a brush which rapidly cleans the
gauze.
FIG.
1
Wolstenholme's Lamp Cleaning Machine.
Special
fittings for the protection of incandescent electric lamps in dusty, damp. and
all exposed positions, are manufactured, and a large stock kept in readiness,
these being in considerable demand by various electrical engineering firms,
especially for lighting up the surface and underground of collieries, in which
the firm of JOHN DAVIS & SON have been of late years actively engaged.
A fitting specially for lighting a
sinking pit has been designed and is now in use at several collieries. It is exhibited
with its lamps alight, and consists of a cast‑iron dish‑strong
glass protector containing three incandescent lamps of 25 candle power each. A
strong flexible cable of twin conductors is told out from a drum at the top of
the pit shaft.
Room 5. A pioneer station for the distribution
of electric current is here installed, and has been at constant work for over
four years. This plant consists of an engine, dynamo and battery of sixty
accumulators, with its accompanying set of switches to regulate the current in
its various distributing cables ; voltmeters to indicate the pressure of the
current, ammeters to show the volume of current going out, and electricity
meters to ascertain the total amount of current consumed during any period.
Regulating switches with resistance coils to adjust the exact pressure to the
varying load, and an automatic switch to disconnect the dynamo from the
accumulators, should the pressure of the former fall below that of the latter.
The whole of the available current is daily in demand supplying neighbouring
hotels, shops, offices, and private houses with electric light, and it may be
here stated that from the day
that the current
was first` laid on" over four years ago, no single hitch or stoppage of
supply has occurred.
Electricity for
transmission of power is daily becoming recognised by coal‑owners as a
reliable agent, and already some hundreds.of horse power is being transmitted
electrically in‑mines‑ of this country, It was found impossible to
illustrate the application of electrical transmission
3 Brake H.P. Davis and Stokes' Patent Safety Motor
(Commutator closed.)
of power to coal‑cutting
and holing on the present occasion, but the same power applied to pumping may
be novel to some of the members.
Up to the present
time a danger has been felt to exist in the use of electric motors in fiery
mines, from the fact that bad setting or wearing of the brushes might result in
sparking, and the possible ignition of any gas that might be present ; in fact,
the use of electric motors in any mine where safety 'lamps are necessary has
hitherto‑been considered unsafe, and the progress of ‑electrical
transmission of power has thereby been greatly retarded.
Previous
attempts at the construction of a safe motor have taken. thel direction of
encasing either the whole machine,.the armature, or the
Safety Commutator open for cleaning
interior and brushes.
commutator and ‑brushes.
These arrangements not only introduced difficulties in the ventilation of the
armature, but also necessarily included a
considerable air space, so that when this space became filled with gas
it would be possible for an explosion to take place inside the case of such
violence as to entirely destroy the cover or case, and communicate with the
outside atmosphere, thus causing an explosion.
The arrangement
illustrated has been designed to overcome these difficulties, and is so
arranged that the commutator itself is practically equivalent to a locked
safety lamp enclosing the brushes, since it cannot be worked unless closed, and
cannot be opened while running; the junction between the fixed and the
revolving portions of the machine being made by a flame‑tight joint which
requires no packing and causes no friction.
The most marked deviation from the ordinary commutator is, that instead of the brush contact being on the outside of the cylinder formed by the commutator segments, this cylinder is bellow, and the brushes bear on the inside face of the segments. The method of construction is as follows:-
The commutator ‑segments are clamped between a ring
and a disc, the latter being keyed on the shaft. This disc foirns a permanently
closed end to the commutator cylinder at the side nearest the armature.
The brass bearing of the shaft is extended nearly up to the disc, leaving room
for a slight end play (the shaft of course only bearing in the usual portion of
the brass), and means are provided to prevent the oil from the bearing working
along the extended portion of the brass and entering the commutator.
Half Section of Commutator shewing bearing with elongated
brass.
The open end of
the commutator cylinder is closed by a disc sliding on the extended brass
bearing and carryingthe brush holders and brushes; and a clamping handle (not
shown in the illustration) provides for setting the disc and brushes in their
proper position. This disc, as stated, closes the end of the hollow cylinder,
the latter revolving with a clearance of 1‑32 in. from the disc; and in
order to avoid the chance of the disc with its brushes being withdrawn while
the machine is running, or started before properly closed, a locking ring is
provided, as shown in the illustration.
Small windows
are provided in the disc, by which any sparking at the brushes can be seen and
corrected, and the brushholders are fitted with springs working on the outside
of the disc, for adjusting their pressure while running.
When it is
necessary to clean the interior of the commutator and brushes, the locking ring
is unscrewed, and the disc, with brushes attached, is slid towards the bearing
as far as possible, thus leaving both commutator and brushes clear for cleaning
and inspection; means are provided for attaching a small slide rest, so that by
the use of a crank handle bolted to the pulley, the commutator can be turned up
in position, should this be required.
Carbon brushes
of a special type, admitting of very easy renewal, are used, thus obviating any
trouble that might occur from accumulation of copper dust within the commutator
with the ordinary copper brushes.
One of the chief
difficulties experienced by the firm is in making a judicious selection from
the various devices which are brought by inventors to be perfected,
manufactured, and introduced.
Amongst
inventions recently taken up at All Saints' Works may be
Mentioned:-
An Electric
Signalling Apparatus for the Navy;
An Electric
Indicator to show high and low water levels in tanks;
A Machine for
Closing and Unclosing Lead Locks of Miners' Lamps;
An Electrical
Time Checking Apparatus;
A Lamp for
Testing Small Percentages of Gas in Mines;
A System of
Humidifying the Air in Mines, so that coal dust is effectually damped.
The inventors
will, no doubt, in due course give the Members of the Federated Institution of
Engineers a more detailed description of their apparatus.