February 5, 1915.

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THE COLLIERY GUARDIAN.

281

Consideration of half-watt law/p, the filament of which
normally burns in nitrogen.

Current consumption of metal filaments of small electr ic bulbs
when in different gases.

In normal condition, i.e.,
filament burning in
usual vacuum.

____________
_________

Filaments. Volts. Amps.

Dull red... 0’45 ... 0’61
Full bright

light ... 2’1 ... 1-09

Same bulb, but with glass
removed and filament
surrounded by nitrogen.

Filaments. Volts. Amps.

Bulb “ K,” i.e., one of the ordinary metal filament bulbs.

Dull red ... 0'75 ... 1’12

Fairly bright
light and
instantly
burntout... 1’8

... 1’54

Bulb “ B.” (Similar to bulb“ AV)

Dull red... 0’4 ... 0*58
F ull bright

light ... 1*9 ... 1*05

.. 0’98 .

... 1’34

Dull red ... 0*7
Fairly bright
light and
instantly
burntout... 1'7

When the bulbs were placed in CO2 (carbon dioxide)
the results were similar to those obtained in the
nitrogen.

We understand that in making up the large half-watt
lamp the neck is much longer than ordinarily, as its
duty is to act as a cooling and condensing chamber for
the gas and evaporated particles which are precipitated,
probably in the form of wolfram nitride. This longer
neck and longer connecting wires are sure to reduce the
efficiency of the comparatively small miner’s lamp bulb,
and as much greater heat is given out by the filament
of the half-watt lamps, additional difficulties will be
introduced in that it will probably ignite pit gas quite
as readily as the naked flame of a miner’s lamp, as it
will in fact be equal to a naked flame, and owing to the
thicker filament may not extinguish so readily as the
present vacuum lamp, so that the safety features claimed
for the present electric lamps may entirely disappear
if the half-watt lamp should become a practicable
proposition.

From the results tabulated above, it is obvious that
with the same length and thickness of wire more
current is needed to raise it to the same temperature in
any gas other than in a vacuum. In other, words, in
nitrogen and other gases extra energy is required in
small bulbs to raise the filament to the same state of
incandescence as in the ordinary vacuum lamp, and that
when this is reached these small filaments will not with-
stand the extra current, whereas, if the filament is
thickened up the current consumption may rise still
higher.

The representative of a prominent maker of electric
lamps in this country informed the wiiter that the
smallest half-watt lamps that have been put on the
market at present are about 200-candle power 50 volts,
but there is difficulty even with these 50 volt lamps, the
best results being obtained with lamps reading into
thousands of candle-power. From the investigations
carried out at our works, it seems to the writer that the
only chance of bringing into use a half-watt lamp per
candle-power is on the very high candle-power lamps,
and that this to some extent maybe due to the fact that
a large amperage is generally employed in this type of
lamp, and the filament consequently heated up to a
point nearer the melting point of the metal, as it is well
known that when metals are raised to their melting
point the state of incandescence at such points jumps
up very rapidly, and it is on this last jump that the
makers of the half-watt lamp appear to rely, therefore
the writer is of opinion that even if it should be
possible—which at present does not seem to be the
case—for a miniature bulb to be produced to take a
consumption of half-watt per candle-power, other
difficulties will be introduced, such as the breakage or
fusing of the filament. Those who now use electric
lamps will have noticed that even with the present type
of bulb, when the filament is incandescent a slight
bump on the lamp will cause the filament to droop,
showing that the temperature of the existing filament is
already dangerously near the melting point.

There are, no doubt, in a pit, certain purposes for
which electric lamps are useful and well worth their
expense and trouble, but they certainly do not seem
suitable for meeting the collier’s inexorable condition of
giving first-class illumination day after day, for a
minimum of, say, about nine hours. In any other
occupation it would not matter if the cells did commence
to give out after eight, seven, six, five, &c. hours, and
this is one of the reasons why the writer contends that
for the average miner the electric lamp will never
become the standard iliumin ant.

_____________________________

Whatman Filter Papers.—In reference to our notice of
the Whatman filter papers in our last issue (p. 228), an error
was unfortunately caused by a transposition of names. As
a matter of fact, Messrs. W. and B. Balston Limited, of
Springfield Mill, Maidstone, are the manufacturers of these
papers, and Messrs. H. Reeve Angel and Company are their '
sales representatives.

Grimsby Coal Exports. — Goal exported from Grimsby
during the week ending Friday, January 29, was :—Foreign :
To Dieppe, 683 tons; Halmstad, 1,359; Malmo, 360; Oxelo-
sund, 3,460; and Rotterdam, 521 tons—total, 6,393 tons
foreign, as compared with 9,949 tons foreign and 96 tons
coastwise during the corresponding period last year. Coast-
wise nil.	. .

Immingham Coal Exports.—Coal exported from Imming-
ham to foreign countries during the week ended Friday,
January 29, was :—To Aalborg, 1,660; Bagnoli, 4,750;
Dieppe, 842; Helsingborg, 1,749; Malmo, 2,055; Reykjavik,
1,045; Ronne, 818; Rotterdam, 4,321; and Trondhjem, 1,454
tons—total, 18,694 tons, against 31,980 tons foreign and
1,250 tons coastwise for the corresponding period of last
year.

The Design and Equipment of Colliery Electric Lamp Rooms.*

By WM. MAURICE, M,I.E;E., F.G.S.

(Continued from page 224.)

Lamp Room Design.

The discussion of lamp room arrangements will
occupy the remainder of this paper, but there are
certain broad general points which call for preliminary
consideration.

The question of location on the colliery site is usually
one which is fixed by local circumstances. When,
however, an entirely new colliery is being planned, it.
may be worth while to consider the respective merits of
Continental as against British practice.

At home the surface works of a colliery are generally
disconnected and open to all and sundry. Continental
practice, on the other hand, favours the complete
enclosure of colliery surface works. Among the prelimi-
naries of lamp cabin design, that of checking should
receive attention. To make the lamp cabin the sole
path to flie mine is clearly not often practicable in the
case of old collieries.. The alternative is either to leave

Fig. 6.—Plan and Elevation of Lamproom,
showing “ Straight-through ” System of
Handling Lamps.

1

Efi

I

the question outside the domain of the lamp room, or to
double the checking, employing one check in the lamp
room and another at, say, the pit bottom. If desired,
checking and lamp distribution can be so arranged as to
become parts of one operation. There are, stated
baldly, two ways of distributing lamps : one is to hand
out each lamp to its regular user; the other to allow each'
user to enter the lamp room and take his own lamp.
Examples of each system are given below.

Building Construction.

, Some recent lamp rooms have been built with steel
girders filled in with brickwork. Others have been built,
with flat ferro-concrete roofs. Usually, however, lamp
rooms are constructed of 9 in. brickwork, strengthened
by pillars between each window. In whatever way the
walls are built, the writer favours a pitched roof (match-
boarded, felted, and.slated) as affording better facilities
for ventilation than a flat roof. In order to make a
really first-class job of a lamp-room, the walls should be
lined up to 4 or 5 ft. from the floor level with glazed
white bricks or tiles. Alternatively they may be lined
with parian cement and painted. As to flooring, the
first essential is that it should be so laid as to admit of
being washed out with a hose, the floor falling in all
directions towards a suitable drain. The lamp racks
and charging stands already described are made with
adjustable feet to allow for standing on a sloping floor.

Black and white tile flooring is probably the most
effective. If concrete is used, it should be of good
quality, and well done, otherwise the surface constantly
“ treads up.” Granolithic paving and artificial stone
pavement squares have been laid with satisfactory
results. The question of laying wooden blocks along-
side the work benches is, perhaps, worthy of considera-
tion. This raises the question of heating. Electric
lamp rooms are, or ought to be, much more spacious
than those used for flame lamps, and, since no warmth
is derived from, the lamps, the rooms require to be
heated. Apart from considerations of comfort, the
matter of temperature affects the charging of the cells.
Undoubtedly, a hot water system of heating is the most
satisfactory. The cost of heating apparatus for a' lamp
room to hold from 1,000 to 1,500 lamps is about £35.

The provision of adequate lighting is a more obvious
necessity, and it is therefore necessary to provide both
ample window area and adequate artificial light. A‘
system of inverted — or, at any rate, well diffused—
lighting is to be preferred to the customary conical iron
pendant illumination, which provides only concentrated
points of light. The provision of a supply of distilled
water is apt to be regarded as an unnecessary refine-,

* From a paper read before the North Staffordshire Insti-
tute of Mining and Mechanical Engineers.

ment, although the use of distilled water lias always
been specified' in accumulator installations,' and is very
desirable as a means'of prolonging the life of the cells.
The steam heated still is usually the most convenient to
apply at a mine. Every electric lamp room should have
as an annexe a mechanical repair shop and a store room,
with lock-up cupboards, for’bulbs and other spares. Space
is also sometimes required for a motor generator and
switchgear. . In the repair shop an open fireplace is
useful, both for heating soldering irons and for
warming food.

The internal arrangements of the lamp room should
be Settled in advance, since there are several ways of
disposing the racks, stands, etc., and the scheme
adopted determines the general shape and dimensions
of the building. Continental practice favours the
division of the building into separate charging rooms
and lamp storing rooms. Experience tends to confirm
the view that this is the best arrangement, although it
will subsequently appear that the home tendency at
present is towards single room installations.

In the example illustrated in fig. 6, which is typical
of the lines followed by tlie:. Sbaveley. Coal and Iron
Company Limited, except that they employ the~ flat
roofed construction, the building is rectangular. As,
however, a repair shop and heating chamber occupy one
end, the space actually available for the lamp room
proper is approximately square. In this instance a
building measuring 39 by 37 ft. (in the main lamp
room) is allowed for an installation of 1,680 lamps. In
arranging the various apparatus the principle is followed
of charging and storing, and partly cleaning also, in the
same room. Lamps are handed in at the windows on
one side of the building, and are unlocked and cleaned
on the receiving bench adjacent thereto. While the
shells, etc., are being attended to, the. cells are put on
trolleys, and are conveyed thereon to the charging
stands. Directly in line with each charging stand is a
lamp rack of the same capacity. When the lamp cases
have been cleaned, they are put on the trolleys and
wheeled alongside the charging stands, where in due
course the batteries are put in, the upper parts
assembled, and the finished lamp, hung up ready for
use. Each giving-out window serves two lamp racks,
and as these are within 2 ft. 6 in. of the narrow delivery
bench, each lampman can get out 480 lamps assigned to
him with a minimum loss of time. On the outer' walls
of the building, near each distributing window, are large
number boards indicating the range of lamp numbers
there obtainable.. The other side of the building is
reserved for lamps returned, and as each window has
number boards corresponding with those on the oppo-.
site side, each series of 240 lamps follows exactly' the;
same,path through the lamp .room every Shift.	'

In the next example (fig. 7) is shown " a lamp room
designed by the writer for an installation of from 1,500
to 2,000 Wolf alkaline lamps. Here, the charging room’
is: isolated from the lainp storing room, the lamp cases
being conveyed from the charging room (which is also,
the receiving room) while the cells arb bn charge. The"
dry cleaning is done at one side, and the wet work at the'
other side of the'room. As the repair shop is adjacent,.*
it would be practicable to transfer all the dusty work to,’
it, and so keep the charging room free from dust.-
Further reference to fig. 7 will show that the whole of
the windows are available for lamp distribution, in or
out.- Another advantage of this" two-roomed arrange-.,,
ment' is. that,' by ■ substituting doors and turnstiles in'
place, of each middle window in the lamp room, the
** fetch-your-own ” system of lamp distribution can be
put into operation. In the example illustrated in fig. 7
the boards and racks are built in 312-lamp units. More,
space than is really necessary has been left in the lamp!
room, so that the ” fetch-your-own ” system of distribu-"
tion could be tried. As in this way several men may .
be between two racks, at the same time, it is desirable to;
leave plenty of space.	/ . . .

In the next example (figs. 8 and 9) an octagonal con-
struction is employed, the. interior .space being so...
divided as. to form an inner charging room and an outer ,
storage and distributing room. The inner room is
further divided into a main charging room , and two.-
smaller compartments, used respectively for a, motor
generator. station and a repair shop. Each corner
window: in the outer wall serves, a different pit, and has
its separate lamp racks, cleaning tables, unlockers, etc.
The lamp racks are fixed on the insides of the outer
w’alls. ' The cells of the Wolf alkaline type (which in
this' installation are charged without removal from the
shells)' are, after taking off the covers, pushed through
the openings in the inner,.wall, and are received on tables*
fitted with washing tanks, filling apparatus, etc. The
cells are there ” topped up,” or receive other necessary
treatment, after which they are placed on the charging
boards situated .in the centre of the room,. The cells
return in due course .to the* benches in the outer room,-/
the' covers are replaced, and the complete lamps:
restored to the racks ready for the, oncoming shjft. The’
installation has a capacity of nearly 2,000 lamps; but as
each ’ group of lamps never moves out . of its. ownt
segment of the lamp room, the distance'which the cells '
have to be-carried in order to be. charged is very shorty

Another interesting installation is that recently pro-
vided for the Sherwood^ Colliery Company, Mansfield.
Owing to there being no. -suitable Aground spacfi for. an
electric lamp room, another.storey was built over the
existifig flame lamp premises, and thus, somewhat
fortuitously, the arrangement approximates in character
to that in vogue at many ^Continental mines. Separate
rooms are provided for damp storage, .for charging and
for lamp top cleaning. The lamps are taken out by the