February 18, 1916.

THE COLLIERY GUARDIAN.

327

THE HIRSCH PORTABLE
ELECTRIC LAMP/

By Hibam H. Hibsch.

The Hirsch lamps, which, though largely used in the
United States of America, have not yet been adopted in
Great Britain, consist of (1) the watchman’s lamp, and
(2) the miner’s lamp, are portable, and have been
designed to provide a safe and reliable light for use by
watchmen, and in mines, rescue work, powder works,
oil refineries, and other places where special precau-
tions become necessary on account of the presence of
explosive materials or gases. The lamps are operated
by a storage battery supplying the current for a minia-
ture incandescent lamp, and each safety lamp forms a
complete unit, which can be carried from place to place,
or held in any position.

Miner's or Watchman's Hand Lamp.—This consists
of a storage battery placed on an asbestos cushion in a
cast aluminium casing with a hinged top. The top
piece is also of cast aluminium, and is provided with a
hook, a reflector, and terminals for making contact with
both poles of the battery. The reflector unit consists
of concentric safety shells, an incandescent lamp, a
safety glass, a crystal, and a switch.

Battery.—The battery consists of two 1 in. horizontal
lead plates in the bottom of a hard rubber jar, and
separated by wood and perforated hard rubber, the
bottom plate being positive. The leads from the battery
plates are enclosed in glass tubing. The solidified elec-
trolyte is a gelatinous substance. The battery is sup-
plied with a vent plug, and the top is sealed with an
insulating compound. Both terminals consist of anti-
monious lead.

Casing. — The battery casing is of cast aluminium
about | in. thick. It is open at the top, the top edges
being provided with tapered or bevelled edges. A mag-
netic spring lock is housed in the bottom casing, and a
soft rubber cushion is placed in the bottom.

Cover.—The combined cover with reflector holder is
of cast aluminium about | in. thick. The sides have
bevelled or tapered edges to fit the bottom casing, and
a hook is attached to the reflector casting. One end
carries a screw, fitting into a hole in the casing, and
securing the two parts in place. Spring clip contacts on
the underside of the cover make contact with both
terminals. A short length of insulated wire connects
to the central contact screw of the miniature lamp
socket.

Reflector.—The reflector has three concentric shells,
the intermediate shell being insulated from the other
two, and connected to the negative pole, and the other
two shells to the positive pole of the battery. The dis-
tance between these shells varies at different points
from /g in- to i in. They are so arranged that if the
reflector should be crushed or punctured, the current to
the lamp is cut off by short-circuiting between the
battery and the lamp, before the lamp bulb can be
broken. The inner shell is fastened to the screw shell
of the lamp socket, and the intermediate shell is
fastened under the central contact of the lamp socket.
A brass screw through an insulating bushing in the back
of the top piece, threads through a square brass nut,
then through an insulating cylinder, and into a brass
hexagonal nut forming the centre contact of the lamp
socket. An insulated contact spring, clamped under
the square nut, and making contact with the top piece,
projects and makes contact with the outer shell of the
reflector. The outer end of the shell is threaded to
receive a ring securing a convex crystal against a soft
rubber jacket.

Lamp Bulb.—The incandescent lamp used is of the
2-volt 0-55-ampere tungsten filament type, with a
miniature lamp base.

Safety Glass—The safety glass is a piece of window
glass 2^ in. long, 1 in. wide, and about 0-05 in. thick,
supported across the reflector shell back of the crystal.

Switch.—The switch on the lantern is a screw switch
fastened to the outer case of the reflector and a knurled-
head screw, which threads through the outer shell and
makes contact with the spring pressing against the con-
tact spring in the corner of the battery case.

Miner's Lamp.—This lamp consists of a storage bat-
tery in a cast aluminium box carried on the miner’s belt.
The box has a handle, and contains the springs for
making contact with the battery terminals. The
armoured cord extends through the upper part of the
box, and is fastened to the headpiece, which is similar
to the reflector of the watchman’s lamp, and consists
of an incandescent lamp, a reflector, safety shells, a
safety glass, a crystal, and a switch.

Battery and Lamp Bulb.—These are of the same con-
struction as in the watchman’s lamp.

Casing. — The battery casing is of cast aluminium
about | in. thick, and has a detachable hinged cover to
lock to the bottom of the case. The top has a wire
handle, and on the back is an opening through which
the miner’s belt passes. Two copper springs, insulated
and fastened to the top of the case, make contact with
the negative and positive terminals of the battery.

Headpiece.—The reflector, which is used as a head-
piece, is the same as that for the watchman’s lamp,
except that the central contact for the receptacle is a
hexagonally-headed screw, which passes through an
insulating cylinder, and threads into a nut. This nut
forms the central contact of the inner insulated wire
inside the armoured cord. The inner wire is negative.

Armoured Cord.—The cord is a single piece of flexible
single-braid rubber-covered wire, made up of sixteen
strands of No. 30 B-and-S-gauge copper wire. The outer
armour consists of a single strip of formed brass, which
overlaps and locks itself between succeeding turns of the
strip.	____

* From a paper read before the North of England Institute
of Mining and Mechanical Engineers.

The weight of the lamp complete is 3J lb., and of the
battery only lb.

Advantages.—The following claims are made for both
the lamps :—

(a)	The storage batteries are easily and quickly
handled in charging, easy to take apart and repair, and
all parts are quickly accessible.

(b)	The sediment that tends to loosen from the
positive or the bottom plate still remains part of the
plate.

(c)	Jarring or upsetting the battery will not affect the
plates as in batteries with thin vertical plates. Short-
circuiting will not injure the plates.

(d)	The battery will not, when short-circuited, arc
sufficiently to. ignite gas, black powder, guncotton,
cartridge powder, alcohol, or other vapours. Immedi-
ately on short-circuit, the voltage drops to zero.

The solidified electrolyte always remains in contact
with the plates, no matter how it is handled, whether
upside down or not, and when in any position will not
ruin a man’s clothes by the spilling of electrolyte.

The batteries will give an average light of 5 candle-
power for 12 hours or more on each charge.

If the crystal and safety glass should get broken in
an explosive atmosphere, the lamp is extinguished by
the safety glass opening the circuit at the switch,, and
thereby eliminating the risk of igniting anything explo-
sive, the lamp becoming extinguished before the bulb
breaks.

The arrangement of the three shells in the reflector or
headpiece will prevent any danger from the bulb igniting
anything explosive if the shells should be crushed or
punctured, as the shells short-circuit the lamp, and the
light is extinguished before the bulb is broken.

Tests show that the heat from a man’s body would
not be sufficient to liquefy the solidified electrolyte and
allow the solution to drip out of the battery, to ruin the
clothing, or cause personal injury.

These lamps provide light which may be used in
the presence of explosive valours, gases, or other
materials with a high degree of safety, even under
extreme conditions of rough usage.

The breaking of the safety glass, or the denting of the
outer case of the reflector, will, in every case, extinguish
the incandescent bulb. It should be understood that the
breaking of an incandescent bulb, even of small candle-
power, may, under favourable conditions, cause an
explosion of a surrounding gas that has a low tempera-
ture of ignition.

(An illustration of the Hirsch lamp was given in the
Colliery Guardian, December 11, 1914, p. 1222.)

Supply of Coal to Italian Gas Works.—The Italian gas
works recently addressed a strongly-worded complaint to the
Government authorities in regard to the supply of coal. They
bought coal at fancy prices, paid-fantastic freights, and then
found the coal held up. The steamer could not get berthed ;
when berthed it could not be discharged for want of wagons ;
when wagons appeared and were loaded they remained where
they were for want of locomotives; and all the while there
was a want of unity, different authorities issuing contra-
dictory orders and directions. In some works the difficulties
had proved too great, and the works had suspended opera-
tions; in most, the stocks of coal were only enough to last
about five days or, in some cases, as much as a fortnight.
Meanwhile the Government has appointed a committee to
deal, without appeal, with the unloading and transport in
Genoa and the ports of Savoy so as to provide for the
needs of the war and of the public services, and reconcile
these as far as may be with the interests of the private
trader; directing ships at what other ports to unload in
case of need, and making arrangements as to railway trans-
port from these other ports. These efforts appear to have
been attended with good results.

Coal Trade Benevolent Association.—The 19th annual
meeting of the Coal Trade Benevolent Association was held
in the London Coal Exchange on Monday, Mr. T. K. Fox
(retiring chairman) presiding.—In their report the directors
recorded that steady and continued support had enabled
them to carry on the work. The year’s income amounted
to £6,016, for which the association was greatly indebted
to the Duke of Norfolk and the numerous company at the
anniversary festival. Lord Airedale promised to succeed the
Duke of Norfolk. In lieu of concerts or outings, subscrip-
tion lists were opened. Mr. T. F. Usher and his stewards
brought in £166, the Reading list realised £41, the Sheffield
branch collected £85, and the Derby and Nottingham branch
contributed £9. The association disbursed £3,171 in relief.
The chairman considered that the year’s results, having
regard to the adverse influence of the war, reflected great
credit on all concerned, and he specially mentioned the efforts
of Mr. W. J. Collins, secretary. — Mr. Ernest Oliver, in
succeeding to the chair, drew attention to the association’s
progress even in war time, and he expressed the belief that
if the objects were more widely known the financial support
would show a large increase. He wanted to see a greater
number of guinea subscribers, and it was his intention to
seek to bring in more coal merchants, colliery managers,
clerks, and others during his term of office.,— Mr. Joseph
Shaw, K.C., spoke of the difficulty in getting people in South
Wales to join, because they were “ so fond of their own
little corner,” but he looked forward to an increase even
there—Mr. G. C. Locket, in moving the re-election of the
retiring directors, Messrs. T. Beam, E. Oliver, H. C.
Rickett, J. J. Smallwood, T. E. B. Swallow, and F. T.
Wright, pointed out that the income was the largest the
association ever had. That was a favourable symptom, for
it proved that the general body of the trade now contributed.
They were now approaching the ideal when the income from
investments would be sufficient to cover the cost of
administration. The Yorkshire branch was making an
excellent showing.—Mr. E. B. Reynish was elected a repre-
sentative director of the North Staffordshire branch, and
Mr. G. C. Locket succeeded the late Mr. E. P. Sells as
trustee. Acknowledgment was made of the services of Mr.
R. C. Phillips and Mr. H. J. Warne, honorary auditors,
and of the useful publicity afforded by the trade Press. At
the close of the proceedings, Mr. Fox, on his own account,
presented a handsome coffee set to Mr. Collings, who
responded appreciatively.

BOOK NOTICES.

The Technical Publishing Company Limited (1, Gough
Square, Fleet-street, E.C.) have favoured us with copies
of the 1916 edition of their, most useful annuals, viz.,
The Practical Engineer Pocket Book and Diary
(Mechanical), and The Practical Engineer Electrical
Pocket Book and Diary. The former, which is now in
its 28.h edition, has been brought up to date with care
and discrimination, amongst the new matter being
amplified notes relating to steam, gas, and oil engines,
turbines and compressors; whilst a new section on the
choice and use of lubricants has been added. The
electrical pocket book has also been largely recast, con-
siderable attention having been devoted to the subject of
-standards, a matter of ever-growing importance in
engineering. Many people are now by force of circum-
stances coming into direct contact with engineering
problems who hitherto have restricted themselves with
uncertain success to the adjustment of simple domestic
devices, such as the hot-water cistern and the bell
battery. For such as these, annuals like those under
review, which may be obtained post free for Is. lOd.
(peltine), or Is. 4d. (cloth) are admirably suited. They
give, in -a small compass, a mass of information in a
really “ get-at-able ” form.

Gas Engineering and Gas Manufacture : A Review of the
Institution of Gas Engineers. Part 2. Edited by
Charles W. Hastings. 132 pp. + xxxiv.; Ilin, x
8f in. London : J. G. Hammond and Company Limited.
1915. Price, 2s. net.

Part I. has already been issued, and covered
the period 1863 to 1883. The present part deals with
the next decade, 1884 to 1894. It is proposed, in the
course of six of these parts, to cover the whole 50 years
from the foundation of the institution in 1863 to 1913.
The notion was well conceived, and is being admirably
carried out by the editor, Mr. Charles W. Hastings. In
the first year coming within the present review, the
Transactions of the Institution of Gas Engineers con-
tained a notable appendix, entitled “ A Brief Enquiry
into the Calorific Value of Coals,” by James Paterson,
F.C.S. In the following year (1885), Mr. H. Townsend
described an interesting experiment in extracting benzol
from coal gas. In 1887, papers were read on ” The
Distillation of Shale for Oil Making,” by D. R. Steuart;
“ Coke,” by C. Gaudon, and “ Gas Coke as a General
Fuel,” by C. E. Jones. Again, in 1891, we notice a
paper by W. R. Chester on “ By-Products in the Manu-
facture of Coal Gas and the Utilisation of the Same,”
and another by J. McGilchrist on “ Coal Storage.” A
paper by the late Prof. Vivian B. Lewes deals with
substitutes for cannel in the enrichment of coal gas, a
subject which reappears for several successive years,
during which this question was much to the front in
gas manufacture. We have selected only a few amongst
the many interesting and valuable papers read before
the institution during these years. The work is a
veritable record of progress in gas engineering, and a
history of inventive activity, both of the fertile and
abortive types. Even the latter have their uses, for
who can say that some neglected process may not some
day assume practical importance?

Elements of Surveying and Geodesy. By W. C. Popplewell,

M.Sc., Assoc.M.Inst.C.E., Lecturer in the University
of Manchester. 240 pp., 179 illus. London : Longmans,
Green and Company. Price, 7s. 6d. net.

This volume deals with practically all branches of
surveying and geodesy, some in considerable detail,
others in less degree, but completely enough to be of
direct practical use. The most thoroughly-treated sec-
tions are naturally concerned with those methods of
survey most commonly in use. The various branches
considered are chain surveying, traversing, plane table,
instruments, calculations of distances and heights,
levelling and contouring, tacheometry, geodetic survey-
ing, geodetic astronomy, hydrographic surveying, under-
ground surveying, setting out and railway curves, and
earthwork calculations. The illustrations are clear and
numerous, including photographs of modern survey
instruments. Much matter not to be seen in many
elementary surveying treatises is presented, and many
familiar problems are handled in a fresh and interest-
ing manner. For special praise we would select the
attention given to the plane table, tacheometry, and
underground surveying, and the insistence upon the
common errors arising in all branches of surveying
practice. We consider, however, that the field book on
pp. 24 and 25 scarcely illustrate common practice, at
least in large-scale surveys, the offsets being too long,
and the lines too distant from the objects to be picked
up. The treatise is clear, concise, and comprehensive,
and is a welcome addition to the literature of surveying.
A useful bibliography, mathematical tables, and a model
index complete this interesting and useful volume.

Grimsby Coal Exports. — Returns for the week ending
February 11, show that the coal exported from Grimsby
was as follows :—Foreign : To Bagnoli, 3,270; Civita
Vecchia, 1,808; Dieppe, 494; and Esbjerg, 224 tons. Coast-
wise—to Gravesend, 200; -and Yarmouth (I.O.W.), 195 tons.
Total, 5,796 tons foreign, and 395 coastwise, against 11,875
tons foreign and 1,333 coastwise during the corresponding
week of last year.

Hull Coal Exports.—The official return of the exports of
coal from Hull to foreign countries for the week ending
Tuesday, February 8, 1916, is as follows :—Amsterdam,
246 tons; Dunkirk, 7,746; Gothenburg, 2,199; Harlingen,
715; Rotterdam, 1,074; total, 11,980. These figures do not
include bunker coal, shipments for the British Admiralty, or
the Allies Governments. Corresponding period, February
1915, total, 33,934 tons.