April 27, 1917.

THE COLLIERY GUARDIAN.

811

The construction and operation of this machine is not
complicated. The fly-balls A in the accompanying
illustration are driven by a sprocket B, which in turn is
driven by direct chain from the drum of the engine.
The stem of the governor, which carries two separate
springs, terminates at its lower end in a disc carrying
the pin C. As the speed of the engine increases and
the balls fly out, the stem descends, and at a predeter-
mined maximum allowable speed the pin C clears the
lever D by a small amount. The fly-balls are now
opposing only one of the springs. If the speed is increased
exceeding the predetermined amount, the fly-balls
compress both springs, and the pin C strikes and throws
the lever D. This immediately applies steam to the
brakes through the three way valve E.

Motion from the sprocket wheel B is transmitted
through. the intermediate shaft and gears F and the
long pinion G to the worm II. which drives the worm-
wheel I. Near the rim of this wheel, ata point adjust-
able to suit the conditions, is placed a double or
graduated incline J. The arrangement is such that,
when the landing is approached, this incline lifts the
lever D into close proximity to the pin C, and unless
the speed is properly reduced and the pin 0 allowed to
rise with the disc and governor stem, the lever D will
be thrown and the engine brought to a standstill.

When the wind is completed and the cage stands in
the dumping position, the steep portion of the incline J
is touching the lever D, and any further movement of
the cage in an upward direction will apply the brakes.
Overwinding, overspeeding and moving the cage in the
wrong direction are thus impossible.

The machine is equipped with a dial provided with
double pointers—one connected with and controlled
from the tight drum and one from the loose drum. The
relative position of the pointers then indicates the level
being served. As the cage leaves the dumping point the
red semaphore at the top of the dial swings down, while
when the other cage approaches the dump, a semaphore
on the other side appears. This gives a visual indication
to the engineer of which cage is to be lowered. ThG
dial thus indicates at all times the exact position of
each cage and which landing it is serving.

When the signal to hoist men is given, the engineer
gives a return signal by throwing a lever. This not
only gives the bottom eager a visual signal (usually an
electric light), but by revolving the crank disc K moves
endwise the worm shaft carrying the worm H and
pinion G, thus revolving the worm wheel I until the
incline J takes a position corresponding to the ground
landing. It now becomes impossible for the cage to
approach the ground landing at too great a speed or to
pass it. A second worm, on the same shaft with the
worm H, operates the worm wheel L, which through a
sprocket chain actuates the pointers on the dial.

LAW INTELLIGENCE.

HIGH COURT OF JUSTICE.

KING’S BENCH DIVISION.—April 19.

Before the Lord Chief Justice, Mr. Justice Ridley, and
Mr. Justice Rowlatt.

Action Concerning Patents.

King v. Board of Trade. — Counsel for the Board of
Trade appeared to show cause against a rule nisi prohibit-
ing the Board from proceeding with two applications by
Messrs. Simon-Carves Limited, Manchester, to avoid or
suspend two Koppers patents covering processes and appar-
atus for the recovery of by-products from gases arising
out of the carbonisation of coal and coke. The Solicitor-
General said the grounds upon which the rule was obtained
were that it was not shown that the person or persons
entitled to the benefit of the patents was a subject or sub-
jects of a State at war with his Majesty, and that upon
the evidence it appeared that the benefit of the patents
was not vested in such person or persons. The two letters
patent were granted to Heinrich Koppers, who was a
German subject resident in Germany, Charles Rudolph
Altenhein, a German interned in England, and Albert
Victor Derry, whose name was formerly Koch, a British
subject, but believed to be of German birth. The mere
statement with no evidence placed before the Comptroller
of Patents Committee, that Derry was a British subject
and a beneficial owner, could not preclude the Committee
from avoiding or suspending the patents.

Mr. Henry Terrell, K.C., said an application was made
to the Board of Trade in 1914 at the instance of Mr. Derry
for the appointment of a controller of the business. The
partnership agreement was then exhibited, and was filed
by the Board of Trade. In order to prove the partner-
ship, he (counsel) was prepared when the proper time came
to adduce complete evidence.

The Lord Chief Justice said Derry’s claim rested upon
a partnership agreement, which he had refused to produce
before the Committee appointed by the Board of Trade to
enquire into such patents. The Comptroller came to the
conclusion there was no evidence before him of beneficial
ownership by Derry, and he was bound to proceed with
the hearing of the applications by Messrs. Simon-Carves
Limited. His lordship had no doubt the Comptroller was
right. The mere assertion in a declaration or affidavit
that a person was interested in a partnership agreement
did not establish the fact. The refusal or omission to
produce the deed of partnership when challenged added
force to the contention that the declaration was not suffi-
cient. The fact that there was said to be evidence in
pigeon holes at the Board of Trade which would have
given the Committee full knowledge and information, was
no answer at ah. The applicants before the Committee
were entitled to know the position. On all points Mr.
Terrell failed, and the rule must be discharged.

Mr. Justice Ridley and Mr. Justice Rowlatt concurred.

Coals for Norwegian Railways.— The Norwegian State
Railway contract has now been apportioned, and the total
quantity is said to be 18,500 tons. The wdiole delivery is
to be confined to April and May; 10,000 tons are booked
at an average of 30s. per ton f.o.b., and the remaining
8,500 tons at 28s, 6d. and 29s. 6d. f.o.b., principally Durham
steam coal.	.

CURRENT SCIENCE

Inflammability of Carbonaceous Dusts.

Mr. H. H. Brown (Journal of Industrial and Engi-
neering Chemistry, vol. 9, p. 269) says that experience
has shown that many other carbonaceous dusts are at
least as easily ignited and capable of propagating an
explosion as coal dust. While most of the dust explo-
sions reported in surface plants occur in mills and
elevators handling wheat, oats, and corn and their pro-
ducts, it appears that no mill handling carbonaceous
material is immune from the possibility of explosion.
The list of known explosions in other kinds of mills
includes those handling dextrine, sugar, starch, malt,
wood, linseed meal, cottonseed meal, paper, cork, ferti-
liser, sulphur, cocoa, and spice dusts.

That flour dust will explode was clearly demon-
strated in 1878 by a tremendous explosion in the Wash-
burn flour mills in Minneapolis. This disaster aroused
milling men to the danger' of existing conditions, and
caused many to take immediate precautions against a
repetition of a similar occurrence. The impression
was not lasting, and, although a large number of grain
dust explosions occurred later, general interest was
not awakened until June 24, 1913, when an explosion
occurred in a feed grinding plant at Buffalo, in which
33 men lost their lives and over 70 men were injured.
This explosion, which occurred during the ordinary
process of milling, completely destroyed the mill, and
considerably damaged the surrounding property. As
a result, an agitation was started between the millers
and the United States Bureau of Mines for the investi-
gation of questions relating to explosions of grain
dust. This was later taken up by the United States
Government, and is being continued in co-operation
between the Bureau of Chemistry and the Bureau of
Mines.

Air as ars Electric Insulator.

Dr. J. B. Whitehead, Professor of Electrical Engi-
neering, Johns Hopkins University, Baltimore, has
contributed a paper to the Journal of the Franklin
Institute on “ The Electric Strength of Air and
Methods of Measuring High Voltage.” He shows that
the properties of air which make it so valuable as an
insulator are its low specific inductive capacity, its very
high resistance, and its high electric strength or resis-
tance to puncture. Its specific inductive capacity is
practically as low as that of any other material, and
differs very little from that corresponding to the ether.
Its ohmic resistance for many years was assumed to
be infinite, although we now know from the rate of leak
of a charged conductor that it really has an extremely
small specific conductivity. Although the electric
strength, or resistance to rupture, of the air was for
many years sufficient for all the requirements of elec-
trical engineers, a limit has recently been reached.
As voltages for long distance transmission of power
have been raised to higher and higher values, it has
been found that the air in the neighbourhood of the
wires breaks down. The phenomenon is visible in the
dark as a glow around the wire, and is known as the
” corona.” The glow or brush discharge is confined
to the region close to the wire, where the electric
intensity is higher than at more distant points. The
phenomenon is accompanied by energy loss, and this
reduces the efficiency of a transmission line.

The value of an electric field at which a breakdown
of air occurs, and the type of discharge, that is,
whether spark or corona, depends largely on the shape
and size of the electric terminals. Sparks will pass
between parallel plates at a field intensity of about
32kv./cm. Between needle points, spheres, and other
forms of terminal, the relation of breakdown voltage
to separation is not regular, and different values of
average breakdown intensity are met.

For these reasons, simple and symmetrical forms of
electrode must be chosen for the experimental study of
the electric strength of air.

The theory of gaseous conduction, as developed by
Thomson and Townsend on the substructure of the
kinetic theory of gases, conceives the current in a gas
to be carried by ions or charged particles of gas.
These particles are the negative electron, positively
and negatively charged single molecules, or aggregates
of molecules' with charges of varying magnitude. A
breakdown or spark-over is due to the progressive
generation in the gas of new ions formed from neutral
molecules by impact of other ions moving with suffi-
ciently high velocity in the electric field. This con-
ception, first due to Thomson, has been elaborately
developed by Townsend under the name “Ionisation
by Collision.”

The sequence of phenomena in the formation of
corona would appear to be somewhat as follow:—There
are always present in the air a number of free elec-
trons (about 1,000 to every cu. cm., or one to each
3-5 x 101G molecules). Under an electric field, these
electrons move and collide with the molecules of the
air. If the field is strong enough, the velocity at
impact may be sufficient to ionise the neutral mole-
cules, and thus form a new electron and a positive ion
of about the size of a molecule. If the field is still
stronger, the slower positive ions will also begin to
form new ions by collision. When this stage is reached
the opposite streams of positive and negative ions
generate progressively an increasing number of new
ions until the whole gas is saturated or ionised. This
is the phenomenon which is accompanied by the blue
glow of an electric discharge, as, for example, the
corona. Obviously, it starts first at the surface of the
corona wire where the electric intensity is greatest.
The ions that move outward come to regions of lower
intensity, and thus lower velocity, and here ions are
no longer generated. These moving ions, however,
constitute an electric current to the opposite side of

AND TECHNOLOGY. '

the circuit, and it is this current, or leakage, that
causes the energy loss in long distance transmission
lines when the voltage is raised above that correspond-
ing to the formation of corona. These ions are pro-
bably single molecules, or groups of two or three mole-
cules, and they move with a velocity of about 1*3 cm.
per second per volt per cm.

The American Institute of Electrical Engineers now
authorises in its standardisation rules two standards for
the determination of high voltage. They are the spark
gap between needle points and the spark gap between
metal spheres 6’25, 12-5, 25 and 50 cm. in diameter.
In each case the voltage is determined by the greatest
distance of separation at which a spark will pass.
Neither of the above instruments has given satisfac-
tion, nor inspired confidence in usage. The sphere gap
is more constant under repeated readings than the
needle gap, although it still shows noticeable varia-
tions. The author proceeds to describe the corona
volt meter, which can be used for 50,000 and 100,000
volts, and even higher voltages.

THE AMERICAN COAL TRADE.

A further easing of the prices of bituminous has
occurred, due to a tendency on the part of the buyers
to go slower, an improvement in transportation faci-
lities, and a growing feeling that the bottom of the
decline has not yet been reached. Pending a readjust-
ment of conditions to meet the new situation in foreign
relations, it is to be expected that the market will be
very mixed and unsettled. The commandeering of a
very large proportion of the coastwise shipping faci-
lities, and a possible heavy call upon the coal men for
military service, are two important issues the industry
may now be called upon to face at any moment (says
the Coal Age of April 7).

Spot prices at Hampton Roads are about on the same
level as a week ago. The demand is less urgent for
prompt coal, and fewer shippers are themselves in the
market to get steamers cleared. The immediate
future of Hampton Roads prices is hard to forecast;
so much depends upon the attitude of the Government,
and the supply of boats for coastwise movement. Only
a fair grade of Pennsylvania steam is quoted at 10-50
dols. f.o.b. vessel Boston, and Pocahontas and New
River at 11 to 11-25 dols. A small tonnage at these
prices has been shipped to the eastward, to relieve
distress at one or two points. The Georges Creek
shippers are still negligible factors in the coastwise
market, so far as new business is concerned.

Prices in Philadelphia have eased to the extent of 25
to 50 per cent. The prices per gross ton f.o.b. cars at
mines are as follow:—Georges Creek Big Vein, 5*25
to 5-50 dols. ; South Fork Miller Vein, 5-25 to 5*50
dols.; Clearfield (ordinary), 5 to 5-25 dols. ; Somerset
(ordinary), 5 to 5-25 dols.; West Virginia, Freeport,
4-75 to 5 dols. ; Fairmont gas, lump, 4-75 to 5 dols.;
Fairmont gas, mine-run, 4-50 to 4-75 dols.; Fairmont
gas, slack, 4-25 to 4-50 dols.; Fairmont lump, ordinary,
4-50 to 4-75 dols. ; Fairmont mine-run, 4-25 to 4-50
dols. ; Fairmont slack, 4-25 to 4-50 dols.

High prices, heavy demand, and many uncertainties
are the dominant notes of the anthracite trade. The
announcement by the largest company that their
circular price for pea coal during April would be 2-30
dols. per ton completely upset the market. One of the
other large companies has come out with a pea coal
price of 3 dols., with a reduction of 50c. for April,
which would indicate that the winter price would be
3-50 dols. The prices per gross ton f.o.b. cars at mines
for line shipment are as follow:—Broken, 4*50 dols. ;
egg, 3-65 dols.; stove, 3-90 dols.; nut, 4 dols. ; pea,
2-80 dols. ; buck, 2-50 dols.; rice, 2 dols.; boiler, 1-80
dols. ; barley, 1-50 dols.

Steamers to take coal to French and Italian Mediter-
ranean ports are almost unobtainable, but there are
boats in the market desiring coal for Spain at reason-
able figures. Coal freights are about 60 to 66 dols.
West Coast of Italy or Marseilles, and 22-80 to 27*60
dols. Spanish ports (including Spanish dues on cargo).

Coke production has increased, and spot prices are
lower. Connsellsville quotes spot furnace 8 to 8-50
dols., and spot foundry 10 to 10-50 dols.

Russian Shale for Fuel.—The representative of the fuel
section "of the Military Industrial Committee, Imperial
Councillor N. Ph. Von Ditmar, has announced, says the
Novoie Vremya, that according to geological investigations,
very extensive deposits of combustible shale exist in the
country. The calorific value of this shale is such that 300
poods of the shale are equal to 1 cubic sazhen (12| cu. yds.)
of wood, or 100 poods of Donetz coal. A grant has been
made for investigating this combustible shale, and pre-
liminary experiments have shown that it is good enough to
justify working the deposits.

Coal by Canal.—Two motor-barges of a new type arrived
on Wednesday evening at a Regent’s Canal wharf in
Pancras-road, London, having brought 50 tons of coal
entirely by inland waterways from the Cannock Chase
Colliery, near Birmingham. The trip was an experimental
one, occupying about 60 hours. The new device is the
invention of Messrs. Coggins and Arthur, coal factors and
colliery agents, Birmingham, in conjunction with Mr. A. E.
Hooke. The motor employed is a four-cylinder 17 horse-
power marine engine, capable of hauling two boats with a
load of 100 tons. It is mounted on the top of the cabin,
and controlled from the helm. Petrol is employed for
starting, and paraffin when running. The engine and
attachments can be transhipped from one barge to another
in a few minutes, and it is claimed that its use means
economy in time and money by comparison with haulage
by horse. The two barges were accompanied by an engi-
neer representing the Government Department in control
of the canals,