1092

THE COLLIERY GUARDIAN.

June 9, 1916.

method was injudicious and unbusinesslike. The
height of the seam and the nature of the contiguous
strata should, within prescribed limits in all seams,
determine the cross sections of all roadways, and the
size of .the- roadway should determine the size of the
tram. The calculations with reference to the facility
with which trams of various weights and coefficients of
friction could be man-handled were very instructive, and
were a feature in determining the size of vehicles used
in the transportation of coal underground, to which
adequate consideration had not been given by operators.
In fact, the labour involved in man-handling trams was
the last factor taken into consideration in the States,
although it was perhaps one of the most vital features
in production. Man-handling in small seams could not
be eliminated, but, by the adoption of a system of
exploitation that would materially reduce the grades,
either in the handling of loads or empties—or, where
this was not feasible, the installation of mechanical
means as an auxiliary power—the unwarrantable expen-
diture of energy could be reduced. The writer did not
agree that wheels on a minimum-sized tram should be
of small diameter, since the friction would be propor-
tionately more. : In standardising cars, it seemed to him
that the adoption of a standard size and construction of
wheels would be one of the first things to demand con-
sideration. For small capacity trams, these might be
lighter than those for large capacity, and the bearings
might, be of simpler construction. Mr. Gibson had
clearly, demonstrated the pecuniary advantages derived
from the use of large trams. It seemed that the best
system of haulage for British collieries was endless rope,
as the writer was informed the conditions prohibited the
installation of electric haulage, although they might be
adapted to haulage by compressed air. Mr. Gibson’s
remarks on the subject of tracks were valuable, and
should receive such consideration as would secure their
adoption. The same conditions as to length.of rails and
construction of track within a specified distance from the
working faces were as prominent in the majority of mines
in the States as in Great Britain, and the loss of time
due to the one, and the number of wrecks and conse-
quent loss of time incident to the other, contributed
largely to reduce the output and increase the cost. In
the States, the rails used were generally of the “ T ”
type, those for rooms and lateral entries being lighter
in weight than those for main haulage. He had seen,
however, a rail that was more convenient for‘use in
rooms. It was known as a “ strap ” rail, and measured
about | in. thick by 2 in. wide, and 15 to 18 ft. long.
Such a rail was laid by driving it edgewise into a
notched tie, so that, when the rail was in position, the
thickness took the place of the ball of the 44 T ” type.
Such a rail could be used without the aid of spikes or
nails. It was adapted to a straight or crooked road,
presented a narrow friction surface, and was as enduring
as the less pliable and more cumbersome 44 T ” rail.
He had found, by comparing the length and width of
car boxings with the gauge of road and the length of
track (between centres of wheel axles) in well-balanced
cars, that they bore a definite relation to each other,
viz., that the length of the boxing was to the width,
(inside measurements in both) as the gauge of the track
was to the length of the wheel base (measured between
centres of axles). ~In standardising cars, the gauge of
the track, the wheel base and the diameters of the
wheels, were three factors that would require little, if
any, modification in making changes in the car capacity.
Mr. Gibson suggested 24 in. as the standard gauge, but
the writer was inclined to think that underground condi-
tions might conduce to a change in that standard. For
example, if the bottom or floor were soft, a narrow-
gauge track would exert more pressure over a given
area than one of a larger gauge with the same load, and
the repairs to the track would be correspondingly
greater. The size of track or wheel base would neces-
sarily have to be such as to- enable the cars easily to
round curves and switches of the size required for the
system of mining employed and the physical conditions
of the seam. A wheel base constructed upon the rule
given, in which the gauge was 1*75 times the distance
between the wheel centres, would, he thought, meet the
conditions, as cars of two tons capacity constructed upon
this plan would round curves and switches of a small
radius. As to wheels, they should not be less than 12 in.
in diameter, and of uniform shape. The gauge and
wheel base having been standardised, the boxing or body
of the car could be constructed to suit these dimensions
or such modifications in form could be made at a com-
paratively small expense, as compared with modifica-
tions in the factors given, if the boxings were constructed
of wood, as would best suit existing conditions. With
the assumed minimum diameter of wheels, the minimum
gauge should not be less than 30 in.

Mr. Gibson’s Reply.

Mr.' Gibson wrote, in reply to the discussion, that his
main purpose was to show the great efficiency and
economy that would follow the adoption of standardised
trams, or even the gauge. Several gentlemen had ques-
tioned the statement that 44 in thin seams a predeter-
mined minimum height and width of gate road is set
up by the size of the tram,” but since a man has no
great difficulty in travelling in a road having a minimum
height of 3 ft. above the rails and a width of 3 ft.
between the narrowest timbers, it followed that, if the
train in use could not pass through any part of a gate
road of such dimensions, the gate road must be increased
in height. Therefore, the tram . predetermined the
minimum height and the width of the gate roads. He
would illustrate his remarks with a 22 in. seam, in
which'2|ft. of ripping, 6 ft. wide, was taken down, so
that the gate road then measured 4 ft. 4 in. high by 6 ft.
wide. Even with a good pavement, the height 30 yds.
back from the face would not be more than 3^-ft. If a
4 in. bar were used, the height would then be 3 ft. 2 in.,
and 'the sleeper and rails would again reduce it to

2 fo. 10 in. above the rails. If the bar sagged 3 in., the
total available height would then be 2 ft. 7 in. Even if
a tram of minimum size were used in such a road, the
drawer would be in danger of losing fingers, of smashing
out the bars, or at least of jamming his full tram between
the rails and the roof. All these conditions were
familiar to those working very thin seams. The same
process went on in connection with the sides; the packs,
were pushed out and toppled over. The cost of repairs
was high, and stowage was usually scarce. Therefore,,,
a road 3 ft. wide between the narrowest timbers sufficed
if the tram could pass, and that width was economical.
If the tram were large, it was evident that gate roads
of greater height and width must be maintained and
repaired, or cross gates must be more frequent. That
extra cost must be charged against the tram. Another
statement that had received adverse criticism was that
in which ho asserted that 14 wheels of small diameter and
simple bearing are suitable for small trams.” Mr.
Lupton and Mr. Parfitt seemed to be of opinion that
friction must be kept down to the lowest practicable
limits in trams of all sizes. Let them take, as an
example, three trams, weighing 3, 4, and 6 cwt. respec-
tively. Assuming that, by the provision of roller or
other bearings, the friction was reduced to T4o> and
that each bearing added 14 lb. to the weight, then the
weights would be 34, 44, and 64 cwt. respectively. The
limits of inclination would be as follow:—

1. Trams with Simple Bearings.

Weight. Friction.

Limit (f inclina-

1 ion (approx.).

1 in 6

I in
lin 14

2. Trams with Roller Bearings.

Weight.	th . r •	Limit of incl ma-

Cwt.	Friction.	tion (approx.).

3^	. ... Ho ... . -	1 in 7

4i ........ Ho ............ 1 in 9

6^	.... Ho ......... 1 in 13’6

The following deductions from those figures were
quite clear :—(1) With a 3 cwt. tram, it was wrong to
use roller bearings or anything in its construction, how-
ever useful, which added 56 lb. to the weight. (2) With
4 cwt. trams, an inclination of 1 in 8| was the dividing
line; steeper roads suited the lighter weight. Less steep
roads gave the advantage to the tram with the lower
friction. (3) With trams weighing 6 cwt., the dividing
line was at 1 in 13|; therefore, in almost every case, the
roller bearing had the advantage. Even easy gradients
demanded some form of self-acting incline, and, of
course, the low coefficient of friction made these practi-
cable, whereas with ordinary bearings they would not
be so. He did not agree with Mr. Jas. Ashworth that
detailed plans of the proposed standard trams should
have been included in the paper. If the writer suc-
ceeded in proving to the satisfaction of the members
the great benefits to be derived from standardisation, he
would be quite content to leave the matter of construc-
tion to settle itself. He was not pledged to or prejudiced
in favour of any form. He agreed with Mr. Bulman
that nine different sizes were not required. In pro-
posing that number, he hoped to gain wider approbation
for the general proposition. After standardisation was
adopted, the sizes least in demand would gradually fall
into disuetude. He quite agreed with Mr. Ashworth
that 44 the Secretary of State could occupy his time more
usefully than in considering the question of the stan-
dardisation of the gauges of rails.” Mr. Ashworth’s
sentence, however, was based on a misunderstanding of
English constitutional practice, which worked in this
way :—Supposing that the reform in question were in
force, and that a coal owner wished to deviate from the
standard gauge for some particular reasons, he would
then apply to the Secretary of State for exemption,
which would be decided by the latter’s expert advisers.
The Secretary of State, however, was .responsible
to Parliament for the decision of his advisers.
Thus, if A could show that he was refused exemption,
whereas B, under the same conditions, obtained, it,■ a
bad state of affairs would exist, but the responsibility to
Parliament of the Secretary of State made such a thing
practically impossible. Air. Kilpatrick had questioned
the accuracy of the statement that a healthy man could,
for a period of 2| minutes, perform work at the rate of
0-24 horse-power. The writer had hoped to take tests
of men and boys on a typical tram road, and present the
results to the members, but lack of time had prevented
him.. In any case, the statement was made in the
course of an argument to prove that, in small trams, it
was more important to keep down weight than to keep
down friction. Supposing it were found that the output
of a man was 0-12 horse-power instead of 0-24, it
strengthened, not weakened, his argument. Indeed, he
had chosen the maximum figure for the purpose of
proving his contention beyond question. Mr. Myles
Brown’s contribution to the discussion was notable in
that he sketched out a mode of procedure for testing the
standardisation proposals, and for bringing them to
fruition. Mr. Gibson finally appealed to the institute
not- to throw aside lightly, without close scrutiny, the
proposal for the standardisation of trams, but to put
forth ah its talents, influence, and prestige to the task of
carrying out the reform, if it should be considered practi-
cable and beneficial.

Coal Dust Explosions.

Air. James Ashworth (Vancouver, British Columbia)
wrote continuing the discussion on Air. A. S. Blatch-
ford’s paper on “ The Influence of Incombustible Sub-
stances on Coal Dust Explosions.” (See Colliery
Guardian, Apr. 14, pp. 704, 705, and 717.) It had been
stated, as a result of experiments, that, when certain
incombustible substances were present in the air, they
would arrest the flame of an explosion .when the mixture
of air and methane was in its most dangerous condition..
If such an experimental conclusion were correct, the

’arrestment must, in his opinion, take place at or'very
close to the point of origin of the explosion. If an
incombustible substance was,to-be effectual in controlling,
the progression of an explosion in a coal mine,-it must
necessarily be intimately mixed with the air before the
flame reached any particular point. In order to postu-
late such a condition in a mine, the theory as to the
presence of a pioneering cloud of dust in advance of an
explosion flame must be accepted. Many asserted that
a pioneering cloud was always a factor, but the writer
took the opposite view, viz., that, after the initiatory
stage, a pioneering cloud in .front of the flame was an
impossibility, excepting only when the speed of the
sound wave was greater than the speed of the flame.
Even then the term 44 pioneering ” was not correct, as
the flame was passing through the cloud continuously
and was not actually driving the dust in front of it. If
the cloud of dust were driven forward by the flame the
latter would be smothered through excess of dust and
want of oxygen. All experiments on the quenching of
a coal dust flame by incombustible dust had been made
with mechanical mixtures of the two dusts, and not with
the dusts as they were found in collieries, where the
different dusts were in layers, with the finest and most
dangerous dusts already floating in the air. Air under
pressure was a totally different flame-carrier from air at
normal air pressure, and there again was a missing
factor in experiments made in galleries on the surface.
With reference to the 'liberation of carbon dioxide from
a quench, it was to- be remembered that the gas under
those conditions was hot, and not, therefore, as effective
as when cold. Consequently,'steam gave better results
when liberated from the quench than did carbon
dioxide. As to the controversies which were continually
arising in connection with coal dust and flame-quenching
he would like to see some notice taken of Air.
W. A. Douglas Budge’s experiments and conclusions on .
the thermo-electrical possibilities of an explosion and its
initiation.

The Late Mr. Geo. May.

Mr. Charles L. Dobson contributed a 44 Memoir of
the late George May.”

On the motion of Dr. Louis, a vote of thanks was
accorded to Air. Dobson, and the meeting ended.

THE AMERICAN COAL TRADE.

The bituminous market continues relatively quiet but
with a well-defined air of expectancy. The situation is
rather mixed, and it is clear that a good many industrial
concerns still have substantial supplies in reserve. The
prompt market is generally dull, but there is a large,
movement on contracts.* Some shippers who were
thought to be permanently out of the market are once
more canvassing actively for business, states the Coal
Age. The scarcity of miners is already making it diffi-
cult to fill orders promptly in some instances, while .
labour difficulties and misunderstandings with the
unions are also seriously interrupting the production at
other points.

Baltimore reports an increased inquiry in the bitu-
minous trade. Prices are a little stiffer for immediate
delivery. Contract rates remain about constant. Prices
to the trade at the mines were about as follows : Georges
Creek Tyson, 1’75 dots.; Miller vein, 1*55 dols.; Quema-
honing, 1*60 dols.; Somerset, 1*50 dols.; Freeport,
1’20 dols.; Fairmont gas, three-quarter, 1*05 dols.; ditto
•run-mine, Idol.; slack, 95c.

Shipments from Hampton Roads have been heavy.
Foreign steamers have arrived in large numbers for both
cargoes and bunkers, and in consequence with a good
coastwise movement the dumpings over all piers have
shown up well. Cargoes for export went to Buenos
Aires, Genoa, Alarseilles, Rio, La Plata, Barbados, St.
Georges, Taltal, Santo Domingo, Bagnoli, Pernambuco,
Para, Alamaos Ponce, and Havana. Shipments of coke
have been small, although one or two parcels were
shipped out.

Inquiries are constantly in the market for large
parcels, from 100,000 tons to one or two millions, but so
far as can be learned no extra large contracts have been
closed on export business.

The meagre demand for anthracite for storage, now
that definite prices are out, has been a distinct
disappointment to the trade; the tendency to hold off is
undoubtedly due in part to anticipation of some relief as
a result of Governmental investigation.

Imports of Pit Props.—During May 1.72,292 loads of pit
props were imported into the United Kingdom, the value
being £562,617. The imports in Alay last year were 252,798
loads, value .£421,712; and in Alay of the preceding year
212,800 loads, value £260,856. The total imports during the
first five months of the year were 867,689 loads, valued at
£2,613,408, as compared with 904,076 loads, valued at
£1,489,381, in the corresponding period last year.

Briquette Industry in the United States.—H.M. Consul-
General at Chicago reports that the production of briquettes
from coal dust in the United States in 1915 amounted to
.221,537 tons (of 2,0001b.), valued at £212,800. The manu-
facture of this kind of fuel in the United States is, however,
still in its infancy, and, according to the United States
Geological Survey, a good many years will probably elapse
before the briquette industry assumes very large proportions.
There were 15 briquetting plants in operation in the United
States in 1915.

Hull Coal Imports.—The Hull Corporation’s coal inspector
(Mr. W. H. Truman) reports that the quantity of coal
arriving at the port during May was 302,692 tons—283,897
tons by rail and 18,795 tons by river—as against 434,134
tons in the corresponding period of last year. Coal shipped
coastwise from the port amounted to 31,952 tons during May,
and 127,809 tons during the first five months of the year.
The exports—exclusive of coal for Admiralty purposes, and
for the use of the Allies—were 78,922 tons during May, com-
pared with 291,152 tons in the corresponding month last
year.