278

THE COLLIERY GUARDIAN.

February 5, 1915.

nition of their labours. In addition to the “ time gap,”
they had a 'further difficulty, that of personality, for in
some cases the true discoverer, and perhaps the highest
type, was little interested in the practical applications of
science. Yet.it was precisely the men who worked in
that spirit to whom the community owed the deepest
debt. It was true that occasionally they found the two
types combined in one individual; for example, in
Pasteur and also in Kelvin. Both sought first causes,
both applied them to the benefit of mankind; and it was
good to reflect that the name of a former occupant of
that chair, Dr. Galloway, might be added as a further
illustration. ;

Such cases were, however, rare. Either branch of
work could well demand any man’s whole energies, and
the secret of progress was to be found in the partnership
of both types.

It appears to me that there is yet a third type (or rather
a “ cross type ”), to the encouragement of which we have
not in this country devoted sufficient attention, namely, the
engineer who, before devoting all his energies to the tech-
nical side of his profession, has received a thoroughly sound
scientific education. It is such men who are likely to appre-
ciate the possible value of some apparently unimportant
discovery concealed—as far as the general public is con-
cerned—within the pages of a scientific journal, and who
can act as a connecting link between the two types to which
I have referred. I do not suppose it is possible, I do not
know that it is desirable, that a large proportion of our
engineers should undergo such a training; the professional
preparation is so arduous and lengthy, and the technicalities
are so numerous and varied, that few could afford the time
or the money involved by a full ante-professional scientific
education. I am sure, however—I know by the results of
personal observation—that those whose circumstances have
enabled them to build their technical education upon a sound
scientific foundation, have not only profited thereby them-
selves, but have been a cause of profit to others. There is
no branch of scientific knowledge to which the engineer can
afford to be indifferent.

Thus the success of the greatest engineering feat the
world had yet seen—the Panama Canal—was, in reality,
due to the biologist. Lamentable as was the present
condition of Europe, nevertheless, it was possible that
opportunities are now presented to the engineers of this
country which might never be repeated—or repeated only
in the manner of the Sibylline books. There was little
doubt that in certain branches of applied science the
Germans had forged ahead. This result was due to
many varied causes, but not the least of those causes
was their appreciation of the importance of pure science
and their encouragement of research. Germans had
been quicker than we to grasp and apply to industries
the researches of the scientific men of their own and
other countries. From what he knew of the German
technical educational system, it appeared evident that
the young engineer in that country had had a more
thorough grounding in pure science than had his com-
petitor in this kingdom; his knowledge stood on a
broader basis, although it might be less intensive. And
the same was true, though perhaps to a lesser extent, of
our American cousins. It was probable that the pre-
valence in this country of the premium system .of
apprenticeship—which he was glad to learn was noyp
dying out—was responsible for some of the difficulties
they had had to contend with. A further handicap had
been the non-adoption of the metric system of
measurements. One undoubted promoting cause of the
extraordinarily rapid advance in the application
of electricity to industry had been the universal
adoption in electrical matters of a rational system
of measurements. Here they had a case where
the engineer had, from the inception of the science,
relied upon the theorist and the mathematician. Nearly
all our English commercial measurements were relative,
and one of the great advantages of an absolute system
was the avoidance of artificial factors. Here, then, they
had an example of the advantage of adopting, even in
commercial transactions, a system of measurement
which was both scientific and international. It was
also an illustration of the benefit of partnership between
the two types: the “theorist” and the “practical
man.” There now existed in this country an institution
(the National Physical Laboratory), which was rendering
a great service by bringing into closer communion the
types to which he had referred.

The President gave some examples of the researches
completed or undertaken in the engineering and allied
departments of the laboratory during the past three
years, as he doubted if the engineers of that district had
hitherto been sufficiently acquainted with the oppor-
tunities offered to them by an institution which he
believed was rendering great services—and would render
yet greater services—to the industries of this country.
He added :—

It is possible that the need for such services may be even
greater in the future than it has been in .the past. Civilised
mankind is now living on its capital. The engineer is
devoting his attention almost exclusively to the partial con-
version into mechanical power of the energy inherent in
coal, and we are probably nearing the limit of efficiency in
its conversion. If the whole world were made of coal, and
we improved our methods of conversion to the maximum
efficiency, this process would remain, from a scientific point
of view, an extravagant one. Our hope for the future lies
in the discovery of some method of utilisation of the practi-
cally , inexhaustible stores of energy with which we are
surrounded.

In recent years we have learnt something of the
tremendous energy concealed within the atoms of
apparently inert matter. Think of the possibilities open
to mankind, if we could but learn the secret of its con-
version ! Again, not only are we wasteful in our genera-
tion of mechanical power, but also in the conversion of that
mechanical into other forms of energy. It is as if we
started business with a limited capital, and then paid £1
for each 6d. obtained. Take the case of the electric lighting
of Cardiff. We convert a small portion of the energy of
chemical separation presented jto us by coal into the
mechanical power of the engines employed. We then-
proceed to heat filaments and carbon gaps up to such a
high temperature that they radiate light, in addition to

heat waves; the energy radiated in the light form being but
a minute fraction of the total radiant energy. When we
learn how to charge and discharge bodies of the size of
molecules some 400 billions of times per second, we shall be
able to produce the light waves without the expenditure of
all the energy now expended in producing the—for this
purpose—unnecessary longer heat producing waves.

We have advanced some little way on the journey, for we
have succeeded in forming electric oscillations giving some 400
million vibrations per second. Could we learn from the
glowworm the trick of radiating the supplied energy in light
form only, it is probable that a small boy could supply
sufficient energy to illuminate the whole of Cardiff city.

In conclusion, he said their wise generosity in
establishing an engineering scholarship—he believed the
most valuable scholarship in Wales—was tangible
evidence of their conviction that a thorough scientific
education is the best preparation for the arduous career
of an engineer. He trusted that such encouragement
would in that district be even greater in the future than
it had been in the past, and he hoped to live to see the
day when there would be established a mining research
fellowship worthy of that great coalfield.

If this dream is realised, I urge that the conditions should
be such as to attract within our gates men of high talent,
fired with real enthusiasm for research. The energies of
such men should be unfettered by rules and regulations.
Above <all, when pursuing some investigation, they should
not be tormented with the question : “ What is the use of
it?’’ The seeds they sow may give little indication of the
nature of the plants which spring from them; the growth
may be slow, but when the harvest comes, I believe that it
will yield fruit a hundredfold, both to the employer and the
employed.

A vote of thanks to Principal Griffiths for his address
proposed by Mr. H. K. Jordan, F.G.S., was seconded
by Mr. Thomas Sugden, and cordially carried.

Arching in Collieries.

On the subject of Mr. R. G. Clark’s paper, discussed
at previous meetings,

Mr. B. 0. Thomas submitted a note on one of the
points raised respecting curved girders for supporting
the roof and sides of the roadways of a mine. He said
that owing to the slow progress made in opening the
main roads, and securing the same with brick arching,
it was decided to experiment with rolled steel girders.
The type of girder first used on main haulage roads gave
a height of 7 ft. 10 in. under the girder, and a width of
9 ft. at the widest point, which is 3 ft. 4 in. above the
floor. The cross section of this girder was as follows :
Depth of web, 4 in.; thickness of web, in.; width of
outside flange, 2Jin.; width of inside flange, 2 in.; and
weighed complete with fishplate 2341b. per ring. The
top half of the girder formed a semi-circle, while the
two legs were drawn inwards towards the roadway, thus
making the width at the bottom less than in the middle
of the ring. This form was very effective in resisting
both top and side weight. These girders were put up
on wooden sole pieces 6 in. thick, and were spaced
1 ft. 6 in. to 3 ft. apart, according to the nature of the
ground. The sides behind the rings were lagged up in
the usual way with timber and rubbish, but the top
half was close lagged with timber, and any space left
above was tightly packed to the roof with rubbish. The
spaces between the webs of the girders were filled in
with brickwork or concrete, this filling being carried up
as high as possible. The brickwork served to keep the
girders from buckling sideways, prevented them being
knocked out by runaway trams, and offered a minimum
area of surface for the accumulation of coal dust, and
also one which could be easily cleaned and watered.
At present five sizes of girders were being used at
collieries with which he was connected, varying in width
from 14 ft. (used for pass-bys or double partings) to

5	ft. 6 in. (used in small airways and walking ways), this
measurement being taken at the widest point. Some
5,000 yds. of roadway,- both intake and return, were
secured by means of these girders, and during the four
years they had been in use there had not been a single
case of failure. By failure he meant the sudden break-
ing down of the supports often causing heavy falls, such
as sometimes happened with timber, even when the
latter was new and apparently in good condition. (Mr.
B. O. Thomas submitted drawings and photographs).

Mr. R. G. Clark, the author of the paper, said the
drawings and photos furnished by Mr. Thomas were
most instructive. Although there were no cases of
sudden failure to report, it was apparent that renewals
and repairs had to be faced from time to time. One of
the sections shown was not, in his (Mr. Clark’s) opinion,
the most suitable to withstand a side squeeze. Turning
the figure at right angles, the side squeeze became a
vertical load, and as the toe was a free end, the joist
became <a cantilever 7 ft. 10 in. long, hinged at the
crown or fishplate. Under these circumstances, the
curving of the girder did not increase the strength, and
any load on this cantilever arm had to be taken up by
the fishplate. As shown in the photograph, it buckled
and took the line of least resistance, and if it were
immovable the tensional stress on the fishplate would be
tremendousHe (the speaker) thought this section
might be considerably strengthened by the introduction
of a tie or strut, joining up the bases, and thus making
a closed figure; or, if that be impossible, strengthen the
crown or hinge by longer and stiffer fishplates, well fitted
into the web of the girder. It would seem, however,
that a channel section, back to back, would be preferable
to R. S. joints of I section, as .a good long lap of, say,

6	ft. could be arranged, and this would immensely
strengthen the arm of the cantilever, and also the crown
or hinge. The total weight of 2341b. per ring need not
be increased. There was one undoubted point the
photographs brought to light, and that was the unsuit-

ability of stone or brickwork, as it was only too evident
that, owing to distortion, the tensional stresses set up
were very great, and had to be provided against.
Although there was brickwork filling for a part of the
height, this was no addition in strength to the arching
proper, as each ring of girder had to take its load without
the assistance of the others, and shown so well in the
photographs, where some arches had sprung from the
semi-circular to the Gothic style, and others near at
hand had crushed in at the crown.

Electric Bell Signalling in Collieries.

Discussion was resumed on the paper of Mr. Thomas
G. Watts, B.Sc., on “ Electric Bell Signalling for Use
in Collieries.”

Replying on the discussion, Mr. Watts said since the
last meeting of the institute he Had tried to see what
effect the admixture of coal dust had on the ignition of
explosive gaseous mixtures by spark discharges. The
method he adopted was to find the lower limit of the
gas in use, i.e., methane, and then, getting below this,
add coal dust, and determine whether the new mixture
would explode. Carrying out these experiments had
disclosed some points which he thought were worthy
of notice. The first experiments were carried out as
follow :—Two wires from the secondary of a large
Rhumkorf coil were brought to the centre of the
chamber. Their points were first of all placed at a dis-
tance of 2|in. apart. Starting with a 6 per cent,
mixture of methane and air, a spark was passed after
the fan had revolved for some five minutes. No explo-
sion occurred. Thinking this was strange, for the lower
limit of methane was in the region of 5’60 per cent., it
was repeated several times, but no explosion occurred.
The spark gap was then diminished to Jin., and imme-
diately on passing a spark a violent explosion occurred.
He mentioned this particular experiment as bearing on
the temperature of spark discharges; for, trying these
two discharges afterwards with a piece of paper, he
found that when the terminals were 2 J in. apart the
spark merely punctured the paper, whereas when |in.
apart they immediately inflamed the same piece of
paper. This was, of course, quite a crude way of
demonstrating the difference, but certainly quite
obvious. From the experience gained, he kept the
spark gap J in. for all the subsequent experiments with
this coil. The percentage of methane was reduced step
by step until it reached 5*50 per cent., when no explo-
sion occurred. The method of procedure was then
altered. Instead of running the fan for five minutes
prior to passing the spark, and then stopping it, it was
kept running while the spark was passed. An explosion
was brought about with 5*55 per cent, under these
circumstances. This was of particular importance, as
it signified the extremely rapid diffusion in methane air
mixtures. The percentage of methane was then reduced
to 5’25 per cent. No explosion occurred, but on stopping
the fan and keeping the spark travelling an effect was
noticed which Dr. Wheeler had described in his paper
on the “ Limits of Inflammability of Methane and Air
Mixtures,” namely, local ignition. Proceeding upwards
from the spark gap were long thin streamers of burning
gas, which intermittently broke off in puffs. Having
arrived at a point where no explosion occurred, coal dust
was placed, as before, on a tray inside the chamber,
and methane introduced to an amount of 5‘25 per cent.
The fan was started, and as soon as the chamber was
filled with a cloud of dust the spark was passed. An
explosion occurred which was quite mild, but sufficient
to burst the paper diaphragm. This was repeated time
after time, and on each occasion an explosion occurred.
They could, therefore, say that the presence of coal dust
did influence the spark ignition of methane air mixtures.
Similar experiments were then conducted with the bell.
The bell was placed inside the chamber and connected
by a push to 10 Leclanche cells outside the chamber.
The same methods were employed as before, that was to
say, the fan was kept running throughout, and by this
means the lower limit for methane air mixtures to be
ignited by means of the spark at the contact breaker at
the bell was found to be 6*25 per cent, methane. There
was no intermediate “ local ignition,” but merely a
condition that all amounts above 6*25 per cent, would
explode; all below would not. He had to admit that
this contradicted the figures he gave in his paper, which
were vitiated by diffusion errors. On the admission of
coal dust as before, the mixture was found to follow the
same rule as before, that was to say, the effect of coal
dust was to bring about an explosion in a mixture
which would not explode when the dust was absent.

Mr. Watts was thanked for his paper, which the
President stated was on an important subject.

Mechanical Stoking.

Mr. E. Kenyon read a paper on this subject (see
p. 275); and the discussion having been opened by Mr.
T. Sugden, its consideration was deferred; and the
proceedings closed.

Partnerships Dissolved.—The London Gaztte announces
the dissolution of the following partnerships :—A. Picard,
on behalf of Oppenheimer and Neveu, and M. Worms,
general merchants and engineers, at Great Marlborough-
street, W., under the style of the G. O. and N.
Trading Company; D. V. Thomas and T. L. Thomas, iron-
mongers, at Sheffield House, Pontardulais, Carmarthen,
under the style of Thomas and Thomas; R. McNeil, W. E.
Hinde, and W. R. McNeil, steamship managers and brokers
and coal exporters, at Boston-buildings, James-street,
Cardiff, under the style of McNeil, Hinde and Company;
R. H. New and A. G. Steeves, consulting engineers . and
motor specialists, at The Albany, Old Hall-street, Liver-
pool, under the style of R. H. New and Company ; T.
Denham, J. R. Denham, and T. H. Denham, coal mer-
chants, at London and North-Western Railway Company
Sidings, Duckworth-street End, Blackburn, under the style
of Thomas Denham and Sons.