878

THE COLLIERY GUARDIAN

October 23, 1914.

Let us keep a level head in this business, and not
destroy foreign sympathy and injure British
commerce J»y idle and baseless recriminations.

One of the most important and

Fatigue Limit often the least intelligible of the
and the problems confronting the colliery

Strength Of manager is the cause of the failure
Materials. of appliances under stresses well
within the accepted limits of safety
factors. To this question the attention of engineers
and metallurgists has for many years been directed,
and a great advance seemed to have been made
when Woehler, some 40 years ago, made his famous
investigations upon the subject of fatigue under
repeated stresses. Since that date many series of
fatigue tests have been made, but unfortunately the
results have proved too discordant to be of much
practical value. The reasons for this are mainly to
be found in the prolonged duration of the tests and
the non-uniformity of the samples. The tests, in
fact, failed to satisfy practical requirements, and it
has not been hitherto possible to form any definite
conclusion as to the number of repeated stresses
any piece of machinery would be capable of
withstanding.

The subject has lately been taken up by Mr. C. E.
Stromeyer, who read a paper upon his results before
the Boy al Society in May last, and has now given a
resume of his investigations in the form of a
memorandum by the chief engineer to the Manchester
Steam Users’ Association. Mr. Stromeyer has
adopted a method which promises well for the
ultimate purpose of placing fatigue tests upon the
same practical footing as tensile, torsion, bending
and impact tests. We do not say that this much
desired result has yet actually been achieved beyond
all criticism, but a new and most important line of
investigation has undoubtedly been opened, and so
far as the experiments have gone there seems to be
ground for confidence in the value of the principle
which Mr. Stromeyer seeks to establish.

Let us examine this principle. We will use the
author’s own argument as closely as possible, pre-
mising, in the first place, that it is based upon an
assumption that may or may not be true—viz., that
there is a certain point at which a perfectly elastic
body begins to develop internal molecular friction.
This point is called the fatigue limit. It is not the
same thing as our old friend elastic limit. The
elastic limit is that point at which departure from
perfect elasticity becomes crudely obvious by
permanent deformation* in the testing machine. In
reality the change takes place at a much earlier
stage—now called the fatigue limit—which is unable
to be detected by ordinary methods. But it is held
that this limit is of practical importance, because if
straining be repeated often enough at or beyond this
point, the cumulative effect will cause rupture, even
although the elastic limit may never have been
reached.

Now, how does Mr. Stromeyer propose to deter-
mine the fatigue limit ? It is here that the ingenuity
of the method becomes apparent. He assumes that
while there is perfect elasticity there will be no
internal friction, and consequently no heat effect.
Thus a steel tuning fork will vibrate in vacuo for
a long time and will not become heated, but a cast
iron, tuning fork, being plastic, would soon come to
rest, and would presumably become warmer by the
transformation of energy into heat through the
medium of internal friction. He then assumes
that any piece of steel subjected to increasing
fatiguing stresses will show a heat effect
as soon as the limit of perfect elasticity is
exceeded. Now in the first place we must admit
that there may be no such thing as perfect elasticity
in any material with which we are acquainted, and
perhaps, least of all, in the case of steel which is an
agglomeration of crystals of different kinds. We
are told by the metallographists that one of the
early effects of strain in metals is to develop slip
planes in the constituent crystals. Is the point at
which these glide planes begin to develop the point
also of a measurable heat effect? It may be so,
and in any case Mr. Stromeyer seems satisfactorily
to have established the fact that at a certain point

there is a heat effect which is so sharply marked
that it can be detected by a calorimeter.

We thus arrive at a comparatively easy method
of determining the fatigue limit from a single test
piece, and with no more expenditure of time and
patience than is required for any other standard
laboratory test. We consequently possess a practical
method of determining the limit of stress which
would produce rupture if continued for a certain
number of times, and we can thence deduce the
number of repetitions necessary to cause breakdown.
Thus, as the author explains, if we wish to compare
a certain chrome nickel steel with a manganese
steel, we find by the calorimeter that the respective
fatigue limits are 12-6 and 11T tons per square inch
respectively ; that is to say, the test prices at these
stresses betray heating effects. By substituting
these values in the empirical formula

N = 106 C4 4- (Sn - Fl)4,
where C is an ascertained constant for the material
in question, Sn is the operating stress and Fl is the
fatigue limit, the number N of repetitions the
material will stand is found. In the above case we
conclude that while the chrome nickel steel would be
better than the manganese steel for a crank shaft,
it would be inferior for clutches or other appliances
subject to violent shock.

The results achieved by Mr. Stromeyer appear to
be almost too good to be true. The point requiring
further proof is the validity of the principle upon
which the author bases the conclusion that when a
heat effect of about 0*01 deg. Cent, becomes
manifest the fatigue limit has been reached, viz.,
internal friction has begun to be developed. We
shall look eagerly for the development of this
principle, which apparently permits a valuable
indication to be obtained of the quality of metals
and their liability to fail under alternating or
repeated stresses. The whole point lies in the truth
or otherwise of the assumption that there is a
definite point when elastic deformation begins to
develop molecular movement before the condition of
a permanent set has been reached.

Coal for the Needy.—The Government Committee on the
Prevention and Belief of Distress has sent to local repre-
sentative committees acting for the City of London and areas
wholly or partly within the Metropolitan Police district a
circular dealing with the offer made on behalf of Sir Arthur
Markham, M.P., and certain coal merchants, for the supply
of coal to necessitous persons. Under the terms of this offer
the merchants making it undertake to deliver coal of a cer-
tain quality, in quantities of not less than 1 cwt. at a time,
at the dwelling houses of any person living within the City
of London or Metropolitan Police district, who hands in at
the office of any of the coal merchants named, who deliver in
the district in which such person resides, a ticket issued by
the local representative committee. The coal will be avail-
able in two classes of case :—(1) Where the committee has
found it necessary to grant relief in a particular case, they
will be able to make a gift of coal in addition to other forms
of relief by issuing a ticket entitling the recipient to get
the coal free of charge. In such cases the committee will
pay the merchant out of their relief funds in exchange for
the tickets collected and returned to them; (2) where the com-
mittee have cases before them in which no claim can be
established to relief from their funds, the circumstances
may be such as to justify them in giving the assistance
which would be afforded by the issue of a ticket entitling
the recipient to a quantity of coal mentioned thereon at the
rate of Is. 2d. per cwt. in the County of London, north of
the Thames, and in West Ham, and Is. 2|d. in the County
of London south of the Thames. Outside that area, but
within the Metropolitan Police district, north of the Thames,
the rate will be Is. 2jd. per cwt., and south of the Thames
Is. 3d. per cwt. Mr. Herbert Samuel suggests that gift
coal tickets should be coloured blue, and reduced price tickets
red. The tickets issued by any committee in one
week should not exceed a number representing 50
tons in all, but should it be desired in special
circumstances to exceed this amount, the assent of the
Government Committee must be obtained. The following
is a list of the merchants and traders associated with the
scheme :—T. W. Bennett and Company, Beadle Brothers
Limited, J. H. Beattie and Company Limited, E. Beckett
and Company, Brown and Clapson, Brentnall and Cleland,
Geo. J. Cockerell and Company, Clay Cross Company
Limited, Corrall and Company, F. Creek and Company,
Edwin A. Cornwall, Herbert Clarke Limited, F. B.
Cameron and Company Limited, Darfield Main Coal Com-
pany, Dowell and Company Limited, J. L. Davies and Com-
pany, J. Elliott and Company, A. T. Everitt and Company,
Earley and Pearsall Limited, Charles Franklin, P. H.
Garner, Gerald and Company Limited, J. and H. Girling,
Gower and Smyth Limited, G. Hickling and Company, Hall
and Company (Croydon) Limited, Thos. Leben and Sons,
William Laver, Lee and Jerdein Limited, Mitchell Main
Coal Company, Thos. Moy Limited, Moger and Company
Limited, J. H. Mitchell and Son, John Neal, Nathaniel
Pegg and Company, Bickett, Smith and Company, Bowland
and Company, Stores Coal Company, Stanley Wallsend Coal
Company, Spiers, Wallace and Company Limited, Stratton,
Gentry and Company Limited, Mark Tooley, Chas. Tucker
and Company, John J. Tims, B. Tozer and Sons, B. M. Tite
and Sons, C. W. Tanner and Sons, Albert Usher and Com-
pany, Spenser, Whatley Limited, Whitwell Coal Company,
J. Whittaker and Company, J. B. Wood and Company
Limited, F. Warren and Company, John Waddell and
Sons.

TRADE AND THE WAR.

The Aniline Dye Industry : Proposed Manufacture in York-
shire—Alleged Breaches of Neutrality in the Philip-
pines—Payment of Debts to Enemies—Insurance of
Cargoes in Neutral Bottoms—Damage to Collieries in
the Pas-de-Calais—The Performance of Contracts—
Competition in the Electrical Industry—Imperial Insti-
tute to Assist Manufacturers — Indian Loco. Contract
Recovered.

The council of the London Chamber of Commerce have
decided to support the Halifax Chamber of Commerce in
their representations to the Government, urging them to
give encouragement to the manufacture of aniline dyes in
the United Kingdom. It is even reported to be the
intention to establish a Government factory. It is under-
stood that in what they propose to do the Board of Trade
will act in consultation with the few British manufacturers
who undertake this class of business, and already suggestions
are being made which may possibly modify the scheme.
The Yorkshire Post is informed that one firm, having
several acres of land available, is prepared to carry out
extensions on a large scale if the Government will finance
the operations as shareholders. On the other hand, it is
stated that there are several works in this country, some of
them of no inconsiderable size, that have for many years
manufactured dyestuffs in every way equal to any produced
on the Continent, and at the present time are working day
and night to cope with the increased demand due to the
stoppage of foreign supplies. • A wide range of colours is
produced by these firms, and it is easy to double or treble
the production at extremely little extra expenditure on
plant. There are, no doubt, several important colours,
such as the vat dyes (synthetic indigo and its derivatives,
indanthrene, &c.) for which in the past we have had to
depend entirely on the Continent. We understand that
applications have now been made for licences to manufac-
ture about fifty patented dyestuffs.

The Institution of Gas Engineers has recommended the
Government to start research w’ork by setting up installa-
tions in the country for making dyes from coal tar. Probably
one of the first places where experiments would be made
would be at the Crowlands Works, at Southport. Altogether,
in Germany something like 1,500 classes of dyes are made,
whereas in England only 100 different dyes were manufac-
tured, and those are chiefly made by one firm, at Hudders-
field.

Sir Cecil Spring Bice, the British Ambassador at
Washington, having called the attention of the State
Department to the alleged violations of neutrality near the
Philippines, where a German ship is believed to have coaled
at sea, an investigation has been immediately ordered.

Much difficulty has been experienced by the business
community in deciding whether payments to the enemy
should or should not be paid in certain cases. Messrs. John
I. Thornycroft and Co. cite a case which has occurred to
them. This firm owe money to the Sheffield branch of the
Poldi Steel Works, an Austrian firm. The Poldi Works
applied for payment, and backed up its demand by a letter
which its solicitor had received from the Foreign Office.
The letter from the Foreign Office was in reply to the
following questions put by the Poldi Steel Works:—(1)
Whether it is illegal in any way for British subjects to
discharge in Sheffield debts already incurred or to be
incurred in favour of the Poldi Steel Works (Sheffield
branch). (2) Whether there are any steps, such as an
application for a licence to trade, which would render the
position of the Poldi Steel Works and those discharging
debts to them more secure. The signatory of the letter
from the Foreign Office in reply to these queries says :—
“ I am directed by Secretary Sir E. Grey to inform you that
it would not be contrary to the Proclamation against
trading with the enemy to trade with a branch of an enemy
company locally situated in British territory. Payments
for transactions with the Poldi Works at Sheffield could
also be made, if desired, and no licence would in this case
appear necessary.” We understand that this position is to
be tested in the courts.

It has been brought to the notice of the Board of Trade
that British insurance companies have insured or reinsured
goods shipped on neutral vessels against the risk of capture
or detention by his Majesty's Government or allied Govern-
ments. The Board of Trade are advised that such
contracts of insurance or reinsurance against the risk of
capture or detention by Great Britain or her Allies are
prohibited by the law of England, and they think it
necessary to warn British insurance companies and under-
writers against undertaking such business.

It is now anticipated that the Turks will have to reopen
the Dardanelles owing to the necessity of replenishing the
stock of steam coal for the navy. It will be remembered
that Turkey took abnormal supplies of coal in August, but
that in September no exports were sent to that country.

A correspondent of the Daily Telegraph reports that the
Germans have created havoc and destruction in the coal
mines in the north of France. Fighting has taken place
round the coal pits, and the enemy previous to their retreat
are trying to leave nothing but waste and ruin behind
them. He further states that the entrances to three of the
biggest mines in the Courrieres district have been destroyed
and all the machinery blown up.

The authorities at San Francisco on Thursday, the 15th
inst., stopped the American freight steamer “ Sacramento,”
formerly the Kosmos liner “ Alexandria,” whilst passing
out of the Golden Gate, because they were not satisfied
regarding the destination of her cargo of coal. Valparaiso
was the destination given in the manifest. The genuine-
ness of the transfer of the vessel from German to American
registry was also questioned.

The Newcastle Daily Journal states that in connection
with the problem of sale and purchase contracts between
coal merchants one local firm has taken legal opinion on
its own account. The circumstances relating to the firm’s
contracts, which are no doubt typical of most of the others,
were submitted to a competent authority, and legal opinion
thereon has now been given. The verdict was that such
contracts must be carried out. Admitting the necessity
for the display of a mutual spirit of equity, and the
importance of avoiding law as far as possible, the legal
position, nevertheless, is that these contracts must be
fulfilled month by month in the absence of any war clause
in the contract note relieving the contractors of their
liabilities. The inference is, of course, that where the