1080

THE COLLIERY GUARDIAN

November 26, 1915.

of by placing a couple of packets of punchings in the
centre of the vent with the teeth cut back somewhat,
the thickness of the packet being proportioned to the
increased air gap of this part of the core, so that each
packet will carry a correct amount of flux. The condi-
tions at the end of each half of the core can similarly
be'taken care of by cutting back the teeth in steps, so
that the air gap is graded here to allow for the fringing
effect from the rotor.

External Short Circuits.

One of the great difficulties anticipated from the start
In the case of these large machines was the effect of a
feeder short circuit, or its equivalent. The chief
requirement is more space between the windings, and
this is obtained by the use of the laminated magnetic
slot wedge described below. The results of short-circuit
tests on a 20,000 k.v.a. machine with this construction
showed the maximum possible short-circuit current found
at full voltage (assuming the short circuit to occur under
the worst conditions of phase) to be only about 14 times
the maximum of the full-load current wave.

Stator Coil Bracing.

As regards protecting the part of the winding external
to the core, the means adopted in this case are believed
to be more substantial than ever before used. The
supporting conditions obtaining throughout the length
of the core by reason of .the teeth and slots are again
reproduced in the end windings by means of bronze
herring-bone castings placed between the two layers of
the end connection winding, the casting having fins pro-
jecting between the coils on each side of it, thus locking
the two layers together, and entirely providing for any
tendency of the one layer of winding to shear relatively
to the other. In every one of the 16 metal supporting
brackets practically slot conditions are reproduced.

Rotor Surface Losses.

It has seldom been the case in the past in turbo-
generator work that much attention was necessary to the
question of rotor-face losses occasioned by the open
stator slots. In the present case, however, with an air
gap of only about 1 in. radially, and with the very high
air-gap inductions involved, great caution was needed.
A slot, smaller than is desirable from an electrical point
of view, is used, and tests have shown it to be approxi-
mately correct, for while some little rotor losses, which
would have been serious had the slots been larger, were
incurred, it was not necessary to use the semi-magnetic
wedges that had been prepared as a precautionary
measure for these slots. For the 13,200-volt machines,
a built-up magnetic slot wedge has been devised, con-
sisting of a group of punchings assembled between little
flanged brass end-plates in sections of about 3 in. in
length. These wedges (1| in. thick in a radial direc-
tion) have a very light magnetic material bridging the
slot, and a large clear vent space through the centre.
The wedge is placed in the slot, and a small fibre wedge
of rectangular section driven between it and the coil.
This device has enabled the use, with a 1 in. air gap,
of a stator slot 1’62 in. wide, and a stator coil which can
be constructed of desirable mechanical and electrical
proportions.

The problem of devising a stator conductor of the
size required, and with the eddy-current losses kept
down to a sufficiently small value, is not entirely easy.
With the protection afforded against external flux by
means of the magnetic wedge, there is no great objection
to using a strip about -J-in. wide across the slot, and
the conductor can be built up of a number of such
strips in parallel. It is usually sufficient to have the
strips insulated from one another, and arranged so that
at the end of the coil the conductor is turned over in
such a way that the strand, which in the one slot is
nearest to the air gap, takes a position nearest to the
bottom of the slot when it occurs in the other half of
the coil; but in the case of the present machine, where
the total depth of the strands of each conductor amounts
to 1-25 in., this disposition is not sufficient to bring down
the loss to a reasonable figure. It is necessary to use a
slightly more complicated connection at the end of the
coil, the coils being connected together strand by strand,
or in groups of strands, in such a way that there is a
more thorough transposition of the location of the
strands in the slot. This gives the same result as a
much smaller conductor with a several-circuit winding,
except that there is but an insignificant voltage between
the several parallel conductors, avoiding the loss of space
■that would be entailed by a multiple-circuit winding.
In view of the considerable length of the machine and
the somewhat severer conditions obtaining at the centre
than near the ends, and also the smaller facility than
usual for end-wise conduction of heat along the copper,
it was considered desirable to use a stator insulation as
nearly fireproof as possible. For this purpose mica
wrappers were applied by machine to the coil, giving
an exceedingly solid insulation, having some 70 or 80
per cent, of solid mica.

Considerations such as the above, however, show that
the difficulties are largely connected with the size of
the conductor used, and that increasing the copper
section to relieve the temperature conditions tends to
introduce fresh troubles. For instance, were it possible
to use, say, a fused silica tube for stator insulation, we
could immediately cut down the size of the slot copper,
at the same time overcoming much of our eddy-current
trouble; and we should have no reason to be alarmed
even should the central part of the active length of the
conductor occasionally reach very high temperatures.
The part exterior to the slot could be of twice the section
or more, and the loss entailed by reason of the higher
ohmic resistance of the stator winding would be entirely
insignificant. Some of the characteristics of fused
silica, and the recent rapid commercial development of
this material, are promising as far as they go, but many
obstacles to its use for this purpose remain.

Feudal Exactions from Minerals in Scotland.

PECULIARITIES OF SCOTTISH LAW.

By JOHN BURNS, W.S.

“ Manorial incidents ” in England and “ feudal
casualties ” in Scotland are very much the same thing;
and it is interesting to find that, in both countries, steps
are at present being taken to get rid of them, com-
pulsorily, once and for all. A commencement has
already been made in Scotland under an Act passed in
1914; and the same thing is in progress for England
under a Bill recently introduced in the House of Lords
by Lord Haldane. Amid much similarity, there are, of
course, great diversities between the two countries. In
Scotland these exactions are far more widely spread
than they are in England—in fact, they may be said to
cover the whole land. Another difference is, that they
hit minerals much more in the north than south of the
Tweed; and it is with that aspect only of the subject
that we are here concerned.

Two further points require to be made plain with
reference to mineral tenure in Scotland. In the
first place, it is more common than in England for one
man to own the surface, while another man or a com-
pany owns the coal and other minerals underneath. In
that case the mineral owner may have a question with
the surface owner as to liability. The other point is
that these exactions differ very greatly in their nature
in different cases. Sometimes the fine or casualty is a
definite fixed sum, which is a case on which this article
has little bearing. Sometimes, however, the fine is a
year’s rent, less rates and taxes; and it is these cases
which raise trouble.

In order to clear the ground, it is useful to consider
thb subject with reference to liability for payment of
casualties or fines from minerals, apart altogether from
the idea of redemption or extinguishment. It is not
difficult to understand that these claims for mineral
casualties are a comparatively modern growth, for the
commercial development of minerals in Scotland is itself
not a matter of ancient history. When the “ lord ” (in
Scotland he is known as the “ superior ”) began to put
forward a claim to a year’s rent, not only of the farms
and houses, but also of the minerals, it is not surprising
that difficulty was felt on the judicial bench. The objec-
tion was raised that mineral returns are not rent or
income, but really instalments of the price for a sale of
part of the corpus of the estate itself. This, however,
was rejected, and the principle of the claim was allowed.
Then arose the further question of the quantum. It is,
of course, to be understood that we are speaking only of
minerals which are being worked, for (with one excep-
tion) not even the keenest solicitor of the most exacting
superior has ever ventured to maintain that, in settling
the amount of a casualty, he was entitled to include
anything for unworked minerals, no matter how certain
might be their existence, or how near the prospect of
their being opened up. It is true that one such attempt
was made at quite a recent date, but it was curtly dis-
missed, for there is not, and never was, any doubt as to
the law on the point, and the case referred to proves
only that lawyers can be got to argue anything.

Confining attention, therefore, to minerals which were
yielding returns in the year in which the amount of
the fine was to be fixed, the question came to be :
whether the superior was entitled to demand the
actual royalties or the fixed rent if more, or only
a certain percentage, say, 4 per cent., on the capital
value of the minerals. Obviously, this was a big
question, and the course of decisions in Scotland was
not uniform. In one case, in 1876, the indications were
in favour of restricting the claim to a percentage on
capital value. Three years later, in a case where the
mineral owners were themselves working, this view
prevailed, and the mode of arriving at the capital value
was to find the average annual return for the preceding
three years, and take 10 years’ purchase of that average.
That case, however, was immediately followed by one
in which the minerals were let, the fixed rent being
£600, the workings trifling, and no suggestion of early
exhaustion; the whole £600 was found due as the fine
or casualty. The controversy came to a head in 1900-
1902, in a dispute between Lord Belhaven and Lord
Home. The Scottish Court, by a very narrow majority,
cut down the claim to 4 per cent, on capital value; but
this was reversed in the House of Lords, and the whole
year’s mineral return was awarded to the superior as
fine. This is now the law as to all fines due and to
become due.

Turning now to the chapter of extinguishment, this
began by an Act of 1874, which allowed all proprietors
to redeem, on terms which were considered somewhat
severe. It has, however, always been recognised as a
proper step to carry through the extinguishment before
beginning to work or let minerals, for then, there being
no mineral return, the compensation money was exactly
the same as if no minerals had existed. If this had
been done universally, the questions now under con-
sideration would have had no existence, but, as the
situation now stands, many mineral fields are still
exposed to these exactions.

The next stage is the Act of 1914. Briefly, the posi-
tion it creates is this : Either the lord or the “ vassal ”
may force extinguishment. The terms of compensation
are considerably reduced from the 1874 scale. Until
notice for redemption is served by one or other of the
parties, fines continue to fall due, by deaths, etc., as
before, but only for 15 years, after which the lord’s
claims are lost for ever, if by that time he has not got
his compensation money. Further, the Act deliberately
creates the anomaly that mineral fines which are due,
or may be allowed to become due, within the 15 years,
shall be fixed by the actual mineral returns for the year,
in accordance with the judgment of the House of Lords,

whereas quite a different standard is to be applied in
fixing the compensation for the extinguishment of
mineral fines. This latter standard is that, for extin-
guishment purposes, the actual mineral return shall be
ignored, and a fictitious mineral income shall be set up,
namely, 4 per cent, on capital mineral value. A curious
feature is that no basis for fixing capital value is pre-
scribed. The words of the Act are : “ Four per cent,
on the capital value of minerals which are being or have
been worked.”

How is capital value to be ascertained? This is the
first, and by far the most important, practical question.
It will be noticed that the Scottish Court, in one of the
above-mentioned cases, took 10 years’ purchase of the
average yearly return, and it is understood that this is
roughly in accord with the views of mining engineers.
However, in Lord Home’s case, in 1900, the court pro-
posed to arrive at the capital value in quite a different
manner, viz., by ascertaining the “ life ” and annual
yield, and discounting that at 4 per cent. This, it is
understood, is totally out of unison with expert opinion.
The points of difference are radical, viz. :—(1) The
expert would take at least 10 per cent.; and (2) he
would take that rate on the whole sum for the whole
period, capital being assumed to be replaced by a sink-
ing fund at about 3 per cent. On a life of 25 years the
capital value, by the method of the Scottish Courts in
Lord Home’s case, is a good deal more than double
what a mining engineer 'would probably report.

The next question is : When are minerals “ being
worked,” and what additional minerals are brought in
by the somewhat cryptic words ‘ ‘ or have been worked ’ ’ ?
If all the seams are included in a current lease, but the
shafts are sunk to the upper seams only, are the lower
seams “ being worked ”? We have been informed that
an affirmative answer would in some cases make the
compensation money larger than if it had been based on
the full return for the year.

The mineral owner has the option to pay the com-
pensation in a lump sum, or to convert it into a per-
petual charge equal to 4 per cent, on the lump sum.
When the minerals are all he owns, this means that a
time must come when the lord is left with a perpetual
annual sum, but no security for it, the minerals having
been worked out. Needless to say, this was never
intended, but it results from the mineral cases being
included in general clauses, which are quite appropriate
to non-wasting properties, but not to such assets as coal
in process of being worked out.

The whole subject is one of much importance, large
interests being involved. Enough has, meantime, been
said to draw attention to its leading features. Those
concerned would do well to keep the following points in
mind :—(1) Extinguish casualties (fines) before breaking
a new field. (2j In all opened mines see that your
solicitor watches that no casualty is allowed to become
due. It can easily be prevented. (3) If the field is
nearly exhausted, it may be thought better to take that
risk if the other side does not move. But this should
only be after a 'thorough examination of the considera-
tions pro and con. (4) Watch the method of ascertain-
ment of capital value. (5) If minerals only arc in
question, never pay lump compensation, but always
create the alternative annual payment. (6) If acting
as referee to fix capital value under the Act, or as
adviser to either of the parties in a compensation case,
the divergence between the methods of arriving at
capital value should be carefully kept in view. Opinions
will differ whether, as to the financial basis, this is, or
is not, a question for a mining engineer.

Minerals and Form IY.—In a paper on “ Case Law Under
the Finance Act, 1909-10,” read before the Surveyors’ Insti-
tution on Monday, Mr. E. M. Konst am, barrister-at-law,
said the provisions with regard to minerals were some of the
most difficult in that Act. It was not easy to say what were
” minerals,” for there was no definition to serve as a guide.
The Scottish Land Valuation Appeal Court had held that
“ minerals ” meant all substances in the earth, apart from
the surface soil, that could be worked, except those specially
exempted; and did not exclude ‘ ‘ those ordinary substances
composing the crust of the earth which are of the nature of
the common rock of the district ” (Anstruther v. Inland
Revenue). Probably the most important case yet decided
with regard to minerals was Foran v. Attorney-General,
which dealt with the effect of section 23 (2). The sub-
section provides that minerals axe to be treated in the general
valuation as having no value, unless the proprietor, in making
his return to the Commissioners, stated the nature of the
minerals, and put a value upon them. The Inland Revenue
contended they had given the proprietor his opportunity in
the questions relating to minerals at the end of Form IV.;
and that where question (W) was not answered, the value
of the minerals must be taken at nil, with the consequence
that when an “ occasion ” should arise for the payment of
increment value duty on minerals otherwise than as an annual
duty, that is, on sale or passing oh death of minerals not
worked or leased, the duty would be payable on the whole
value of the minerals. The Court refused the Crown’s con-
tention, and held that Form IV. was not the return referred
to in section 23 (2). because it “ was not a proper or intelli-
gible mode of requiring a return of particulars respecting the
minerals, and certainly did not treat them, as the Com-
missioners were bound to do. as a separate parcel of land.”
Tn Mr. Konstam’s opinion, the Commissioners have been
unfortunate in their drafting of Form IV. in regard to theit
questions regard’ng minerals.