January 2, 1914.

THE COLLIERY GUARDIAN.

37

respiration could not be kept up even for five minutes
when left to the automatic activity of the apparatus. The
result was evidently better when the respiratory alterna-
tions of the machine were guided by hand, so as to have 16
to 20 respiratory cycles per minute. But even under these
circumstances the circulation could rarely be kept up
in a normal state for longer than 12 or 15 minutes. When
the thorax was opened the lungs were seen becoming
gradually smaller and smaller. After the pulmotor had
been used for awhile the lungs often presented an uneven
appearance, small collapsed areas alternating with much
dilated areas. After connecting with the ordinary
laboratory respiratory apparatus this unevenness soon
disappeared.

The sub-committee add :—

These observations on animals indicate that there are
two factors which interfere with the efficiency of the
pulmotor as a reliable device for artificial respiration.
The first is its automatic activity and the ease with
which inspiration is turned into expiration. Inflation
and deflation of a bag—the method used by agents to
demonstrate the action of the pulmotor—is deceptive,
because the bag, unlike the air passages of the body,
offers no resistance until full. As soon as the inspiratory
blast meets an obstacle in the air passages it is auto-
matically cut off and turned into expiration, and thus
frequently no efficient inspirations are performed. In
lower animals, certainly, the blast often meets obstacles
while passing from the pharynx into the alveoli, and the
inspiratory pressure of the automatically working
pulmotor is in many cases insufficient to overcome them.
When guided by hand the inspiratory pressure is
permitted to increase; hence the greater efficiency
under these circumstances.

The second harmful factor brought out by these
experiments is the performance of expiration by suction.
In normal respiration expiration is accomplished by a
power which does not suck, but drives the air out by
the elasticity of the distended or compressed tissues,
aided, sometimes, by muscular contraction. The finer
bronchioles have no cartilages ; when air is sucked out
from the trachea and larger bronchi, the bronchioles
are liable to close before the suction reaches the alveoli.
Furthermore, when the air is actively sucked out the
walls of many of the bronchioles and alveoli are liable
to collapse and stick together, so that the next inspira-
tory pressure, which is barely sufficient to overcome the
elasticity of the lung, is not strong enough to overcome
the resistance offered by the adherent surfaces. . . .

Finally, observation shows that the entrance of air
into and escape of air from the stomach may cause
movements of the thorax which simulate respiration
while actually no air enters or leaves the bronchial tree.

Upon the basis of these observations the conclusion
was reached that the automatic mechanism of the pul-
motor, while being an ingenious technical contrivance,
instead of assuring artificial respiration, may interfere
greatly with its efficiency, because it is liable to cut off
inspiration prematurely. The management of the
changes in the phases of respiration when the pulmotor
is worked by hand is more reliable. But when handled
in this maner no practical difference exists between the
pulmotor and the Dr. Brat apparatus, at least so far as
the mechanism is concerned. In both machines, how-
ever, the expiration is accomplished by suction, which
is again a serious defect. The sucking action of these
devices might prove even dangerous if they were used
continuously to keep up respiration for a long time. In
connection with the experiments on animals, which in
most instances could be continued a relatively short
time only, it is pertinent to recall the fact that the
successes reported by the physicians connected with the
Carnegie Steel Corporation were obtained in cases in
which the pulmotor was used for a short period only.

That both machines are heavy, expensive, and waste a
great deal of oxygen, with which they are not sufficiently
provided, are minor points in their disfavour. The
absence of careful analysis of the action of the pulmotor
in clinical cases, the ease with which it may fail to cause
inflation of the lungs, the bad effects which occur if its
sucking action in expiration is permitted to continue for
a long period, are all important considerations which
should be taken into account in judging the instrument.
When they are taken into account the high credit given
the machine in popular opinion seems not to have a
substantial foundation.

In view of the facts obtained by a study of the Dr.
Brat apparatus and the pulmotor, the members of the
sub-committee agreed 'upon the following suggestions :
In cases without any respiration the pulmotor should be
used only when guided by hand, and then not faster
than 12 to 15 complete respirations per minute; when
left to run automatically it is liable to be inefficient and
dangerously deceptive. Because of suction on the lungs
neither the pulmotor nor the Dr. Brat apparatus should
be used longer than for a few minutes (five to six) at a
time, and if there be no better contrivance, should be
alternated with the Schafer method combined with
oxygen inhalation. In cases of slow and stertorous
breathing, however, both machines can probably be used
for a longer time with benefit and without danger.

A New Appliance.

The report concludes with a brief account of the
mechanical method of pharyngeal insufflation recently
invented by Dr. Meltzer (head of the Department of
Physiology and Pharmacology in the Rockefeller
Institute for Medical Research).

Two methods may be used to convey the air to the
respiratory passages—the pharyngeal and the mask
methods. In the pharyngeal method insufflation takes
place through a metal pharyngeal tube which has been
made to fit the human anatomy. When the tube is in-
serted the end of the upper side should touch the posterior
wall of the pharynx, while the lower side terminates at
about the root of the tongue. The entrance to the naso-
pharynx is thus closed, while air enters freely into the
lower pharynx. The size of the tube almost completely
prevents the escape of air through the mouth. The
outer end of the tube carries a neck for connection with
the respiratory apparatus, and has a hole through which
a well-fitting tube can be introduced into the stomach.
When not used this hole is kept closed by a movable
plate. The neck of the pharyngeal tube is connected by
means of a short piece of strong rubber tubing with the
proximal end of the “ respiratory valve.” This little
device is a metal cylinder containing a valve which is
readily moved by a ring outside. When the ring is
moved to the right, air or oxygen passes through the
cylinder in the direction of the pharynx, thus causing
an inspiration. When the ring is moved to the left, the
cylinder is closed for the inspiratory air or oxygen, and
instead an opening is made above the valve through
which the expiratory air can readily escape. The cylinder
can be conveniently held in the hand and the ring
moved to right and left by the thumb. The distal
end of the respiratory valve is connected either with foot
bellows, which give practically a continuous air current,
or with an oxygen tank. A safety valve is interpolated
between the source of pressure and the respiratory
valve; some heavy weight and astrong belt to compress
the abdomen complete the outfit.

When a suitable pharyngeal tube is not at hand, arti-
ficial respiration may be executed with the aid of a well-
fitting face mask provided with a tube for connection
with the respiratory valve. All other parts needed for
artificial rsspiration are the same as with the pharyngeal
tube, except that no stomach tube can be introduced.
Both methods have been tried on numerous animals and
have been demonstrated keeping animals alive for many
hours while under the exacting conditions of curare and
ether and of opened thorax. The Commission recom-
mends this apparatus as a satisfactory means of
continuing artificial respiration and suggests that in
cases of suspended breathing the modified prone pressure
method be supplemented as soon as possible by the use
of the Meltzer apparatus.

TESTING OF SAFETY LAMPS.

Part II. of the General Report on Mines and Quarries
for 1912 contains a brief summary by Capts. Desborough
and Thomas of the work done up to the time of writing
since the conclusion of the preliminary experiments
carried out by the safety lamp committee in connection
with the construction of the programme of official tests.

One hundred and five different patterns of lamps have
been examined and tested, of which 81 have been
approved by the Secretary of State under Statutory
Rules and Orders No. 886. Nine have since passed the
tests, but have not yet been officially approved, and 15
(altogether) have failed. Of the above, the total number
of flame safety lamps that have passed is 78, while 10
have failed, and the total number of electric lamps that
have passed is 12, and the number that have failed is
five. With regard to flame safety lamp glasses 11
different makes of glass have passed, and have appeared
in Statutory Rules and Orders No. 886, while four
makes have passed and have not yet been officially
approved. The approval of a make of glass has
generally necessitated the testing of three or more
separate sizes in order to cover the whole range for
which the glass manufacturer or agent desired approval.
Many tests of glasses were at the beginning unsuccessful,
but the quality of the glass has now been so much
improved that failures, whether in the mechanical or
temperature tests, have lately been unusual.

A few doubtful samples of lamps have been forwarded
for examination and test by H.M. inspectors of mines.
It.is anticipated that work of this nature will greatly
increase in future in order to ensure that safety lamps
and flame safety lamp glasses are kept up to the
standards required by the official specifications. In
testing a type of safety lamp, which in most cases
covered a number of modifications, the principle has
been to submit that modification to the tests under
which it would be most likely to fail. Thus in the
case of a type comprising different lengths of glass,
areas of inlet holes, and strength of construction, lamps
with the longest glasses and largest inlet holes have
been submitted to the explosive atmosphere tests, and
the weakest lamps to the mechanical tests. If, for
example, the weakest made lamp passed the mechanical

tests, the remainder of the type would be considered as
having passed also, but if the weakest lamp failed the
next in order of weakness would be tested.

With regard to the failures, it may be interesting to
mention generally the chief causes. Before submission
for the official tests, most makers appear to have
satisfied themselves that their lamps were construc-
tionally sound enough to withstand the mechanical
tests. In some cases, however, flame safety lamps gave
way under Test 3 (where the lamp is suspended from
the upper portion, and a 10 lb. weight, attached by a
cable to the lower part of the lamp, is dropped from a
height of 7 ft.), the chief causes being either inferior
metal in the pillars or rings, weak riveting, or insufficient
area of screw thread. With officials’ lamps experience
so far has been that aluminium pillars will always give
way under this test; brass pillars, however, riveted or
screwed to aluminium rings, can be made sufficiently
strong to stand the test.

Under Test 1, where the lamp is dropped five times
from a height of 6 ft. on to a wooden platform, glasses
have occasionally broken, but no lamp has failed to pass.
Unbonneted lamps, whether of the Mueseler or double-
gauze types, which have been submitted to the test of an
explosive current (of about 1,200 ft. per minute), have
passed flame and failed. Unbonneted lamps, unless for
some special purpose, are now not accepted for testing. In
certain cases lamps have not been allowed on account of
what is considered defective construction under para, (ii)
Appendix I. of the Memorandum for Testing. Under
this head, Messrs. Desborough and Thomas have not
considered it advisable to recommend the approval of
lamps with unprotected openings in the bonnet, situated
in such a position that the gauze would be exposed to
injury or to a direct explosive current. Lamps in which
the gauzes reach to above the bottom of the outlet holes
are, they consider, objectionable for the same reasons;
moreover, with such a lamp, the top of the gauzes may
be so close to the crown as to be liable to injury in the
event of a weight falling on to the lamp.

They also have not recommended approval of lamps
which contained devices upon which their safety
depended, and which would, they considered, have been
liable to get out of order under reasonable working
conditions, such, for instance, as those which depended
for their efficiency upon thorough lubrication and
freedom from dust and grit.

The failures of electric lamps have all been due to
lack of candle-power at the beginning, or, more generally,
at the end of a nine-hour run. In certain cases, small
constructional alterations have had to be made to lamps
originally submitted, in order to meet requirements.
In some instances new batteries were submitted for the
tests which had not developed their full capacity, while
in others inferior or uneven bulbs were put forward, so
that the first tests have on several occasions ended in
failure.

The desirability of themselves submitting their lamps
to the photometric test (after a full nine-hours’ run)
before sending them to the testing station is now always
impressed upon manufacturers.

Owing to the proximity of the Home Office Experi-
mental Station, the services of Dr. R. V. Wheeler, and
his assistants, have been obtained on occasions for
carrying out laboratory experiments in connection with
miners’ safety lamps. The'results of these experiments
are given in the following report by Dr. Wheeler. Little
time has been available for experimental work at the
lamp testing station owing to that required for the
official tests. The following, however, among other
work has been done. A series of trials were made with
a view to compare the strengths of flame safety lamp
glasses to resist blows analogous to those of a pick point.
For this purpose a pendulum was arranged, the bob of
which consisted of a pointed iron rod. The angles
through which the pendulum was required to swing in
order to break through the different glasses were
recorded. In these trials, moulded glasses (whether hot
or cold), proved themselves to be stronger than the
blown glasses tested. Experiments were made, at the
suggestion of a firm of manufacturers, to ascertain
whether, in an explosive current of about 1,200 ft. per
minute, the shield of a double-gauze lamp would give
sufficient protection when the gauzes were slightly
damaged. One strand of wire in each gauze was severed
and the ends of the wire bent away to expose the
adjacent meshes. The lamp passed [flame in each case
in a few seconds. Owing to the violence of the explosions
in the testing gallery, it was found that severe damage
was being done to the building. In August, therefore,
it was considered advisable to remove the gallery, fan
and carburettor, and place them outside in such a
position that observation can be conducted from inside
the building. This work has now been completed and
testing resumed.