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From these enquiries it seems that the London school child takes little notice of variations of
temperature between 56 deg. F. and 64 deg. F., and apparently does its best work about 58 deg. F., but
in this regard there are considerable individual differences. There seems to be no advantage whether
the air at these temperatures is dry or saturated, or whether at rest or in gentle movement. A fall below
55 deg. gives rise to comment, and a rise above 65 deg. to unpleasant subjective symptoms in some
persons. It is to be remembered that temperatures of 65 deg. to 70 deg. are almost habitual in America,
and in continental lands where closed stoves are used, so that habit may establish tolerance. With high
temperatures 65 deg. F. or more, whatever other factors may be present, high or low proportions of
carbonic acid gas, moisture or not, movement of air or rest, the high temperature alone has an evil influence
in determining deterioration in mental work in the children.
On two occasions boys attributed headaches to the noise of the fan, but restlessness, inattention,
and listless attitudes were noticeable. Above 70 deg. three or four children in the class got headaches,
and others flushed faces, and this whether the carbon dioxide was in high or low quantity, or the air
fresh, or unpleasantly stuffy from human exhalations. The only occasions with high temperature
where no mental deterioration was determined was when, with high C02 and unpleasantly stuffy condition,
the air was kept pleasantly moving by the fan, on occasions with 77 deg. dry and 74 deg. wet bulb
readings, no subjective signs or mental deterioration was noticed when the fan in the room was thus
kept working.
It was found impossible under school conditions to obtain a high temperature, 70 deg. or more,
with considerable humidity, that is over 60 per cent. Possibly this may be attained in suitable weather,
and help to solve the question of what part humidity plays. Meanwhile, the conclusion seems justified
that below 65 deg. F. relative humidity plays no important part in affecting mental work. But
humidity appears intimately related to high temperature and loss of body heat from the surface. The
nearer the wet bulb temperature comes to the body heat, the more important physiologically it seems
to be, as the difficulty of getting rid of heat increases disturbance in the metabolism, probably setting
up toxic symptoms, first in diminished working capacity, flushing and restlessness, and later by headache,
sickness, and rapidly increasing and marked failure of working power.
Carbonic acid gas in the usual concentration seems to exert no appreciable effect on mental capacity.
Above 35 or 40 parts in 10,000, this may not be true. Dr. Brincker and Dr. Hogarth personally experienced
subjective feelings as of a light band round the forehead and temples, and round the chest, and
although no effect in change of atmosphere was apparent to teacher or scholars the test shewed, and the
teacher actually noticed at the time, that after about an hour there was a remarkable collapse in the
mental capacity of the children. They appeared exhausted mentally, whilst at the same time, there was
entire absence of the headache oppression and nausea, or of the laziness, restlessness and irritability shewn
in a hot close atmosphere alone. It yet remains to be determined whether there are not two trains of
symptoms capable of disentanglement, due to different toxic causes, one from so-called " heat retention"
(Warm Anstauung) the other an ultimate effect of carbon dioxide poisoning.
Summary. Although many gaps remain to be filled ere these observations constitute a complete
series, the following conclusions seem indicated.
i. Mental alertness and accuracy is improved by two or three hours of school work, provided
that the atmosphere is satisfactory.
ii. Temperatures above 65 deg. F. give rise to definite subjective symptoms ; slackness and
inattention in some, headaches in others. Although it is not easy to assert definite mental alteration
till about 70 deg. F.
iii. Symptoms do not appear at 65 deg. if the air is kept in gentle movement by a fan in the
room. At higher temperatures the symptoms and mental conditions are ameliorated by such
movement of the air.
iv. With temperatures 70 deg. F. and above, other factors being normal, there are marked
symptoms and very evident deterioration in mental alertness and accuracy.
v. Relative humidity does not affect the mental capacity of children, at low temperatures.
Increase of humidity appears to increase the effects of high temperature.
vi. Carbonic acid gas in considerable excess, although not producing the symptoms found in
a hot and close atmosphere, seems to produce, after a time, considerable fatigue in the performance
of mental functions by the children.
LECTURES ON HYGIENE.
It has been decided to modify the scheme of teaching for the examinations in theory and practice
of physical exercises. Unfortunately our suggestions have been only partially followed. As there
are many opportunities open to teachers of obtaining instruction in hygiene, attendance at the lectures
has not been made compulsory, or a necessary qualification for admission to the examinations. A word
of warning should therefore be given. The lectures which are to be given are very simple, but quite out
of the usual line of the elementary physiology book or introduction to hygiene and so specialized on points
concerning school hygiene, and the knowledge that it is necessary teachers should have, that there is
very little hope of any one doing even a fair paper, who has not attended the lectures, the material of
which cannot be gathered from books alone.
The course will be divided into the theoretical lectures, a series of 12 to 14 lectures by the doctors,
and the practical demonstrations by the instructors in physical exercises. The syllabus,which has been
abbreviated by leaving out the terms printed in italics, is the one which was used ten years ago for lectures
to teachers in Bradford, and has since been slightly modified and approved by a committee of the
Incorporated Society of Medical Officers of Health as suitable for medical men who may be required
to lecture to teachers.