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Report of the Medical Officer (Education).
163
and for which the eye has been adapted. The protective strain thrown on these mechanisms of the
eye is the usual cause of the ordinary glare by natural illumination, and is evident as a sensible and
painful reflex to any one coming from a dark to a brightly lighted room. It is mostly caused in school
by the use of certain forms of ribbed glass, or by badly set prism glass, or patterned glass which refracts
small beams of light at low angles or nearly horizontally across rooms at about the level of the children's
heads. These causes of glare are now becoming rarer in schools. The other variety, seen mostly in
secondary schools, is where an excessive amount of specular reflection occurs from surfaces of books
or paper. This occurs mostly with artificial light or in rarer cases where the student faces the daylight.
The windows behind the children still existing in older class rooms are a source of troublesome
glare to many teachers, especially those with low degrees of astigmatism.
Illumination has a very important bearing on the size of classrooms. Whilst the illuminating
window should be as large as possible for the sake of lighting, it has, in winter at any rate,
to be as small as possible for the sake of warmth and prevention of draughts. The best lighting
value on the furthest part of the room is obtained by a window carried right to the ceiling. If this
be 13 feet, which is about the most useful limit from ventilating considerations, then the furthest
centre of a desk to be sufficiently illuminated will be 20 feet off the window; this gives a limiting width
for the ordinary class room of 22.5 feet. Artificial illumination of school rooms was discussed
some years ago, and now is being considered by a committee of the Illuminating Engineering Society,
so that it need not be further dealt with at present.
Ventilation.
The schools are most generally ventilated by natural means, which are the open doors,
windows and Tobin s tubes provided, aided by wind, and by the heat produced by the warmth of
open fireplaces, large low pressure water pipes, and the children's bodies themselves.
Fortunately the climate of London makes such arrangements tolerable for a considerable part
of the year, but they can scarcely be called hygienic. In hot weather ventilation fails and the rooms
become almost unendurable, in cold either stuffiness or draughts have to be withstood. In respect
to ventilation practically all the elementary schools are unsatisfactory if judged by the standard of
what is attainable and desirable.
Certain schools are ventilated mechanically and complaints of this ventilation are of regular
recurrence. Some of them may almost be described as museums of mistakes, but speaking generally
the ventilating arrangements are much below the capacity required, and it is too late to make effective
improvements. The plenum system is the one adopted. It necessitates closed doors, or with open
doors the short-circuiting and air-starvation of other parts of the building comes into effect. The
conditions reported on in the Annual Report for 1904 still hold good.
Neglecting as lacking confirmation the observations of Weichardt, which assert a powerful
fatigue toxin in expired air, the conditions already mentioned for efficient ventilation are easily
realisable.
The nutrition of the body is partly aided by the excretion of moisture by the skin and mucous
membranes, and by the removal of heat at the same time, which becomes late nt in evaporation. If
there is any hindrance or slowing in the removal of this heat in the evaporationof the water from the
skin, metabolism is interfered with, imperfect changes take place in the tissues, and feelings of malaise,
fatigue and exhaustion result. This process of heat removal is carried on continuously and naturally,
the air under the usual conditions being below the body temperature and not saturated with moisture.
Such air coming in contact with the warm skin becomes heated, takes up quantities of moisture, and
at the same time renders much heat latent by the evaporation. The heating of the air and absorption
of aqueous vapour considerably reduces its specific gravity so that it rises, to be replaced by cooler and
drier air, which again takes up heat and moisture, and thus a continuous circulation is kept up by each
person, naturally ventilating themselves. If this air film is already considerably heated as in the
plenum system, where the air carries the heat from the furnace to the rooms, and if the air is much
moistened, then the process is interfered with, hindered and made slower. The air acts as if it were
already used up, and malaise originates with fatigue and exhaustion. Although on the other hand, all the
benefits of air flushing, are obtained in keeping down dust, and doing a little to dilute objectionable
odours, or even infections from the persons or clothes of particular children, and chemical testing
shows it to be very pure.
The naturally ventilated school with its smaller air supply has many hygienic disadvantages,
but not always, or so evidently, this drawback of heat accumulation in the body which results in the
plenum school, where air is used for carriage of heat. If the air in a naturally ventilated school was
kept in sufficient movement, it might be very foul and yet seem quite comfortable on most days.
The ventilation of the class room has been so fully detailed in previous reports that it need not
be further elaborated. The impossibility of getting sufficient air through a naturally ventilated room,
and the evils of carriage of heat by the air in propulsion systems will have to be remembered. The
whole subject, in view of the new ideal of classes of forty, requires very careful inquiry by the Council,
as it is now purely a matter of space and cost, and rooms have been devised to take advantage of wind,
and by supply of large amounts of heat to have some of the advantages of natural ventilation without
the disadvantages of the mechanical. To what has been written in previous reports, which sum the
whole problem, it may be added that on the ten square feet basis satisfactory natural ventilation of
school classrooms is almost impossible, that in any mechanical system without a supply of 1,500 cubic
feet per head per hour there will be complaints, and that they will persist whenever the greater part of
the carriage of the heat to the rooms is by the air.
Swimming
baths.
Dr. Jborbes has investigated the conditions of the water of tne swimming oath at Drury
Lane Industrial School. The pool, which has been in use for sixteen years, is 20 ft. by 12 ft.
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