we take into the lungs than to the air which surrounds the
body. Dirty air is apt to carry with it small particles of
mineral matter which pierce the lining of the lungs and
set up an irritation which may result in the begiiming of
tuberculosis.
3.^ Air moist, not dry. The third rule is that air should be
moist, not dry. All outdoor air carries with it a great deal of
moisture. When we take a cubic foot of out-of-door air at
136 HEALTHFUL SCHOOLS
a temperature of thirty-two degrees and heat it to seventy
degrees, we have multiplied its capacity for holding mois-
ture three and one-half times. If we do not add to our
heating plant some method of supplying the extra moisture
which is needed, we fill our classrooms with dry, thirsty air,
which quickly flows around the bodies of the children and
absorbs the moisture on their skins and mucous membranes.
As soon as this protective covering of moisture is taken
away the skin becomes dry and parched, the face is flushed,
and the mucous membrane surfaces become irritated, so
that they are peculiarly sensitive. As was suggested earlier,
dry, hot air renders children especially liable to catch con-
tagious diseases.
In considering this question of the action of dry air upon
the skin it is interesting to compare the complexions of girls
in Ireland, the Maritime Provinces of Canada, and the coast
districts of Washington and Oregon, with the complexions
of the women in those of our Western and Middle Western
States where there is little rainfall and the air is particu-
larly dry. Humidity, of course, is not the only factor which <
enters into the question of clear skin and r osy cn eeks. \
Moderate temperature, for instance, seems to be a help,
and extreme hot or cold weather a hindrance. But, in gen-
eral, it seems to be true that under ordinary outdoor tem-
perature the body thrives when the humidity shows from
fifty to eighty per cent of saturation, and suffers when the
humidity drops very much below this point. When we read
the reports of the various educational surveys, which tell
us that the average air in classrooms visited ranges from
only twenty to thirty degrees of saturation, we can easily
understand why it is that plants in a classroom wither and
die and children become weary.
.4. Air moving, not still. In the fourth place, air must be
moving, not still. Sometimes in a cold room it is found that,
HEATING AND VENTILATING 137
although the radiators are very hot, they do not seem able
to pass their heat out into the room. If we open the doors
and windows for a minute or two and then quickly shut
them we find that something seems to have happened to
the way the radiators work, and the room becomes quickly
warm. The explanation is that in the quiet classroom each
radiator has become surrounded by a thick blanket of quiet
air which has held in the heat and prevented it from passing
to the rest of the room. When doors and windows were open
a draught was created, which broke up this blanket and set
the air of the room into motion.
In certain ways human beings are very much like the radi-
ators. They are constantly giving heat off into the air. If
the air is very still, it forms a blanket around the body,
which holds in the heat and prevents it from being properly
carried away. If the air is hot and dry, it absorbs the mois-
ture around the body, and this process of evaporation cools
the skin; but if the air is damp, evaporation cannot take
place, and the body is held by a hot, sticky blanket which
renders the person most uncomfortable. If doors or windows
are opened, or an electric fan is started, just as was the case
with the radiator the air is set in motion and driven away,
so that heat is carried off and the body is bathed in a moving
stream of fresh, cool air. Under ordinary classroom tem-
peratures absolutely quiet air is extremely uncomfortable.
All the air in the classrooms should be moving all the time.
A few years ago air entering the classrooms was calculated
on the basis of the amount each child needed to breathe.
Now we are coming to believe that the important thing is
to find out how much air the child needs to bathe in.
5. Air of changing temperature. The fifth rule is that
air should be of changing temperatures. Dr. Ellsworth
Huntington, of Yale, was one of the first people to demon-
strate clearly the stimulating effect of changes in tempera-
138 HEALTHFUL SCHOOLS
ture. Dr. Huntington studied the wages of factory workers
in Connecticut, and the marks of students at West Point
and Annapolis. He found that hot weather makes people
somewhat inefficient and cold weather makes them even
more so. But, generally speaking, when the temperature
is not above seventy or below forty-three, any change in
weather, whether it be warmer or colder, seems to have a
distinctly stimulating effect.
It is a well-known fact that warm countries seem to make
people lazy, and Northerners are apt to speak scornfully
of those who have the "to-morrow" habit. It is true that
living in the land of perpetual summer does have a curiously
discouraging effect upon the desire to work, and the reason
probably is to be found in this very question of changes in
temperature. Where the range of temperature is very slight,
and the thermometer registers very nearly the same day
after day and week after week, even though there are no
excessively hot periods, mind and body begin to work slowly.
The human organism needs the stimulus of change.
So we have our five modern principles of ventilation. Air
should be warm, not hot; clean, not dirty; moist, not dry;
moving, not still ; and of constantly changing temperatures.
If these principles are valid, and all the evidence seems to be
pointing that way, it means that all our present systems of
heating and ventilation must be subjected to careful scru-
tiny, for they were devised to fit very different theories. We
shall retain some of our methods because we find they work,
and our changes will come in the explanation we give for
them. There are other schemes which we have tried, how-
ever, and with which we have already had to acknowledge
failure. Here we must cast aside the old apparatus and sys-
tems of heating and ventilating, and experiment with new
methods and new processes in the light of our more recent
discoveries.
HEATING AND VENTILATING 139
The ventilating engineer. There are two main reasons
why the ventilating of schoolhouses is usually so unsatis-
factory. In the first place, it is not until very recently that
physiologists or medical men have begun to find out what
they mean by fresh air. Even now, statements as to what
kinds and conditions of air are most suited to the human
body are in the nature of hypotheses, which furnish us with
guides for practice and experiment, but have still to be sub-
jected to more definite proof. Ventilating engineers have
been trying to give good ventilation without knowing what
good ventilation is.
The other probable reason for unsatisfactory conditions
in schoolhouses lies in the fact that even at the present time
school boards and superintendents fail to realize that the
problem of ventilating and heating belongs to a special field,
and must be handled by experts in that field. When a new
building is being erected the architect is usually asked to
take charge of installing the ventilating system. In some
cases he secures the assistance of a competent heating and
ventilating engineer, and places the whole matter in his
hands. All too frequently, however, the architect feels that
he knows enough to supervise such work himself, and the
heating and ventilating plant is installed by a contractor
under the supervision of the architect. Mr. G. G. Kimball,
one of the members of the New York Commission, has esti-
mated that the cost of the very best engineering services for
the design and supervision of a heating and ventilating plant
varies from one half to three quarters of one per cent of the
cost of the building. Where a first-class engineer is em-
ployed the amount saved in installation and operation is
immensely greater than his charge for services. The installa-
tion t)f such a plant is always costly. Errors in planning and
building are easily made, and once made are frequently
impossible to repair. An inferior plant is so difficult to
140 HEALTHFUL SCHOOLS
handle and so seriously impairs the efficiency of the school
that neglect to hire competent engineering service in the
first place is evidence of a stupid and short-sighted policy.
Not only must the equipment be planned and installed
under expert supervision, but care must also be taken to
see that adequate funds are placed at the disposal of the
engineer. It is peculiarly true in the field of heating and
ventilating that an adequate initial investment saves con-
stantly incurring heavier expenses later. Whenever a school
board contemplates cutting down the appropriation, it
should first give the heating engineer a chance to argue in
defense of his original plan.
Legislation. As those who are building schoolhouses try
to put into practice the modern theories of heating and
ventilating they will find that in many cases progress is
seriously hampered because, in an effort to insure good
conditions in school buildings, laws have been placed upon
the statute books making compulsory conditions which
now seem unadvisable. For example, in Delaware, Idaho,
Indiana, Massachusetts, Montana, New Jersey, New York,
Pennsylvania, South Dakota, and Vermont, the law requires
that the temperature be kept at seventy degrees Fahren-
heit. Recent investigation seems to show that if the air is
properly humidified temperatures not higher than sixty -five
degrees are desirable, and seventy is certainly too high.
In twenty -one States the law requires that fresh air be pro-
vided at the rate of thirty cubic feet per pupil per minute.
The wording of these laws and regulations varies, but it is
possible that in many States attempts to install systems of
re-circulation of air will be blocked by existing laws.
In a similar way, various States give definite direction for
the location of air inlets and outlets, their size, the instal-
lation of registers, flues, dampers, and the like. In New
Jersey the velocity of the air introduced should not be over
HEATING AND VENTILATING 141
three hundred feet per minute. In New York it must be
over three hundred, but not more than four hundred feet
per minute. In some States the regulations concerning heat
and ventilation are the results of legislative enactment and
can only be changed by legislative procedure. In others the
matters have been left to the discretion of the State board
of health, chief of police, or board of education. It is to be
hoped that future regulations will be of this latter type, so
that they may be changed if scientific experiment later
points to the desirability of doing so.
Stoves. Practically all rural schools of the United States
are heated by stoves. In all too many cases the stove is
placed in the middle of the room and is of the old-fashioned
type with direct radiation, so that children sitting near are
uncomfortably warm and those at a distance are cold. For-
tunately, in many States there has been a direct and strong
movement away from the old-fashioned unprotected stove
and in favor of the jacketed stove. In some cases this is
brought about by prohibitory rulings or legislation. For
example, Indiana makes it a requirement that all stoves
shall be surrounded by a jacket consisting of two sheets, the
outer sheet being of heavy galvanized iron lined with sheet
asbestos. The inner jacket, which must be not less than
three quarters of an inch distant from the outer, must be
of tin or some other suitable metal. The jacket must stand
at least three inches away from the stove, and must extend
to the floor.
North Dakota and Minnesota, while actually not legislat-
ing against the unjacketed stove, provide State aid where
stoves of the proper kind are supplied. In Minnesota, if
aid is to be granted, the jackets must be of iron or copper-
plated steel, with a lining of asbestos and an inside lining of
tin, with ample air space between. It must stand six inches
away from the stove, and the lower edge must not be less
142 HEALTHFUL SCHOOLS
than twelve inches above the floor. South Dakota makes
the approval of rural-school plans by the State Superintend-
ent dependent among other things upon having stoves sup-
plied with a metal jacket extending one or two feet above
the stove, and with arches around the bottom extending
from eight to ten inches above the floor.
The reason why so much emphasis is placed upon using
a jacket for schoolroom stoves is, that without the jacket
heat is distributed only to those children who are sitting
near the stove. No currents of air are set up, and the heat
is not carried to other parts of the room. With the jackets
properly made and adjusted, cold air is admitted from the
outside of the building, is carried up inside the jacket, and
warmed as it circulates around the stove, and passing up
through the jacket, flows out through the room near the
ceiling. The foul air of the room is drawn under the jacket
and acts as a draught for the fire. Part of it also mixes with
the fresh air being admitted from the outside, and is re-
circulated throughout the room. Where jackets are prop-
erly made and installed, the system works fairly well. It
is usually necessary, however, to open the windows instead
of merely depending on stoves for ventilation. Ventilation
secured in the latter way is thoroughly successful only when
great difference is noted between inside and outside tem-
peratures.
Furnaces. The furnace is constructed on the same prin-
ciple as the jacketed stove. It consists roughly of a fire-box
inside, a jacket outside, and space between to which air
is admitted and where it becomes warm and is then sent
through pipes to the rooms of the building. Furnace fires
form an easy way of heating school buildings. They cost
very little, are simple and inexpensive to repair, and are
so simple to run that very little special training is necessary
for the job. Another and very important factor is that the
HEATING AND VENTILATING 143
furnace fire can be allowed to go out at the end of the
school day without danger of putting the system out of
order. The chief disadvantage of heating by means of
furnaces is that it is very easy to make the fire too hot, so
that the air when sent up into the classrooms is actually hot
instead of warm. As we have already seen, children do not
need to be supplied with hot air in order to keep them com-
fortable on cold days; what they do need is a plentiful supply
of rapidly moving, warm, moist air. It is possible to equip
furnaces with fans and moistening apparatus, so that these
two latter requirements may be provided, but there are
at present very few places where this has been done.
It is also difficult to distribute the warm air evenly in
the different rooms of the building. Usually one or two
rooms will receive more than their share because the supply
pipes are shorter and run at a more direct angle to these
rooms. Even where all supply pipes are furnished with
dampers, it is not always easy to see to it that every room is
properly heated.
In the third place, furnaces frequently get out of order,
and the gases formed in the fire-box are allowed to leak
through cracks into the air-box and so find their way into
the classrooms. Furnaces are still being used in our old
buildings and in some of our new small buildings, but they
are rapidly being displaced by other forms of heating.
One of the difficulties most frequently encountered in
using hot-air furnaces for school buildings is that when a
wind blows strongly against one side of the building the air
pressure on that side becomes so strong that it prevents hot
air from rising through the furnace pipes into the rooms on
that side. When candles are carried from room to room it
is found that in certain rooms the flame flickers outward,
but in others it is actually drawn down toward the register,
because, instead of having hot air come up into the room,
144 HEALTHFUL SCHOOLS
the cold air already contained in the room is being sucked
down by the furnace.
It was because of the difficulty of distributing heat evenly
to all the rooms of the building on windy days that furnace
heating fell so much into disfavor. It is interesting to note,
therefore, that recently experiments have been made which
seem to show how to obviate this difficulty. At present
some of our most carefully planned private residences have
given up the idea of steam heating and returned to hot-air
furnaces. Each room in the house is provided with a flue
which goes up through the walls and empties into an air
chamber at the top. By means of this construction, even
when all the doors are closed between rooms and strong
winds are blowing against one side, the air pressure through-
out all the rooms is equalized and the heat from the furnace
is therefore able to distribute itself to all parts of the house.
These new houses, also, are usually provided with a means
of cutting off the outdoor intake. When the weather is
extremely cold the intake from outdoors is closed and the
air already within the house is re-circulated, either through
natural circulation or with the assistance of an electric
blower. This means, of course, an immense saving of fuel
and the results secured seem entirely satisfactory.
The experiments just described have been actually tried
out in a sufficient number of cases so that there seems to be
little doubt of the success of the scheme. It is probably true
that when school buildings of moderate size are built with
flues and equalizing air chamber, the hot-air furnace will
form an economical and exceedingly satisfactory method
of heating.
Hot- water heating. Systems of heating schoolhouses by
hot water seem to be much more used in England than
in the United States. In this country they are rather out
of favor, probably because after being installed they are
HEATING AND VENTILATING 145
constantly getting out of order and because, since they need
a large radiating surface, the installment of pipes and radia-
tors is rather cumbersome and expensive. Systems of hot-
water heating are simple and very easy to handle. They do
not require either very constant attention or very much
skill. Admirers of the system claim that hot-water plants
easily carry heat for long distances, so that the system is
particularly adapted to central heating plants which supply
rooms of buildings at some distance from the center.
Steam heating. In the United States'" the commonest
form of heating for school buildings is by low-pressure
steam plants. Steam radiators give out a steady supply of
warm air which is never overheated, and the steam supply
may easily be turned on or cut off from different rooms by
a very simple mechanism. As is the case with hot- water
heating, it is possible to carry the steam from a heating
plant at a considerable distance from the room or building.
Steam is particularly useful as a heating medium, moreover,
because it can be supplied in so many different ways for
various types of direct and indirect heating. The disad-
vantages of steam heating are, first, that it is rather expen-
sive to install and repair; second, changes must be made
slowly so that if it is necessary to turn on the heat in a
building in a short time or to cool a room rapidly trouble
is usually experienced; and third, in cold weather it is nec-
essary to have fires going all the time because otherwise
there is danger of pipes bursting.
In general it is probably undesirable to use high-pressure
steam systems for public schools, unless the heating plant
is in a separate building from the rest of the school. High-
pressure plants are much more dangerous than low-pressure,
and not very much more effective for school purposes.
Heating and ventilating schemes. There are a great many
different combinations of methods of heating and ventilating.
146 HEALTHFUL SCHOOLS
Most of these belong to one of three groups. The term
"direct heating" is usually used to mean heating by means
of radiators placed under the windows or pipes run around
the sides of the classrooms. The windows are the coldest
spots in the room. Cold enters around the glass and radi-
ates from the glass pane. When radiators or steam pipes
are placed directly below windows, they heat this cold
entering air before it has time to escape into the rooms.
Many school buildings and most office buildings are heated
by the direct method alone.
Indirect heating means that air is drawn over pipes or
radiators and then carried by flues to the classrooms. Some-
times these pipes are in the walls very near the opening of
the inlet, where the air enters the room. Sometimes they
are placed in rooms in the basement and warm the air for
several classrooms.
At one time the indirect system was highly recommended
for heating schoolhouses, but it was found difficult to keep
the rooms warm enough by this method alone. Radiators
were then added underneath the windows, and the com-
bination of flues and radiators was described as the direct-
indirect method. This is now one of the commonest forms
of heating for larger school buildings.
Flues; use of windows. The building of the air flues is
a matter over which there is great controversy. For exam-
ple, Dr. Fletcher B. Dresslar, specialist in school hygiene
and school sanitation for the United States Bureau of Edu-
cation, says that the best position for the inlet duct is about
eight feet from the floor, a little back of the middle of the
inside wall opposite the windows. On the other hand, Dr.
E. A. Winslow, Chairman of the New York State Commis-
sion on Ventilation, suggests that it will frequently be best
to take advantage of the natural upward tendency of air
which is being warmed by supplying cool, fresh air below
HEATING AND VENTILATING 147
and removing the warm air above. Other authorities divide
about equally between the two positions. In the same way
very different directions are given for the size and shape of
flues; although most of the authorities agree that large flues
are more desirable than small ones, because they make it
possible to admit large quantities of air without causing
a strong draught. For the school superintendent the wisest
plan is probably to secure the services of the best ventilat-
ing engineer available, and leave the question of location
and size to his judgment.
In many of our modern buildings, equipped with elabo-
rate heating systems and thermostats, there is an iron-
bound rule that no teacher shall open the windows during
school hours. Suppose, for example, that it is a very cold
day and the teacher throws open the classroom window for
a minute or two in order to get a breath of fresh air. Power-
ful fans downstairs are driving hot air into all the rooms
of the building. When the window is opened one of several
things may happen. A draught may be created, for example,
and the stream of hot air which is rushing up from the fan
may be carried straight across the classroom and out the
window. The draught is so strong that this room gets more
than its share of heat and the temperatures in other rooms
fall. As soon as the temperature falls the thermostats in
other classrooms start their mechanism into motion, so that
more steam is turned on for all the radiators. Downstairs
the fireman shovels in coal to generate more heat to take the
place of the huge volume of warm air which is rushing out
through the one teacher's open window.
Or again, suppose that instead of warm air going out
through the window a volume of cold air rushes in. The
teacher opened the window because the room was too warm;
but, it has not yet had time to cool off. When the cold
air strikes the thermostat it automatically registers and
148 HEALTHFUL SCHOOLS
acts, so that more steam is turned on to the radiators. The
teacher now closes the windows, but the radiators are work-
ing even more actively than before and in a few minutes the
room is intolerably hot again. As the heat increases, the ther-
mostats become warm and the steam is turned off from the
radiators. The teacher, however, finding the room quickly
uncomfortable, again throws the window wide open, cold
air rushes in, the thermostat becomes chilled, the steam
heat is turned on in the radiators, and the same story is
repeated over and over. No wonder janitors object when