[Footnote: A paper read before the Gas Institute, Manchester, June,
1885.]
By WILLIAM SUGG, of London.
Ever since the introduction of electric lighting, the public have been
assured, by those interested in the different kinds of lamps--arc, glow
or otherwise--that henceforth, by means of such lamps, rooms are to be
lighted without heat or baneful products such as they assert attend the
use of gas, lamps, or candles. But I think it must not be implied, from
what any one has said in favor of the electric light as a means of
lighting our dwellings, that gas is unsuitable for the purpose, or that
the glow lamp is a perfect substitute for gas, or that there is a very
large difference throughout the year on the points of health,
convenience, or comfort, or that the balance in favor rests with
electric light upon all or any of these points. The fact is, the glow
lamp is only one more means (not without certain disadvantages) of
producing light added to those which already exist, and of which the
public have the choice. Now, looking to best means of lighting rooms,
and particularly the principal rooms of a small dwelling-house, I beg to
say that the arguments which can be adduced in favor of gas lighting in
preference to any other means greatly preponderate, and that it can be
substantiated that, light for light, under the heads of convenience,
health, comfort, reliability, readiness, and cheapness, gas is superior
to all.
As a scientific means for the purposes mentioned, gas is comparatively
untried. This assertion may sound somewhat astounding; but I think it is
a true one. More than that, even in the crude and unscientific way in
which it has most frequently been used up to the present, it has been
far from unsuccessful in comparison with electricity or other means of
lighting; and in the future it will prove the best and cheapest
practical means, although, for effect, glow lamps may be used in
palatial dwellings in conjunction with it.
It must be remembered that, in laying down a system of artificial
lighting, we have to imitate, as well as we can, that most beautiful and
perfect natural light which, without our aid, and without even a thought
from us, shines regularly every day upon all, in such an immense volume,
so perfectly diffused, and in such wonderful chemical combination, that
it may safely be said that not one atom of the whole economy of Nature
is unaffected by it, and that we and all the animal kingdom, in common
with trees and plants, derive health and vigor therefrom. This glorious
natural light leaves our best gas, electricity, oil lamp, and all our
multiplicity of candles, immeasurably behind. But although we cannot
hope to equal, in all its beneficent results, the effects of daylight,
or to perfectly replace it, we can more perfectly make the lighting of
our homes comfortable (and as little destructive to the eyes and to the
general health) by the aid of gas than by any other means. It must also
be borne in mind that, in this country at least, we have to fulfill the
conditions of artificial lighting under frequent differences of
temperature and barometric influence, exaggerated by the manner in which
our homes are built; and that for at least nine months of the year we
require heat as well as light in our dwellings, and that for the other
three months (excepting in some few favored localities) the nights are
often chilly, even though the days may be hot. Therefore, independently
of any effect produced by the lighting arrangements, there must be
widely different effects produced in the temperature and conditions of
the air in rooms by influences entirely beyond our control.
As an example of what I mean, a short time ago I had to preside over a
meeting which was held in a large room--one of two built exactly alike,
and in communication with each other by means of folding doors. These
rooms formed part of one of the best hotels in London--let us call it
the "Magnificent." Of course, it was lighted by electric glow lamps, in
accordance with the latest fashion in that department of artificial
lighting, viz., suspension lamps, in which the glow lamps grew out of
leaves and scrolls, twisted and twirled in and out, very much after the
pattern of our most æsthetic gas lamps, which, of course, are in the
style of the most artistic (late eighteenth century) oil lamps, which
were in imitation of the most classic Roman lamps, which followed the
Persian, and so on back to the time of Tubal Cain, the great
arch-artificer in metals, who most likely copied in metal some lamps he
had seen in shells or flints. Both rooms were heated by means of the
good old blazing coal fire so dear to a Briton's heart; and they were
ventilated with all due regard to the latest state of knowledge on the
subject among architects and builders. In fact, no pains had been spared
to make these rooms comfortable in the highest acceptation of the word.
There were, some of our members remarked, no gas burners to heat and
deteriorate the atmosphere, or to blacken the ceilings; and therefore,
under the brilliant sparkle of glow lamps, the summit of such human
felicity as is expected by a body of eighteen or twenty business men,
intent on dispatching business and restoring the lost tissue by means of
a nice little dinner afterward, ought, according to the calculations of
the architect of the building, to have been reached. I instance this
case because it is a typical one, which, under most aspects, does not
materially differ from the conditions of home life in such residences as
those whose occupiers are likely to use electric lighting. The rooms
were spacious (about 20 feet by 35 feet, and about 15 feet high); and
they were lighted during the day by means of large lantern
ceiling-lights, with double glass windows. The evening in question was
chilly, not to say cold.
Upon commencing our business, we all admired the comfort of the room;
but as time went on, most of the company began to complain of a little
draught on the head and back of the neck. The draught, which at first
was only a suspicion, became a certainty, and in another hour or so, by
the time our business was over, notwithstanding a screen placed before
the door, and a blazing fire, we were delighted to make a change to the
comfortable dining-room, which communicated with the room we had just
left by means of folding doors, closed with the exception of just
sufficient space left at one end of the room to allow a waiter to pass
in and out. Very curiously, before the soup was finished, we became
aware that the candles which assisted the electric glow lamps (merely
for artistic effect) began to flare in a most uncandlelike manner--the
flames turning down, as if some one were blowing downward on the wicks;
and at the same time the complaints of "Draughts, horrid draughts!"
became general, and from every quarter. Finding that, as the dinner went
on, the discomfort became unbearable, even although the doors were shut
and screens put before them, I gave up dining, and took to scientific
discovery. The result of a few moments' observation induced me to order
"those gas jets," which I saw peeping out from among the foliage of the
electroliers, to be lighted up. In two or three minutes the flames of
the candles burned upright and steadily, and in less than ten minutes
the draughts were no longer felt; in fact, the room became really
comfortable.
The reason of the change was simple. The stratum of air lying up at the
ceiling was comparatively cold. The column of heated air from the bodies
of the twenty guests, joined to the heat produced by the movements of
themselves and the waiters, together with the steam from the viands and
respiration, displaced the colder air at the ceiling, and notably that
coldest air lying against the surface of the glass. This cold air simply
dropped straight down, after the manner of a douche, on candles and
heads below. The remedy I advised was the setting up of a current of
hotter steam and air from the gas burners, which stopped the cooling
effect of the glass, and created a stratum of heated steam and air in
slow movement all over the ceiling. The effect was a comfortable
sensation of warmth and entire absence of draught all round the table.
Later on, to avoid the possibility of overheating the room, the gas was
put out, and the electric lights left to themselves. But before we left,
the chilliness and draughts began to be again felt.
The incident here narrated occurred at the end of the month of April
last, when we might reasonably have hoped to have tolerably warm nights.
It is therefore clear that in this instance neither electricity nor
candles could effectually replace gas for lighting purposes. They both
did the lighting, but they utterly failed to keep the currents of air
steady. I have always remarked draughts whenever I have remained any
length of time in rooms where the electric light is used. On a warm
evening the electric light and candles would undoubtedly have kept the
room cooler than gas, with the same kind of ventilation; I do not think
they would have put an end to cold draughts. This the steam from the gas
does in all fairly built rooms.
It is a well-known fact that dry air parts with its relatively small
amount of specific heat, in an almost incredibly rapid manner, to
anything against which it impinges. Steam, on the contrary, from its
great specific heat, remains in a heated state for a much longer time
than air. It is not so suddenly reduced to a low temperature, and in
parting with its own heat it communicates a considerable amount of
warmth to those bodies with which it comes in contact. Thus the products
of the combustion of gas (which are principally steam) serve a useful
purpose in lighting, by keeping at the ceiling level a certain stratum
of heated vapor, which holds up, as it were, the carbonic acid and
exhalation from the lungs given off by those using the room. The obvious
inference, therefore, is that if we take off these products from the
level of the ceiling, we shall take off at the same time the impure and
vitiated air. On the other hand, if we make use of a system of
artificial lighting, which does not produce any steam, then we shall
have to adopt means to keep the air at the ceiling level warm, in order
to prevent the heated impure air from descending in comparatively rapid
currents, after having parted with its heat to the ceiling. It may very
frequently be observed on chilly days that a number of currents of cold
air seem to travel about our rooms, although there may be no crevices in
the doors and windows sufficient to account for them; and, further, that
these currents of cold air are not noticed when the curtains are drawn
and the gas is lighted. The reason is that there is generally not enough
heat at the ceiling level in a room unlighted with gas to keep these
currents steady. Hence the complaints of chilliness which we constantly
hear when electric lights are used for the illumination of public
buildings. For example, at the annual dinner of the Institution of Civil
Engineers, held at the end of April last in the Conservatory of the
Horticultural Gardens, the heat from the five hundred guests, and from
an almost equal number of waiters and attendants, displaced the cold air
from the dome of the roof, and literally poured down on the assembly
(who were in evening dress) in a manner to compel many of them to put on
overcoats. If the Conservatory had been lighted with gas suspended below
the roof, this would not have been the case, because sufficient steam
would have been generated to stop these cold douches, and keep them up
in the roof. In fact, if electric lights are to be used in such a
building, it will be necessary to lay hot-water pipes in the roof, to
keep warm the upper as well as the lower stratum of air, and thus steady
the currents.
Having pointed out difficulties which arise under certain conditions of
the atmosphere in rooms built with care, to make them comfortable when
electric lighting is substituted for gas, I will lay before you some few
particulars relative to the condition of small rooms of about 12 ft. by
15 ft. by 10 ft., or any ordinary room such as may be found in the usual
run of houses in this country. The cubical contents of such a room
equals 1,700 cubic feet. If the room is heated by means of a coal fire,
we shall for the greatest part of the year have a quantity of air taken
out of it at about 2 feet from the floor by the chimney draught, varying
(according to atmospheric conditions and the state of the fire) from 600
to 2,000 or more cubic feet. This quantity of air must, therefore, be
admitted by some means or other into the room, or the chimney will, in
ordinary parlance, "smoke;" that is, the products of combustion, very
largely diluted with fresh air, will not all find their way up the flue
with sufficient velocity to overcome the pressure of the heavy cold air
at the top of the chimney. If no proper inlets for air are made, this
supply to the fire must be kept up from the crevices of the doors and
windows. In the line of these currents of cold air, or "draughts" as
they are usually called, it is impossible to experience any
comfort--quite the contrary; and colds, rheumatism, and many other
serious maladies are brought on through this abundant supply of fresh
air in the wrong way and place.
According to General Morin (one of the best authorities on ventilation),
300 cubic feet of air per hour are required for every adult person in
ordinary living rooms. Peclet says 250 cubic feet are sufficient; less
than this renders the atmosphere stuffy and unhealthy. It is generally
admitted that an average adult breathes out from 20 to 30 cubic inches
of steam and vitiated air per minute, or, as Dr. Arnott says, a quantity
equal in bulk to that of a full-sized orange. This vitiated air and
steam is respired at a temperature of 90° Fahr.; and therefore, by
reason of this heat, it immediately ascends to the ceiling, together
with the heat and carbonic acid given off from the pores of the skin.
This fact, by the bye, can be clearly demonstrated by placing a person
in the direct rays from a powerful limelight or electric lamp, and thus
projecting his shadow sharply on a smooth white surface. It will be
observed that from every hair of the head and beard, and every fiber of
his clothing, a current of heated air in rapid movement is passing
upward toward the ceiling. These currents appear as white lines on the
surface of the wall; the cause probably being that the extreme
rarefaction of the air by the heat of the body enables the rays of light
to pass through them with less refraction than through the denser and
more moist surrounding cold air. An adult makes, on an average, about 15
respirations per minute, and therefore he in every hour renders to the
atmosphere of the room in which he is staying from 10 to 15 cubic feet
of poisonous air. This rises to the ceiling line, if it is not
prevented; and thus vitiates from 100 to 150 cubic feet of air to the
extent of 1 per cent, in an hour. General Morin thought that air was not
good which contained more than ½ per cent, of air which had been exhaled
from the lungs; and when we consider how dangerous to health these
exhalations are, we must admit that he was right in his view. Therefore
in one hour the 15 foot by 12 foot room is vitiated to more than 2 feet
from the ceiling by one person to the extent of ½ per cent., and it will
be vitiated by two persons to the extent of 1 per cent, in the same
time.
It must be remembered here that the degree of diffusion of the vitiated
air into the lower fresh air contained in the remaining 8 feet of the
height of the room depends very materially on the difference of
temperature between these upper and lower strata and the movements of
air in the room. The heavy poisonous vapors and gases fall into and
diffuse themselves among the fresh air of the lower strata--very readily
if they are nearly the same temperature as the upper, but scarcely at
all if the air at the ceiling line is much hotter. Hence it occurs that,
in warmed rooms of such size as I have mentioned, where one or two
petroleum lamps are used for lighting them, after two or three hours of
occupation by a family of three or four persons in winter weather, the
air at the ceiling line has become so poisonous that a bird dies if
allowed to breathe it for a very short time--sometimes, indeed, for only
a few minutes. With candles, if the illumination of the room is
maintained at the same degree as in the case of lamps, the contamination
of the air is very much worse. It is doubtless the case that poisonous
germs are rapidly developed in atmospheres which are called "stuffy;"
and although, in a healthy state of the body, we are able to breathe
them without perceptible harm, yet even then the slight headache and
uneasiness we feel is a symptom which does not suffer itself to be
lightly regarded, whenever, from some cause or other, the general
condition is weak.
The products of combustion from coal gas (which are steam and carbonic
acid mixed with an infinitesimal quantity of sulphur) are,
proportionately, far less injurious to animal life than the products
from an equal illuminating power derived from either oil or candles.
They are, however, it is certain, destructive to germ life; and
therefore, if taken off from the ceiling level, where they always
collect if allowed to do so, no possible inconvenience or danger to
health can be felt by any one in the room. But in our endeavors to take
off the foul air at the ceiling, we encounter our first serious check in
all schemes of ventilation. We draw the elevation and section of the
room, and put in our flues with pretty little black arrows flying out of
the outlets for vitiated air, and other pretty little red arrows flying
in at the inlets; but when we see our scheme in practice, the black
arrows will persist in putting their wings where their points ought to
be; in other words, flying into instead of out of the room.
One of the best ways of finding the true course of all the hot and cold
currents in a room is to make use of a small balloon, such as used to be
employed for ascertaining the specific gravity of gases; and, having
filled it with ordinary coal gas, balance it by weights tied on to the
car till it will rest without going up or down in a part of the room
where the air can be felt to be at about the mean temperature, and free
from draught. Then leave it to itself, to go where it will.
As soon as it arrives in a current of heated air, it will ascend,
passing along with the current, and descending or rising as the current
is either warm or cold. The effect of the cold fresh air from windows or
doors, as well as the effect of the radiant heat from the fire, can be
thus thoroughly studied. Some of our pet theories may receive a cruel
shock from this experiment; but, in the end, the ventilation of the room
will doubtless be benefited, if we apply the information obtained. It
will be discovered that the wide-throated chimney is the cause of the
little black arrows turning their backs on the right path and our
theoretical outlets for vitiated air becoming inlets. The chimney flue
must have an enormous supply of air, and it simply draws it from the
most easily accessible places. From 1,000 to 2,000 cubic feet of air per
hour is a large "order" for a small room. Therefore, until we have made
ample provision for the air supply to the fire, it is quite useless to
attempt to ventilate the upper part of the room, either by ventilating
gas lights or one of the cheap ventilators with little talc flappers,
opening into the chimney when there is an up draught, and shutting
themselves up when there is any tendency to down draught. The success of
these and all other ventilators depends upon there being a good supply
of air from under the door or through the spaces round the window
frames. These fresh air supplies are, of course, unendurable; but if one
of the spaces between the joists of the floor is utilized to serve as an
air conduit, and made to discharge itself under the fender (raised about
two inches for the purpose), quite another state of things will be set
up. Then the supply of air thus arranged for will satisfy the fire,
without drawing from the doors and windows, and at the same time supply
a small quantity of fresh air into the room. But the important fact that
the radiant heat from the fire will pass through the cold air without
warming it all must not be lost sight of. In reality, radiant heat only
warms the furniture and walls of the room or whatever intercepts its
rays. The air of the room is warmed by passing over these more or less
heated surfaces; and as it is warmed, it rises away to the ceiling.
Therefore, if we desire to warm any of this fresh air supplied to the
fire, it must be made to pass over a heated surface. The fender may be
used for this purpose by filling up the two inch space along the front,
as shown in the drawing, with coarse perforated metal. This will also
prevent cinders from getting under it. It will be found that for the
greater part of the year the chimney ventilator and the supply to the
fire will materially prevent "stuffiness," and keep those disagreeable
draughts under control, even although the room be lighted with a 3 light
chandelier burning a large quantity of gas.
[Illustration]
With improvements in gas burners, we may expect to light rooms perfectly
with a less expenditure of gas than we now do. But we cannot light a
room without in some measure creating heat; and I think I have shown
that we want this heat at the ceiling line for the greater part of the
year.
In summer we do not use gas for many hours; but, on the other hand, it
is more difficult, with an outside temperature at 65° to 70° Fahr., to
keep the air in proper movement in small rooms. There are also times in
the fall of the year, and also in spring, when the nights are unusually
warm; and, with a few friends in our rooms, the lighting becomes a "hot"
question, not to say a "burning" one. On these occasions we have to
resort to exceptional ventilation, which for ordinary every-day life
would be too much. It is then, and on summer nights, that the system of
ventilation by diffusion is most useful. To explain it, when two volumes
of air of different temperatures or specific gravities find themselves
on opposite sides of a screen or other medium, of muslin, cloth, or some
more or less porous substance, they diffuse themselves through this
medium with varying rapidity, until they become of equal density or
temperature. Therefore, if we fill the upper part of a window (which can
be opened, downward) with a strained piece of fine muslin or washed
common calico, the air in the room, if hotter than the external air,
will, when the window is more or less opened, pass out readily into the
cooler air, and the cooler air will pass in through the pores of the
medium. The hotter air passing out faster than the cooler air will come
in, no draught will be experienced; and the window may be opened very
widely without any discomfort from it.
It is, of course, quite impossible, in the limits of a paper, to do more
than indicate a means of ventilation which will be effective under most
circumstances of lighting with those gas burners and fittings usually
employed, and which will lend itself readily to modifications which will
be necessitated by the use of some of the newest forms of burners and
ventilating gas lights.
[Illustration]
In conclusion, I wish to draw attention to an important discovery I have
made in reference to blackened ceilings, for which, up to the present
time, gas has been chiefly blamed. I have long entertained the belief
that with a proper burner it is possible to obtain perfect combustion,
without any smoke; and a series of experiments with white porcelain
plates hung over some burners used in my own house proved conclusively
that the discoloration which spread itself all over my whitewashed
ceilings arose from the state of the atmosphere, which in all large
towns is largely mixed with heavy smoky particles, and from the dust or
dirt created in rooms by the use of coal fires as well as from the smoke
which, more frequently than one is at first supposed to imagine, escapes
from the fire-place into the room. I therefore, in two of my best rooms,
which required to have the ceilings whitened every year, substituted
varnished paper ceilings (light oak paper, simply put on in the usual
way, and varnished) instead of whitewash. I also changed the coal fires
for gas fires. These alterations have gone through the test of two
winters, and the ceilings are now as clean as when they were first done.
The burners have been used every night, and the gas fires every day,
during the two winters. No alteration has been made in the burners
employed, and no "consumers" have been used over them. If the varnished
paper ceilings are tried, I am sure that every one will like them better
than the time honored dirty whitewash, which is simply a fine sieve.
This fact is clearly shown by the appearance of the rafters, which,
after a short time, invariably show themselves whiter than the spaces
between.
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