This method is frequently adopted in combined schemes of heating and ventilating; the fresh air is warmed by being passed over their surfaces previously to being admitted through the gratings into the room.
Underground boilers placed near the up-cast pit so that the smoke and gases help the ventilating furnace have been largely used but are now less favourably regarded than formerly.
The usual form of ventilating furnace is a plain fire grate placed under an arch, and communicating with the upcast shaft by an inclined drift.
The heating and ventilating arrangements are much the same as in the lean-to, only the top sashes which open are on the back slope, and therefore do not interfere so much with the vines on the front slope.
Efficient ventilating can only be effected by the exercise of common sense and vigilance, and care must be taken to avoid cold draughts through the houses.
Ventilate but little, and with care; raise the ventilating sash only high enough to let the heated air from the greenhouse drive back the outer air so as not to chill the plants.
- Watering, ventilating and fumigating (or the use of tobacco in other forms for destruction of aphides) must be attended to.
He took a leading part in ventilating the Bulgarian and Armenian "atrocities," and his combative personality was constantly to the fore in support of the campaigns of Gladstonian Liberalism.
A representative list includes: - the Charity Organization Society, the primary object of which is to organize the work of the others; the Baltimore Association for the Improvement of the Condition of the Poor, which seeks to discourage indiscriminate alms-giving; the Bay View asylum or city poorhouse; the Children's Aid Society; the Thomas Wilson Fuel-Saving Society, for furnishing coal at low rates; the Woman's Industrial Exchange, for assisting women in need to support themselves; Johns Hopkins hospital, noted for the excellence of its equipment especially for heating and ventilating; Saint Joseph's general hospital; hospital for the women of Maryland of Baltimore city; nursery and child's hospital; Baltimore eye, ear and throat charity hospital; Maryland hospital for the - insane; the Sheppard asylum, intended especially for the cure of the insane; the Sheppard and Enoch Pratt hospital; the Baltimore orphan asylum; Saint Vincent's infant asylum; the Thomas Wilson sanatorium for children, intended for children under three years of age, who are suffering from disease, during the warm summer months; the Free Summer Excursion Society, for affording a change of air to the indigent sick; home for the incurables; homes for the aged; homes for friendless children; institutions for the blind; and institutions for the deaf and dumb.
The best form of open fireplace is the ventilating stove, in which fresh air is passed around the back and sides of the stove before being admitted through convenient openings into the room.
Ventilating radiators are similar, but have an inlet arrangement at the base to allow external air to pass over the heating surface before passing out through the perforations.
The principal publications on heating are: Hood, Practical Treatise on Warming Buildings by Hot Water; Baldwin, Hot Water Heating and Fittings; Baldwin, Steam Heating for Buildings; Billings, Ventilation and Heating; Carpenter, Heating and Ventilating Buildings; Jones, Heating by Hot Water, Ventilation and Hot Water Supply; Dye, Hot Water Supply.
In cases where the direction of the air motion is always the same, as in the ventilating shafts of mines and buildings for instance, these anemometers, known, however, as air meters, are employed, and give most satisfactory results.
In a mine with two shafts a ventilating current may result from other conditions creating a difference in the temperature of the air in either shaft - for example, the cooling effect of dropping water or the heating effect of steam pipes.
Ventilation may be produced by heating the air of the mine, as for example, by constructing a ventilating furnace at the bottom of an air shaft.
The efficiency of such ventilating furnaces is low, and they cannot safely be used in mines producing fire-damp. They are sometimes the cause of underground fires, and they are always a source of danger when by any chance the ventilating current becomes reversed, in which case the products of combustion, containing large quantities of carbon dioxide, will be drawn into the mine to the serious danger of the men.
So far as possible, vitiated air is led directly to the shaft instead of passing through other workings; for example, mine stables when used are placed near the upcast shaft and ventilated by an independent split of the ventilating current.
By the adoption of more refined methods of construction, especially in the shape of the intake and discharge passages for the air and the forms of the fan blades, the efficiency of the ventilating fan has been greatly increased so that the dimensions can be much reduced and a higher rate of speed adopted.
The increased resistance, due to the large extension of workings from single pairs of shafts, the ventilating currents having often to travel several miles to the upcast, has led to great increase in the size and power of ventilating fans, and engines from 250 to Soo H.P. are not uncommonly used for such purposes.