Slow Combustion Grates

This term is applied to all fireplaces in which means is provided for shutting off the air supply from beneath the fire by a fixed or removable screen or " economises "

Canopy grates are provided with a metal hood arranged to slide upwards or swing outwards for the purpose of regulating the flue opening. This device is useful as a"blower," to control combustion in the grate, but is not essential if the flue opening be properly shaped and proportioned in the first instance, and there are other means of regulating the draught.

Another appliance, which is designed for the same purpose, is a fire regulator, which effects the adjust-ment of the flue opening with greater facility, and is said to give perfect control of the combustion, so that the fire may be made to burn feebly when the room is not occupied, and at once be re-stored to briskness when desired. The construction of this device is clearly shown in the sectional diagram.

Section of the Teale grate, showing the forward tilt of the firebrick back and the method by which the grid and airway are contrived

The dog grate. This is practically a fire-basket to stand on the hearth. Its quaint, unusual appearance may commend it to some persons, but as an economical grate it has doubtful value, as it is innocent of any means for regulating the combustion of the fuel, and the absence of any large firebrick surfaces makes it a bad radiator. Its efficiency depends to some extent on the construction of the flue and its back approach.

If the latter be tiled and its surfaces be disposed so as to act as reflectors, some of the waste heat may be gathered up and utilised. These grates are more suited for the burning of wood logs than for coal fires.

The Nautilus grate, so called from its shell-like form, is stated to be economical in use and to be capable of burning coal, coke, or wood. It is practically a closed stove in disguise, and has the objection that highly heated iron surfaces are exposed to the air of the room.

Some Other Types Of Grate

The Eagle grate is of the ordinary slow-combustion type, but is provided with sliding doors, by which the flue opening may be partly or entirely closed. These doors act as blowers, giving a wide range of control of the combustion, and enabling coke and other refractory fuel to be burnt. Their defect seems to be that when the doors are in use, and the combustion most intense, the bulk of the heat must be drawn up the flue.

Two types of grate occasionally found in old houses, and not therefore of recent design, deserve notice, because they both embody excellent features, and where they are found they may well be retained.

The first is the Leamington fireplace, which has much in common with some of the newest types of grate. The position of the fire is near the hearth, and its setting is between two brick or tiled cheeks, the flue opening being situated high up.

The well grate, in which bars are dispensed with, the fire being made on a removable grid below the level of a raised hearth

An ordinary canopy grate, in which a metal hood is arranged to slide upwards or swing outwards to regulate the flue opening and thus control combustion

From what has already appeared in regard to the good points of a grate, it will be seen that this arrangement is simple and economical.

The Stafford shire fireplace is constructed on somewhat similar lines, but the back is a plain flat surface. This brings the fire well out into the room, giving a very wide angle for the heat rays to pass out.

The Mantelpiece

The frame in which grates are set may form part of the grate structure, as in the Teale grate already described and illustrated, or it may be a separate affair, built around the grate proper. It is, in the main, a decorative feature, and, as such, will not be treated at length in the present section. It only need be said that, whatever its material or design, it should accord generally with the other architectural features of the room, and that no part of it should project in such a way as to intercept the heat rays of the fire. This applies not only to the sides, or jambs, but also to the shelf, which if too wide may cut off a very sensible proportion of the heat which otherwise would pass upwards to the ceiling and warm the air.

The behaviour of radiant heat has already been described (page 3726, Vol. 6), and here it may be added that its effects may be felt, not only when it strikes our bodies, and there becomes sensible heat, but when it warms us indirectly by first impinging upon the walls and ceiling, and raising their temperature, whence it is dispersed partly as reflected and partly as convexed heat.

Materials for Mantels

Wood mantels, being bad conductors of heat, do not themselves become over-heated, and on this account are preferable to cast iron ones, but unless they be made of well-seasoned and dried wood they are liable to crack and warp under the influence of the warmth.

Cast-iron mantels are now very popular, and are produced in tasteful designs. They are low in cost and very durable, their only disadvantage being a tendency to become heated. This may sometimes result in inconvenience, as, for instance, when the heat is conveyed by a metal candlestick to the candle and softens it, or when a piece of sealing-wax is inadvertently left upon the shelf, to be afterwards discovered as a flattened disc.

Marble, stone, slate, and such materials are for those who like them. They have no special virtues in relationship to the efficiency of the grate, and are more often than not devoid of decorative character, though sometimes of interest to the geologist.

Dr. Lee's regulating canopy, by means of which a perfect regulation of the combustion can be obtained

Removing Refractory Stoppers and Corks

An iron skewer, if manipulated carefully, will be found a good means of extricat-ing a broken cork from a bottle

A cork can be removed from the inside of a bottle by looping a piece of string round it and then drawing it upwards. The operation is easier than it appears

When drawing a cork one finger should be placed on it. as seen above. If this is done, the corkscrew will not drag through the cork

To remove a refractory stopper, loop a piece of string round the neck of the bottle and pull it backwards and for-wards. The frictional heat will cause the opening of the bottle to expand, and the stopper can be removed with ease