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R, of enameled cast iron, which empty into another bowl, S, forming the top of a down-pipe, U, of which there is one for each seat, but which, by a simple arrangement, might have been more economically made common to the three floors. These down-pipes carry the contents to a large hemispherical basin, O, of cast iron, always filled with water, in which their ends dip so as to prevent the gas from the well at the bottom from rising through the pipes. The contents run off from the basin O through the space X in the well, which is closed air-tight, and which, according to the regulations, should be provided with a pipe for the escape of gas to the top of the building.

It follows from this arrangement that the only gases which can rise to the top of the down-pipes in the closets are those which are formed in the pipes. To prevent them from entering into the closets, and at the same time to renew the air in the latter, M. L. Duvoir has connected each of the under-bowls S with a pipe, T, leading to a ventilating-chimney common to all the closets.

The draught exerted by this pipe V, increased by the use of hot-water pipes or by other means, not only removes the gas developed in the down-pipe, but it carries off from the closets, through the hole in the seat, an amount of air equal to 1,200 cubic feet or more an hour to each seat.

Arrangements similar to the preceding have been applied with success in privies with Turkish seats in building b of the Vincennes Hospital.

SINKS.

112. When sinks, intended to receive kitchen-slops, give out a bad smell in spite of the precautionary measures prescribed by the sewerregulations, or when these regulations are not or cannot be observed, this unpleasantness may be removed by means similar to those just mentioned.

DINING ROOMS.

113. In these rooms, where the steam from the dishes and the heat from numerous lights, added to that produced by the people present, cause a temperature often insupportable, it is easy to apply the rules previously given.

It will usually suffice if the air be renewed four or five times an hour, producing the draught near the floor, and making use, as will often be very easy, of the heat from the wall-brackets to give it the required force.

If the room is brilliantly lighted by many chandeliers placed over the tables, an escape should be provided for the hot gases arising from the combustion by openings in or near the ceiling.

The openings for the admission of fresh air should be placed below the former, but removed as far as possible from the people.

It will then be found, as in the case of night drawing-schools, that the general rules will have to be modified.

As examples, chosen among those which apparently offer the greatest difficulties, I select the dining-rooms of the Hôtel de Ville, Paris.

114. State dining-room.—This immense room has the following dimensions: length, 156 feet; breadth, 34 feet; height, 38 feet; cubical content, 200,000 cubic feet; floor-surface, 5,300 square feet. There are usually at dinner there 180 persons at one table 152 feet long by 13 feet wide, which gives a contour of 2 × (152 + 13) = 330 feet, and allows each guest but 1.8 feet of space.

At dinners, the number of waiters cannot be less than 60. There are therefore 240 persons in the room.

The cubical space to each person is then

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The amount of floor-surface to each person is

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Under these conditions, it is illuminated by26 chandeliers, each containing 100 candles. Table-candelabra of 6 or 7 candles each....

Total number of candles

2,600 592

3, 192

At the dinner given by the city to the Emperor on the occasion of his marriage, there were 420 persons at table. The number of waiters was at least 100; the cubical space for each person was then

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The room was lighted, on this occasion, by 26 chandeliers of 100

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Admitting that each candie develops 476 units of heat, the same as a person, the total number of units of heat developed in an hour, on that occasion, would be

(5203192) × 476 1,766,912 units.

=

Supposing that air, at a temperature of 59°, had been admitted at a height of 20 or 26 feet, and that this air, after its temperature had been raised to 950, had escaped through openings in the ceiling, every cubic foot of air introduced would have carried off

.0766 × 36 × .237 = .6536 unit.

It would then have been necessary to admit into and withdraw from the room every hour the enormous amount of—

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or 751 cubic feet a second, which corresponds to a complete renewal of the air of the room effected

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By means of chimneys extending to the roof, a velocity of discharge equal to at least 7 feet a second could have been obtained, and their sectional area and that of the openings into them would have to be 114 square feet. Supposing five of the latter to be placed in the ceiling, each would require to be 23 square feet in area.

However great the amount of air to be removed and the areas of flues may seem, there need be no serious difficulty in obtaining them.

115. Throne-room.-This room has the following dimensions: length, 94 feet; breadth, 36 feet; height, 26 feet; cubical capacity, 88,000 cubic feet; floor-surface, 3,380 square feet. It accommodates 95 guests at a table 77 feet long by 13 feet wide, having, therefore, a circumference of 180 feet, which gives each guest but 1.9 feet of space.

The number of servants is about 25. There are then 120 persons in the room.

The cubical space to each person is

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Allowing, as before, that a candle gives out 476 units of heat an hour, the same as a person, the total number of units of heat given out an hour would be

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Supposing that the air had been introduced at a height of 20 feet, and at a temperature of 59°, and that this air, after having become heated to 950, had escaped through openings in the ceiling, every cubic foot of air introduced would have carried away, as in the preceding case, .6536

It would then be necessary to admit into, and discharge from, the room every hour the amount of

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or 352 cubic feet a second, which corresponds to a complete renewal of the air of the room effected 14.27 times an hour. If the velocity of discharge reaches 6 feet a second, the total sectional area of the openings should be 54 square feet.

The amount, 1,268,000 cubic feet, is about that which can easily be withdrawn from the lecture-rooms of the Conservatory, and introduced there at a mean height of less than 20 feet without inconvenience to the audience.

116. Dining-room.-This room has the following dimensions: length, 49 feet; breadth, 23 feet; height, 25 feet; cubical capacity, 28,000 cubic feet; floor-surface, 1,120 square feet.

It accommodates 54 guests at a table 42 feet long by 10 feet wide, having therefore a circumference of 104 feet, and giving to each guest but 2 feet of table-space.

The number of servants is about 14. There are then 68 persons in the room.

The cubical space for each person is—

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Admitting the same bases of calculation as before, the total number of units of heat developed in an hour by the people and the candles will be (68+510) × 476-275,128 units,

and the amount of air to be admitted and withdrawn every hour would be

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or 117 cubic feet a second, which corresponds to a complete renewal of the air of the room effected 15.23 times an hour.

The amount, 421,000 cubic feet, is less than that which is constantly admitted into and withdrawn from the small lecture-room at the Conservatory.

Under the arrangements at present in use, it is not uncommon to find at the close of a meal a temperature of 86° without any change of air,

which is very unpleasant, and the supposition that it will be 950 near the ceiling is probably below the truth.

The three preceding examples present extreme difficulties; and it is besides evident that if the proportions referred to be adopted, it would be necessary to reserve means of regulating and of moderating, according to circumstances, the amounts of air to be admitted and carried off. For the winter season, the latter should be taken from places near the rooms where a suitable temperature can be maintained.

RECEPTION-ROOMS.

117. What has already been said in regard to dining-rooms applies equally to large reception-rooms, where many lights serve to a great extent to heat and vitiate the air.

There, as in evening drawing-schools, it will not be sufficient merely to produce a change of air proportioned to the number of persons pres ent; it is necessary at the same time to carry off the hot gases of combustion through the ceiling under the influence of the draught which they produce, and to establish at the same time if possible an outward draught near the floor, which will draw to it a part of the fresh air. The fresh air should be introduced at a considerable height, and as far as possible from the people in the room.

In such cases, it will be advisable to secure the complete renewal of the air six or eight times an hour.

Observations made at the school in the Rue des Petits-Hôtels having shown that, with an external temperature of 50° and an internal temperature of 79°, there will be produced from free openings, disconnected from any chimney, a velocity of about 3 feet a second, the surfaces of the openings to be made above may be calculated by assuming that 75 per cent. of the amount of air to be removed escapes through these openings; and that the balance, or 25 per cent., will be drawn off at the bottom, with a velocity also equal to at least 3 feet a second.

118. Application to the Hall of Marshals in the Tuileries.-This reception-room is 63 feet long, 53 feet wide, having therefore 3,340 square feet of floor-surface, and 48 feet in mean height, the cubic content being about 160,000 cubic feet. It accommodates at most six hundred people at balls, or about one person to every 5 square feet.

It is lit up on reception-days by 548 candles and by 166 lamps, (equivalent to 498 candles,) which would develop together about 500,000 units of heat an hour.*

The illumination corresponds then to

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If it is desired that the air be renewed in this hall six times, it will be necessary to admit and discharge—

6 × 160,000 = 960,000 cubic feet an hour,

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