to a comfortable degree. The additional fresh-air ducts would then be often found unnecessary, and might be closed.

The amount of air brought into the room through the openings in the ceiling was found the same day, February 7, to be equal to 60,000 cubic feet an hour, confirming the previous opinion.

The amount of foul air carried off by the ventilating-chimney was as much as 65,000 cubic feet the same day and under the same circumstances. The mean temperature in the chimney was

Thus, with this mean winter-temperature, that of 61° was maintained in the room, and, with an excess of 40° in the chimney over that of the air, almost 63,000 cubic feet of foul air was carried off, as has been stated.

The consumption of fuel an hour was—

The babies being left in the morning and taken away by their mothers in the evening, it will be sufficient, in ordinary weather, if the fires be kept up at most eight hours a day. The daily consumption will then be on a mean 10×8=80 pounds a day.

The fuel used is composed of 75 per cent. of coke and 25 per cent. of coal, and it will be estimating it above its value to charge it at $10 a ton. The expense of fuel during the winter would then be at most 80 × 10

2240

=36 cents a day, or $36 for 100 days, to obtain a change of air at the rate of 63,000 cubic feet an hour.

During the season when artificial heat is not required, the ventilating-fire alone should be used, and will usually burn not more than about 3 pounds of coal an hour, or 27 lbs. a day, for the period when the opening of windows 200 × 27 × 10 2240

will not be sufficient, or during 200 days, $24. The total annual expense would then be at most $60 for an asylum which, though intended for but 50 children, might easily receive 100 in the large wellventilated apartment, which has a content of 23,000 cubic feet, giving, in that case, 230 cubic feet for each child; while in the primary schools of Paris there is allowed, on an average, but about 155 cubic feet to each child of from 6 to 12 years of age.

Under these conditions, the ventilation of 63,000 cubic feet for 100 beds, or 230 feet a bed, an hour would be almost double what is necessary, and could easily be reduced to 42,000 cubic feet an hour. But even supposing that it be kept as it is, the mean expense for each child would be at most 60 cents a year.

It should be added that, without urging the ventilating-fire, it is easy, with the proportions adopted, to increase the amount of air removed to more than 88,000 cubic feet an hour.

In conclusion, we see from these experiments that the dimensions adopted in this first application to infant-asylums are much larger than necessary, and that the results intended have been more than realized. It may then be considered certain that in making similar arrangements, even with smaller dimensions, all requirements for good and complete ventilation will be satisfied at an expense much less than that incurred in the asylum which the parish of Saint Ambrose owes to its venerable curate, M. Langenieux.

60. Proportions for an asylum of fifty cradles.-According to the results of the experiments which have just been mentioned, and the conditions of service imposed by the regulations, the arrangements adopted by the Saint Ambrose Asylum greatly exceeding the necessities of the case, the following data may be assumed for a similar asylum: Amount of air to be carried off and replaced for 50

children, at 530 cubic feet each per hour.... For attendants and visitors...

Floor room, 164 feet to each cradle...

Total cubical contents..

26, 500 cubic feet.

8, 800 cubic feet.

35, 300 cubic feet.

812 square feet. 13 feet. 10, 600 cubic feet.

Interior height.....

Equivalent to 212 cubic feet to each cradle.

The air of the room should be changed

35300
10600

=

=33 times an hour.

The volume of air to be carried off and replaced in a second would be -9.8 cubic feet.

35300 3600

From these data, following the preceding rules in the calculation of the dimensions of openings and flues, all the expenses of founding and carrying on the establishment will be kept within narrower limits than those which have attended its first application.

PRIMARY SCHOOLS.

61. The plans adopted should be designed to carry off and replace a volume of 400 to 500 cubic feet an hour for each child.

The ventilating-openings should be placed in or against the vertical walls of the two long sides of the room. It is only in case of great constructive difficulties that they may be confined to a single side. There should be as many of them as possible, and they should have a clear cross-sectional area that will give to the air carried off a velocity of more than 28 inches a second. They should connect with descending flues leading in the cellar or under the floor to a collecting-pipe, which, in

most cases, should be carried directly to the foot of the ventilatingshaft.

The latter should be placed for its whole length beside the smoke-pipe of the heater, the heat from which will assist the draught. But this heat will not usually be sufficient to give proper activity to the draught even when the external temperature is very low, and it will be necessary to keep up a little coal-fire at the bottom of the ventilating-shaft in a grate detached from the walls.

If local arrangements prevent making the fire at the bottom, it may be made at the floor-level or at the top, keeping the ventilating-openings, however, in the vertical walls and near the floor.

The fresh air, warm or cold, should be admitted near the ceiling, and preferably parallel to its surface. In the season for fires, the air supplied by the heater should be mixed with the external cold air. The proportion of each may be regulated by means of registers easily controlled from the interior of the room, so that the mixture may have only the temperature of 85° to 95° at most.

The fresh-air openings should be arranged, if possible, along the whole length of the room, or at least be very numerous, and their section calculated so that the entering air should have a velocity of 40 inches a second, if it is directed horizontally parallel to the ceiling, or 20 inches, if it has a vertical direction.

Fig. 15.

62. Example. School in the Rue des Petits Hôtels, Paris, (Fig. 15.)-This school-building is intended for two perfectly distinct uses. The ground floor is used for the children's playroom. It is unnecessary to ventilate it, and a single stove is sufficient to warm it.

The second floor is occupied by the primary school kept by the Christian Brothers, and is divided into four rooms, intended for 400 children. The capacity of these rooms corresponds to a mean of 155 cubic feet for each child, which is about the proportion adopted by the city government, and seems to us totally insufficient; 250 to 280 cubic feet for each child appears the proper amount, especially as many schools for children are used in the evening as schools for adults.

The third floor is devoted to a drawing-school under the charge of a private professor, and contains 270 desks, of which 200 are in the main

room, which, in the evening, is lighted by 90 gas-burners. The capac ity of this room corresponds to 200 cubic feet to each person.

Ventilation in the two rooms during the day is limited to 350 cubic feet to each person, which necessitates the renewal of 140,000 cubic feet an hour in the second story and 70,000 cubic feet an hour in the third story.

The rooms are warmed by two heaters found by direct experiment to have a heating-capacity equal to 81 per cent. of the heat generated by the fuel, and having proportions corresponding to 4 square feet of heating-surface for every 1,000 cubic feet of room-area, supposed to be ventilated by a complete change of air twice an hour.

The warm air is carried to each floor by three vertical flues leading into a large and long pipe extending throughout the whole length of the rooms, which receives fresh air from without in order to regulate the temperature of the air admitted into the room. This air enters horizontally near the ceiling.

The volume of warm air, at a temperature of from 140° to 150° ascending in the flues before being mixed with cold air, was found to be, in the second story, 106,000 cubic feet an hour; in the third story, 73,000 cubic feet an hour; and this has been found sufficient to maintain in the rooms a temperature of from 60° to 70°, when that of the exterior air was 350 or 40°.

According to the instructions given to the builder, the foul air should have been carried away from the second story by thirteen flues, the proportions of which had been determined by applying the rule adopted in § 51, which fixes 28 inches a second as the velocity which the foul air should have in the first series of ventilating-flues, as indicated in the following table:

SCHOOL-ROOMS, (SECOND FLOOR,)

* Annales du Conservatoire des arts et métiers, 6e vol., p. 325.

17.4

Note. The builder actually gave smaller sectional areas to the flues; still the intended results have been secured.

In the first series of collecting-flues in each story, where the velocity is to be 39 inches a second, the sectional area should be

For the second story, amount to be renewed in 1 second = 39 cubic feet, sectional area

For the third story, amount to be renewed in 1 second =20 cubic feet, sectional area

Square feet.

12

6

In the two collecting-flues terminating at the bottom of the general ventilating-chimney, the required velocity being 4 feet a second, their total sectional area was fixed at—

The latter flues carry the foul air to the bottom of the chimney, which is 56 feet high, and has a sectional area of 11 square feet. The two smoke pipes being each 8 inches in diameter, or 2 feet in circumference, and having consequently 56×2=112 square feet of surface exposed to cooling, were not able, even in ordinary weather, to sustain the draught of the chimney, and a small auxiliary fire was deemed necessary. To this was given a surface of about 100 square inches, which, when burning 33 pounds of coal an hour, carried off, on an average, 140,000 cubic feet of air an hour in the second story, and 70,000 in the third story. If the dimensions of the ventilating-flues given to the builder had been followed instead of being reduced to 16 square feet in the second story and 8 in the third, it is evident that the amount of air carried off would greatly exceed the prescribed amount, which shows that the rules which have been given allow for even serious defects in construction.

The observations made in this building in regard to the results of warming and ventilation lead to this important conclusion, that with well-made heaters and a properly-arranged system of ventilation, schoolrooms with 350 cubic feet of air to each pupil may be comfortably warmed and ventilated by the use of no more fuel than is required for the injurious heat obtained from the cast-iron stoves used in most schools.

ADULT-SCHOOLS.

63. Similar plans should be adopted for adult-schools; the only change to be made consists in increasing to 500 or 700 cubic feet the amount of air to be carried off every hour for each person; or, in other words, to increase the size of the foul and fresh air flues.

NIGHT-SCHOOLS OF DESIGN.

64. These present a peculiar difficulty in changing the air and moderating the temperature, in consequence of the large number of lights