The

above the ceiling, communicating with the ward by five openings. The former will be used for winter ventilation, the latter in summer. The ducts are of galvanized iron, or lined with that material to prevent leakage. Each ward wiil have a small propelling fan, designed to force air through the heaters and flush the ward two or three times a day. heaters are placed in the basement of each ward, along the outer walls; they consist of steam-coils. The diagram (Fig. 107) shows that the supply of fresh air is taken from out-doors; but the air of the basement (which is used for no other purpose) can in cold weather be drawn upon. The "basement" is not a "cellar," being wholly above ground.

A

B

D

D

0,00,

The Boston City Hospital (375 beds), finished in 1864, on the pavilion plan, was at first supplied with air forced through underground brick ducts, exposed to pollution. The system for the original pavilions has since been entirely changed; propulsion is abandoned, and local steam-coils are placed in air-chambers under the points to be supplied. The beneficial effect upon the health of surgical cases was shown Hospital. 4, House-wall. B, Valveby the fact that the rate of deaths from com- regulating heat, in position to give the pound fractures fell from forty-one to twenty greatest heat. D, Handles for workper cent.; after amputations, from forty-four in B and C, placed close to register to thirteen per cent.

FIG. 107.-Massachusetts General

opening through wall. C, Valve for

in ward.

Certain observations made in the new one-story wards have already been mentioned. These wards are 94 x 263 feet in the clear, and with curved roofs averaging 18 feet 5 inches in height. Each has twenty-eight beds, giving 88 square feet of floor-space, and 1,629 cubic feet of air-space to each bed. Air is introduced as in the Johns Hopkins wards, and is removed through ridgepole ventilators without traction. A general uniform upward movement is observed, with little tendency to areas of stagnation. Analysis gave the following results: mean carbonic acid, 0.0505 per cent. ; that of outside air, 0.0325; air-supply per head per hour, 3,333 cubic feet; respiratory impurity, 0.018 per cent.

The accompanying diagram (Fig. 108) gives the curve of the central axis of the hot air currents entering the room from opposite sides. It passes through points of greatest velocity, ascertained by measurements by anemometer, taken at intervals of a foot in perpendiculars erected on the points A, B, C, D, D, C, B, A, the latter being three feet apart. The drawing is to scale, and shows that the horizontal impulse is nearly expended at D, about seven feet from the floor and nine feet in from the walls. Above the height of twelve feet the general upward movement becomes sluggish, to be much quickened near the point of exit E. It is thought that the air might leave the room more quickly, with less risk of readmixture, if the ceiling were lowered to the height of at most fourteen feet.

The New York Hospital has four stories There is one window to each bed. The foul air flues are contained in the external piers, which are lined with hollow brick to prevent the escape of heat. The openings for discharging air from the wards are, partly near the ceiling, partly near the floor, and one under the middle of each bed. Hot air is conveyed by castiron tubes running through the middle of these flues, fitted so as to be airtight; but this collocation of foul and fresh air tubes seems questionable.

There is the peculiarity of two fans-one for propulsion and one for exhaust. The average air-supply is stated at 2,400 cub. ft. per bed and hour. The hall of the House of Representatives, at Washington, is supplied with air taken from a distant high tower, and passing through a tunnel. Forced in by fan-power, it enters through apertures having a total sectional area of 300 square feet on the floor and 125 in the galleries, and passes out through the ceiling. A fan was formerly so placed as to accelerate the exit, but the result was to create a partial vacuum in the hall, with a strong ten

dency of the air in the corridors to enter through the doors, bringing dis agreeable odors. This fan is now employed in aspirating from the corridors, with satisfactory results. An analysis made after three and a half hours of session, 550 persons being present, showed a proportion of 7.67 parts of CO, per 10,000.

The Madison Square Theatre, in New York City, is one of the best ventilated buildings of its class. The air is taken in at a tower above the roof; it is sifted through a conical bag of cheese-cloth, forty feet long, suspended in the tower; it is heated by steam in winter, and cooled in summer by passing over ice, four tons being required for each evening. One fan, at the foot of the tower, forces the air in; another, on the roof, exhausts it. The doors and windows are kept closed. Heating, cooling, and distributing take place in the cellar. The air is introduced by pipes, running under the risers; an opening in the riser, at each seat, discharges a forward current, with a velocity of two and a half feet per second. Other jets enter at the front of the footlights, and below the balconies. The exits are chiefly under the balconies, so that there is a general movement away from the stage. It is thought that the acoustic effect is improved by this circumstance. The footlights are ventilated into a horizontal duct, in which the gas-pipe is laid, thus heating the gas before it is burned. The great dome light, and the other gas-lights, are enclosed in glass, and ven

tilated upward. The supply is 1,500 cubic feet per hour and head; the theatre seats 650 persons.

The New York State Reformatory at Elmira contains 500 cells. A block of cells resembles a huge one-story shed, through the middle of which runs a pile of boxes, two deep and three high. The boxes represent cells. The free space near the outside walls is supplied with warm air from below; this freely enters at the grated doors of cells; the foul air passes out by two orifices in the rear wall of each cell, one of which is so arranged as to ventilate the niche for the night-pail. The foul air ducts are 4 × 4 inches, and terminate in heated chambers and aspirating chimneys in the roof. The intake of fresh air is in a tower, and a fan is used to force the current.

One of the best ventilated churches in the United States is said to be the Presbyterian Church in Fifth Avenue, New York (Dr. Hall's), which has a capacity of seating 2,000. The intake is by a tower 100 feet high, and the supply is from 10,000 to 15,000 cubic feet per minute, depending on the speed of the fan. At the lower rate of speed, and with a congregation of 1,400, the result, after a service of an hour and a half, was a proportion of 12 parts carbonic acid per 10,000. The fan, however, is continued in operation during the interval of morning and afternoon service, thus thoroughly flushing out the room. The entire basement story forms an air-chamber, from which the warmed air passes through openings in the risers of the stationary foot-benches of each pew, the supply to each pew being under the control of its occupants. The air-supply is warmed, first, by 4,410 feet of steam-pipe in the duct, just after passing the fan; second, by 9,000 feet of pipe fixed to the ceiling of the basement. The latter pipe aids greatly in warming the floor.

A plan of combined heating and ventilation has become popular in the Lake States and Canada, under the name of the Ruttan system. The proprietors profess to produce remarkable heating effects by means of large tubular cast-iron furnaces, which are said to weigh, in general, four times as much as "ordinary stoves" (their largest weighing 5 tons). Owing to their size, they are able to warm large amounts of air to a point not above 90° F. The foul air is extracted by openings in the base-boards, close to the floor, and thence passes under the floor to an exhaust-shaft heated by an iron smoke-flue. It is said that the air is changed once in half an hour or less.

The principle of induction of air-currents is applied in Gouge's ventilator. This consists of a small metal tube, heated by a gas-jet, with an open end near the floor; at a sudden enlargement, near the ceiling, a second opening is made, into which air is drawn by the inductive force of a current already established. If the tube passes through another story, other openings and enlargements are made. The principle of induction is the same that is used in the water-blasts, for ventilating mines.

Where funds are scanty, a very cheap and fit plan is to run plain straight tin pipes from some point near the floor to a point above the roof, capping them to prevent rain and wind from entering. There must be no bends, and no exposure to cold until the roof is passed. While the house is warmed, the current in such pipes is constant.

"Aspiration from above" is used in many schools and institutions. Pipes are run upward from the rooms to one large tin-lined box in the garret, which is heated by steam, and discharges through the roof. The plan is adapted to old buildings without flues, provided the pipes run straight. For dormitories, it may serve a very excellent purpose.

The small space allowed in railroad cars makes it extremely hard to ventilate them. An ordinary passenger car gives about 33 cubic feet per man; a smoking-car 50 feet. Nichols' results of analyses of air were correspondingly unfavorable, viz.: For smoking-cars, from 12.7 to 36.9 of CO, per 10,000; average 22.8. For passenger cars, lowest 17.4, highest 36.7, average 23.2.

Some cars are furnished with valve-boards at the ends, on which a notice is painted to show their use. In others, the windows are arranged so that they can be raised only a couple of inches-in the hope of protecting passengers against indiscriminate ventilation. In others, a positive ventilation is secured by valves in the monitor roof, which are regulated by the conductor with a stick.

The elevated railroads in New York warm their cars by steam pipes under the seats; each car is connected by rubber tubes with its neighbors, and the whole system is constantly supplied with dry steam from the engine, the condensed water being blown through to the rear of the train and there discharged by a vent. This does not secure ventilation.

A supply of fresh warmed air can be furnished by making use of the motion of the car to force air over the heater. The heater is inclosed in a fresh-air box at one end of the car, from which the heated air is led in wooden pipes to any part where the supply is wanted. The supply necessarily ceases when the car stops; but usually the need for ventilation also ceases at the same time.

A combination of hot-water pipes circulating around the base, and nopressure, open steam-pipes at a high level, distributes the heat effectively.

The problem of cooling the air of a sick-room in connection with ventilation was illustrated during the illness of the late President Garfield. An outside temperature of from 80° to 100° F. was to be expected. It was computed that from three to four tons of ice daily (?) would be required in order, by its melting, to cool the necessary amount of air (twelve thousand cubic feet per hour). Air was forced by an engine through an ice-box of the capacity of six tons; on leaving this the air traversed another apparatus consisting of a box 6 feet long and 27 inches square, provided with a large number of cotton screens, kept constantly wet by the water which dripped from the ice; thence it was taken to the President's room by a tin tube. To prevent the noise of the engine reaching the room, a tube of canvas was afterward substituted, when the sound entirely ceased. A 14-inch blower being found insufficient, one of 36 inches was substituted. The temperature of the entering air was found to be 55.1°, while that of the open air was 84.6°. The process, however expensive, was satisfactory in accomplishing the object desired.

In the Fifth Avenue Presbyterian Church of New York City the air is cooled in the inlet shaft by spray from a perforated pipe. When the temperature of the water was 69°, the air passing through the spray was cooled from 77° to 73°; by the use of ice the temperature has been lowered as much as six degrees.

General M. C. Meigs has experimented with window-sashes containing double thickness of glass, for the purpose of checking the loss of heat by radiation and otherwise. A thermometer placed between the panes indicates a temperature very nearly half-way between that outside and that within the room.

REMOVAL OF HOUSE-WASTE.

By EDWARD S. PHILBRICK, M.A. S.C.E., BOSTON, MASS.

THE NEED OF PROMPT REMOVAL.

THE opinion of all intelligent persons is unanimous upon this question. Nevertheless the practice of most communities is very far behind the theory. It needs no argument to convince us that it is not proper or conducive to health to allow fecal matter or organic waste in any form to accumulate, either in the interior of our dwellings, or in their immediate vicinity. Nature has given us a sense which is disgusted by such practices, and it requires no high degree of refinement to condemn them from the tribunal of good taste alone, without recourse to hygienic laws or local statistics.

It seems strange that, with such unanimity of opinion, no better devices should be used by the majority of our people than the old-fashioned privy with its vault, or the more modern water-closet with its cesspool. The former is often located within the house-walls, or under a roof connected with the house, while the latter is rarely far from the dwelling, even when the house-lot is large enough to allow it to be so.

This firmly rooted custom probably originated in the popular belief in certain supposed powers of the soil for purification and disinfection. But this belief is founded on a fallacy which we think it quite time to expose.

Soil is capable of such action only to a very limited extent, depending mostly for its efficiency upon the oxygen in the air which it holds in its pores, or upon the plant roots which may find their way into it.

When once the soil has become saturated with filth around a vault or cesspool, its purifying power ceases and can never be resumed, unless air or the roots of plants can penetrate the mass. It is evident that these agents have a very limited access to the soil around a large majority of the cesspools and vaults now in use. In cities or towns, very little if any such absorption by roots, or thorough decomposition by air in the pores of the soil, can be possible

The inevitable result, then, is an accumulation of a dangerous, putrescent mass, which would not be tolerated if it happened to be within the reach of our senses. It is certainly not the part of intelligence or wisdom. to ignore these facts simply because they do not constantly offend the eye or the olfactory nerves.

The evil influences arising from such accumulations are manifold. Wherever the water supply is drawn from wells or springs near the house, the drinking-water is liable to become infected with the germs of contagion. This may happen though the well is on higher ground than the cesspool or vault. For the supply of water is drawn from the bottom of the well, which is generally twenty feet or more in depth, and often below