THE HEATING AND VENTILATION OF THE STATE HOUSE. The following letters in relation to the heating and ventilation of the State House are self explanatory. PORTLAND, May 24, 1889. Dr. A. G. Young, Secretary State Board of Health: DEAR SIR-The matter of the ventilation of the State House is an important one to the State Board of Health. The amount of suffering in the old building has been immense, and it has not been at all infrequent that I have been asked: "Can't your Board of Health devise something that will give relief?" The people seem to connect us more or less with the sanitary arrangements of the State institutions as well as an advisory Board upon local nuisances, etc., and rightly so, I think, as this is the practice in other States. While we consider ourselves experts, and possibly specialists upon certain lines, it is all the more important, especially in a matter so intricate as good ventilation, that we guard ourselves from errors. The new building itself is only ordinarily difficult to arrange for, but to plan in a manner that the old part may be provided for by the new plant, as would be the part of wisdom, requires the service of a specialist. I consider it unsafe to be guided by an interested advocate of this or that system. Professor Woodbridge is a specialist who knows the law under which good heating and ventilation may be had and would be capable of advising the State as to the system and its modifications that is applicable to the conditions to be met with. His opinion would not be warped by interest, and his experience and acquirements make him a valuable man. I think we should urge the Commission to send for him before deciding upon any particular scheme. Yours truly, E. C. JORDAN, C. E., Member of State Board of Health. MAINE STATE Board of HEALTH, | The undersigned Standing Committee on Ventilation of the State Board of Health would respectfully make the following recommendations to the State House Commissioners on the heating and ventilation of the State House. 1. The adoption of a system of heating and ventilation in which the warmed air is forced into the building and the various rooms by means of a fan. 2. The employment of a specialist to advise in regard to the plans and specifications for the application of such a system of ventilation. 3. The choice of Prof. S. H. Woodbridge of the Massachusetts Institute of Technology as such specialist. In accordance with the recommendations of the Committee on Ventilation of the State Board of Health, the State House Commissioners sent for Prof. Woodbridge to confer with them and advise in regard to the heating and ventilation of the building. The following report was subsequently made by him to the Governor, as chairman of the State House Commissioners: MY DEAR SIR:-I beg leave to present a re-statement of my opinion, informally rendered before the commissioners on Friday of last week, in regard to the heating and ventilation of the capitol. In the absence of any definite statement, either as to the nature of the plans which had been previously proposed, or as to the amount of ventilation it was desired to effect, I gave the time available before meeting the commissioners to a study of the present capitol building and also the plans of the extension. AIR SUPPLY REQUIRED.-All the rooms requiring ventilation may be classified under three heads: offices, committee rooms, and assembly rooms. To insure freshness of air in offices, including the library, I advise an air supply equal to their cubic contents once in twenty minutes. For the committee rooms I assume that provision should be made for a maximum attendance of from twenty-five for the smallest to fifty for the largest rooms, and I place 1000 cubic feet of air supply per capita an hour as the limit of safety for these rooms when full, if the danger of draughts is to be avoided. The larger per capita space in the assembly rooms makes it safe to put the rate of supply at 1500 cubic feet for each occupant per hour. Seventeen rooms in the extension require continuous ventilation, and during the sessions of the legislature nine committee rooms in the extension require ventilation, while the legislative halls are not in use, and vice versa. Adding to these such rooms in the present building as may be continuously used or devoted to committees, the air volume which a ventilating system including the entire and completed capitol should be capaple of supplying, may be stated thus: (a) for continuous ventilation, 500,000 cubic feet per hour; (b) for committee rooms, 450,000 cubic feet per hour; (c) for assembly rooms, 1,050,000 cubic feet per hour; or, since (b) and (c) are used alternately, 1,550,000 cubic feet per hour. METHOD OF SUPPLYING THE AIR.-Such a volume of air can be moved through ordinary wall flues without mechanical assistance only when the conditions of weather and of working are exceptionally favorable-as in very cold weather and by the use of large and short course flues. But the system must be able to move the air demanded though the most unfavorable conditions of weather during which artificial ventilation is called for. The general character of the building and the impractibility of carrying vertical flues of sufficient size through its interior walls for ventilation by natural currents, make the use of mechanical means advisable, if not imperative. The simplest, most effective, and economical mechanism for moving air for ventilation purposes is a properly adapted fan. The fuel required to run it is very small, if steam is used, and the exhaust steam is passed into the heating system. Furthermore, the use of a fan, because of its effect in producing rapid movement of air over the steam pipes, and the resulting increased rate of steam condensation within them, may so reduce the needed amount of heating surface as to affect a saving more than enough to meet the cost of the fan. THE VACUUM AND THE PLENUM METHODS.-The Vacuum method effects a movement of air into a room by creating a partial vacuum within it. The air then flows into the room through every available channel, both provided and accidental. Just as air supplied to a room under slight pressure will find its escape in large quantity from the room, though sealed as tight as putty, paint, paste and paper can seal it, so outside air will as freely leak into such a room when a vacuum condition is maintained within it. The undesirable results are several. 1. The inward leakage of cold outside air, settling to the bottom of the room, tends to produce a chilly floor. This in turn makes it necessary to heat the air of the room sufficiently high to bring the temperature of the floor up to the point of comfort, or a superheating of the air in the upper part of the room for the sake of comfortable warmth in the lower part. This results in a greater temperature difference between the ceiling and the floor than would exist without the inward leakage of cold air. That is, the chilly floor necessitates the maintaining of a higher mean temperature within the room for the purpose of raising the floor temperature to the point of comfort than would be otherwise required. The consequence is an increased consumption of fuel over that which would be required were the temperature uniform from floor to ceiling. This defect with the exhaust method is identical with that peculiar to and inseparable from the use of the old fashioned fire-place. It is the more defective as the climate in which it is used is colder and the maintained vacuum greater. 2. Another result attending the use of the vacuum method is that, unless all outlets including fire-places, etc., are connected with the exhaust system, the vacuum condition within the room tends to retard and to reverse the desired flow through such flues. Fireplaces are more likely to smoke, and the action of other independent flues to be weakened or reversed. 3. The source of a room's supply is not as completely under the control of the occupant as in the plenum method. The air moves from a greater and toward a lesser pressure. From whatever point, therefore, the pressure may be greater than in a room ventilated by a vacuum method, from that point it will move toward the room. A reduction of the vacuum, or what is the same thing, an increasing of the pressure in adjacent rooms or parts of the building, as by the opening of windows or the shutting of the exhaust flues taking air from them results in air movements toward the room in which the vacuum is maintained. Each room is therefore, more or less at the mercy of its surroundings, and of conditions beyond the control of its occupant. 4. Inrushing air is felt as a current by those within a room very much more than an out-rushing current of the same volume. An in-rushing current is concentrated in volume, diverging slowly, and maintaining its high velocity to a considerable distance from the point of inlet. An out-rushing current, being strongly convergent toward the outlet in its movement from every possible point of approach, becomes sensible as a draught only on near approach to the outlet. Because of the relatively large volume of air to be moved through an audience room, and the necessary energetic action of the exhausting apparatus, the vacuum within it is generally greater than that in corridors or rooms outside it, when the ventilation is by other method. The opening of doors into the corridors or lobbies is then attended by an in-rush of air. The Plenum method of ventilation on the other hand, puts each room under a slight pressure, and retards or prevents inward leakage of cold air, and renders more possible that uniformity of temperature within a room which is essential to the highest economy in the use of heat; it tends to accelerate rather than retard the flow of air through other vents, including fire-places, etc; it gives an occupant of a room control over the source of his air supply; and it results in an outward flow through open doors. For these reasons I have no hesitation in recommending the Plenum rather than the vacuum method for your use in the proposed ventilation of the capitol. The vacuum method is as much better for certain kinds of work as is the Plenum for others, as in the production of concentrated ventilated draughts through hoods, etc., or in giving direction to slowly moving air freely supplied to a building for distribution by means of corridors, stair wells and open doors. The greater vivacity sometimes attributed to air supplied by the vacuum method, if it exists at all, may be due in part to the process going on within the room of the mixing of cold inward leakage with the warmer air of the room. Monotony is as depressing as variety is refreshing. Uniformly warmed and quietly moving air at 70 degrees will doubtless have a different and less pleasing effect than bodies of air at 65 degrees and 75 degrees imperfectly mixed and in active movement. The depressing effect said by its opponents to be inseparable from Plenum ventilation is, however, more likely due to the faulty way in which the air supply is heated. METHOD OF HEATING.-If a room is heated by the ventilating air, it can be heated only when ventilated. To heat the room the air may be supplied either in large volume at low temperature, or in small |