New York SUBWAY VENTILATION HISTORY AND REMEDY i£x Safaris SEYMOUR DURST When you leave, please leave this book Because it has been said "Ever'thing comes t' him who waits Except a loaned book." Avery Architectural and Fine Arts Library Gift of Seymour B. Durst Old York Library NEW YORK SUBWAY VENTILATION (ILLUSTRATED BY DIAGRAMS) By JAMES G. DUDLEY, A. B. CONSULTING ENGINEER NEW YORK PART I HISTORY (Pages 1-24) PART II REMEDY (Pages 25-40) September I, 191 5 r CLASSES AA Copyrighted 1915 BY JAMES G. DUDLEY Consulting Engineer 50 Church St. New York Press of JOHN C. RANKIN CO. 54&56 DeySt., N. Y. \ PART I. HISTORY MEMO FROM - E. V. HALBMEIER A very trifling addition to your collection, with the regards of EVH Present "Piston" Ventilation PART L HISTORY Survey The diagrams accompanying this paper naturally do not and need not show anything other than the merest skeleton of the construction as it exists, or as it is planned to be made, nor will the attempt be made to prove all the statements herein by means of statistics as dry as the very dust in the subway, nor bulwark the technical contentions with an array of unnecessary data, as to volumes, velocities, temper- atures, etc., since, naturally, access has not been given to the figures which are possibly buried in the archives of the engineers who designed the subway. However, it is a fact that within a fortnight after the first subway was opened, on October 27th, 1904. the author made a special trip through it as it then existed from end to end with the sole purpose of studying the ventilation, or lack of it. having in mind the possibility of being able to make suggestions which might be of service. From that day to this further studies have been made and quite a large amount of data, clippings, etc.. in regard to the ventilation of the old subway and of other subways and tunnels, have been collected, there- fore, when statements are made which may seem dogmatic it is to be noted that they are made after mature deliberation and exhaustive study into the question viewed from probably every possible angle. In like manner the attempt will not be made to go into the many tech- nical sides of the broad subject of ventilation covering as it does a field which is growing wider every day owing to research by engineers, sanitarians and hygienists of eminence, who are attacking the ques- tion of what constitutes good and bad ventilation with the most modern weapons of science, and. curiously, are overturning many theories here- tofore well accepted upon this subject. It should be enough for the purpose of this memorandum to assume it as taken for granted that, from the standpoint of hygiene, efficiency, safety, comfort and even the production of profits, it is not only a desirable thing to have the subways well ventilated, but it has at last come to be a compelling neces- sity. In defence of science and modern engineering, it may be said that in those circles at least there never has been any question that the subway was not ventilated, nor that it could not be ventilated, hence it is well worth most serious consideration to find why it is that the sub- ways have not been properly ventilated, and why the proposed plans for those projected are so obviously inadequate. Possibly this introduction may seem a trifle irrelevant but in view of the fact that now. after ten years of use and experiment, proper venti- 6 Subway Ventilation lation is not incorporated in the design or operation of the subway, it will readily be conceded that we must get a proper perspective before attempting to pass upon the strictly engineering and structural features of the plans which have been tried, or those which are proposed to be tried. Diagram A Original Design Reverting now to the very inception of the first subway, attention is called to the Diagram A which shows the subway as it was origi- nally designed and built and put into commission on Oct. 27th, 1904. It may be recalled that this was done under the Rapid Transit Rail- road Commission and that it was not until some years afterwards that the present Public Service Commission took over the rights and duties which were covered originally by the Rapid Transit Railroad Com- mission. Xo sooner had the subway been officially opened to the public than strong criticism developed of the ventilation or rather lack of ventilation since, strange as it may seem, no provision therefor had been made by those responsible for the design. In passing it may be said, as far as possible, there will not be sub- mitted herein mere opinions, but when such statements are made, they are in reality quoted from official documents although in order to develop this subject in a logical and historical fashion, the authorities for the statements may not come out until well along in this paper. Technical Investigations As evidence that this public criticism was immediate and spon- taneous, it is sufficient to say that the author's studies were begun within less than a month of the opening of the subway and because of History and Remedy 7 this criticism. Incidently, because of the actual conditions, the Rapid Transit Commission and its Chief Engineer, who at that time was Mr. George S. Rice, immediately began an investigation the results of which are embodied in the formal report of the Hoard of Rapid Transil Railroad Commission for the City of New York for the year ending Dec. 31st, 1906, and published on or about Jan. 1st. 1907. copy of which is available for inspection by anyone in the Library of the present Public Service Commission at the Tribune Building. In this report on page 81 this statement appears: "The first advent of warm weather showed rather an unexpected condition of the atmosphere of the subway." Here we see that the designers proceed upon the false assumption that the subway would ventilate itself, or, in other words, that the agita- tion of the air by train movement and any excess heat of the air within the subway would be effectively provided for by egress and ingress of air through the passenger stations which perforated the tube at more or less frequent intervals. In justice to the designers it might be noted in passing, that, at that time, subways were somewhat of a novelty and this one being the first in New York, it might have been assumed that the conditions were so peculiar that results would obtain here which did not obtain in sub- ways of London, Paris and Boston. On the other hand it is quite as evident that engineers, expert in ventilating, were not called into con- sultation. Technical Reports As a result of the investigation made in the Spring of 1905 by the Commission, it was decided to call in one of the foremost sanitarians of this country, if not of the World. Accordingly Prof. Geo. A. Soper of Rensselaer Polytechnic Institute of Troy was retained by the Com- mission to make a scientific report upon the actual conditions of the subway relative to the health of the employees and the travelling public. In addition to this, the Chief Engineer of the Commission conducted certain practical investigations with his own staff, and also made a report to the Commission already referred to. It is very evident from a reading of these reports that Dr. Soper confined his investigations strictly to the scientific aspects of the matter and left the practical details fully in the hands of the Commission's Chief Engineer, Mr. Geo. S. Rice, all of which Dr. Soper takes some pains to make clear in his report. It is now necessary to anticipate the findings of these reports in order to make clear the physical conditions governing this matter of ventilation or lack of ventilation. As it was later developed, more than 85°^ of all the energy generated at the power stations of the subway is dissipated in the form of heat inside the subway itself in the stopping 8 Subway Ventilation of the trains, in the agitation of the air, in the action of the friction of the brake shoes upon the wheels, of the pounding of the wheels upon the rails and other such mechanical evidences of heat, all of which are supplemented by the heat of the electric lights and the body heat from the passengers, etc. etc. The result of all this excess heat produces a condition which, in warm weather at least, is considered by the public at large as "most uncomfortable.' ' First A Iterations By reference then to Diagram A it will be noted that the subway had been opened for probably six or eight months before any alteration or addition was made to remedy defective ventilation. While Prof. Soper was conducting his investigations, Chief Engineer Rice was beginning to make certain alterations which it was assumed would help, if they did not entirely remedy the evils complained of. From a construction standpoint then, the subway consisted of a continu- ous underground tube with a number of perforations in its envelope between the two terminals which perforations were the passenger stations, nor were there any other vent openings provided. We now find that the engineers proceeded on the assumption that by punching additional holes preferably in the covering of the subway, the excess heat would escape to the atmosphere. This could only take place if such a perforation is connected to a fan or chimney which will produce a draft and as this was not done naturally no benefit followed. In addition to this, the Chief Engineer not only suggested refrigeration of the air, but actually made quite an extensive attempt to do this at the Brooklyn Bridge station. Undoubtedly, many have noticed the fan chamber and ducts, and other evidences of this so-called refrig- erating scheme, but may not have known what it was intended for. The method followed consisted of driving a well to a considerable depth from which relatively cold water was obtained. This being pumped to the surface was sprayed through nozzles and air from the station was drawn in by fans and was forced through this mist of water and thereby somewhat cooled, whereupon the air was forced out through ducts to lower the rising temperature of the waiting passengers at the stations. When one realizes that in the old subway from the Brooklyn Bridge to Columbus Circle a length of 4J/2 miles, there is something like 27,000,000 cubic feet of air to be cooled by an amount equal to 85% of all the heat energy generated at the central stations, one does not have to be a scientist or an engineer to see the utter futility of such a scheme and the very statement of the attempt is a sufficient criticism of it. This cooling plant was completed and put into commission on Aug. 29th, 1906 (see pages 197 to 203 of the report). Prof. Soper's investigations cover a period between July 1st, 1905, and Dec. 31st, History and Hk.mf.dv 9 1905. Although he made a preliminary report on Oct. 19th, 1905, the main findings were not available for public inspection prior to Jan. 1st, 1907. Many excerpts have been made from this report giving the essentials of the investigation which can readily be verified in substan- tiation of any statement herein made. Accompanying the report to the Rapid Transit Commission by Prof. Soper was a report from Chief Engineer Rice, which contains amongst other things the following recommendations and suggestions in addition to the cutting of the open- ings already spoken of and the installation of the so-called refrigerating plant. On page 194 of the report, it was recommended that there should be a complete renewal of the contents of the subway every half hour, which means, as will be noted, the removal of 54,000,000 cubic feet of air per hour. These are very large figures, but the subject and the subway are likewise large propositions, and consequently call for large terms. That this was a very conservative recommendation is clear when it is learned that in good ventilating practice the cubic contents of a building, say of a hospital or a theatre occupied by large numbers of people, are in many cities, required by law to be changed from four to six times per hour. Installation of Fans It quickly became obvious to the engineers that the cutting of holes in the roof of the subway was not going to effect a real change of the cubic contents of the subway at all, however it might effect it in spots, hence there were installed at various points in connection with these roof openings some 25 blowers ranging from five to seven feet in diameter driven by electric motors of 15 to 30 H.P. each which com- bined were capable of exhausting from the subway fully 1,000,000 cubic feet of air per minute. The application of a little arithmetic will show that these fans would then exhaust from the subway an amount of air every hour in excess of the recommendations of the engineers, or in other words, 60,000,000 cubic feet as against the required 54,000,000 feet. Even assuming that these blowers were operated at all times at their full capacity, the question naturally arises, what results were accomplished thereby? Chief Engineer Rice on March 22d, 1906, says in his report, on page 82 that " a large part of the construction \vas completed in the Summer (1905) with the result that the subway was noticeably cooler. The refrigeration experiments were also car- ried on with satisfactory results. " If a straw vote were taken from the passengers in the subway during the Summer of 1915, it may very well be doubted that a very large majority would even at this date agree with Chief Engineer Rice in his findings. In view of the recent accident and fire in the subway, it is most significant to note that the Chief Engineer in his report on page 196 fore- 10 Subway Ventilation saw the possibility and dangers of smoke and recommended blowers for meeting such an emergency and further, on page 200, a still wiser recom- mendation was made that a separate power cable and emergency ser- vice should be provided for driving these blowers should the main power circuit be put out of commission. Prof. Soper s' Conclusions Coming now to the report of Prof. Soper, and without referring to hypertechnical details, the whole might be summed up in his "Digest of Results" in the following which appears on page 214 of the report: "For the main part the air analyzed has been that at an elevation of 18 inches to 2 feet above the pavement. This height was decided on as the most convenient and suitable after comparative tests of the air at different elevations. But few samples were taken of the air of the cars, since this was the desire of your Chief Engineer" meaning George S. Rice. This might fairly be said to be the mouse which the mountain brought forth! For, in the name of common sense, it may be asked why a few specific points, at a few specific stations, should be selected at a height of 18 inches or 2 feet above the floor, at which to determine whether the subway was or was not properly ventilated; and, why in the name of engineering and science, were but a few samples taken of the air of the cars; and why was it the Chief Engineer's desire that more should not be taken? One may ask the Rapid Transit Commission and its experts whether the public travel "on the stations" or "in the cars?" Granting that the public do use the stations, it is but for a very small percentage of the time spent within the subway, hence it is fundamental that the determination of ventilation, or lack of ventilation should be reached by an analysis of the air within the cars almost to the exclu- sion of the air at any other point. Accompanying these very volumi- nous reports will be found drawings Nos. 1 and 2 showing plans of the ventilation of the subway between the Battery and 96th St., also charts Nos. 3 and 4 showing the temperature variations within the subway; also plans of Brooklyn Bridge cooling plant. Care has been taken to bring out the essence of this report since that is the foundation from which any investigation should start. That it was not considered of small impor- tance is seen in the fact that it was followed in 1908 by the publication, through John Wiley, of a book entitled "Air and Ventilation in Sub- ways" by George A. Soper. Ph. D.. Member of American Society of Civil Engineers, Member American Chemical Society, Member of Society of American Bacteriologists, Member of the American Public Health Association. Supplementary Changes It will be noted that at the time of the submission of these reports, which were published on or about Jan. 1st, 1907, the subway had been History and Remedy 11 altered from the construction shown in Diagram A at 34 stations and 34 points between stations to that shown in Diagram B which illus- trates the perforation made in the roof of the subway in the attempt to permit the excess heat to escape by natural means. Supplementing this change there was devised the scheme shown in Diagram C consist- ing of vent chambers between stations at the sides of the subway. This was an attempt to control the inflow and outflow of the subway air by the " piston-like" action of the trains and check valves or louvres hinged in a most ingenious and elaborate fashion in the side wall of the subway. As will be noted from these vent chambers ducts connected with sidewalk gratings, the idea being that upon the approach of a train the air would be compressed in the neighborhood of these chambers and the flaps would be opened and the air would be expelled through the grating as is the case, and that when the train had gone by the air suction created thereby would pull these check valves closed and air would be drawn into the subway at the next nearest hole which would probably be at the station immediately behind the oncoming train. See title page. In theory the scheme of the louvres is most ingenious and desirable provided that the trains did in reality act as pistons within a cylinder, but such is not, and cannot be the case, inasmuch as it is clear that a local train in the compartment on the extreme right of the subway and nearest to these vent chambers would practically have to fill all four 12 Subway Ventilation compartments in order to so act. Since this is not the case there results simply an agitation of the air with some slight and casual expulsion of air through these louvres and vent chambers. Diagram D shows the so-called refrigerating plant at the Brooklyn Bridge. Cost of Fan Operation In order to get some comprehension of the initial, and operating cost of such blowers, which, according to the Chief Engineer, were operated by motors ranging from 15 to 30 H.P., it will be seen ^hat, assuming an average of 20 H.P. apiece, 500 H.P. per hour would have been required according to the Chief Engineer for removing the 60,000,- 000 cubic feet of air within the subway between the Battery and 96th St. and thereby change its cubic contents once every half hour. A very little arithmetic shows that this would amount to $120.00 for every 24 hours of continuous fan operation on the assumption of a cost $.01 per H.P. per hour. It cannot be questioned that 25 such blowers so driven Diagram C would exhaust from the subway the amount of air specified, but especial attention is called to the fact that this does not by any manner of means insure that the cubic contents of the subway "from the Battery to 96th St.," would ever be changed even once in a year — for the very obvious reason that an amount of air exactly equal to that exhausted by the fans must, and will, flow back into the subway through the openings nearest to the fans and would, unless provision be made there- for, result in short-circuiting of the air and thereby practically defeat the plan and only partially relieve the conditions at a few points. History and Remedy 13 Metallic Dust The "deposits" on the floor of the subway in Diagram E are diagrammatic representations of one of the very interesting facts which was developed by the reports referred to, namely: "That it is a matter of official information that the loss of weight in brake shoes has amounted to one ton per mile per month." The iron so ground up into powder and so deposited, or remaining in suspension in the air of the subway, probably now amounts to more than 900 tons! Obviously this metallic dust either remains in suspension to be breathed in by the passengers or is too heavy and falls to the floor of the subway there to remain until the suction of the train sets it into motion. Either of these assumptions is another strong reason for frequent and positive flushing out of the entire contents of the subway. Suggested Remedies Before one leaves this stage of the investigation, it is interesting to note that on Sept, 19, 1906, Charles S. Churchill, Member of the American Society of Civil Engineers, submitted a paper to his society upon "The Ventilation of Tunnels" which paper was discussed by Reginald P. Bolton, George S. Rice and the author himself. In this paper distinct issue is taken with the methods pursued, or not pursued, in the attempt to ventilate the subway; and reference is made to the suggestions of Mr. Churchill in 1904 preceding the opening of the sub- way, in which he called attention to the absolute necessity of employing mechanical ventilation, i.e. fan ventilation. It is worthy of note that it was in this discussion that Engineer Rice called attention to the possibility of the presence of smoke in the subway and its dangers, and that it was also in this discussion that Mr. Bolton suggested "agi- tators" within the cars — a suggestion which obviously cannot add one iota to the ventilation of the subway but merely stirs up the foul and heated air within the cars themselves. In this discussion it was also brought out that the air in the Boston subways was figured to be renewed six times per hour, or once every ten minutes, which, if duplicated in the New York subways, would unquestionably result in excellent conditions. On March 15th, 1906, Prof. Soper read a paper before the New York Academy of Medicine in which he says, in conclusion, "I should say that I think the subway as a whole is sufficiently ventilated and free from conditions injurious to health except as to presence of metallic dust, lack of sanitarv care, and conditions inseparable from overcrowd- ing." The Arnold Investigation Leaving now the subway as "ventilated" by Prof. Soper and Chief Engineer Rice, we pass over the year 1907 to Aug. loth, 1908, when, as 14 Subway Ventilation the result of the public's disagreement with the learned gentleman above quoted, Bion J. Arnold, the great electrical engineer and trac- tion expert of Chicago was retained by the Rapid Transit Railroad Com- mission to make a second report upon the ventilation or lack of venti- lation of the subway. This report is also available to any investigator, for it is in the Library of the Public Service Commission at the Tribune Bldg., but the essence of it is found in the following exact transcripts: On page 1 the statement is made that: "when the subway was originally built no special provision was made for the disposal of the accumulative heat or for its positive ventilation. " On page 7 it says: "The heat of the sub- way comes from the operation of the trains due to the fact that about 85% of the electric energy produced by the power plant which operates the road is dissipated in the subway in the form of heat. The amount of heat given off by the train operation in 24 hours in the subway between 96th St. and the Brooklyn Bridge approximates the heat liberated from burning directly in the subway two tons of coal at each of the twenty stations in this section, or a total of 40 tons during the 24 hours. The most available ways for reducing the temperature of the air in the subway are as follows: 1, Refrigeration; 2, Cooling by water; 3, Block- ing the automatic louvres open and providing additional openings; 4, Frequent air changes by means of a centre wall and train movement. Now the opposite train movements churn and whip the air producing opposing pressures and a rotating effect of the air about the train. The result is that most of the air has no definite direction of travel and remains in the subway instead of being discharged through openings History and Remedy L5 along the route. Piston ventilation would make a change of air therein at least six times per hour." However, on page 12 of his report, Mr. Arnold suggests that "4 disk fans should be installed at each station at a cost of not over $5,000. per station." Examining the different recommendations of Mr. Arnold it is clear that subway construction and operation would practically cease if it were necessary to ventilate them by means of actual mechanical "refrig- eration" predicated upon anything known to science today. As to the second recommendation that of "cooling the air" by water spray as was done at the Brooklyn Bridge, enough has already been said to show the futility of this method. The third suggestion, to "keep open the louvres" and cut additional gratings in the sidewalks and elsewhere, is equivalent to throwing away the louvres as useless and resorting to the original suggestion of Engineer Rice to punch more holes in the roof of the subway and let the agitation of the trains take the place of agita- tion for better ventilation by the people themselves. The fourth suggestion of building within the subway a "division wall" between the uptown and downtown tracks which, to quote Mr. Arnold, "would result in a change of the air in the subway once every 10 minutes," would obviously result only in an enormous additional cost without accomplishing anything whatsoever since, to be effective, the piston would have to be as wide as the two divisions instead of one-half as wide as is the case. The fifth suggestion made was that "disk fans be installed at every station, " but just how this was to change the entire contents of the sub- DlAGHAM E L6 Subway Ventilation way a definite number of times per hour was not made clear. Hence we can fairly dismiss this report with all its recommendations as again failing utterly to accomplish any step in advance. Criticisms Ignored From 1908 on there appears to have been no further attempts to ventilate the subway, as far as official documents are available to the public, and certainly the public will not claim that any change in the operating conditions have been noticed. As a result the public has suffered and from time to time voiced its complaints with no noticeable benefit. About the time of the settlement of the involved question relating to the building of new subways and extensions of the old, public criti- cism became so acute that the operators of the subway, the Interborough Rapid Transit Co., did install in the cars themselves, the "agitators," suggested by Mr. Reginald R. Bolton on Sept. 19th, 1906 — only throw- ing, literally and figuratively, more dust in the eyes of the people! V. ntilation of New Subways When on " March 19th, 1913, the City of New York by the Public Service Commission for the First District, entered into separate con- tracts with the Interborough Rapid Transit Co. and the N. Y. Municipal Railway Corp. for the construction, equipment and operation of the Dual system, " the public again lifted up its voice in protest upon the subject of subway ventilation. This protest first took shape in letters to the newspapers, editorials, comments, etc., calling attention to the conditions to which the travel- ling public seriously object and demanded from the designers of the subway the incorporation of a real remedy in the new subway. When the plans of the proposed Broadway subway, as designed by the Rapid Transit Commission, became available for public inspection, this protest took a definite form. Amongst the first to voice an organ- ized protest was the Broadway Association, who on Oct. 24, 1913, held a public meeting at the Hotel McAlpin at which many representative citizens and engineers spoke in unqualified condemnation of the plans providing for ventilation by cutting holes in the sidewalks along the route of the subway and adjacent to the retail stores. Much that has already been presented herein was brought out at this meeting which resulted in the appointment of a special committee to go further into the matter and take up consideration of the same with the proper authori- ties. The method at that time proposed by the Public Service Com- mission is shown in Diagram F and is a representation of the typical vent chambers in which the 25 blowers were installed according to the design and specifications of Chief Engineer Rice. History and Remedy 17 Diagram F Before leaving Diagram F attention is called to the extreme lia- bility of this divisional wall complicating the operation of the subway and becoming a fresh scource of danger to at least the employees who are compelled to work within the subway on foot. It will be noted that this plan is nothing more nor less than an extension and elaboration of Diagram E and the construction and scheme provided for by Mr. G. S. Rice back in 1906, and that again no real advance is made since there is omitted entirely any control of the points of admission of the air drawn in by the fans and hence there must result in consequence the " short circuit" objection to which the scheme shown in Diagram E was open. In addition to this, the holes through which these fans would discharge are the same sidewalk gratings already referred to, but to which the Broadway Association so rightfully objects even when the air is expelled only by the casual " piston-like" action of the trains. One might also ask how much more will they, and the public, object when the air is expelled by a huge blower with a powerful motor driving it? For its own guidance and protection the Broadway Association had retained as its technical adviser, Mr. Henry G. Opdycke, Consult- ing Engineer, who presented a definite alternative scheme as depicted in Diagram G. It is now in order to critically examine each of these plans in detail, for inasmuch as they are the outcome of more than ten years agitation upon this subject, and are seriously offered by engineers of undoubted ability and prominence in their respective fields, they are entitled to stand or fall strictly upon their merits. Subway Ventilation Diagram G Alternatives Analyzed Referring to Diagram F it is evident that this is in its main fea- tures only an elaboration of the first suggestion of Chief Engineer Rice with the actual complications of those suggestions, as they were carried out on the old subway early in 1906 save and except that it was proposed to incorporate into the subway design and construction a central division wall suggested by Bion J. Arnold in his report of 1908. Detailed analysis has already been made of the results which would or would not follow from the construction of such a divisional wall, and we have seen that no material benefit could result. It now develops that this divisional wall separating, as it does, the uptown tracks from the downtown tracks is actually designed and contracted for to be built with a multiplicity of openings provided for therein so as to give em- ployees ready access from one side of the subway to the other not only in the conduct of their regular work, but also in the event of emergency for themselves and passengers, and in addition to permit escape from oncoming trains. These openings are of such size and frequency, viz 2 feet wide by 7 feet high at 10 feet centers, that the divisional wall is little less than a huge grating! What possible service it could perform in even the contemplated scheme of ventilating the subway by the " piston action" of the train is almost beyond comprehension! It is possible to get some idea of the cost involved when one realizes that this divisional wall is built of concrete 10 in. thick and is some 13 ft. in height and requires forms to make the openings referred to. In addition to this, the wall in question runs the entire length of the subway, but is omitted entirely at all stations for the length of the stations, doubly emphasizing its failure to perform its intended function. Even if this were a solid and continuous wall, it could not aid in any History and Remedy 1!) material sense the subway ventilation, since the so-called "pistons" would occupy but one-half of their respective cylinders, and would therefore only agitate the air as Bion J. Arnold originally pointed out. Street Grating Drawbacks The merchants, hotel proprietors and other members of the Broad- way Association as well as the public at large to say nothing of the women of the city have made very clear certain other fundamental objections solely from the standpoint of affecting trade, such as the possible blowing of foul and heated air in the faces of intending pur- chasers who might gather in front of the stores which are to be flanked by these grated holes in the sidewalk, etc. Another very obvious objection to this scheme lies in the fact that street sweepings and all sorts of possible dirt are given entrance into the subway from which by every canon of engineering and sanitation these should be rigidly excluded. As if all these objections were not enough there develops a final objection so overwhelming that it is almost unbelievable that it could have been overlooked by the designers, or that, in not being overlooked, they have disregarded it. This is nothing else than the influx into the subway of surface waters which already have resulted within a very recent time, in four short circuits within one day in the electric power which propels the trains. Even granting that some provision has been made in the depths of the subway to get rid of such surface water, why, it may be asked, should intentional openings be provided to admit the same? As though all this was not enough, consider just for one minute the problem of scavenging these open sewers after they have been in use for any length of time! That they are nothing short of open sewers is obvious to a child, and an engineer cannot well withhold his most drastic criticism of them on that score. Contributary Defects We pass now to a study of Diagram G, the scheme suggested by Mr. Henry G. Opdycke, Engineer for the Broadway Association. As outlined in the press, and in the public meetings, this contemplates cut- ting great ducts through the side walls of the subway into, and through, the basement of abutting properties at intervals along both sides of the subway, and then erecting on private property great chimneys extend- ing well above the roofs of the surrounding buildings and discharging therefrom the contents of the subway by means of huge blowers with powerful electric motors placed at the entrance of the ducts or the base of chimneys referred to. Even granting that these installations were made midway between every station and that thereby the new subway could, and would, be perfectly ventilated, it is only reasonable to ask how the City could possibly secure the perpetual easements that would be required and pay for the enormous damages which would result to 20 Subway Ventilation owners of private property? In the judgment of at least one of the Rapid Transit Official designers: "This plan would bankrupt the City." Without indulging in any very elaborate computations it is evi- dent that each of these ducts and chimneys, even if located between each pair of stations, would necessarily have to be probably not less than 6 feet internal diameter or in the neighborhood of 8 feet external diameter! Any one who has ever paid for chimneys of such dimensions properly constructed, say of the height of even a 6 or 8 story building, can readily realize to what figure the cost would run ! If this scheme does nothing else than show the desperation to which the Broadway merchants are driven it is most valuable and instructive. Report of Realty Interests Before passing to other plans attention is called to the action taken by the Real Estate Board of Brokers who in 1913 appointed a "Special Committee on Ventilation of the Broadway Subway" who reported to the Board of Governors on Jan. 9th, 1914. The essence of this is some- what as follows: "The Public Service Engineers suggest fans instead of gratings at an estimated expense through capitalizing the cost of running and the actual outlay at approximately $100,000 and for plants between stations, 34 in all, or $3,400,000, but the actual cash outlay for these plants is not over $10,000 each, not including the cost of real estate required for the stack." In that report it showed that there were provided between the Battery and 59th St., 68 sidewalk gratings approximately 4 ft. x 200 ft. long or 800 square feet each, making a total of such openings into, and out of, the subway equal to 54,400 square feet. If one will make a mental picture of these openings some idea may be had of the extent of the troubles which must ensue in the future if this scheme is adhered to. For reasons not known, the agitation for improvement in the venti- lation of the subway lay dormant during 1914 until it was again started up about the close of December when quite an imposing group of Broad- way property owners again lodged a protest with the Public Service Commission under the guidance of Wm. R. Willcox, ex Chairman of the Public Service Commission. These interests then presented the ventilating scheme set forth in Diagram H as designed by Mr. George Hallam Clark, formerly one of the Divisional Engineers under Mr. G. S. Rice in 1906, but now no longer officially connected with the Public Service Commission. Here again we see a most drastic scheme for solving the subway problem consisting, as it does, of a series of ducts superimposed upon the roof of the subway with openings connecting into them from the History and Remedy 21 Diagram H subway. As publicly outlined, these ducts were to be joined together at intervals along the route of the subway in such open spaces as Union Square, Madison Square, Herald Square, etc., and there connect up to chimneys with fans at their bases which would probably exceed in size the hugest employed even by mining engineers. If this plan is for psychological effect upon the city authorities, it probably is well worth the time, money and energy spent upon it, but that it should have the serious endorsement of any body of Ventilating Engineers, is beyond belief! Diagram I 22 Subway Ventilation Again, granting that this plan would efficiently accomplish its intended purpose, it is fully answered by the trenchant criticism of the before mentioned official designer who calmly stated that: "The road- bed of the tracks would have to be depressed by exactly the amount required for the superimposed ducts" — hence this plan also falls by the board because of the enormous additional expense in time and money which would be involved thereby. Diagram I illustrates a condition which would exist if, and when, three partitions be erected as is the case in certain sections of the new subways. Subway Dangers and Requirements The disaster which occurred in the subway on Jan. 6th of this year with its resultant deaths and with the asphyxiation of several hundred passengers, crystallized public attention upon the subject of ventila- tion as probably nothing else could have done and has aroused a storm of criticisms from press, public and engineers which it will be hard to still until a final and real solution is found of the problem. In passing, it may be of interest to learn that one writer to the press pointed out that in the London tubes "They have put in opera- tion suitable air cleaning plants, so that 80,000,000 cubic feet of air charged with ozone is forced through the tunnel daily, 75,000 cubic feet of pure air is forced through every minute drawing an equal amount of vitiated air out." A sufficient answer may be made right here to such a suggestion by stating that if, and when, the subway is flushed out so that the contents are as fresh, and approximately as cool, as the air out of doors, the public will undoubtedly be well satisfied. It is not sufficient answer to say that "only two passengers have been killed during the operation of the subway;" nor to try and appraise in money value these lives, for, at any moment, a similar disaster may occur and blot out, not one or two, but hundreds of lives. Since there is no financial equivalent for human life, the only answer is: to provide such safeguards in the way of ventilation and security of train opera- tion that no means or method known to engineering or science shall be left untried. As though the fire was not a sufficient warning there followed on Feb. 2d, the four short circuits which again tied up the subway and startled, even if they did not endanger, the thousands of subway pas- sengers. Attention is again called to the fact that these short circuits were due to surface water reaching the 3d rail and power cables through comparatively small openings which already exist in the subway. What then, we may ask, will be the condition of the new subways when in operation with holes in the roof aggregating 54,400 square feet to let in the dirt, snow and water? History and Remedy 23 It is interesting to note that the Public Service Commission t hrough its Chief Engineer was stirred to action by the firsl accident in the sub- way and had barely announced certain changes to be made in the present subway, in order to make same safer and more reliable in operation, when the four short circuits occurred which have just been mentioned. Proposed Solution If the author had nothing more than history and criticism to present there would be little occasion for the publication of this paper. Definite recommendations and remedies for all the ills that have been specified are however embodied in the Diagrams J and K and are hereinafter elaborated. The essence of the proposed plan for ventilating the old subway, or those projected, or, as a matter of fact, for ventilating all such under- ground transportation tubes having a plurality of openings intermediate the terminals of said subway, is, in fact, to cut up such tube into short lengths and ventilate it, "piece-meal, " at it were. It should now be quite evident, that this plan, or any successful plan, must be predicated upon mechanical, i.e., fan, ventilation, assuming, as is the case, that the subway supposed to be ventilated is not a single-compartment, continuous tube, with no passenger stations intermediate the two terminals. In other words, if we have a tube with no apertures between the ends and we introduce into it a car which practically fills the tube and propel that car through the tube, necessarily the car acts as a piston and we secure more or less successful ventilation whether the tube be vertical or horizontal. Such a condition practically does obtain in the Hudson tunnels and in certain other subaqueous tubes, but we may dismiss it from consideration because such conditions do not exist in the subways which we are considering! Now, having split up our subway into small sections, the second essential requirement comes into play, viz: to absolutely control the direction, velocity and volume of the inflowing and outflowing air. Unless this is done, it is obvious that "short circuits" will result and all control of the ventilation be lost! This control can be secured in many ways, but the most feasible one for the subways, as built and projected, is to install at the various apertures in the envelope of the subway, "air- lock" doors, which permit free egress (or ingress) of passengers but, as the name indicates, effectually prevent all escape of air save through the fans. Next comes into play the trained judgment of the ventilating engineer to properly determine: the points of ingress and egress for the air; the size, type, location and motive power of the fans; and the size, type, construction and location of these "air-lock" doors. From a study of the old subway there seems to be no question that: the entire 24 Subway Ventilation contents of the subway can be exhausted just as many times an hour as is desirable, provided that sufficient power is supplied to the fans; and, further, that this can be done by controlling, say, every alternate station, or rather pair of stations, at the same general location along the axis of the subway. It is obvious that all other openings such as the gratings provided in the sidewalks, etc., would necessarily have to be closed so as to avoid the " short circuits" referred to, and thus compel the entering air to take its intended course through one set of stations and be exhausted by fans at the next adjacent pair of stations. For further data see Part II following. PART II. Subway Ventilation PART II. REMEDY The Problem Defined It must be admitted by all who are competent to speak thereon that the problem of ventilating the subways of New York is almost wholly one of cooling the air within them. Prof. Geo. A. Soper in his report upon the atmospheric conditions which existed in the first subway in 1905 made this clear; and Bion J. Arnold the great Chicago electrical engineer and transportation expert made this still clearer when he declared, as the result of his tests and computations in 1908, that fully 85% of all the energy generated at the power stations is dissipated in the form of heat within the subway. In order to give the layman an elementary illustration of just what this means Arnold further stated that this heat which was thrown off in the section of the old subway between the Battery and 96th St., was equal to that which would result from burning inside the subway of two tons of coal at every station every 24 hours or more than 40 tons daily. Geo. S. Rice, who w r as chief engineer for the Rapid Transit Rail- road Commission in 1905 which was responsible for the design of the old subway, stated in his report on the ventilation made to this Commis- sion in 1906 that this excess heat and other shortcomings would be cured by changing the air in the subway once every ten minutes or six times an hour, which, in the section referred to, would be equivalent to exhausting approximately 2,700,000 cubic feet per minute, or obviously, 162,000,000 cubic feet per hour. Every one competent to pass upon the subject of ventilation will instantly admit that this subway standard set by Geo. S. Rice and concurred in by Prof. Geo. A. Soper and by Bion J. Arnold is in con- formity with the very best practice in the ventilation of schools, hospi- tals, theatres and other such buildings occupied by large numbers of people for considerable periods of time. Without at this time, taking the pains to prove that the subways now built, now building, or hereafter to be built, would be ventilated to the satisfaction of the city, or of the operators, or of the public, even if this standard were fully carried out every hour of every day of the year, it is reasonable to take it for granted that, if the subways are com- pletely flushed out from end to end every ten minutes, the resultant conditions would be tremendously improved and the present outcry against the intolerable and dangerous conditions which now prevail, would be largely stilled. Even in 1905 Chief Engineer Rice foresaw History and Remedy 29 the possibility of, and the dangers resulting from, the presence of fire and smoke in the subway and therefore advised at least an approxi- mation of this standard and further actually installed some 25 exhaust fans which (combined) had the capacity for sucking out of the subway 1 ,000,000 cubic feet of air every minute, or sufficient to change the ent ire contents twice an hour. The recent fire, loss of life, and suffocating of hundreds of pas- sengers within the subway, are the most convincing proofs that this inevitable danger was clearly sensed even when a sufficient remedy therefor was not applied. Right here is an apparent discrepancy which, when exhaustively examined, explains, to a great extent, the uncomfortable and danger- ous conditions which still exist. "Short Circuiting" If a change of air every thirty minutes would produce comfortable and safe conditions within the subway, and if there are still installed and capable of instant operation powerful fans which are capable of flushing out that subway every thirty minutes, then only two conclu- sions can be reached. First, either the fans are intentionally not operated at all, or Second, when the fans are operated, they are so placed that even though they do literally exhaust 1,000,000 cubic feet of hot air every minute, the 1,000,000 cubic feet of cool air (which must perforce bal- ance that exhausted) is, in ventilating and engineering language, short- circuited and hence results in no material benefit to the subway as a whole. Now, whether the original 25 fans ever were operated and tested out at their combined capacity for any considerable period; or, whether they are capable of being so operated today, even from a source of power other than that for train service (as is absolutely essential for " safety first" reasons), is altogether unimportant, as will be seen. In order to ventilate the New York subway (or for that matter any other structure) a comprehensive plan or system must be designed which will produce results (calculated, and calculable, in advance) with the same absolute certainty with which a water pumping plant is installed. It should be obvious to any intelligent person, however untechnical, that, if 25 pumps of various sizes withdraw water through different sized pipes from a common reservoir (which is to be filtered and into which the pumps again discharge) the water will necessarily flow to each pump by the shortest and easiest route and in exact proportion to the size of the pump and the pipes which connect it to the reservoir. 30 Subway Ventilation Air, in this respect at least, acts exactly like water, hence it is abso- lutely necessary to know at the very outset through which inlets the air will flow into the subway (reservoir) relatively to those outlets through which the air is to be discharged. Clearly, air must flow into the subway through those inlets which are the nearest to any given discharge, or fan, outlet, and directly in proportion to the number and size of the combined inlets relatively to this single outlet. In other words, if there be 25 (fan) outlets capable of discharging the total (assumed) 1,000,000 cubic feet (or say, 40,000 cubic feet each per minute) at any assumed velocity, and if there be 250 inlets (each free to admit say, 40,000 cubic feet of air per minute at the same assumed velocity) it is self-evident that all the air discharged will flow into the subway only through those 25 inlets which are nearest to their respective fan outlets, and that the entire remaining 225 inlets (together with the sections of the subway next adjacent to them) will be valueless for the purposes of ventilating the subway, because of the "short-circuiting" already referred to. It is almost self-evident that, to prevent such " short circuiting," all openings such as existing or proposed gratings must be permanently and completely closed. Necessity of Mechanical Ventilation It might very properly be asked, why are fans at all necessary for subway ventilation? The answer is very simple and is as follows : It must be admitted by every one, as has already been assumed, that to ventilate any structure (and certainly to ventilate a subway) its entire atmospheric contents must be removed and renewed with fresher, that is cooler, air a given number of times per hour which, in the case above, is assumed to be two times. Now there are but two satisfactory, really but two known, methods of moving air, namely; thermally and mechanically. To move large volumes of air thermally at even a low velocity, there must be a very considerable difference in temperature between the air at the inlets and the outlets of the assumed structure. The difference in temperature between the air (even at the roof) of the subway and that out-of-doors is probably not more than 10 degrees Fahrenheit under the most extreme Summer conditions which difference is utterly inadequate — as the subway with its inlets and out- lets is now constructed — to produce any air movement worth a moments consideration. Increasing the velocity of the air movement by means of chimneys for outlets, even if that were within the realms of feasi- bility, would still be valueless. It must be borne in mind that the excess temperature in the subway air over that out-of-doors, even though it is actually but a few degrees History and Remedy Ml yet physiologically is comparatively great, and, being exceedingly "uncomfortable" to the average passenger, is at least "not beneficial to health" — Prof. Soper, Engineer Rice, Expert Bion J. Arnold, the Public Service Commission and the Authorities of New York to the contrary notwithstanding. Need of Safety and Comfort For ten years the public has sensed the "discomfort" but seemed not to be aware of the " danger" in the lack of air movement, until the recent disasters resulting from electrical short-circuits and fires. Now, the psychological conditions are reversed, and the insistent demand is for a " safety -first " system of ventilation. In short then, the fundamental requirements of subway ventilation are: " safety" and " comfort" for the public. To secure either or both of these requirements demands moving such volumes of air as shall at least meet the very low standard quoted above, to wit: the changing of the air of the entire subway at least twice an hour. To accomplish even this is physically impossible by the " thermal-difference " method, as was abundantly proven when an electric furnace recently raised the subway temperature to a metal- fusing point. This reasoning compels the adoption of some " mechanical" method for moving the subway air. "Piston" Ventilation The attempt has been made for ten years to ventilate the old sub- way, in part at least, by the so-called "piston" action of train move- ment and it is planned to ventilate the new subways almost entirely by the same method — which, it must be admitted, is superior to the inadequate "thermal" method since it is (at the least) "mechanical" ventilation. According to the Engineering Department of the Public Service Commission these "attempts" to ventilate the existing subway have cost upwards of $750,000.00. This plan might fairly be dismissed with the one comprehensive criticism that it becomes absolutely inoperative the very instant train propulsion ceases for any reason, and, obviously, may so become use- less at the moment when most necessary for "safety first" reasons — as in the event of fire and smoke within the subway. Without attempting to analyze the so-called "piston" ventilation in all its various forms, it is considered sufficient to admit that it might produce the assumed two air changes per hour, provided that: first, each train track should be confined in a single continuous tube without connection with any other tube; and, second, that the trains completely 32 Subway Ventilation filled the tube in which they ran. Since neither of these conditions are met in the old, or the new, subways this " scheme" should be abso- lutely disregarded. In passing, it might be well to note that in the under-water sections of some subways — such as the " Hudson tubes" where both of the above requirements are almost completely met — this so-called "piston" action has not been relied upon to produce the admittedly very excellent venti- lating results which therein obtain — but there have been installed in addition at one terminal of these tubes, powerful fans which discharge the subway air into a great chimney of considerable height. Ventilation Logic Attention is now called to the following fundamental contentions in regard to the subways of New York City as now built, as now build- ing, or as to be built: (1) Adequate mechanical ventilation of any subway is absolutely essential to safety and comfort of passengers and incidentally attracts traffic and insures profits. (2) Subways elsewhere are adequately ventilated by mechanical, that is, fan methods. (3) The subways of New York City never have been, and are not now, adequately ventilated, either on the score of passenger safety, comfort or profits. (4) The subways of New York City can be adequately ventilated by means of fans driven by electric motors taking current from a source of power other than that for train propulsion. (5) The problem of mechanically ventilating all the subways of New York City which now faces the City authorities, the Public Ser- vice Commission, the Interborough Rapid Transit Co., the New York Municipal Railway Co. and the Public — is wholly a question of which one of the many plans proposed for so ventilating the subways shall be adopted. Skeleton Specification The system herewith outlined is well and fully comprehended under the title of "sectionalized," or "piece-meal, " ventilation. Primarily this system requires (in addition to electric fans and power cables which are an inseparable part of any adequate mechanical system of ventilation) nothing more costly or complex than the specified "air-lock" doors and, either some comparatively slight additions to, or alterations of, the subway ("kiosk") entrances, or the alternative installation of light air-tight structural partitions at the station plat- forms. History and Remedy 33 All the apparatus, additions and changes would be confined wholly to the stations themselves, and, at that, would probably be installed, in general, only at alternate pairs of stations along the axis of the subways. This system neither contemplates nor requires one square foot of property not already an integral part of the subway system and is equally applicable to any of the subways now built, now building or projected — subject only to the limitations already outlined. Operation of System Taking up then this system in its broad aspects it should be readily grasped, even by the layman, that if there be installed at the various entrances of any given station, say at 18th St., four electric fans (of the proper size, type, and power capable of exhausting a certain fraction of the 2,700,000 cubic feet of air per minute which it is assumed would be necessary to adequately ventilate the old subway between the Battery and 96th St.,) and if in addition to the fans there be installed at the same entrances suitable " air-locking" doors which would permit free ingress and egress of passengers but no ingress or egress of air — then it must necessarily follow that for every cubic foot of the subway contents discharged by these fans at 18th St. an amount exactly equal thereto must flow into the subway from the next adjacent openings. In the case taken, approximately half of the fresh air would enter at the 14th St. station and the other half would be drawn in at 23d St. As already noted, all sidewalk gratings and other such intentional or chance openings would, naturally, be sealed or otherwise done away with. Now if there were a total of twenty such installations between the Battery and 96th St. there would be needed, say, one hundred such fans to exhaust the total required 2,700,000 cubic feet of air per minute. If these fans averaged 54 inches in diameter and consumed even 10 horse power each, there would be required a total of 1000 horse power hourly to adequately ventilate the entire assumed subway. If operated even 20 hours daily for 200 days in the year, and if the cost of electricity be taken at one cent per horse-power-hour, the total annual cost would be but $40,000.00 — certainly a small insurance upon the lives, health, comfort and efficiency of the subway patrons and employees ! If instead of the assumed standard of ventilation it is necessary or desirable to change the air more frequently or less frequently, or, to ventilate a subway having cubic contents ten fold that of the assumed subway — it is necessary to inform only the layman that the comparative 34 Subway Ventilation cost of operation (as between any two or more systems which will secure like results) will not vary enough to constitute a merit or a demerit to one or the other. Comparative Merits The foregoing should now be sufficient to make it clear that the comparative advantages of any proposed and adequate system may be resolved into such questions as: ease and simplicity of installation; initial cost; interest charges; maintenance; depreciation; ease of exten- sion or modification; appearance, etc. Assuming that only wholly adequate systems are being compared and that all are practically on a parity on such scores as: operating cost, durability, manipulation, ini- tial cost of fans, motors and electric cables — all further consideration of this "sectionalized" or "piece-meal" system of subway ventilation may be confined to the very practical questions of : structural changes or additions to the subway and abutting property ; and to the time and manner of installation and completion. To begin with, as has already been pointed out, all work required for the installation of this system is absolutely limited to the stations, and to approximately only half of them at that. No work whatsoever need be done in the portions occupied by the tracks, hence train move- ments could not possibly be affected either by the installation or oper- ating of, or addition to, this system. Methods of Installation It will be noted by an examination of the explanatory diagrams that either of two broad methods may be followed for the installations at the stations — the purpose and result of which is to absolutely insure against all "short circuiting" of air movement and to guarantee con- trol over the direction, velocity and volume of the air moved by the fans so that the results calculated in advance of installation shall actually take place when the equipment is operated. The first of these two methods, and the preferable one, is to install the "air-lock" doors at the entrance of the "kiosks" with the fans in the "kiosk" cowls whence they would discharge through louvres as shown in the right halves of Diagrams J and K. The second method is to erect suitable simple air-locking "bulk- heads" or partitions at the station platforms, say taking the place of the railing, etc., on the line of the ticket choppers stand. In this par- tition would be installed the specified "air-lock" doors, while the fans might also be installed in this same "bulkhead" partition, or could be located at any convenient point beyond and be connected to the parti- tion by suitable ducts. See left halves of diagrams. History and Remedy 35 A very little study of this system will make it evident that if, and when, it is desirable so to do, any number of stations may be " air- locked" and the fans omitted thereat, provided that due provision is made at the first adjacent "fan station" to handle the proportion of the air discharged which should have been taken care of at the station so "air-locked." It should now be clear that the secret, so to speak, of this system and the essential feature (which differentiates it from all others hereto- fore tried or now being proposed) is the scientific employment and loca- tion of these "air-locking " doors constituting as they do elementary simple ventilating tools of proven worth, and which, on the very face of it, guarantee control of the predetermined movement of the air and hence insure success. Initial Cost One of the greatest gains which would result from an adoption of this system would lie in the possibility of immediately stopping all the costly construction required for the proposed "piston" system of venti- lation now being carried out in the new subways. As has already been shown this so-called "piston" system is totally inadequate for safe and comfortable subway ventilation regardless of whether its cost is one dollar or several millions of dollars — as is probably the case. Even a cursory examination of the plans, specifications and actual construction of the new subways as now under way is sufficient to prove this contention. In passing it may not be amiss to point out that, to provide for this "piston" system, there is to be built in the middle of the subways, separating the uptown from the downtown tracks, a concrete wall some ten inches thick and thirteen feet high with large apertures formed therein every ten feet for free "safety" passages for the employees, and possibly for the passengers, from one side of the subway to the other. This partition is to be omitted altogether at all stations and since each train occupies but one-half the cross section of the "tube" in which it runs, and since the central partition is but a huge "grating," "short circuiting" of the air is inevitable, hence this wall can, by no stretch of the imagination, fulfill the purpose for which it is intended! In addition to this concrete wall there is incorporated in the designs and construction, the system of great concrete ducts paralleling the sub- way on both sides which, at the bottom, open into the subway, and at the top open onto the sidewalk through the iron gratings to which the public in general, and the Broadway merchants and realty interests so seriously object. 36 Subway Ventilation It might almost be said that the new subways are built around the system of " piston" ventilation, instead of including a system of ventilation in the subway construction! These ducts must prove in use to be little else than open sewers incapable of being flushed out, and in addition must admit surface waters into the bowels of the subway, with the extreme liability of causing costly and dangerous " short-circuits" to the power cables serving train propulsion, as occurred, recently four times in one day! Contributary Gains All the time, skill, labor, materials, defects and dangers involved in these constructions necessary for the " piston system" may be wholly saved by the adoption of the proposed "fan and air-lock" system! In addition to these savings the "air locking," "piece-meal" system may be installed at any time, and in the minimum time, with- out even retarding a train or a passenger. Since there is nothing whatsoever experimental about this system, and since all the results can be calculated in advance, and since its cost is certainly much below any plan suggested, it should apparently appeal to the City, the operators and the public. On the ground of a " safety-first " system alone the method proposed seems to meet every requirement for quickly exhausting any smoke which might possibly be produced in the subways. That the proposed system is a " safety -first " system, as well as adequate on the score of health, is almost self-evident when it is realized that, even if it were idle at the time of a fire, a single master electric switch at the power house could be instantly thrown into action, auto- matically or manually, thereby starting every fan at maximum capacity. This would insure, as has already been shown, the flushing out of "the entire cubic contents of the subway in ten minutes!^ Incidentally the smoke, because it is heated, would naturally rise first to the roof of the subway and it is from this level that the fans would always be drawing the strongest. Summary of Advantages The advantages of this "sectionalized," "air-locking," system of electric-fan subway ventilation may be summed up as follows: (1) Is calculable and results can be guaranteed in advance of installation. (2) Is absolute in results sought. (3) Is independent of all train movement. History and Remedy ^7 (4) Is controllable as to results secured to correspond to hourly, daily or seasonal demands. (5) Is positive since " sectionalized " into multiple units insuring against crippling of system by failure even of several motors at the same time. (()) Is economical in installation and maintenance costs. (7) Is efficient in operation since employing only apparatus espe- cially developed for its intended purpose. (8) Is cheap to operate since all cost rates are at the minimum. (9) Is an insurance on lives, comfort, health and efficiency of pas- sengers and employees. (10) Is available for all subways. (11) Is harmonious in appearance. (12) Is hygienic since unaffected by street conditions. (13) Is weatherproof since devoid of street openings. (14) Is alterable to suit changing conditions. (15) Is simple to operate. (16) Is rugged in use. (17) Is a " safety first" and an "emergency" system being operable instantly from an idle state. (18) Is divisible to meet all requirements of subway design and operation. (19) Is a final solution of the public's demands, the City's experi- ments, and the operator's obligations, throughout the ten years of plan- ning, building and operating the subways of New York City, which, when completed will, it is estimated: Comprise more than 240 miles of track, and will have Cost more than $250,000,000 and will Carry more than 2,000,000,000 passengers per Annum. 38 Subway Ventilation History and Remedy 39 1*1 1