Report of the 
 
 Chicago 
 
 Commission on Ventilation 
 1914 
 
 The Chicago Commission on Ventilation was 
 organized in February, 1910. 
 
Copyright, 1915 
 
 by 
 Chicago Commission 
 
 on 
 -Ventilation 
 
 v / 
 
Organization Members 
 
 Organizations having representation in the Chicago 
 Commission on Ventilation, together with a list of mem- 
 bers: 
 
 Chicago Department of Health 
 George B. Young, M. D. E. V. Hill, M. D. 
 
 Chicago Board of Education 
 
 John Wilkes Shepherd 
 
 Illinois Chapter of the American Society of Heating 
 and Ventilating Engineers 
 
 Samuel R. Lewis James H\ Da\:yP^ 
 
 H. M. Hart 
 
 - 
 
 Illinois Chapter of the American Institute of Architects 
 George Beaumont 
 
 Illinois Society of Architects 
 Meyer J. Sturm 
 
 Western Society of Engineers 
 Fred J. Postel 
 
Dedicated to one of 
 Humanity's Greatest 
 Assets Public H^Ith. 
 
Preface 
 
 The Chicago Commission on Ventilation is now in its 
 fifth year, and this is its first publication. This publication 
 appears for two reasons : 
 
 (1) In order that all members of the organizations 
 holding membership in the Commission may have a de- 
 tailed report of the Commission's work. 
 
 (2) In order to meet the requests from cities and from 
 civic and other organizations that are asking for reports of 
 the work of the Commission. 
 
 This report comprehends : 
 
 (1) A history of the organization of the Commission, 
 including a statement of its methods and working principle. 
 
 (2) A statement of some of the problems undertaken 
 by the Commission. 
 
 (3) Reports of tests made by the Commission on the 
 ventilation of passenger cars, picture theaters, an experi- 
 mental schoolroom, an office, and an experimental cabinet. 
 
 (4) The opinion of the Commission on phases of ven- 
 tilation as set forth in resolutions. 
 
 (5) An appendix containing a description (in most 
 cases an illustrated description) of the apparatus and 
 methods used in the tests made by the Commission. 
 
 The organizations holding membership in the Commis- 
 sion are sufficiently established and also sufficiently varied 
 in their purpose to bespeak the value of its findings. It is 
 but fair also to state that almost all of the resolutions em- 
 bodied in this report have been the subject of careful ex- 
 perimentation, from time to time, by members of the Com- 
 mission. 
 
Organization of the Chicago Commission 
 on Ventilation 
 
 The Chicago Commission on Ventilation was organized 
 in February, 1910. The call for the meeting at which the 
 organization was effected was made by Dr. W. A. Evans, 
 who, at the time, was Commissioner of Health of the City of 
 Chicago. In addition to Dr. Evans, the following named 
 persons were present by invitation : Messrs. George Mehr- 
 ing, W. L. Bronaugh, and Samuel E. Lewis, members of the 
 Illinois Chapter of the American Society of Heating and 
 Ventilating Engineers; Dr. F. 0. Tonney, Director of the 
 Municipal Laboratories, City of Chicago, and Mr. J. W. 
 Shepherd, from the Public Schools of the city. At this 
 organization meeting, Mr. George Mehring was elected 
 chairman, and Mr. J. W. Shepherd secretary. 
 
 A COMMISSION ON VENTILATION NEEDED. 
 
 Full and free discussion on the general subject of ven- 
 tilation was indulged in by all present at the organization 
 meeting, and some of the conclusions reached may throw 
 light on the purposes and methods of the Commission. All 
 were agreed that : 
 
 (1) In the construction of new buildings, ventilation 
 is not receiving the consideration which its importance war- 
 rants. 
 
 (2) Our present methods of ventilation are based on 
 standards which are more or less traditional and without 
 scientific foundation. 
 
 (3) All the factors which influence the ventilation of a 
 building are not understood. 
 
 (4) The importance of ventilation makes it most de- 
 sirable, if not entirely necessary, to conduct such experi- 
 
8 .-.;;;.'. .ORGANIZATION OF COMMISSION 
 
 ments as will make the practice of ventilation a branch of 
 applied science. 
 
 FIRST REPRESENTATION ON THE COMMISSION. 
 
 At the time of the organization, the Commission con- 
 sisted of delegated representation from the Department of 
 Health and from the Public Schools; also representative 
 members of the Illinois Chapter of the American Society of 
 Heating and Ventilating Engineers. Soon after the organ- 
 ization was effected, the three members who belonged to 
 the Illinois Chapter of the American Society of Heating 
 and Ventilating Engineers were authoritatively delegated 
 as representatives from their society. 
 
 FORMULATION OF OPINION. 
 
 From the beginning, it has been the custom of the Com- 
 mission to indicate progress or clarify opinion through" the 
 medium of resolutions. These resolutions are formulated 
 by the various members and reported to the Commission at 
 one of its regular meetings. Eesolutions must be reported 
 at least one meeting prior to the time of their consideration 
 and adoption or rejection. Moreover, when a resolution has 
 been adopted, it may be reconsidered at any subsequent 
 meeting. 
 
 The first resolutions were necessarily general in char- 
 acter, but aimed at fundamental principles, which must be 
 considered in the practice of all ventilation. 
 
 MEETINGS. 
 
 It has been the custom of the Commission from the be- 
 ginning to hold meetings on the first and third Tuesdays of 
 each month, throughout the year, with the exception of the 
 summer months. Call meetings, however, sometimes are 
 issued even during the vacation period. 
 
 ADDED MEMBERSHIP. 
 
 Early in the year 1911, it became evident that in order 
 to be most effective the Commission should have member- 
 
ORGANIZATION OF COMMISSION 9 
 
 ship from the Architects' organizations of the city. Ac- 
 cordingly, an invitation was extended to the Chicago Archi- 
 tects ' Business Association and to the Illinois Chapter of 
 the American Institute of Architects to appoint one delegate 
 each to be a member of the Commission on Ventilation. 
 Accordingly, Mr. W. H. Tomlinson was delegated from the 
 Illinois Chapter of the American Institute of Architects, 
 and Mr. Meyer J. Sturm from the Chicago Architects* 
 Business Association. 
 
 At the close of the year 1912, Mr. W. L. Bronaugh and 
 Mr. George Mehring found it necessary to withdraw from 
 the Commission. Accordingly, Mr. H. M. Hart and Mr. 
 James H. Davis then became members of the Commission 
 from the Illinois Chapter of the American Society of Heat- 
 ing and Ventilating Engineers. At the same time, the pres- 
 sure of outside work also compelled Mr. W. H. Tomlinson 
 to withdraw and Mr. George Beaumont became the repre- 
 sentative from the Illinois Chapter of the American Insti- 
 tute of Architects. 
 
 When Dr. George B. Young became Commissioner of 
 Health in February, 1912, he accepted membership in the 
 Commission. In January, 1912, the City of Chicago estab- 
 lished a ventilation division of the Bureau of Sanitation, 
 with Dr. E. V. Hill in charge. It was the sense of the Com- 
 mission that the city's Chief Ventilating Inspector should 
 be a member of the Commission on Ventilation, and Dr. Hill 
 became a member in July, 1912. 
 
 The Western Society of Engineers accepted represen- 
 tation in the Commission and accordingly Mr. Fred J. Pos- 
 tel became a member of the Commission in January, 1914. 
 
 THE ENLAKGED MEMBERSHIP OF THE COMMISSION. 
 
 The Chicago Commission on Ventilation, as now con- 
 stituted, is a delegated voluntary organization, composed of 
 representation from the following organizations : 
 
 Department of Health of the City of Chicago. 
 
 The Illinois Chapter of the American Society of Heat- 
 ing and Ventilating Engineers. 
 
 The Public Schools of Chicago. 
 
10 ORGANIZATION OF COMMISSION 
 
 The Illinois Society of Architects. 
 The Illinois Chapter of the American Institute of Ar- 
 chitects, and 
 
 The Western Society of Engineers. 
 
 THE COMMISSION'S WORKING PRINCIPLE. 
 
 The Chicago Commission on Ventilation believes that 
 ventilation must become an applied science and, therefore, 
 conclusions regarding ventilation must be open to revision 
 in the light of experimental evidence. 
 
The Work of the Commission 
 
 Except for the work done with the experimental cab- 
 inet, all studies and tests made by the Commission are made 
 in rooms or buildings of full size, and substantially under 
 normal conditions of use. Much criticism is sometimes of- 
 fered against conclusions drawn from studies made with 
 models or miniature structures usually housed within a 
 room. If such criticism be just, then it is fortunate that our 
 work was necessarily done in enclosures of full size and 
 built in accordance with various architectural designs. 
 
 One of the first things the Commission undertook was 
 to make a general study of the ventilation in restaurants, 
 cafes, hotel dining rooms, bakeries, printing offices, office 
 buildings, and other places in which health might be im- 
 paired because of the lack of good ventilation. Some of the 
 present ordinances in the city code are based upon these 
 studies. 
 
 From time to time, the work has become more definite 
 and intensive. The following is a statement of the main line 
 of work for the Commission during the year 1913-14 : 
 
 (1) Tests were made with different classes, of picture 
 theater buildings. These tests were made with the buildings 
 unoccupied. It was planned to make tests of an occupied 
 theater, but these tests were necessarily postponed. 
 
 (2) Tests were made with street and elevated cars. 
 
 (3) Tests with the experimental cabinet were started. 
 
 (4) It was planned to make some tests of an unoccu- 
 pied church building, but these could not be made in the 
 time which the Commission had at its disposal. It is hoped, 
 however, that within the coming year it will be possible to 
 make these tests. 
 
 Most of the reports which follow are taken from the 
 work done in 1913-14, and ^is^f airly representative of what 
 the Commission is undertaking. It is not to be understood 
 that the work done on these lines is completed. The field is 
 large and the conditions so variable that much remains for 
 the future. The value of such investigations will increase 
 in proportion to their number. 
 

 
 ^ 
 
 1 
 
 
 
 1 
 
 fe *n n 
 
 III 
 
Street Car Ventilation 
 
 The problems involved in street car ventilation must be 
 considered under two distinct headings : 
 
 (1) Those relating to cars used for interurban trans- 
 portation, such as day coaches and sleepers ; 
 
 (2) Those relating to cars used for transportation 
 within the city, as street and elevated cars. 
 
 In the former class, the speed is relatively high, the 
 stops infrequent, .and the proportion of air space to passen- 
 gers is large. With cars coming under this classification, 
 the problem of ventilation is not so serious as with the lat- 
 ter class. 
 
 With regard to street and elevated cars operating 
 within the city, these conditions are reversed. The speed 
 is relatively low, the stops frequent, and the air space per 
 passenger small; consequently the air leakage observed in 
 cars traveling at a high rate of speed is almost entirely ab- 
 sent in this class. Moreover, the leakage is further reduced 
 by modern methods of construction. The old loose window 
 sashes that rattle with the movement of the car and the 
 action of the wind have been replaced by metal sash and 
 double glass construction, and arch-roofed cars are being 
 substituted for the old monitor decks. The tendency is to 
 make these cars virtually airtight boxes and the question of 
 ventilation can no longer be left to chance. 
 
 It is to be understood in discussing the ventilation of 
 street and elevated cars we refer only to the operation of 
 such cars during that part of the year when artificial heat is 
 required. At such time, it is necessary that all windows be 
 kept closed and that the doors remain open as short a time 
 as possible. 
 
 The intramural transportation companies of Chicago 
 are operating 4,600 cars. According to the Fourth Annual 
 Eeport of the Board of Supervising Engineers, for the year 
 ending January 31, 1911, the total number of passengers 
 
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 Street Car Ventilation. Report Form. 
 
STREET CAR VENTILATION 15 
 
 carried for the period mentioned is 853,785,689, which is 
 over 2,340,000 per day. At the present writing these figures 
 can safely be increased 15 per cent. 
 
 Considering the restricted space passengers occupy in 
 surface and elevated cars, especially at the rush hours, and 
 the consequent intimate contact enforced, the necessity for 
 proper ventilation of these cars becomes apparent. 
 
 Of the total number of cars in service 4,600 3,284 are 
 operated by surface line companies, and 1,431 by the ele- 
 vated companies. Of the surface cars, 1,982 are of the old 
 monitor deck type, ventilated only by means of deck sash 
 windows; 250 are equipped with so-called automatic ven- 
 tilators, and 990 with mechanical exhaust appliances. 
 
 The Commission on Ventilation is making tests of the 
 various cars in service to determine the relative efficiency 
 of the different systems of heating and ventilating, and to 
 decide, if possible, what would be reasonable requirements. 
 
 TESTS. 
 
 In our investigations during the past two years, we 
 have endeavored to determine four important elements : 
 
 (1) Air supply, at present obtained by the various 
 methods of ventilation employed : 
 
 a By anemometer readings, 
 b By C0 2 analyses. 
 
 (2) Temperature maintained in cars in service during 
 cold weather. 
 
 (3) Dust: 
 
 a Amount, 
 b Character. 
 
 (4) Bacteria. 
 
 METHOD OF MAKING TESTS. 
 
 In determining the air supply in mechanically ventil- 
 ated cars, the following method is employed : 
 
 In one type of installation using a mechanical exhaust, 
 each car is equipped with fourteen outlet registers situated 
 in the ceiling of the car. The air is exhausted through these 
 
16 STREET CAR VENTILATION 
 
 registers into an air space between the head lining and the 
 roof, by means of a 10%-inch cone fan driven by a specially 
 designed direct connected motor. By means of a galvan- 
 ized iron tube six inches in diameter, fitted with a coarse 
 mesh wire screen at one end and a suitable fastening device 
 at the other, an anemometer is suspended at each register. 
 Test runs are made in every direction, covering a period 
 of from two to eight hours, and the average velocity of the 
 air through each register is determined. The velocity in 
 feet per minute is multiplied by the area in square feet of 
 the opening and by the number of openings, which gives 
 the C. F. M. exhausted. The results obtained in this man- 
 ner are checked by means of analyses to determine the 
 amount of of carbon dioxide when the car is in service. 
 
 For taking air samples, an ordinary Paquelin cautery 
 bulb with about sixteen inches of rubber tube is employed. 
 Four samples are usually taken at a time in an occupied car, 
 in the same manner as in theaters and other ventilation 
 work. (See appendix.) 
 
 Analyses for carbon dioxide are made to determine the 
 amount and distribution of the fresh air supply and not 
 because it in itself is considered injurious in the amounts 
 found, or that it is an indication of other organic impuri- 
 ties. 
 
 In cars equipped with automatic ventilators, an anem- 
 ometer is placed in each outlet opening. In the cases of 
 ceiling outlets, the method used is the same as just de- 
 scribed. Where the ventilators have been installed in deck 
 sash openings, the anemometer is fastened to the lower rail 
 of the deck sash. Tests are then made in a car running in 
 every direction and C0 2 analyses made as a check on the 
 anemometer readings. In cars ventilated only by deck sash 
 windows, the carbon dioxide anlyses are relied upon to de- 
 termine the air supply. In all of these tests, careful obser- 
 vations of the outside weather conditions are made, the tem- 
 perature of the air, direction and velocity of the wind hav- 
 ing a very important bearing on the efficiency of the ven- 
 tilating equipment. This is especially true of the auto- 
 matic ventilators, as the amount of air exhausted depends 
 
STREET CAR VENTILATION 17 
 
 almost entirely on the speed of the car and the direction and 
 velocity of the wind. 
 
 TEMPERATURE. 
 
 Temperature observations are made in four locations 
 within the car, at the waistline of seated passengers. 
 
 DUST. 
 
 Dust determinations are made by the filter method. 
 For this work, it is necessary to run a special car without 
 passengers, as the noise of the machine and the observa- 
 tions necessary would seriously interfere with the comfort 
 of the passengers. These tests are made for the purpose 
 of determining the effects of various intake locations on the 
 dust content, and the fact that the car is unoccupied is of no 
 importance. 
 
 BACTERIA. 
 
 Quantitative determinations of the number of bacteria 
 are made by substituting sand for sugar in the filter and 
 plating, incubating and counting the same according to the 
 method described in the appendix. Eough approximations 
 of the quantitative tests are made by exposing standard 
 Petrie dishes for two minutes in occupied cars. The method 
 of recording and reporting these various tests and observa- 
 tions is given in the accompanying charts and diagrams. 
 
 (See Charts, pages 12 and 14.) 
 
 DISCUSSION. 
 
 These observations have not been carried on for a suffi- 
 cient length of time to warrant the commission in publishing 
 conclusions. We feel, however, that the work so far merits 
 the reporting of certain pertinent observations. It is appar- 
 ent from the work done that the method of ventilating street 
 and elevated cars by means of deck sashes is very unsatis- 
 factory. In cold weather, disagreeable drafts are produced 
 when the deck sash windows are open. During rain or snow 
 
18 STREET CAR VENTILATION 
 
 storms they must of necessity be closed. With a crowded 
 car when this method of ventilation is used, repeated tests 
 have demonstrated that the air supply per person will fall as 
 low as 4 or 5 cubic feet per minute. This condition has been 
 apparent for some time to the public and to persons investi- 
 gating the question, and at the present time, the transporta- 
 tion companies have given tacit acknowledgment to the fact, 
 and are not purchasing or building cars of this typ#. The 
 next step forward was the substitution of the so-called 
 automatic ventilators. These operate on the principle of 
 the ' ' T " tube, and depend for their efficiency on the speed of 
 the car and the direction and velocity of the wind. They 
 have some features to recommend them; they are not ex- 
 pensive to install or maintain, and are always in operation. 
 The serious objection, however, to their use is that the air 
 supply cannot be controlled, since it depends entirely on 
 the velocity at which the outside air passes through the 
 device. When cars are in service in congested districts, they 
 are moving slowly and make frequent stops. They are also 
 loaded to their maximum capacity. This is the time when 
 the greatest air supply is required. Owing, however, to the 
 slow speed and frequent stops, the automatic ventilators 
 are operating at their lowest efficiency. As the car leaves 
 the congested district of the city, the number of passengers 
 decreases, the stops become less frequent, and the speed 
 becomes higher. The automatic ventilators, at this time, are 
 working at their maximum efficiency, but at a time when the 
 least amount of air is required. 
 
 The mechanical method of ventilation, by means of 
 plenum or exhaust fans, is a comparatively new proposition 
 and is being taken up by the transportation companies with 
 reluctance. Such systems are more expensive than the auto- 
 matic ventilators, require more attention, and there is a 
 slight expense for operation and maintenance. It is, how- 
 ever, perfectly apparent that up to this time an adequate 
 air supply properly distributed and under control can be 
 obtained in no other way. With mechanical ventilation the 
 amount of air required is actually supplied. No street car 
 yet placed in service in the city of Chicago has heating 
 surface of capacity sufficient to warm this amount of air. 
 
STREET CAR VENTILATION 19 
 
 This causes the real objection on the part of the transporta- 
 tion companies, to mechanically ventilated cars. 
 
 While the mechanical systems at present in use are open 
 to criticism in some details, we feel that unless great im- 
 provement is made in natural systems, for many excellent 
 reasons, mechanically ventilated cars should be required in 
 all cities. 
 
Picture Theater Ventilation 
 
 From the standpoint of methods for ventilation, the 
 picture theaters in Chicago fall into five classes or types, as 
 follows : 
 
 (1) Unventilated. 
 
 (2) Ventilated by exhaust fans only, without definite 
 provision for air supply. 
 
 (3) Theaters ventilated by exhaust fans at one end, 
 with suction air supply through tempering coils at other 
 end. 
 
 (4) Theaters ventilated by supply fans forcing air 
 through tempering coils at one end and exhausting by pres- 
 sure at the other end. 
 
 (5) Theaters ventilated by supply fans forcing air 
 through tempering coils and special distributing ducts and 
 inlets, exhausting through distributed outlets with or with- 
 out fans, temperature control, etc. 
 
 During the winter of 1913-14, the Commission has made 
 tests of several picture theaters in the city. These tests 
 were made with the theaters unoccupied. The aim was to 
 determine the general movement of air within the theaters, 
 and this could be done quite as well without the usual picture 
 theater audience. In order to produce convection currents 
 somewhat similar to those set up by the audience, standard 
 candles were placed on the seats and lighted. 
 
 Some tests were made with a candle in each seat and 
 others with candles in alternate seats. The purpose in 
 using the candles in the latter arrangement was to produce 
 approximately the same amount of heat and C0 2 that would 
 be produced by an audience. 
 
 The candles did more than merely to furnish convection 
 currents within the audience chamber as may be noted in 
 the following reports on the ventilation of typical theaters 
 under classes 2, 3, and 5. If the convection currents were 
 not interfered with by longitudinal currents, one would ex- 
 
PICTURE THEATER VENTILATION 21 
 
 pect the maximum content of carbon dioxide to be found in 
 the upper stratum or air. The facts, however, were that in 
 general the maximum carbon dioxide content did not occur 
 in the upper stratum, for the reason that longitudinal air 
 currents were found especially along the ceilings, due to the 
 general method of air introduction and removal. 
 
 The general longitudinal air movements were studied 
 by means of clouds of ammonium chloride formed from the 
 intermingling of gases or vapors from concentrated ammo- 
 nium hydroxide and concentrated hydrochloric acid. 
 
 The behavior of the general longitudinal and vertical 
 currents combined was studied by means of toy balloons 
 which were inflated with hydrogen gas and counterpoised 
 by means of weights, in order that the balloons might fol- 
 low the currents in w r hich they were placed. In some in- 
 stances it was difficult to obtain satisfactory results, be- 
 cause of the very great difference in temperature between 
 the incoming air and that which had been in the room for a 
 few minutes. This condition was particularly true in the- 
 aters in which the supply of air for ventilating purposes was 
 brought in through the doors. 
 
 It is only in the construction of recent picture theater 
 buildings that a general attempt has been made to provide 
 both inlets and outlets for ventilation purposes. Except in 
 special cases, in the older types no effort was made to pro- 
 vide either inlets or outlets. 
 
 So far as the comfort as well as the health of the the- 
 ater patrons is concerned, there needs to be required a 
 better connection between the heating and the ventilating 
 of picture theater buildings. Specifically, it is evident from 
 our investigations that the air for ventilation purposes 
 should be compelled to pass through heaters before it comes 
 in contact with the audience. 
 
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Test of Senate Picture Theater, 
 
 736 W. MADISON STREET, CHICAGO, 
 February 21, 1914. 
 
 See Plans, page 22. 
 
 TYPE. 
 
 The theater is classified under Type 3 in the introduc- 
 tion. The fan draws air through vento heaters and forces it 
 into the room. The air finds its way out through doors and 
 windows, no special outlet being provided. 
 
 SEATING CAPACITY. 
 Seats are provided for three hundred. 
 
 SYSTEM OF HEATING. 
 
 Low pressure gravity steam. Theater is supplied with 
 five (5) 100 square foot direct radiators, with 300 square 
 feet of vento for tempering the air. 
 
 SYSTEM OF VENTILATION. 
 
 Supplied by dilution under fan pressure, the fresh air 
 diluting and displacing vitiated air, the latter escaping from 
 the auditorium through the lobby and entrance doors. It is 
 possible to keep these doors open on account of the extreme 
 length of the lobby. 
 
 INTAKE. 
 
 Thirty-six-inch, circular, through roof fourteen feet 
 above alley grade. 
 
24 PICTURE THEATER VENTILATION 
 
 SUPPLY FAN. 
 
 One full housed steel plate blower with a wheel forty- 
 two inches in diameter, speed 350 R. P. M., delivering 6,000 
 cubic feet of air per minute. 
 
 INLET OPENINGS. 
 
 Two grilles about nine feet above the floor at front end 
 of theater. 
 
 EXHAUST FANS. 
 None provided. 
 
 OUTLET OPENINGS. 
 
 No special provision is made for outlets on account of 
 the peculiar construction of the building, the entrance doors 
 being continuously open and serving this purpose. 
 
 DISCHARGE OPENINGS. 
 None provided. 
 
 HEATER. 
 
 Consists of three stacks of regular forty-inch vento, 
 nine sections to each stack. At the time of the test the coils 
 were not operating properly, owing to some trouble with the 
 air valves or other connections. 
 
 TEST WITH FAN RUN NING. 
 
 ( a ) Time 9 :45 to 11 :30 a. m. 
 
 (b) Temperature Outside was plus 28 deg. F. 
 throughout test. One hundred and fifty standard candles, 
 corresponding closely in heat output to 300 occupants, were 
 evenly distributed on the seats throughout the auditorium, 
 one candle being placed on each alternate seat. These 
 
PICTURE THEATER VENTILATION 
 
 25 
 
 heated the theater from plus 60 deg. F. to plus 80 deg. F. in 
 a very short time. The temperature was very rapidly low- 
 ered as soon as the fan was turned on. (See chart on 
 plate 3.) 
 
 (c) C0 2 Test Samples were taken as marked on the 
 plans at levels of 1, 5, and 9 feet above the floor in each 
 location. The sample bulb was broken after two sets of 
 samples had been collected ; analyses of these samples, how- 
 ever, gave an average of 7.1, 8.8, and 8.2 parts of C0 2 at the 
 levels previously mentioned. 
 
 Thermometer Readings. 
 
 Fan not Running 
 
 Fan Running 
 
 
 No. 
 
 9.45 
 
 10.00 
 
 10.25 
 
 10.40 
 
 Out- 
 side 
 
 A-l 
 
 nVz 
 
 80 
 
 Q9 1 A 
 
 67 
 
 28 
 
 1-2 
 
 73 
 
 82K 
 
 69 
 
 67 
 
 28 
 
 A-6 
 
 69^ 
 
 78^ 
 
 62^ 
 
 62 
 
 28 
 
 1-6 
 
 69M 
 
 77^ 
 
 62 
 
 62 
 
 28 
 
 A-l 6 
 
 69^ 
 
 76 
 
 56 
 
 59^ 
 
 28 
 
 1-16 
 
 69J/2 
 
 78 
 
 5iy 2 
 
 60 
 
 28 
 
 (d) Ammonium Chloride Test The ammonium chlo- 
 ride was liberated at the inlet openings. It traveled the 
 length of the room in one and a half minutes. With the 
 doors open and the fan running the air became clear in ten 
 minutes. 
 
 (e) Bacteria, Relative Humidity, and Dust No tests 
 to determine the number of bacteria, the relative humidity, 
 or the number of dust particles were made. 
 
 (f) Balloon Test Standard balloons were liberated 
 at the inlet openings. The course taken by these balloons 
 indicated that a part of the fresh air currents struck the 
 projecting operator's room, turned upward and returned 
 along the ceiling towards the point of air introduction. 
 Other balloons passed underneath this projection and trav- 
 eled to the rear of the theater, indicating that probably 
 three-quarters of the air supply followed this course, trav- 
 eling the length of the auditorium, thence into the lobby and 
 out the exit doors. When the entrance doors were closed 
 some of the balloons passed backward from the inlet open- 
 ings to the projecting operator's booth and from this point 
 
2 PICTl'RE THEATER VENTILATION 
 
 descended directly to the floor line, where they remained 
 with very little movement. When the doors were opened, 
 however, these balloons passed backward to the rear of the 
 theater with a slow and uniform velocity. 
 
 DISCUSSION. 
 
 The rapid rise of temperature, due to occupants (can- 
 dles) is striking. It is also evident, from the quick drop in 
 temperature when the fan was started, that untempered air 
 cannot be introduced into a theater in cold weather, for de- 
 spite the fact that the direct radiators were all hot, the tem- 
 perature fell from 80 deg. when the fan was started to from 
 51 deg. to 69 deg., depending upon where the observations 
 were made, in twenty-five minutes. This was undoubtedly 
 due to the fact that the tempering coils were air bound and 
 inoperative. The operator's room is located in a peculiar 
 manner, being about midway between the front and rear 
 of the theater and projecting downward within ten feet of 
 the floor. (See plan.) The situation of the operator's room, 
 as described, has the effect of breaking up the air currents 
 from the inlets and makes it rather difficult to obtain proper 
 air distribution. The analyses of the air samples and the 
 behavior of the balloons, together with the ammonium chlo- 
 ride test, indicate that the air currents at the front of the 
 theater are broken up at the operator's booth. Back of this 
 point the air currents are hardly noticeable, but the air sup- 
 ply and distribution are good. 
 
 DEDUCTIONS. 
 
 The drop in temperature when the fan was in operation 
 emphasizes the fact that proper installation and operation 
 of tempering coils is imperative. It is also necessary that 
 provisions be made properly to control the temperature of 
 the incoming air. There must be provided adequate means 
 of air discharge, usually independent of the doors or win- 
 dows. In this instance, however, the peculiar construction 
 of the building, viz. : the long lobby, makes it possible to 
 utilize the entrance doors to advantage. 
 
Test of Austin Picture Theater, 
 
 5619 W. MADISON STREET, CHICAGO, ILL. 
 BY THE CHICAGO COMMISSION ON VENTILATION, 
 
 March 7, 1914. 
 
 See Plans, pages 28 and 29. 
 
 TYPE. 
 
 This theater is classified under Type 5 in the introduc- 
 tion. The fan forces air through a heater and the ducts, 
 and into the room by distributed floor inlets. The air is 
 driven out through openings in the ceiling by the fan pres- 
 sure. 
 
 SEATING CAPACITY. 
 
 Five hundred and thirty-three. 
 
 SYSTEM OF HEATING. 
 
 Furnace plenum system. The furnace is under the 
 highest part of the sloping floor. The heated air must be 
 driven down the inclined masonry ducts, against its natural 
 tendency to rise, a distance of about 75 feet to drainage 
 point, thence through balance of duct 50 feet with a slight 
 upward incline. The ducts contained from one-half to two 
 inches of ice and water at drainage points. This had accumu- 
 lated, as the building had not been in use or heated for sev- 
 eral months previous to test. There are no direct radiators. 
 The building can be heated only when the fan is in opera- 
 tion. There is danger of overheating and resultant injury 
 to the furnace if the fan is not operated when the furnace is 
 fired. 
 
 SYSTEM OF VENTILATION. 
 
 By displacement under fan pressure. The incoming air 
 is introduced into the theater through 105 six-inch mush- 
 
30 PICTURE THEATER VENTILATION 
 
 room inlet openings distributed under the seats of the the- 
 ater and the air escapes through outlets in the ceiling. 
 
 INTAKE. 
 
 From a point three feet above the roof line 2x5 feet in 
 size. 
 
 SUPPLY PAN. 
 
 One full housed steel plate blower with wheel 48 inches 
 in diameter, 378 R. P. M., delivering 15,000 C. F. M. 
 
 INLET OPENINGS. 
 
 One hundred and five in number, six inches in diameter, 
 capped with adjustable mushroom deflectors. 
 
 OUTLET OPENINGS. 
 Four, 30-inch in diameter, located in the ceiling. 
 
 EXHAUST FAN. 
 None provided. 
 
 DISCHARGE OPENINGS. 
 Same as outlet openings. 
 
 HEATER, 
 
 One No. 80 Harrison air tube furnace. This is a coal 
 burning firebox below a series of horizontal iron tubes, 
 through which the air is forced by the fan. The heater con- 
 tains 64 four-inch tubes. 
 
 TEST WITH FAN RUNNING. 
 (a) Time 11 :30 a. m. to 1 :30 p. m. 
 
PICTURE THEATER VENTILATION 
 
 31 
 
 (b) Temperature The outside temperature was plus 
 33 deg. F. throughout the test. Two hundred and sixty 
 standard candles, corresponding nearly in heat output to 
 533 occupants, were distributed on alternate seats. Tem- 
 peratures noted at various times and at different points are 
 indicated on the plans. Thermometer stations shown by 
 "T" were five feet above the floor. Thermometer stations 
 in the supply ducts are shown by 1-2-3, etc. The tempera- 
 ture of heated air at the furnace was in excess of plus 210 
 deg. F., the limit of the thermometer. It was probably as 
 high as 400 deg. F. The tubes of the furnace became red 
 hot, as did the breeching. 
 
 (c) C0 2 Tests Samples were taken at "A," "B," 
 "C," etc., marked on the plans, at levels 1, 5, and 9 feet 
 above the floor. These samples were unsatisfactory, due 
 to some mistake in technique. 
 
 Station 
 
 11.53 
 A.M. 
 
 12.25 
 P.M. 
 
 12.55 
 P.M. 
 
 1.15 
 P.M. 
 
 1.30 
 P.M. 
 
 1.45 
 P.M. 
 
 Air Vel. 
 
 Duct Stations 
 
 1 
 
 40 
 
 54 
 
 60 
 
 63 
 
 65 
 
 72 
 
 580 
 
 2 
 
 39 
 
 54 
 
 65 
 
 69 
 
 70 
 
 72 
 
 464 
 
 3 
 
 38 
 
 55 
 
 61 
 
 67 
 
 67 
 
 64 
 
 430 
 
 4 
 
 39 
 
 84 
 
 100 
 
 103 
 
 111 
 
 111 
 
 650 
 
 5 
 
 39 
 
 111 
 
 128 
 
 135 
 
 141 
 
 144 
 
 770 
 
 6 
 
 39 
 
 110 
 
 130 
 
 138 
 
 140 
 
 142 
 
 820 
 
 7 
 
 39 
 
 108 
 
 124 
 
 130 
 
 138 
 
 142 
 
 830 
 
 [House Stations 
 
 A 
 
 36 
 
 46 
 
 52 
 
 58 
 
 61 
 
 63 
 
 
 B 
 
 37 
 
 50 
 
 56 
 
 63 
 
 66 
 
 67 
 
 
 C 
 
 37 
 
 54 
 
 58 
 
 64 
 
 67 
 
 68^ 
 
 
 D 
 
 37 
 
 54 
 
 58 
 
 65^ 
 
 68 
 
 70 I 
 
 E 
 
 39 
 
 56 
 
 64 
 
 71 
 
 74 
 
 76 
 
 
 F 
 
 38 
 
 56 
 
 64 
 
 74 
 
 74 
 
 77 
 
 
 (d) No ammonium chloride test was made. 
 
 (e) Bacteria, Relative Humidity, and Dust Tests to 
 determine the number of bacteria, the number of dust par- 
 ticles, and the relative humidity were not made. 
 
 (f) Balloon Test The standard balloons were lib- 
 erated at various points in the theater; first, at about four 
 feet above the floor, along the front row of seats nearest the 
 stage. These balloons took a uniform course backward over 
 the tops of the seats, moving at a very slow velocity. They 
 would usually gain a position in the aisle and pass back- 
 ward to the low point of the auditorium at about 40 
 
32 PICTURE THEATER VENTILATION 
 
 feet from the stage. Here they would rise vertically to 
 within three or four feet of the ceiling, pass forward to 
 the stage and down again to the point where liberated. One 
 balloon, it was noted, made this excursion six times. At the 
 end of the sixth circuit, it escaped into the large ceiling vent. 
 Some of the balloons, if they succeeded in passing this cen- 
 tral point in the theater, traveled backward toward the rear 
 at a uniform low velocity, showing a continuous preference 
 for the aisles. 
 
 (g) Anemometer Test Anemometer readings are 
 marked on the plans. The mushroom deflectors were re- 
 moved for temperature and anemometer readings No. 1 to 
 No. 7. 
 
 DISCUSSION. 
 
 The theater is architecturally handsome, but the con- 
 struction and arrangement of its heating plant is unfortu- 
 nate. The roof slab forms the ceiling without any insulat- 
 ing space. The distributing ducts are wet, rough, and in- 
 cline downward from the furnace to the central point, and 
 then slightly upward to the stage end of the theater. Ap- 
 parently no attempt had been made previous to test to 
 equalize the air distribution by means of proper adjustment 
 of mushrooms. After three hours of continuous operation, 
 in order to maintain a temperature of plus 64 deg. at the end 
 of the theater nearest the stage, which is farthest situated 
 from the heating plant, the end nearest the heater was 
 warmed to plus 80 deg. F. The owner evidently intended 
 to secure a high-grade ventilating system, which embodied 
 provision for reasonable air distribution and a uniform tem- 
 perature. The cold ceiling, the wet ducts, and the improper 
 location of the heater all combine to defeat this end. 
 
 DEDUCTIONS. 
 
 An underground masonry duct must at all times be dry. 
 The ducts must be well proportioned. In systems of this 
 type, they should not run downward from the heater, owing 
 to the inherent difficulties in heat distribution. They must 
 be carefully tested and the delivered air must be thoroughly 
 
PICTURE THEATER VENTILATION 33 
 
 equalized. When starting the heating plant in a cold the- 
 ater, equipped with masonry ducts, sufficient time must be 
 given to warm the ducts thoroughly. It is improper for 
 ventilating purposes to heat even a small quantity of air to 
 a high temperature. The air supply should be large in vol- 
 ume and comparatively low in temperature if good results 
 are to be obtained. The ducts must never be heated to such 
 extent that the introduction of air at a temperature lower 
 than the air in the room is prevented. The incoming air 
 must be cooler than the air in the room to prevent an^excess 
 temperature when a large percentage of seats is occupied. 
 Some local means of heating at the end farthest from the 
 heating plant seems desirable. Such wide variation of 
 temperatures as were found here is most objectionable. 
 There should be simple and efficient mixing dampers at the 
 furnace so that part or all of the air may be by-passed 
 around the heater as requirements indicate. Perfect drain- 
 age of ducts is of vital importance. 
 
Test of Bell Picture Theater, 
 
 2407 W. MADISON STKEET, CHICAGO, ILL. 
 January 10, 1914. 
 
 See Plans, page 35. 
 
 TYPE. 
 
 This theater is classified under Type 2 in the introduc- 
 tion. Exhaust fans draw the air out. It is supposed to 
 enter through doors and windows and two openings pro- 
 vided at the floor line in the opposite end of the theater. 
 
 SEATING CAPACITY. 
 Three hundred and fifty. 
 
 SYSTEM OF HEATING. 
 Low pressure gravity steam with direct radiators. 
 
 SYSTEM OF VENTILATION. 
 
 Exhaust, by dilution. No special provision has been 
 made for heating the entering air. 
 
 INTAKE. 
 
 No special provisions made for intake. Air must gain 
 entrance through lobby doors. Two 20x36-inch openings in 
 the floor at the rear of theater, allowing some air to enter 
 from the lobby. 
 
 OUTLET OPENINGS. 
 Directly to fan placed in the rear wall. 
 
IF 
 
 IB 
 
 
 r trt4lb,*J0 ~S 
 I99*S rfrzf' 
 
M PIC TURK THEATER VENTILATION 
 
 EXHAUST FANS. 
 
 Two 24-inch propeller type fans situated in the front 
 wall of the theater, one on either side of the stage ; capacity, 
 about 4,000 C. F. M. each. 
 
 DISCHARGE OPENINGS. 
 
 Two 36-inch roof ventilators are provided. These were 
 closed at the time of test. The fans discharge directly to the 
 outer air. 
 
 HEATER. 
 
 TEST WITH FANS RUNNING. 
 
 (a) Time 11 :30 a. m. to 1 :00 p. m. 
 
 (b) Temperature The outside temperature was plus 
 27 deg. F. One hundred and seventy-five standard candles, 
 corresponding nearly in heat output to 350 occupants, were 
 distributed throughout the theater, one being placed in 
 each alternate seat. The various temperatures noted are 
 marked on the plans. The direct radiators were hot. 
 
 (c) C0 2 Test Samples of air were taken at points 
 one-third, one-half, and two-thirds of the distance from the 
 entrance to the stage of the theater, at levels of 1, 5, and 9 
 feet from the floor. The averages at the one-foot level were 
 7.2 ; at the five-foot level 7.3 ; and at the nine-foot level 6.9 
 parts of C0 2 per 10,000 parts of air. 
 
 (d) Ammonium Chloride Test This was made with 
 the doors open and both fans operating. It required ten 
 minutes to clear the air in the room. 
 
 (e) Ammonia Test Standard Shepherd phenolphtha- 
 lein cartridges were placed as marked on the plans about 
 five feet from the floor. Ammonia was introduced at the 
 entrance. The cartridges showed no reaction. 
 
 (f ) Bacteria, Eelative Humidity, and Dust No tests 
 to determine the number of bacteria or of dust particles, and 
 no relative humiditv observations were made. 
 
PICTURE THEATER VENTILATION 37 
 
 (g) Balloon Test Standard balloons were released: 
 No. 1 from an open door. This passed along the floor, down 
 the aisle, and stopped after traveling half way to the stage. 
 No. 2 traveled the entire length of the theater at the floor 
 line in the aisle in thirty seconds. No. 3 followed the course 
 of No. 1 to the center, then rose to the ceiling and moved 
 slowly towards fan " L, " stopping permanently about thir- 
 ty-five feet from the fan at the ceiling. No. 4 and several 
 others were released near the entrance doors when the lat- 
 ter were closed. The balloons moved very slowly, some- 
 times in the aisles and sometimes under the seats, to about 
 the center of the theater ; they remained at the floor line. 
 No. 5 and several others were released in the center of the 
 length of the theater at the sides, with the doors open. They 
 moved toward the exit end about twenty feet and stopped at 
 the floor. 
 
 DISCUSSION. 
 
 In order to ventilate this theater to any appreciable 
 extent, it was necessary for the entrance doors to be open. 
 The theater could not be heated with the doors open. The 
 air movement was sluggish when the doors were closed. 
 With the candles and radiators in operation, the tempera- 
 ture rose to only plus 61 deg. F., when the outside tempera- 
 ture was plus 27 deg. F. Evidently the room cannot be 
 heated adequately in zero weather with the fans operating. 
 The incoming fresh air if cold tends to create drafts along 
 the floor, as indicated by the balloon tests. This incoming 
 air, if at a low temperature, travels at the floor line until it 
 has passed about half the length of the theater, when it be- 
 comes broken up and mixed with warm inside air. From 
 here it rises and takes a more or less direct course toward 
 the exhaust fans. 
 
 Another interesting observation was that the air cur- 
 rents, as indicated by the balloons, tended to follow closely 
 and be confined to the limits of the aisles. 
 
 The analyses of the air samples indicate that about 
 1,500 cubic feet of air were being supplied per person per 
 hour in the breathing zone. 
 
38 PICTURE THEATER VENTILATION 
 
 DEDUCTIONS. 
 
 It is necessary that adequate air inlets properly located 
 be provided. Provision must also be made for properly 
 regulating the temperature of the incoming air. No ventila- 
 tion of any value is in effect when the doors are closed, 
 cold drafts, as well as operative conditions, militate against 
 the doors being left open continuously in cold weather. 
 
 In systems of this type, it is very important that the 
 temperature of the incoming air be controlled, as the cold 
 air will follow the floor and create objectionable drafts. If 
 the air is too warm, it will rise to the ceiling and pass over 
 the breathing zone. 
 
An Experiment in Ventilating 
 ^ a School Room 
 
 One of the first experiments determined upon by the 
 Chicago Commission on Ventilation pertained to the ventil- 
 ation of a schoolroom. For a long time many of the teach- 
 ers of the public schools of Chicago complained of the ven- 
 tilation within their rooms. Therefore, with the hearty 
 approval and co-operation of the Board of Education, the 
 experimental work was undertaken in the autumn of 1910. 
 The attitude of the Board of Education has always been to 
 improve the present system of mechanical ventilation within 
 our public schools, if possible. All expenses in connection 
 with the experiments on schoolroom ventilation are gladly 
 borne by the Board of Education. 
 
 The public school buildings of Chicago are equipped 
 with the plenum system, operating at a pressure of approxi- 
 mately one-half ounce. 
 
 PLACE OF EXPEBIMENT. 
 
 The Chicago Normal College, Sixty-eighth street and 
 Stewart avenue, Chicago. 
 
 TIME OF EXPERIMENT. 
 
 The experimental work has continued from the autumn 
 of 1910. 
 
 QUANTITY OF AIR. 
 
 The first tests made were somewhat in the nature of 
 checking up the worfc of the builders. A rule of the Board 
 of Education requires the delivering of a minimum of 1,800 
 cubic feet of air per pupil per hour. Anemometer readings 
 made in several of the rooms of the Normal College showed 
 thru it was being delivered. There remained, 
 
40 VENTILATING A SCHOOL ROOM 
 
 however, a closely related question : namely, whether or not 
 each pupil is supplied with his share. 
 
 DISTRIBUTION OF AIR. ^ 
 
 Studies were made for air currents in two classrooms 
 and one laboratory room. 
 
 DEVICES USED. 
 
 The tests for air currents were made by the use of toy 
 balloons which were inflated with hydrogen gas and coun- 
 terpoised in the rooms by means of improvised weights. In 
 addition to the toy balloons, small turbine wheels were used. 
 These were made from aluminum, cork, and steel needles, 
 and were especially constructed for these tests. The blades 
 of the turbines were made from aluminum and set into hubs 
 of cork. Across one end of a cork hub and parallel with the 
 plane of the blades, was fastened a strip of aluminum con- 
 taining a slight indentation in which the pivot of the device 
 turned. The fine point of a steel needle served as a pivot, 
 and when ready for use the turbine revolved in a horizontal 
 plane. These turbines are very sensitive to vertical cur- 
 rents of air in fact, they respond to convection currents 
 from the heat of one's hand. The counterpoised balloons 
 were useful in tracing all air currents, irrespective of their 
 direction, whereas the turbine wheels could be used only in 
 testing for vertical currents. 
 
 TESTS FOR AIR CURRENTS. 
 
 One of the classrooms tested is 25 by 25 feet and has an 
 east exposure. The other walls of the room have no imme- 
 diate contact with the outdoors. The inlet and outlet ducts 
 in this room are installed in the north wall, and the air en- 
 ters the room with a velocity of about 650 feet per minute. 
 When balloons were pushed into the entering currents, they 
 were hurried across the room near the ceiling to the south 
 wall. From the ceiling at the south wall, the balloons usu- 
 ally took one of two general courses, depending largely upon 
 
VENTILATING A SCHOOL ROOM 41 
 
 outdoor weather conditions. If the outdoor temperature 
 was low and the wind was blowing directly against the win- 
 dows, then the balloons moved over to the outside wall, 
 down the wall or windows, and over to the outlet duct. If 
 the outside temperature was moderate, then instead of the 
 balloons crossing over to the outside wall, they were likely 
 to poise in the southeast corner of the room, or possibly 
 move vertically down along the wall opposite the inlet duct 
 to within a foot or two of the floor, and then over to the 
 outlet duct. It was very noticeable that air currents estab- 
 lished themselves in aisles and other open spaces along the 
 floor. During the winter season the turbine wheels, when 
 placed on the window ledges, revolved almost all the time. 
 Their direction of rotation indicated the downward move- 
 ment of a sheet of cold air ; moreover, this sheet of cold air 
 was very perceptible to any one seated near the outside 
 wall or windows. 
 
 The other classroom is 26 by 45 feet; is a northwest 
 corner room. It has about twice as much exposure on the 
 north as on the west side. As already stated, there are two 
 inlets and two outlets in this room, and they are located in 
 the long inside wall. The velocity of the incoming current 
 of air was practically the same as in the smaller room. 
 Anemometer readings showed an adequate supply of air 
 for good ventilation. Balloons placed in the incoming cur- 
 rent were hurried across the room to the opposite wall, the 
 outside wall with the north exposure. After reaching the 
 outside wall, they almost always went vertically downward 
 to within a foot or two of the floor ; then they moved over to 
 the outlets near the floor and almost directly under the in- 
 lets. The hot incoming air driven against the cold outside 
 north wall and windows, reduced the influence of wall and 
 window chill. But in cold weather, especially with a north 
 or northwest wind, a downward moving sheet of cold air 
 was very noticeable. The small turbine wheels revolved 
 constantly in cold weather when placed upon the window 
 ledges or near the exposed walls. In the central part of the 
 room, that is, between the two sets of inlet and outlet ducts, 
 the balloons did not show perceptible air currents. Fur- 
 
42 VENTILATING A SCHOOL ROOM 
 
 thermore, there seemed to be eddies in close proximity to 
 the currents at either end of the room. 
 
 The laboratory room in which the tests for air currents 
 was made is 26 by 45 feet, and is a northeast corner room. 
 It has about twice as much exposure on the north as on the 
 east side. The room has two inlets and two outlets on the 
 long inside wall. The inlet duct at the west end of the room 
 is so close to the west wall and ceiling that when the current 
 of air is delivered against the north or outside wall, it takes 
 a diagonal course downward and inward along the north 
 wall, and across the windows. By this action of the air cur- 
 rent shown by balloon tests, there is a considerable section 
 of the west end of the room in which no perceptible air cur- 
 rents can be found. At the east end of the room, the air 
 current behaves as might be expected, namely, the incoming 
 air crosses from the south to the north end of the room 
 along the ceiling, strikes the cold outside wall and windows, 
 drops vertically downward, and moves over to the outlet. 
 Turbine wheels placed near the windows or outside wall 
 during cold weather were constantly rotating. The direc- 
 tion of rotation indicated a downward current of air. 
 
 CONCLUSION. 
 
 From the evidence obtained in the use of the balloons 
 and turbine wheels, it is fair to conclude that air within the 
 schoolrooms tested did not act as anticipated in the plenum 
 system. Moreover, the action of the balloons and turbine 
 wheels under varying weather conditions, especially as re- 
 gards direction and velocity of winds, warrants the conclu- 
 sion that in the type of construction with which we were 
 concerned, air distribution is seriously interfered with by 
 conditions for which the plenum system, as generally in- 
 stalled, is not responsible. 
 
 THE EXPERIMENTAL ROOM. 
 
 The first constructive effort in the ventilation of a 
 schoolroom in which the plenum system had been installed 
 was made in one of the regular schoolrooms of the Chicago 
 
VENTILATING A SCHOOL ROOM 43 
 
 Normal College. The schoolroom was fitted up as an ex- 
 perimental room. One of the factors considered in the 
 selection of the experimental room was that of subjecting 
 it to our northwest winter winds. 
 
 The experimental room is 24 by 32 feet, on the basement 
 floor, and has a west exposure. The room originally had a 
 thirteen-foot ceiling. In the original installation for ven- 
 tilation, air entered the room near the ceiling at the center 
 of the east wall. The main air current was across the room 
 from the east wall to the west (outside) wall, then down the 
 cold outside wall, and back to the outlet duct near the floor 
 in the east wall. The changes made in the room were as fol- 
 lows: First, the outlet duct, near the floor, was closed; 
 then an airtight false floor was built about eighteen inches 
 above the regular floor of the room, and a false ceiling was 
 hung about eight inches below the room ceiling; then an air 
 shaft was constructed to connect the inlet duct of the orig- 
 inal installation with the air reservoir between the floors. 
 
 (See Plates 1 and 2, pages 85 and 86.) 
 
 Outlet duct was tapped near the ceiling connecting it 
 with the compartment between the ceiling and the false 
 ceiling. Three-inch circular holes were cut through the 
 false floor, and galvanized iron pipes, fitted into these open- 
 ings, led under each desk to within an inch of the desk bot- 
 tom. Openings also were made through the false ceiling so 
 that air delivered into the room might move on through it. 
 It will be noted that these changes turned the operation of 
 the plenum system upside down. Instead of the air enter- 
 ing at the ceiling and leaving near the floor line, this new 
 scheme delivered the air below the floor, and outgoing cur- 
 rents left the room at the ceiling. As already intimated, the 
 idea in this scheme was to furnish a positive distribution of 
 air to all the pupils within a room, and also to take advan- 
 tage of the heat liberated by them in the production of 
 upward moving currents. The new installation was tested 
 in two ways : (1) Simple tests were made with anemomet- 
 ers placed at the edges of the desks. Every test showed an 
 up current. (2) A more striking test than the one with the 
 anemometer, and one as fully convincing, or even more so, 
 was a chemical test made with ammonia and an indicator 
 
44 VENTILATING A SCHOOL ROOM 
 
 known as phenolphthalein. This chemical test was made as 
 follows: Linen strings were stretched over the rows of 
 desks at the height of the breathing zone for children seated 
 at the desks. Upon these strings, at intervals of ten or 
 twelve inches, were hung pieces of unsized paper made wet 
 with an alcoholic solution of phenolphthalein. When the 
 room was thus dotted over with these wet papers, it looked 
 much like a laundry drying room flecked with white. Before 
 the wet papers had time to dry, a handkerchief, made thor- 
 oughly wet with concentrated ammonia water, was hung in 
 the air duct leading from the plenum chamber, or distribut- 
 ing room, to the experimental room. Within two minutes 
 after hanging the handkerchief in the duct, every paper on 
 the linen threads in the experimental room became red in 
 color. When ammonia is added to a colorless solution of 
 phenolphthalein, the solution becomes red; therefore, the 
 change in the color of the papers was conclusive evidence 
 that ammonia from the handkerchief had been distributed 
 to every piece of paper wet with the alcoholic solution. The 
 test was repeated at another time with the same result. 
 Still another test was made which contained an added fea- 
 ture. In addition to the papers supended in the breathing 
 zone over the desks and seats, others were hung on strings 
 stretched parallel with those over the rows of desks about 
 seven feet from the floor, but directly over the aisles. In 
 this test all the lower papers reddened in approximately the 
 same time as before, and the upper ones reddened soon 
 thereafter. These tests are conclusive evidence that the air 
 in the experimental room is delivered to each desk, and that 
 the movement of the air in the room is upward, and quite 
 uniformly so. Moreover, anemometer tests made at the 
 outlets of the galvanized iron tubes before the desks were 
 placed, showed that each tube delivers approximately the 
 same volume of air in unit time. 
 
 THE EXPERIMENTAL BOOM BECOMES A HIGH SCHOOL 
 
 ROOM. 
 
 As soon as the before-mentioned changes in the experi- 
 mental room had been made and tested, the room became a 
 regular high-school room, in use throughout the day. It is 
 
VENTILATING A SCHOOL ROOM 45 
 
 customary for classes to change rooms for different recita- 
 tions, and, therefore, the experimental room was occupied 
 by different classes each hour. This arrangement added 
 somewhat to the difficulty of our experiments. 
 
 A REQUIREMENT FOB VENTILATION. 
 
 However satisfactory the quantity of air furnished for 
 the ventilation of a room, and however satisfactory may be 
 the means employed for properly distributing it, both of 
 which in the long run are very important, nevertheless the 
 human body makes an immediate demand which may over- 
 shadow either or both. IMMEDIATE PHYSICAL COMFORT is THE 
 STANDARD OF THE HUMAN BODY, whatever the consequences, as 
 exemplified either in the drowsy stupor that descends on 
 one immersed in a hot, stifling atmosphere on a cold wintry 
 night, or in the quiet repose that comes from a balmy sum- 
 mer breeze outdoors. Good ventilation shall produce imme- 
 diate comfort. 
 
 One of the most prominent as well as immediate factors 
 in the production of comfort, is temperature, and therefore 
 a study was made to determine the best temperature for a 
 schoolroom. The comfort of the human body is largely in- 
 fluenced by the temperature of the surrounding air, and 
 also, and at the same time, by the rate at which perspiration 
 may evaporate into the air from the body. Relative humid- 
 'ity influences the rate at which such evaporation occurs, but 
 it is only in recent years that much consideration has been 
 given to atmospheric humidity in relation to temperature 
 and comfort. 
 
 TEMPERATURE AND HUMIDITY IN RELATION TO COMFORT. 
 
 It has become traditional in this country that the best 
 temperature to maintain in a room is 68 to 70 degrees. 
 There are, however, some who urge that these temperatures 
 are too high, and they cite the English practice of 59 to 62 
 degrees as evidence of their claim. The difficulty with both 
 these positions is that in deciding on the best temperature, 
 proper consideration is not given to relative humidity. Any 
 
46 VENTILATING A SCHOOL ROOM 
 
 adult knows that sultry days are much less comfortable 
 than days of even higher temperature when the atmosphere 
 is comparatively dry. This well-known fact of outdoor ex- 
 perience must be taken into account, especially since it is 
 now recognized that in cold weather we need to humidify 
 air indoors. On this point of humidity, it may be said that 
 the human organism seems to be adapted to a large range of 
 relative humidity, but it is not accustomed to abrupt 
 changes such as one might experience on a cold day in pass- 
 ing from the outdoors into a heated room. In a word, it 
 seems important from the standpoint of health and comfort 
 to maintain a fair degree of correspondence between the 
 relative humidity of outdoors and indoors. 
 
 Any system of ventilation, to be practicable, must pro- 
 duce a feeling of comfort, and therefore both the tempera- 
 ture and the relative humidity of the air are important in 
 ventilation. Temperature and relative humidity jointly 
 help determine comfort. 
 
 It has generally been considered that a temperature of 
 from 68 to 70 degrees with a relative humidity of 70 per 
 cent, is a most desirable condition to obtain (the 70 per cent 
 relative humidity also is largely traditional). In our tests 
 it was assumed that the best temperature may or may not 
 be 68 to 70 degrees ; and also the most satisfactory relative 
 humidity may or may not be 70 per cent. 
 
 The experimental room was equipped with an auto- 
 matic temperature control, and also an automatic humidity 
 control. Moreover, the temperature in the different parts 
 of the room was determined by means of a sling psychro- 
 meter. For the most part, the tests on relative humidity 
 and temperature in relation to comfort, were made by a 
 member of the Commission and a graduate student from the 
 University of Chicago. Frequently individual high school 
 pupils in the room were asked whether or not they felt com- 
 fortable, and in each case the pupil answering did not know 
 that any other pupil had been asked. The teachers in charge 
 of the room also were asked for opinions. All these opin- 
 ions, together with our own, served as a basis for record. 
 
48 VENTILATING A SCHOOL ROOM 
 
 COMFORT ZONE. 
 (See Chart, page 47.) 
 
 Before working very long, it became evident that there 
 was a temperature and humidity range within which the 
 occupants of the rooms were comfortable, and this range 
 gave rise to what is called the Comfort Zone. This term, 
 comfort zone, means that there is a maximum temperature 
 with a minimum relative humidity, and minimum tempera- 
 ture with a corresponding maximum relative humidity 
 between which limits the occupants of a room are comfort- 
 able. In other words, there seems to be no best tempera- 
 ture and also no best relative humidity; but the maximum 
 temperature at which one is comfortable will be associated 
 with a minimum relative humidity, and the minimum tem- 
 perature for comfort will have associated with it a maxi- 
 mum relative humidity. Under the conditions with which 
 we were working, we found that a temperature of 64 to 70 
 degrees with a corresponding relative humidity of 55 to 30 
 per cent, seems to be the limits; that is, the comfort zone 
 for us was between 64 degrees and 55 per cent and 70 
 degrees and 30 per cent. 
 
 It is worthy of note that with a temperature below 67 
 or 68, with a proper relative humidity, the pupils were bet- 
 ter able to give attention to their work than if the conditions 
 were otherwise. 
 
 OUTSIDE WALL AND WINDOW CHILL. 
 
 The problem of how to prevent outside wall and window 
 chill from seriously interfering with ventilation, has never 
 been satisfactorily solved. 
 
 With the change in installation in the experimental 
 room, it was necessary to make some provision for prevent- 
 ing a sheet of cold air from falling down the exposed walls 
 and windows. We tried to do this by installing steam pipes 
 along the window casings just in front of the windows. The 
 idea in this installation was to induce convection currents 
 around the windows, and in this way prevent the downward 
 currents of cold air. Tests were made of the scheme in two 
 ways: (1) By the use of the small turbines it was found 
 
VENTILATING A SCHOOL ROOM 49 
 
 tliat down currents of air were established from a few inches 
 to a foot or more above the horizontal steam pipes. A sec- 
 ond method was that of getting temperature readings at dif- 
 ferent heights from the floor in the aisles between the desks 
 and the outside wall. These temperature readings showed 
 a variation from almost nothing to eight or ten degrees, 
 between the floor and the top of the desks. During the very 
 severe weather of January and February, 1912, it became 
 evident that this installation was only partially satisfac- 
 tory. When the outside temperature was ten or more de- 
 grees below zero, there was a cold current of air that spilled 
 out from the window over the top of the heating pipes above 
 the window sills. This fact led to a proposed installation 
 to overcome the window chill in another way by means of 
 a sheet of hot air. This new installation will be tried during 
 the coming winter. 
 
 VENTILATING AND HEATING COMBINED. 
 
 The plenum system with which we have worked com- 
 bines the heating and the ventilating of a building. The 
 heating is accomplished by means of hot air which also is 
 used subsequently for ventilation. 
 
 INSULATED BUILDINGS. 
 
 Too much importance cannot be placed on the quality 
 of construction in a building in its relation to the efficiency 
 of the ventilating system. This is particularly true with 
 reference to installation. In the usual type of building 
 construction, it is sometimes necessary, in order to heat 
 the building properly, to introduce more air than is 
 required for ventilation. The other alternative might be 
 to introduce the air at an unduly high temperature, but 
 this procedure is always objectionable because of its effect 
 upon the comfort of the occupants. When separate means 
 of heating the building are provided, as with direct radia- 
 tion, there is a tendency to operate the plant without venti- 
 lation. In general, the lower it is possible to maintain the 
 temperature of the incoming air, without discomfort, the 
 
50 VENTILATING A SCHOOL ROOM 
 
 better are the results with reference to ventilation. 
 From the standpoint of economy, it is always desirable to 
 introduce no greater volume of air than is actually required 
 for ventilating purposes. 
 
 OUR LATEST INSTALLATION. 
 
 Our first attempt at insuring an equitable distribution 
 of air for ventilation purposes within the experimental 
 room led us to a more permanent installation. In the new 
 installation, we have separated the heating of the experi- 
 mental room from the ventilating, in so far as they seem 
 to impair the efficiency of each other. The scheme in brief 
 consists in bringing the air for ventilating purposes into the 
 room through galvanized iron ducts insulated with asbestos 
 and located under the false floor. This system of ducts ter- 
 minates in three-inch iron pipes securely fastened to the 
 floor and leading up under the desks. The room is heated 
 by means of hot air driven under the floor. The idea in this 
 scheme is to warm the floor. In order to reduce the effect 
 of window chill, double windows are to be installed, and the 
 heated air from under the floor will be forced upward 
 between the two sets of windows and thus effectually over- 
 come window chill. As in the older installation, the air 
 comes in below the desks and leaves the room through 
 twelve registers in the false ceiling. The air used for ven- 
 tilating, being introduced through separate insulated ducts, 
 may be at a much lower temperature than that of the air 
 used for heating. 
 
Report of Test Made by the Chicago Commis- 
 sion on Ventilation 
 
 At the Office of 
 
 Joseph T. Ryerson & Son, Chicago, 111. 
 April 9, 1914 
 
 (See Plans, pages 52 and 53.) 
 
 TYPE. 
 
 General office, consisting of the entire top floor (3rd) 
 of the building. This is divided into one very large room, 
 with a few adjacent smaller private offices. The large room 
 has many low partitions, counters, etc. The ceiling is largely 
 of glass under a sawtooth type skylight. 
 
 NUMBEK OP OCCUPANTS. 
 Normally about 235. 
 
 SYSTEM OF HEATING. 
 
 Entirely indirect steam with both supply and exhaust 
 fans, with air washer and automatic temperature control. 
 
 SYSTEM OF VENTILATION. 
 
 By dilution. The inlet openings are about 8 feet above 
 the floor on the outside walls, averaging about 20 feet apart. 
 The outlet openings are at the floor, in the outside walls 
 and parallel with the inlet openings. Ducts connect the vari- 
 ous supply and exhaust flues with the fans, being run, of 
 sheet metal, along the ceiling of the partially heated metal 
 warehouse under the office. 
 
54 VENTILATING AN OFFICE BUILDING 
 
 SUPPLY FANS. 
 
 Two double wide double inlet full housed 8-blade fans, 
 changed, evidently after the original installation, by adding 
 8 blades about 6 inches wide alternating with the original 
 blades. 
 
 The fan wheels are 42 inches in diameter and about 42 
 inches wide at the periphery. Both are on the same shaft 
 and are operated at 292 R. P. M. Were they of the 8-blade 
 type, they should deliver 22,000 cubic feet of air per min- 
 ute at this speed. They are delivering, by anemometer test 
 of the tempered air which they handle, about 27,000 C. F. M. 
 This increase is accounted for by the extra blades. The 
 fans are belt driven by a 15-horsepower motor. 
 
 EXHAUST FANS. 
 
 These have a rated capacity of about 80 per cent of 
 the capacity of the supply fans and discharge the air 
 exhausted from the office into a storage shed. 
 
 INTAKES. 
 
 Cold air is drawn from three windows, each 4 feet by 
 4 feet 6 inches, about 30 feet above the street. The room 
 inlet openings have horizontal blade diffusers installed by 
 the owner after having had experience with cold drafts. 
 
 OUTLETS. 
 
 The outlet openings from the rooms are in the side 
 walls. Many are obstructed by furniture. There is no pro- 
 vision for any air removal at or near the ceiling. 
 
 HEATER. 
 
 Eight rows of 1-inch pipe, controlled by diaphragm 
 (thennostatic) valves, between the air washer and the 
 intake. 
 
VENTILATING AN OFFICE BUILDING 55 
 
 Twelve rows of 1-inch pipe, automatically controlled, 
 between the air washer and the fan. 
 
 Free area for air passage, 29.2 square feet. 
 Total surface 2,500 square feet. 
 
 AIR WASHEK. 
 
 Multiple spray type, with automatic water line gover- 
 nor and electric driven belted centrifugal pump. The elim- 
 inators are vertical. No humidity control or means of heat- 
 ing the water is provided. The water was very dirty. The 
 eliminator was coated with dry deposit, % to % inch deep. 
 The washer is 13 feet wide, 6 feet high, and 5 feet parallel- 
 ing the direction of the air passage. 
 
 DUCTS. 
 
 Ducts are of sheet metal, have very long runs, and are 
 figured for 800 to 1,500 lineal feet per minute velocity. They 
 are not insulated from each other or from the surrounding 
 air, which often gets as low as 30 degrees. As the ducts are 
 rather minutely subdivided, with separate automatic mixing 
 dampers in each, the skin friction is considerable. 
 
 PLENUM CHAMBER. 
 
 There are no heating coils between the air washer and 
 the fan. and the tempered air used for cooling the office evi- 
 dently is often insufficiently heated. By means of double 
 dampers and a complicated series of baffles between the tem- 
 pered air and hot air chambers, an attempt has been made 
 to warm the tempered air by forcing hot air to mix with it, 
 under thermostatic control. 
 
 TIME OF TEST. 
 2 to 5 P. M. 
 
56 VENTILATING AN OFFICE BUILDING 
 
 TEMPERATURES. 
 
 Outside air, plus 37 deg. F. 
 At air washer, plus 46 deg. F. 
 Air washer water, plus 46 deg. F. 
 Hot air chamber, plus 98 deg. F. 
 Tempered air chamber, plus 67 deg. F. 
 In the office, average, plus 72.2, ranging from plus 68 to 
 plus 76 deg. F. 
 
 RELATIVE HUMIDITY. 
 
 Eelatiye humidity outside, 33.5 per cent. 
 Average in the office, 38.4 per cent, ranging from 26 per 
 cent up to 50 per cent. 
 
 BACTERIA. 
 
 Petrie dishes were exposed for two minutes each at the 
 points marked "IX, 2X," etc., on the plans, with the results 
 shown on the margin, following the index numbers. 
 
 AIR DISTRIBUTION. 
 
 A. Samples of the air were taken at the points marked 
 "A, B," etc., on the plans, with the results shown on the 
 margin, following the index numbers. The outside C0 2 at 
 the beginning of the tests was 3.8 parts per 10,000. 
 
 B. Ammonium chloride formed from the combination 
 of ammonia and hydrochloric acid was introduced into the 
 plenum chamber, to visualize the air distribution. 
 
 DUST. 
 
 The dust content in the entering air at the supply win- 
 dows was 5,600,000 per cubic centimeter. Between the wash- 
 er and the fans it was 4,000,000 per cubic centimeter. In 
 the office, it was 1,600,000 as tested at two representative 
 points. 
 
VENTILATING AN OFFICE BUILDING 57 
 
 DISCUSSION. 
 
 The plant has been in use about five years. The tem- 
 pering coils, being exposed to the weather are very rusty. 
 Several pipes, having frozen, are blanked off. The washer 
 is very dirty. 
 
 The fan wheels and housings are covered with oil and 
 dust averaging % inch deep. The plenum chamber and* 
 ducts are very rusty. The plant otherwise is in good order. 
 There is considerable discoloration of the walls around the 
 room intakes. The neighborhood of the plant is smoky and 
 dirty. 
 
 -The average relative humidity was lower than would be 
 desirable, and if an average of 45 per cent had been main- 
 tained, greater comfort and a lower temperature would be 
 possible. 
 
 The bacteria colonies were very low in number, indi- 
 cating excellent cleaning in the room, and an ability in the 
 plant to maintain a high efficiency in this regard. 
 
 The carbon dioxide analysis indicates a very poor fresh 
 air distribution, as where it showed by this index 12 parts 
 of C0 2 per 10,000 only 750 cubic feet of air per hour per 
 occupant were being delivered in such localities. For the 
 whole room nearly 6,900 cubic feet of air per hour per occu- 
 pant are really delivered. 
 
 The air distribution test showed that the greater part 
 of the fresh air supply is being delivered to the north side 
 of the room. The adjustment of the volume dampers which 
 effected this evidently was made in order to warm the 
 room in cold weather, this being especially necessary since 
 the heating plant is on the south, and the supply ducts 
 are run long distances in a very cold place without insula- 
 tion. 
 
 The high dust content at the inlet and the low dust 
 count in the room are striking, especially as the air washer 
 seems to have an efficiency of but 28 per cent. 
 
 It may be accounted for by the disturbance of local 
 settled-out dust in the intake and fan rooms by the opera- 
 tives of the instruments and by the fact that much of the 
 
58 VENTILATING AN OFFICE BUILDING 
 
 dust so stirred up settled in the fans and ducts before reach- 
 ing the room. 
 
 CONCLUSIONS. 
 
 The owner evidently made and is making a conscien- 
 tious endeavor to provide the best possible working condi- 
 tions. The provision of some direct radiation along the 
 north side, or indirect radiator boosters in the ducts running 
 to the north side, by enabling the room to be heated evenly 
 would permit of a more perfect air distribution, correcting 
 the condition indicated by the C0 2 and air distribution tests. 
 The trouble would be ameliorated by heating the room under 
 the office, or by insulating the ducts. 
 
 The supply fans are running very slowly in considera- 
 tion of the length of the ducts and there is ample power 
 to speed them up to at least 350 R. P. M. The entire air 
 handling mechanism should be thoroughly cleaned at fre* 
 quent intervals. 
 
 The installation of automatic humidity control is not 
 difficult, and would improve the conditions. 
 
 The closing of the inlet openings on one side of the 
 room and the closing of all vent openings on the opposite 
 side is suggested for use in warm weather especially, as it 
 is believed that such a procedure would insure a more thor- 
 ough sweeping with fresh air of the entire area. 
 
 For hot weather operation, it would probably be an 
 improvement if ceiling outlets were provided, whereby the 
 hot air accumulating there by reason of the sun effect could 
 be forced directly out by the incoming cooler air. 
 
 DEDUCTIONS. 
 
 A similar new plant should be so designed that there 
 will be no long ducts run in cold air, especially to the north 
 side. It should have its vertical flues thoroughly insulated, 
 especially if they must run up outside walls. It should 
 have both floor and ceiling inlets and outlets so that efficient 
 summer operation may be effected. 
 
VENTILATING AN OFFICE BUILDING 59 
 
 INSTRUMENTS. 
 
 The various instruments used in this test are described 
 in the appendix, pages 70 to 83. 
 
GV/G4GO 
 
 TEST&FQPr 
 
 /D/9W3 
 
 /70 
 
 
 WrV0a 87//.S&VQD 
 
 Z123 
 
 2:4? 
 
 3,'CO 
 
 3140 
 
 
 7Z-73 
 
 84-fZ 
 
 77 
 
 go 
 
 3 
 
 70 
 
 76 
 
 So 
 
 84- 
 
 68 
 
 7B 
 
 So 
 
 80 
 
 80 
 
 79 
 
 80 
 
 8/ 
 
 t- s/r. 
 
 41 
 
 tz 
 
 7* 
 
 ft 
 
 73 
 
 7* 
 
 go 
 
 s/ 
 
Cabinet Tests 
 
 (See Plate 3, page 86.) 
 
 A series of cabinet tests is being conducted by the Com- 
 mission under varying air conditions, with particular ref- 
 erence to volume, movement, temperature, humidity, carbon 
 dioxide, dust and bacteria. It is the intention to repeat 
 these tests with subjects of different types. 
 
 The cabinet, which is shown in the accompanying illus- 
 tration, is built of heavy galvanized iron, 28 inches wide, 6 
 feet long, and 6 feet high. All seams are soldered and 
 painted. On one side are two observation windows, each 
 2 feet square. At one end is an air tight door, and at the 
 other end is a three-speed direct connected Sirocco fan, 
 having a maximum capacity of 84 C. F. M. The installation 
 of the fan is such that the air may be re-circulated in the 
 cabinet, or fresh air introduced. The fan discharges the air 
 into the cabinet through either or both of two compartments 
 in which chemicals or other material may be placed for con- 
 trolling the temperature, humidity, C0 2 , etc. In addition 
 to the above a small air washer is about to be installed. 
 
 The cabinet easily accommodates two persons. The 
 tests are usually conducted with two subjects of different 
 age and type, at the same time, in order to obtain a check 
 on the effects noted. 
 
 Observations are taken, at stated periods throughout 
 the tests, of the air conditions as well as the physical and 
 mental condition of the subjects. 
 
 The tests thus far have been only of a preliminary 
 nature, to enable us to determine the best method of con- 
 ducting them, and also to determine the best apparatus 
 required to maintain the desired atmospheric conditions. 
 
 Five of these tests have been made, ranging from one 
 to three hour periods and an illustration of one of the test 
 sheets is given herein. 
 
Revised List of Resolutions of the Chicago 
 Committee on Ventilation 
 
 November, 1913 
 
 1. RESOLVED, That carbon dioxide, as encountered in 
 working practice is not the harmful agent of major impor- 
 tance in expired air or air otherwise contaminated. 
 
 2. RESOLVED, That a temperature of 68 deg. F. with a 
 proper relative humidity is the proper maximum tempera- 
 ture for living rooms artificially heated. 
 
 3. RESOLVED, That in the present state of knowledge, 
 it is impossible to designate all harmful factors in or asso- 
 ciated with expired air. 
 
 4. RESOLVED, That the principle of ventilation by cur- 
 rents is preferable to the principle of ventilation by dilution. 
 
 5. RESOLVED, That for adequate ventilation, smaller 
 volumes of air suffice when introduced by currents than 
 when introduced by dilution. 
 
 6. RESOLVED, That ventilation which utilizes the prin- 
 ciple of convection in producing currents is more effective 
 and economical than that which neglects this principle. 
 
 7. RESOLVED, That upward ventilating currents in 
 crowded rooms are desirable, provided the sources of air 
 supply are free from contamination. 
 
 8. RESOLVED, That in making use of upward ventila- 
 tion, attention should be given to the counteracting of wall 
 and window chill. 
 
 9. RESOLVED, That in those processes of manufacture 
 where considerable CO 2 is liberated, the C0 2 content is not 
 a proper index of air pollution. 
 
 10. RESOLVED, That for the removal of kitchen odors, 
 body odors, stable odors, and other odors associated with 
 heat production, upward ventilation is more efficient than 
 downward ventilation. 
 
REVISED LIST OF RESOLUTIONS 63 
 
 11. RESOLVED, That the delivery of a certain volume of 
 air per unit of time, per occupant, into a given space does 
 not necessarily constitute ventilation. 
 
 12. RESOLVED, That air which is introduced into an 
 occupied room in such a way that it strikes the occupants 
 should be not lower in temperature than 60 deg. F. 
 
 13. RESOLVED, That heating and ventilating are two 
 distinct problems, and therefore, the installation of heating 
 and ventilating systems, whether separate or combined, 
 should be such that neither system shall interfere with the 
 efficiency of the other. 
 
 14. RESOLVED, That from the standpoint of health, rel- 
 ative humidity is one of the important factors in ventilation. 
 
 15. RESOLVED, That efficient air cleaning devices are 
 desirable in all ventilating installations where the air sup- 
 ply is liable to be contaminated by dust, or other objection- 
 able matter. 
 
 16. RESOLVED, That the bacterial content of the air is 
 an important factor in all ventilation, arid bears a direct 
 relation to the source and quantity of air supply. 
 
 CAR VENTILATION. 
 STREET CARS. 
 
 17. RESOLVED, That ventilation by deck sash is never 
 satisfactory in street cars. 
 
 18. RESOLVED, That either the plenum or the vacuum 
 principle of ventilation is applicable to the ventilation of 
 street cars. 
 
 19. RESOLVED, That air inlets should be of such size 
 and location that drafts are not perceptible when the air 
 enters at a temperature of from 50 to 60 deg. F. ; and they 
 should be of such number and distribution as to supply the 
 maximum number of occupants with the proper amount of 
 air. 
 
 20. RESOLVED, That in street car ventilation, the use 
 of a plenum system without outlets, or an exhaust system 
 without inlets is not compatible with a high degree of effi- 
 ciency. 
 
64 REVISED LIST OF RESOLUTIONS 
 
 21. RESOLVED, That air delivered into street cars 
 should be not colder than 50 deg. F. 
 
 22. RESOLVED, That in street cars in which wraps are 
 worn, a temperature of not less than 50 deg. F. or more 
 than 60 deg. F. should be maintained during artificial 
 heating. 
 
 ELEVATED CARS. 
 
 23. RESOLVED, That ventilation by the deck sash is 
 never satisfactory in elevated cars. 
 
 24. RESOLVED, That either the plenum or vacuum prin- 
 ciple of ventilation is applicable to the ventilation of cars 
 on elevated railways. 
 
 25. RESOLVED, That inlets should be of such size and 
 location that drafts are not perceptible when the air enters 
 at a temperature of from 50 to 60 deg. F. ; and they should 
 be of such number and distribution as to supply the maxi- 
 mum number of occupants with the proper amount of air. 
 
 26. RESOLVED, That in elevated car ventilation, the use 
 of a plenum system without outlets or of an exhaust system 
 without inlets is not compatible with a high degree of effi- 
 ciency. 
 
 27. RESOLVED, That air delivered into elevated cars 
 should not be colder than 50 deg. F. 
 
 28. RESOLVED, That in elevated cars, in which wraps 
 are worn, a temperature of not less than 50 deg. F. or more 
 than 60 deg. F. should be maintained during artificial 
 heating. 
 
 RAILROAD CARS. Day Coaches, Sleeping Cars, Suburban 
 Cars, and other Cars making long runs. 
 
 29. RESOLVED, That ventilation by the deck sash alone 
 is never satisfactory in railroad cars. 
 
 30. RESOLVED, That either the plenum or vacuum prin- 
 ciple of ventilation is applicable to the ventilation of rail- 
 road cars. 
 
 31. RESOLVED, That inlets should be of such size and 
 location that drafts are not perceptible when the air enters 
 at a temperature of from 50 deg. to 60 deg. F. ; and they 
 should be of such number and distribution as to supply the 
 maximum number of occupants with the proper amount of 
 air. 
 
REVISED LIST OF RESOLUTIONS 65 
 
 32. RESOLVED, That in the ventilation of railroad cars, 
 except sleeping cars, the use of a plenum system without 
 outlets or of an exhaust system without inlets is not com- 
 patible with a high degree of efficiency. 
 
 33. RESOLVED, That air delivered into railroad cars 
 should not be colder than 50 deg. F. 
 
 STANDARDS. 
 
 34. RESOLVED, That the following standards should 
 apply to the ventilation of cars : 
 
 Street cars, elevated cars, or other cars making fre- 
 quent stops, during which the doors are opened, shall be 
 so ventilated that the amount of air entering the car for 
 ventilation, through openings provided for such purposes, 
 shall be at the rate of not less than 500 cubic feet per hour, 
 per occupant, based upon the maximum carrying capacity 
 (seats and standing room included) of such car, provided 
 that the total amount from all sources shall not be less than 
 750 cubic feet per hour. 
 
 Day coaches, sleeping cars, suburban cars, and other 
 cars making long runs, shall be so ventilated that the 
 amount of air entering the car for ventilation, through open- 
 ings provided for such purpose, shall be at the rate of not 
 less than one thousand (1,000) cubic feet per hour, per occu- 
 pant, based upon the maximum seating capacity of such car. 
 
 Smoking cars and smoking compartments in cars shall 
 be so ventilated that the amount of air introduced for ven- 
 tilation shall be at least 20 per cent in excess of the amount 
 required for the same type of car under the above standard. 
 
 35. RESOLVED, That the carbon dioxide content of the 
 air of cars should not exceed ten parts by volume in each 
 ten thousand (10,000) parts of air; provided that in street 
 cars, elevated cars, and other cars used in local interurban 
 service the carbon dioxide content may not rise above 
 twelve parts by volume in each ten thousand (10,000) parts 
 of air. 
 
66 REVISED LIST OF RESOLUTIONS 
 
 PICTURE THEATERS. 
 
 36. RESOLVED, That in the ventilation of picture thea- 
 ters provision must be made for warming and regulating 
 the temperature of the air introduced. 
 
 37. RESOLVED, That when cold air for ventilation is 
 introduced into picture theaters above the breathing zone, 
 either 
 
 (1) There will be an insufficient supply of air for prop- 
 er ventilation, or 
 
 (2) The occupants of the theater will be uncomfortably 
 cold. 
 
 38. RESOLVED, That upward ventilation in picture 
 theaters is more efficient than downward ventilation; also 
 it is more economical from the standpoint of operation. 
 
 39. RESOLVED, That in the ventilation of picture thea- 
 ters the fans and ducts should be designed for a pressure 
 not exceeding, in normal cases, % ounce per square inch. 
 
 40. RESOLVED, That in the ventilation of picture thea- 
 ters in which furnace heating apparatus is used, the space 
 between the furnace and its casing must be under air pres- 
 sure at all times when the fan is in operation. 
 
 41. RESOLVED, That when furnace heating apparatus 
 is used in the ventilation of picture theaters, the furnace 
 must never be under suction when the fan is in operation. 
 
 42. RESOLVED, That in the downward ventilation of 
 picture theaters, the room must be practically an air-tight 
 enclosure above the breathing zone. 
 
 43. RESOLVED, That in the cooling of picture theaters 
 in the summer time, the system of downward ventilation is 
 inefficient. 
 
 44. RESOLVED, That air delivered into picture theaters 
 for ventilation purposes should not be delivered at a tem- 
 perature colder than 60 deg. F. 
 
 45. RESOLVED, That the temperature in picture thea- 
 ters at the breathing zone should not be lower than 60 deg. 
 F. nor higher than 70 deg. F. 
 
 46. RESOLVED, That in the breathing zone the number 
 of colonies of bacteria on a standard agar plate should never 
 exceed 15 for a five-minute exposure. 
 
REVISED LIST OF RESOLUTIONS 67 
 
 47. RESOLVED, That the carbon dioxide content of the 
 air in the breathing zone in picture theaters should not 
 exceed 10 parts per ten thousand. 
 
 48. RESOLVED, That the relative humidity of the air 
 when brought into picture theaters for ventilation pur- 
 poses should not be less than 35 per cent. 
 
 49. RESOLVED, That the velocity of the air delivered 
 into picture theaters for ventilation purposes by upward 
 ventilation shall not exceed 150 feet per minute. 
 
 50. RESOLVED, That the quantity of air delivered into 
 picture theaters for ventilation purposes shall not be less 
 than 25 cubic feet per occupant per minute. It shall be 
 understood that in determining such quantity, the maximum 
 seating capacity shall be considered as the number of occu- 
 pants of the room. 
 
 51. RESOLVED, That fresh air registers in the floors of 
 the aisles and lobbies of picture theaters should be pro- 
 hibited. 
 
 52. RESOLVED, That both the design and location of 
 fresh air inlets in picture theaters should be such as to 
 minimize the possibility of contaminating them or the air 
 which they deliver. 
 
 SCHOOL ROOMS. 
 
 53. RESOLVED, That either the plenum or vacuum prin- 
 ciple is applicable to the ventilation of school rooms. 
 
 54. RESOLVED, That in the artificial ventilation of a 
 school room, the air inlets and outlets should be of such 
 size, number, and location as to insure equal distribution 
 of air throughout the room. 
 
 55. RESOLVED, That the maximum temperature for a 
 school room, artificially heated, should not be more than 68 
 deg. F. 
 
 56. RESOLVED, That the relative humidity of a school 
 room, artificially heated, should not fall below 40 per cent. 
 
 57. RESOLVED, That in the present state of knowledge 
 and practice the quantity of air supplied to school rooms 
 for ventilation should not be less than 30 cubic feet per pupil 
 per minute. 
 
68 REVISED LIST OF RESOLUTIONS 
 
 58. RESOLVED, That both the design and location of the 
 air intake for a school building should be such as to minim- 
 ize the possibility of contaminating the air supply. 
 
 59. RESOLVED, That efficient air cleaning devices are 
 desirable in all ventilating installations where the air sup- 
 ply is liable to be contaminated by dust, or other objection- 
 able matter. 
 
 60. RESOLVED, That in the automatic control of tem- 
 perature within a school room, the thermostat should be so 
 located as not to be influenced by wall chill. The thermostat 
 should be so located as to be influenced by the average tem- 
 perature of the room only. 
 
 61. RESOLVED, That in mechanically ventilated school 
 buildings, it is desirable at stated periods to flush all the 
 school rooms in the building with fresh air by means of open 
 windows. 
 
 62. RESOLVED, That careful consideration should be 
 given to the sweeping and cleaning of the school room as 
 effecting its ventilation. 
 
 63. RESOLVED, That the temperature of a school room 
 should be kept as low as the comfort of its occupants will 
 permit; and that the temperature may be kept down by 
 increasing the relative humidity. 
 
 64. RESOLVED, That in the proper ventilation of a 
 school building in cold weather, it is necessary to provide 
 means for humidifying the air introduced into the building. 
 (See note.) 
 
 65. RESOLVED, That a constant temperature and a con- 
 stant relative humidity are not conducive to the highest 
 degree of comfort in a school room. 
 
 66. RESOLVED, That in the production of comfort for 
 the occupants of a school room, the maximum temperature 
 should be associated with a minimum relative humidity, and 
 the minimum temperature should be associated with a maxi- 
 mum relative humidity. 
 
 67. RESOLVED, That in a school building artificially 
 ventilated and heated the comfort zone should be estab- 
 lished in order that the engineer may properly operate the 
 heating and ventilating system. 
 
REVISED LIST OF RESOLUTIONS 69 
 
 68. RESOLVED, That the carbon dioxide content alone 
 is not always an index of the contamination of air for venti- 
 lating purposes, within an enclosure. 
 
 NOTE : Relative humidity may be increased in a school 
 room by means of properly muffled jets of steam introduced 
 into the plenum or fan chambers from the boiler supply. 
 
Methods and Devices Employed 
 
 This appendix describes the methods and devices 
 employed by the Commission in making tests. 
 A AIR VELOCITIES : 
 
 1. Anemometer. 
 
 2. Pitot Tube and Gauge. 
 AIE MOVEMENTS : 
 
 1. Ammonium Chloride Test. 
 
 2. Phenolphthalein Tests. 
 
 3. Balloon Tests. 
 
 4. Pin Wheel Tests. 
 AIR ANALYSES (C0 2 ) : 
 
 1. Method of Taking Samples. 
 
 2. Petterson-Palmquist Apparatus. 
 B BACTERIA : 
 
 1. Cultures. 
 
 2. Caldwell Tubes. 
 
 3. Sand Filters. 
 
 C CABINET TEST METHODS : 
 
 1. Sphygmomanometer. 
 
 2. Thermometers. 
 
 3. Psychrometers. 
 
 4. Air Samples. 
 
 5. Cultures. 
 D DUST: 
 
 1. Sugar Filter. 
 
 2. Koniscope. 
 
 3. Aiken Portable Dust Counter. 
 E STANDARD CANDLES. 
 
 A AIR VELOCITIES. 
 
 The velocity of air or other gases may be measured 
 directly by means of an anemometer, or indirectly by com- 
 
METHODS AND DEVICES EMPLOYED 71 
 
 puting the velocity from the differences in pressure that 
 cause the flow, measured with the Pitot tube and gauge. 
 
 ANEMOMETER. 
 (See Plate 4, page 87.) 
 
 The Biram pattern anemometer consists of a small 
 wheel carrying 8 vanes. The wheel is connected by suitable 
 gearing to indicating hands on the dial and the instrument 
 so calibrated that the revolutions of the vanes indicate the 
 velocity of air in feet per unit of time. The wide diver- 
 gence in the readings obtained by two persons with the same 
 anemometer, under the same conditions, should not be at- 
 tributed to inaccuracy of the instrument, but rather to 
 ignorance or carelessness in its use. 
 
 The first requisite is that the instrument be in good 
 repair and properly calibrated. The second is that the 
 readings be accurately timed. The third is that the proper 
 method of taking the readings be employed. 
 
 In taking readings at the register face the method of 
 slowly moving the anemometer across the register or up 
 and down as the case may be, is only mentioned to be con- 
 demned. The reading will be inaccurate except at those 
 registers where the velocity is uniform throughout the 
 entire area. In taking readings, where the velocity varies 
 over different areas of the register face, it can readily be 
 seen that in moving the instrument slowly across the face 
 of the register the momentum acquired by the revolving 
 vane over the areas of high velocity will cause it to continue 
 to revolve at a much higher rate than it should while pass- 
 ing over the areas of low velocity, consequently a higher 
 average velocity reading will be obtained than the condi- 
 tions warrant. The proper method is to divide the face of 
 the register or other opening into equal areas of approxi- 
 mately 6 inches, and take one-half or one minute readings 
 at the center of each square. The average of the total num- 
 ber of readings times the area of the opening will give the 
 cubic feet of air delivered. 
 
72 METHODS AND DEVICES EMPLOYED 
 
 PITOT TUBE. 
 (See Plate 5, page 87.) 
 
 The velocity of air flowing through a given duct de- 
 pends on the difference in pressure maintained between the 
 entrance and outlet. It is necessary to consider this pres- 
 sure as made up of two components: (1) that which is 
 required to compensate or overcome the loss due to com- 
 pression and frictional resistance (static pressure) ; (2) 
 that which is necessary to move the volume of air at the 
 given velocity (velocity pressure). The sum of the two is 
 the total or dynamic pressure. The air velocity is deter- 
 mined from the formula v = V2 gh, which transferred into 
 terms of air becomes v = 1096.5 V~|r where v is the velocity 
 in feet' per minute, P is the velocity pressure in inches of 
 water, and W is the weight of one cubic foot of air at the 
 given temperature. 
 
 As there is no way of determining the velocity pres- 
 sure directly the total and static pressures must be deter- 
 mined and the latter subtracted from the former to obtain 
 the velocity pressure. For making these determinations the 
 Pitot Tube is the most satisfactory instrument from the 
 standpoint of accuracy and convenience. The tube used 
 by the Commission is of the American Blower type, 48 
 inches long with a tip 4% inches long. The static openings 
 are four in number, two on either side, and .02 of an inch 
 in diameter. The static branch of the tube is on the for- 
 ward or tip side and the total pressure branch at the rear. 
 
 The readings are taken on an Ellison draft gauge, the 
 scale graduated to .01 of an inch. The gauge has been pro- 
 vided with a special head and leveling device to be used in 
 connection with a level tripod. This makes a combination 
 that is portable, can be set up in any location and leveled 
 quickly and accurately. (See Plate 6, page 88.) 
 
 AIR MOVEMENTS. 
 
 The velocity and direction of air movements in audi- 
 toriums, school rooms, etc., are studied by means of the 
 
METHODS AND DEVICES EMPLOYED 73 
 
 ammonium chloride test, phenolphthalein indicators, small 
 counterpoised balloons, and pin wheels. 
 (1) AMMONIUM CHLORIDE TEST: 
 
 When strong NH 4 OH and HC1 are volatilized and the 
 two gases brought into contact, a chemical reaction results 
 with the production of NH 4 C1. This ammonium chloride 
 occurs in a very finely subdivided state, is distinctly visible 
 as a white cloud, and does not readily settle out of the air. 
 This is a valuable method of studying air currents visually. 
 
 The test is made by saturating large desk blotters with 
 the two reagents, bringing them in close proximity, 6 or 8 
 inches from each other, and shaking the blotters gently. 
 The ammonium chloride is liberated as a cloud in the man- 
 ner described, usually at a fresh air intake. The course 
 which it takes and the velocity of its travel are noted. With 
 100 cc of each of these reagents enough ammonium chloride 
 can be produced to become visible throughout the auditor- 
 ium of a moving picture theater in about five minutes. The 
 following modification of this test is useful where local air 
 currents are to be studied : 
 
 The ammonium hydroxide is placed in one of the small 
 125 cc bottles and the acid in another. By means of the air 
 sampling bulb, air is driven through these two bottles sim- 
 ultaneously, and the finely divided ammonium chloride is 
 formed at the nozzle of the apparatus. (See Plate 7, page 
 88.) With this apparatus, a dense white cloud of ammonium 
 chloride may be produced in any locality desired and its 
 course and velocity studied. 
 (2) PHENOLPHTHALEIN TEST: (See Plate 8, page 89.) 
 
 This test depends upon the reaction which occurs in a 
 weak alcoholic solution of phenolphthalein when acted upon 
 by a strong alkaline reagent. For this test Soxhlet extrac- 
 tion shells are suspended by strings from wires at various 
 points throughout the room where test is being conducted. 
 A pledget of absorbent cotton saturated with distilled water 
 is placed in the shell. The outside is saturated with a y 2 
 per cent solution of phenolphthalein in 60 per cent alcohol. 
 Strong ammonium hydroxide is then volatilized at the fresh 
 air intake and the time when the reaction at various sta- 
 
74 METHODS AND DEVICES EMPLOYED 
 
 tions is observed, noted. This gives us a method of deter- 
 mining the time required for the air supply to reach the 
 various locations where the indicators are placed. 
 
 (3) BALLOON TEST: 
 
 Small toy balloons are inflated with hydrogen gas and 
 counterpoised with small improvised weights. These 
 weights are just sufficient to keep the balloons in the air at 
 the temperature in which the test is being made. They are 
 liberated at various points and give a very interesting vis- 
 ual demonstration of air travel and the action of air cur- 
 rents. As the balloons become less buoyant some of the 
 counterpoising weight is removed. 
 
 (4) PIN WHEEL TEST : 
 
 During the experimental work at the Chicago Normal 
 College, Professor Shepherd devised these pin wheels for 
 testing vertical air currents, especially the effect produced 
 on the movements of air in a room by wall and window 
 chill. The pin wheel is constructed of very light aluminum 
 foil fastened into a cork hub, and balanced on a fine cambric 
 needle thrust into cork or other suitable substance to form 
 a base. A thin glass pivot made by drawing glass tubing 
 may be used instead of the needle. These little devices 
 are so delicate that the air currents produced from the heat 
 of the experimenter's hand will cause the wheel to revolve. 
 
 AIR ANALYSES. 
 
 (1) SAMPLING DEVICE : (See Plate 9, page 89.) 
 
 After experimenting with various methods of taking 
 air samples for C0 2 analysis the following has been 
 adopted : 
 
 The apparatus consists of a clean rubber stoppered 
 bottle of about 120 cc capacity, a Paquelin cautery bulb and 
 24 inches of tubing. The apparatus is held at arm's length 
 from the body, great care being exercised that the expired 
 air from the observer's mouth does not contaminate the 
 samples. The cork is removed and the tube inserted to the 
 bottom of the bottle. The tube is closed by pressing it 
 between the thumb and the neck of the bottle and the bulb 
 is compressed until the reservoir is distended. The thumb 
 pressure is then released and the air in the reservoir allowed 
 
METHODS AND DEVICES EMPLOYED 75 
 
 to rush into the bottle, displacing the residual air. This 
 operation is repeated three times in order to be sure that 
 all of the air originally in the bottle and apparatus has 
 been replaced by the air to be sampled. The tube is then 
 removed, the bottle corked and sealed and taken to the 
 laboratory for analyses. 
 (2) ANALYSES OF AIR SAMPLES : (See Plate 10, page 90.) 
 
 Analyses are made for carbon dioxide with the modi- 
 fied Petterson-Palmquist apparatus. This consists essen- 
 tially of a manometer (A) for obtaining similar pressure 
 conditions at the beginning and end of the analyses; an 
 absorption chamber (B) for removing the carbon dioxide 
 in the sample, by means of potassium hydroxide; and a 
 graduated scale (E) for reading the volume of the sam- 
 ple before and after the carbon dioxide has been removed. 
 
 The absorption chamber with its potassium hydroxide 
 chamber, the bulb of the pipette, and the pressure compen- 
 sating chamber, are all enclosed in a glass case and sub- 
 merged in water to prevent slight changes in the tempera- 
 ture of the room from effecting the air under analysis. By 
 means of an air bulb and a short piece of glass tubing, the 
 water in this chamber is continually kept in motion during 
 the analysis. 
 
 The procedure is as follows: (See Plates 11 and 12, 
 pages 91 and 92.) 
 
 In analyzing a sample the mercury cup " F " is raised 
 until the mercury fills the bulb of the pipette "D," the 
 bottle containing the sample of air is now connected to 
 "0" by a piece of rubber tubing, "N" being open; the 
 mercury cup is lowered until the mercury rests at zero. 
 This draws the sample of air into the bulb of the pipette, 
 which holds 25 cc. Salt water is allowed to flow into the 
 air sample bottle to replace the air which is drawn into 
 the apparatus. The stop cock "N" is now closed, "P" 
 opened and the location of the bubble in the manometer 
 recorded. " P " is now closed and " M " opened. By lifting 
 the mercury cup the air is now driven over into the absorp- 
 tion chamber "B," the bulb again lowered and the air is 
 returned to the pipette. This is repeated three times when 
 all of the carbon dioxide in the sample will have been 
 
76 METHODS AND DEVICES EMPLOYED 
 
 absorbed. The air is now brought back into the pipette 
 and the mercury column lowered until the potassium 
 hydroxide stands at exactly the same level it did at the 
 beginning of the analysis. The stop cock ' * M " is now closed 
 and "P" opened and by means of the pressure thumb screw 
 "G-," the pressure is increased or reduced until the mano- 
 meter bubble registers the same pressure that it did before 
 the carbon dioxide was removed from the sample. This com- 
 pletes the analysis, the reduction in volume being read 
 directly on the graduated scale in parts of C0 2 per 10,000 
 parts of air. 
 
 B BACTEEIA. 
 
 (1) CULTURES: (See Plate 13, page 93.) 
 
 Agar plates are made by pouring 10 cc of agar, made 
 according to the formula set as standard by the American 
 Public Health Association for water and milk analyses, into 
 Petrie dishes 10 centimeters in diameter. These plates are 
 exposed 5 or 10 minutes in theaters and 2 minutes in street 
 cars. They are incubated for 48 hours at room temperature 
 and the colonies which develop, counted. A quantitative 
 count has been made in some instances by means of a tube 
 recently devised by Dr. Caldwell of the Municipal Labora- 
 tories. This is a galvanized iron tube 13 inches long and 
 about 3V2 inches in diameter, capped at both ends. The tube 
 is of such dimensions that its capacity is exactly 2 liters. In 
 taking a sample of air the caps from both ends are removed, 
 the tube passed through the air by a horizontal motion until 
 the observer is confident that all the air in the tube has been 
 replaced by the air in the room. The upper cap, is now 
 replaced and the tube inverted over an uncovered Petrie 
 dish and allowed to stand for 20 minutes. At the end of 
 this time, it has been determined experimentally that all 
 of the bacteria in the tube will have settled on the plate, 
 which is then incubated and the colonies counted. Enough 
 work has not as yet been done with this apparatus to war- 
 rant a statement as to its accuracy; the indications are, 
 however, that it will give, with some modifications, a simple 
 method of making a quantitative determination of the bac- 
 teria in a unit volume of air. 
 
METHODS AND DEVICES EMPLOYED 77 
 
 (2) SAND FILTER: (See Plates 14 and 15, page 94.) 
 
 The apparatus for making quantitative bacterial deter- 
 minations consists of the following: 
 
 A small gas meter is used for measuring the air. On 
 the inlet of the meter a glass filter is fastened, as shown in 
 the accompanying illustration. This filter contains sand to 
 a depth of 1.5 centimeters, the sand being sifted through 100 
 mesh wire screen. Air is drawn through the meter by a 
 high pressure centrifugal blower. From 10 to 50 cubic feet 
 of air are usually drawn through the apparatus. The sand 
 is shaken in sterile water and allowed to settle. A measured 
 portion of the water is plated in agar, incubated and the 
 number of colonies counted. 
 
 C CABINET TEST METHODS. 
 
 (1) BLOOD PRESSURE (SPHYGMOMANOMETER) : See Plates 
 16 and 17, page 95.) 
 
 For determining blood pressures in cabinet test experi- 
 ments, a diaphragm dial Sphygmomanometer is used. The 
 manometer proper consists of two free connecting air cham- 
 bers, the diaphragm of one being so connected to the needle 
 on the dial that changes of pressure are indicated directly 
 in millimeters. 
 
 The pressure determining apparatus consists of a cloth 
 covered rubber bag 9 inches long and 5 inches wide, pro- 
 vided with two short rubber tubes connecting with the inte- 
 rior. The bag is wrapped around the arm of the subject, 
 the manometer attached to one of the tubes and the inflating 
 bulb to the other. The bulb is also provided with a release 
 valve so that the pressure in the sleeve may be reduced and 
 accurately controlled. 
 
 In order to obtain a clear understanding of the use of 
 this apparatus, it is necessary first to understand the prin- 
 ciple on which it operates. 
 
 Each heart beat is composed of two parts, the systole 
 or contraction, at which time the blood is forced out and 
 into the arterial system, and the diastole, or expansion, 
 when the heart relaxes and blood from the venous system 
 re-enters the heart. 
 
78 METHODS AND DEVICES EMPLOYED 
 
 The resistance in the circulatory system is made up of 
 friction of the blood passing through the vessels and the 
 work performed in expanding them. This may be con- 
 sidered as the static pressure against which the heart oper- 
 ates. 
 
 The pressure recorded during the contraction of the 
 heart is the highest and is, therefore, the maximum pres- 
 sure. 
 METHOD OF USING: (See Plate 17, page 95.) 
 
 If now the rubber bag or sleeve is carefully adjusted on 
 the arm of the subject and air pumped into the same until 
 the pressure of the bag obliterates the pulse at the wrist, 
 the pressure will be greater than the maximum pressure of 
 the arterial system. With the release valve the pressure is 
 now carefully reduced until the pulse is again just percept- 
 ible. At this point the dial indicates the maximum pressure 
 of the arterial system in millimeters of mercury. 
 
 The pressure is now further reduced until every pulse 
 beat is distinctly shown by the movement of the needle. At 
 the point where the needle's excursion at each beat is the 
 greatest will be the point of minimum pressure, corre- 
 sponding to the resistance offered to the flow of blood by 
 the circulatory system. The difference between the maxi- 
 mum and minimum pressure will be the pulse pressure or 
 the surplus which the heart exerts above the resistance 
 encountered. The maximum pressure in a normal adult 
 male ranges from 105 to 145 millimeters. The normal min- 
 imum pressure ranges from 25 to 40 millimeters below the 
 maximum. The normal pulse pressure ranges from 25 to 40 
 millimeters. 
 
 ( 2 ) TEMPEKATUEES : 
 
 These are taken with standard Fahrenheit thermom- 
 eters graduated from 10 to +120 degrees at two loca- 
 tions at the floor line and two locations at the ceiling. One 
 recording thermometer 3 feet above the floor line is used as 
 a check on the other observations. 
 
 (3) PSYCHKOMETER : (See Plate 18, page 96.) 
 
 The psychrometers used are of the standard sling pat- 
 tern adopted by the United States Weather Bureau of the 
 Department of Agriculture, illustrated herewith. In taking 
 
METHODS AND DEVICES EMPLOYED 79 
 
 readings, the wet bulb is thoroughly saturated and the 
 instrument swung for fifteen or twenty seconds and a read- 
 ing taken. The instrument is now swung again, the pre- 
 vious reading of the wet bulb being kept in mind. This 
 operation is repeated until the wet bulb reaches the lowest 
 point on the scale and begins to ascend, when the observa- 
 tions of the wet and dry bulb temperatures are recorded. 
 
 The relative humidity determinations are taken from a 
 humidity chart prepared by the Carrier Air Conditioning 
 Company of America. 
 
 (4) AIR SAMPLES: 
 
 Air samples are taken and analyzed for carbon dioxide 
 according to the method described under appendix "A." 
 
 (5) BACTERIA: 
 
 Cultures are taken as described under appendix "B." 
 
 D DUST. 
 
 (1) SUGAR FILTER: 
 
 The filter for determining the amount of dust in a unit 
 volume of air is described under appendix "B" for quan- 
 titative determinations of bacteria, except that sugar is sub- 
 stituted for sand in the filter. The filters are prepared as 
 follows : 
 
 Twenty-five grams of sugar are used in the filter. This 
 is sifted through a 25-mesh wire screen and again on a 100- 
 mesh wire screen. The sugar used is that which is retained 
 on the 100-mesh wire screen. Before beginning a test a 
 large quantity of sugar is sifted and a control count made. 
 After collecting the sample, the sugar is dissolved in 100 cc 
 of distilled water, the water agitated and the sample placed 
 in a Sedgwick-Kafter counting cell and the count made. 
 (See Plate 19, page 97.) 
 
 The Sedgwick-Rafter counting cell is made by cement- 
 ing a rectangular brass rim on an ordinary glass slide. The 
 internal dimensions of the cell are : Length, 50 millimeters ; 
 width, 20 millimeters ; and depth, 1 millimeter, giving it an 
 area of 1,000 square millimeters, and a capacity of 1 cubic 
 centimeter. A thick cover glass (No. 3) having dimensions 
 the same as those of the outside of the brass rim forms the 
 
80 METHODS AND DEVICES EMPLOYED 
 
 roof of the cell. The cell and cover glass are thoroughly 
 cleaned and the latter placed diagonally over the top of the 
 cell, so that an opening is left at either end. One cc of the 
 solution is now introduced by means of a small pipette at 
 one side of the cover glass, the air escaping through the 
 other. The glass is now turned to cover the cell, which is 
 now ready for the count. 
 
 An ocular micrometer, consisting of a square, ruled 
 upon a thin disc of glass, is placed upon the diaphragm of 
 the ocular of the miscroscope. The square is of such size 
 that with a certain combination of objectives (No. 3 Leitz) 
 and ocular (No. 4 Leitz) and with a certain tube length of 
 the miscroscope, the area covered by it on the stage is just 
 1 square millimeter. The large square is 1 square milli- 
 meter and with the ocular we have been using the small 
 squares are 1/36 of a square millimeter. 
 
 The tube length was determined by comparison with 
 the Thoma- Zeise blood counting cell. The cell filled with 
 the solution is placed upon the microscope stage and the 
 dust particles within a ruled square are counted in a num- 
 ber of representative fields. Inasmuch as some of the par- 
 ticles are light and rise to the top, while others are heavy 
 and sink to the bottom, the focus of the microscope must be 
 constantly changed to include all of these particles. 
 
 The number of dust particles in one cubic foot is then 
 determined in the following manner : 
 
 Let A represent total number of particles counted. 
 B represent number of squares counted. 
 C represent dilution of the sample. 
 D represent number of cubic feet in sample. 
 
 A 1 000 
 
 ^-x ^ = number of dust particles in 1 cubic foot of air. 
 
 SOURCES OF ERROR: 
 
 1 Particles adhering to the filter. 
 
 2 Particles of dust in any of the apparatus used in the 
 dilution water. 
 
 3 Disintegration of dust particles in the solution. 
 
 4 Presence of unnoticed dust in the objective or ocular 
 or on the micrometer or the mirror of the micro- 
 scope, or on the cover glass of the cell. The mirror 
 
METHODS AND DEVICES EMPLOYED 81 
 
 on the microscope and the glass cover are especially 
 liable to gather dust, even during the progress of 
 counting. To avoid errors control counts must be 
 made on all samples of sugar and duplicate samples 
 should be taken and counted, all apparatus care- 
 fully washed with soap and water and rinsed with 
 distilled water. The count should be made as soon 
 as possible after dissolving the sugar. The micro- 
 scope must be carefully cleaned and the slide, mir- 
 ror, and objectives examined from time to time 
 during the progress of the count to see that they are 
 free from dust. 
 (1) KONISCOPE: (See Plate 20, page 97.) 
 
 This is the original instrument devised by Professor 
 John Aitken for determining the amount of dust in air. The 
 principle on which it operates depends upon the well known 
 physical fact that in saturated air, water condenses in 
 minute droplets on every dust particle, if the dew point is 
 lowered either by reducing the temperature or the pressure. 
 The apparatus consists of an observation tube about 22 
 inches long provided with an eye piece at the proximal end, 
 and an observation window at the distal end. The tube is 
 lined with hygroscopic material throughout its entire 
 length. Connected to the observation tube near the eye 
 piece is a hand exhaust pump. At the other end of the tube 
 a stop cock is provided for introducing the air to be sam- 
 pled. In using the apparatus the hygroscopic lining is sat- 
 urated with water. The stop cock is now open and by oper- 
 ating the pump, the air sample is drawn into the tube. The 
 stop cock is now closed and by one or two quick movements 
 of the piston the air in the tube is rarified, the dew point 
 is consequently lowered, and a minute drop of moisture con- 
 denses on each dust particle, forming a dust fog or haze 
 which is observed through the eye piece. The density and 
 color of this fog is compared with a chart provided, which 
 gives the relative amount of dust in the sample. 
 
 Owing to the personal element involved in the use of 
 this apparatus its value is questionable, except where 
 always used by the same person, and even then the results 
 are only relative. 
 
82 METHODS AND DEVICES EMPLOYED 
 
 (3) AITKEN POKTABLE DUST COUNTER : (See Plate 21, page 
 98.) 
 
 Owing to the limited application of the Koniscope, for 
 the reasons just enumerated, Professor Aitken has devel- 
 oped the principle of moisture condensing on the dust par- 
 ticles, when the dew point is lowered, in the design of his 
 new machine. Instead of observing the density or color of 
 the haze produced, the dust particles, with their attendant 
 droplets of moisture, are precipitated on a ruled object 
 glass and counted. If now a definite quantity of the air to 
 be examined is saturated, and precipitation made the num- 
 ber of dust particles, with slight magnification, can be read- 
 ily observed and counted. 
 
 This machine consists of a precipitation chamber with 
 pump, filter, eye piece, etc., mounted on a tripod in a very 
 convenient and portable manner. The precipitation cham- 
 ber (a) holds exactly 50 cubic centimeters. The stop cocks 
 (b and c) are bored and calibrated to hold % an d 1/20 of a 
 cubic centimeter each. The chambers of these cocks are 
 bored horizontally as well as vertically, so that air may be 
 passed through from the filter, or a measured quantity 
 introduced from the outside. These are situated between 
 the filter (d) and the precipitation chamber. If these cocks 
 are set longitudinally and the pump (e) operated, the air 
 is drawn into the opening (o) through the filter and into 
 the precipitation chamber. The pump piston is depressed 
 10 or 12 times in this manner, removing all of the residual 
 air and dust in the apparatus. 
 METHOD OF OPERATION: 
 
 The stop cocks (c and x) are closed and the pump pis- 
 ton depressed once. This slightly rarifies the air in the pre- 
 cipitation chamber. The three-way cock (b) is now turned 
 horizontally and the bore filled with the air to be sampled, 
 by means of the rubber tube (n). It is then turned verti- 
 cally, the stop cock (x) opened and the negative pressure, 
 caused by the previous depression of the pump piston, 
 draws the air into the precipitation chamber. By means 
 of the stirring rod (g) the sample is now mixed until the 
 air is saturated. The stop cock (x) is closed and the pump 
 piston again depressed. Looking through the eye piece (n) 
 
METHODS AND DEVICES EMPLOYED J S3 
 
 a fine shower of rain is observed to fall on the ruled object 
 glass, where the droplets are counted. 
 
 Noting the dilution of the sample and counting the num- 
 ber of dust particles in a given portion the total number of 
 dust particles per cubic centimeter of air is calculated, the 
 formula being as follows : 
 
 A represents total number of particles counted. . 
 
 B represents total number of squares counted. 
 
 C represents dilution of samples. 
 
 ^- x 100 C = the number of dust particles per cubic centi- 
 meter. 
 
 If the upper stop cock is used C will be 200 ; if the lower 
 is used C will be 1,000. As each square is one square milli- 
 meter in area and one centimeter high its cubic content is 
 .01 of a cubic centimeter. C must, therefore, be multiplied 
 by 100 to obtain the average number of particles per cubic 
 centimeter. 
 
 A modification of the method, suggested by Mr. Hoskins 
 is to insert a smoked cover glass on the ruled objective. 
 The precipitation then makes a permanent record, which is 
 removed and preserved. (See Plate 22, page 99.) 
 STANDAKD CANDLES : 
 
 Candles employed in theater tests are of pure paraffin 
 wax 1% inches in diameter and 6 inches high. By careful 
 test they decrease in weight 9.8 grams per hour. The heat 
 units given off as determined by the bomb calorimeter gives 
 370 B. T. U. per hour. The amount of carbon dioxide pro- 
 duced is .48 of a cubic foot per hour. Each candle, there- 
 fore, very closely approximates the heat and carbon dioxide 
 production of two adult persons, per unit of time. 
 
METHODS AND DEVICES EMPLOYED >, t ., 
 
 Plate No. 1. Desk in Experimental School Room showing 
 individual air supply. See page 43. 
 
; .METHODS A^I) DEVICES EMPLOYED 
 
 Plate No. 2. Experimental School Room. See page 43. 
 
 Plate No. 3. Test Cabinet. See pages 60 and 61, 
 
METHODS AND DEVICES E/MFJ^Q^ED ' \ '', \ . 87 
 
 Plate No 4. Anemometer. See page 71, 
 
 Plate No. 5. Pilot Tubes. See page 72. 
 
88 ' '' : '' 'METHODS' 'AND' DEVICES EMPLOYED 
 
 Plate No. 6. Ellison Draft Gauge. See page 72. 
 
 Plate No. 7. Ammonium Chloride Apparatus. See page 73. 
 
METHODS AND DEVICES 
 
 Plate No. 8. Phenolphthalein Test Tubes. 
 See page 73. 
 
 Plate No. 9. Air Sampling Device. Paquelin Cautery. See page 74, 
 
90 . | , i c ^: ; V!ta&T&&ps 
 
 DEVICES EMPLOYED 
 
 Plate No. 10. Analyses of Air Samples. Petterson-Palmquist 
 Apparatus. See page 75. 
 
METHODS AND DEVICES 
 
 91 
 
 Plate No. 11. Petterson-Palmquist 
 Apparatus. See page 75. 
 
92 , ,, , .METHODS AND DEVICES EMPLOYED 
 
 Plate No. 12. Petterson-Palmquist 
 Apparatus. See page 75. 
 
METHODS AND DEVICES EMPLOYED 
 
 , , . 93 
 
 Plate No. 13. Culture Plate. See page 76. 
 
94 .<,... , ME,THOI)S ^AJSTD DEVICES EMPLOYED 
 
 Plate No. 14. Sand Filter. See page 77. 
 
 \\l 
 
 -JFilter 
 
 Meter 
 
 F.'lter 
 
 Plate No. 15. Sand Filter. See page 77. 
 
METHODS AND DEVICES EMPLOYED- : .; :\: : ;;J95 
 
 Plate No. 16. Method of using Sphygmomanometer. See page 77. 
 
 Plate No. 17. Sphygmomanometer. See page 78. 
 
AND DEVICES EMPLOYED 
 
 Plate No. 18. Psychrometer. 
 See page 78. 
 
METHODS AND DEVICES EMPLOYED 
 
 Plate No. 20. Koniscope. 
 See page 81. 
 
 Plate No. 19. Sedgwick- 
 
 Rafter Counting Cell 
 
 on Microscope. 
 
 See page 79. 
 
&ET!l>DS : AND DEVICES EMPLOYED 
 
 Plate No. 21. Aitken Portable Dust 
 Counter. See page 82. 
 
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