The Journal of hygiene
Nuttall, George Henry Falkiner, 1862-1937
_i;;rij^'iili|i|llm|<j Fig. 1. It then passes upwards to the chamber immediately below the JJcbating Chamber, known as the equalizing chamber. From the latter the air passes up through gratings in the floor, and beneath the seats, of the Debating Chamber. The gratings are covered by open-mesh matting, and one of the main objections raised against the present system of ventilation was that the inflowing air to the Chamber is W. J. A. BUTTERFIELD 489 liable to be vitiated by thus passing through the matting which covers the floor over which Members are constantly passing. Reference to the longitudinal and transverse sections of the Debating Chamber of the House of Commons, given herewith (Figs. 2 and 3), by 490 Aii' in the House of Commons kind permission of the First Commissioner of H.M.'s Office of Works, will show the course taken by the air into and through the Chamber. The arrows indicate the manner in which the air supply enters, and is distributed over the Chamber, and the vitiated air withdrawn from it. Tiie outflow of vitiated air takes place through the ceiling of the Chamber, which is lighted by means of a large number of Argand gas Fig. 3. (A) Debating Chamber. (B) Equalizing Chamber. (C) Space above ceiling of Debating Chamber, with flues to gas burners. (D, Fig. 2) Main exit for vitiated air. (F, Fig. 2) Secondary exit for vitiated air, leading to downcast shafts leading to the Clock Tower. Approximate positions from which air for analysis was drawn: — (1) Centre of Equalizing Chamber; (2), (3) and (4) About breathing level in Debating Chamber; (5) 6 inches below ceiling of Debating Chamber. W. J. A. BUTTERFIELD 491 burners, the products of combustion from which are carried away by the flues shown in Fig. 2 into a main flue. These burners assist the outflow of vitiated air from the Chamber, and further a strong pull is main- tained on the openings in the ceiling by means of coke fires at the base of the upcast shafts by which the air eventually escapes to the open. The arrows in the illustration indicate the courses taken by the vitiated air. The bulk of it is discharged up the shaft above the Commons Lobby, but a portion passes through downcast shafts which lead to the base of the Clock Tower, and escapes up the latter. The chemical analyses of the air in the Chamber comprised merely the estimation of the proportion of carbonic acid present at various points, and incidentally the proportion of moisture was ascertained. With regard to the choice of method for the determinations, on the one hand the Committee Mashed the results obtained to be not merely sufficiently accurate for most practical purposes, but as accurate as it was possible to obtain by any method of estimation, and on the other hand the taking of samples had to be carried out without violating the historic rule against the admission of strangers to the floor of the House during the sittings. The gravimetric method of Haldane and Pembrey^ was chosen as fulfilling these conditions. It presented the further advantage of affording facilities for making simultaneous ob- servations on the bacteriological condition of the air without the use of additional or independent measuring and sampling appai-atus. The bacteriological determinations were carried out by Dr G. S. Graham- Smith, and he is giving an account of them in another jjart of this number of the Journal of Hygiene'^. The arrangements adopted for the determinations on the air at the breathing level in the body of the Chamber may be briefly described as follows. Lead or " composition " gas piping was laid from the equalizing chamber through holes beneath the seats to each of the places at which it was decided to make an examination of the air. The places actually selected are approximately indicated by the figures 2, 3 and 4 in Figs. 2 and 3. The end of the pipe within the Chamber was bent over so that for about six inches it was at an angle of about L5'' to the horizontal. This end protruded, in the case of two positions, over a vacant seat on the benches, and at the appointed time for the com- mencement of a determination, Members, who had offered their aid, attached to the end of each pipe a glass tube packed with sterilized glass wool for filtering out the germs in the air which was drawn through 1 Philosophical Magazine, April, 1890. - See p. 498. 492 Air in the House of Commons the pipe. The other position was against the wall on one side of the chamber about 5 feet from the floor level, and the end of the pipe was bent over, and the germ filter attached in the same manner. These positions were varied slightly in the different sets of determinations. The piping was carried to convenient positions in the equalizing chamber for stands to support the tubes for the absorption of carbonic acid and moisture, as well as the aspirators which served to suck the air at the desired rate of flow from the Debating Chamber through the germ filters, piping, and train of absorption tubes, and to measure the volume of air so drawn through the apparatus. In addition to the three sets of tubes, piping, and aspirators already referred to, a similar set of apparatus was established in the equalizing chamber to draw air from that chamber in order to obtain, for comparative purposes, de- terminations on the fresh air about to be supplied to the Debating Chamber. This position may be conveniently numbered " 1," as it represents the incoming air to the Chamber of the House. A fifth set of apparatus was established on the roof of the Chamber, the end of the composition piping being passed in to a point about six inches below the ceiling near the bar end of the Chamber. The object of this set of apparatus was to obtain determinations on the air as it was about to leave the Chamber, The germ filters were prepared, and the subsequent bacteriological investigations carried out, by Dr G. S. Graham-Smith (see p. 499). A rate of flow of about one litre per minute has been found most convenient for the carbonic acid determinations with the Ibrm of absorption tubes employed, and a suitable duration for a determination was known to be from 30 to 40 minutes. The same rate of flow also answered for the bacteriological investigation. The aspirators therefore had to have each a capacity of fully 40 litres, and to be capable of affording measurements accurate on this volume to within 0"5 per cent. .In order to avoid measuring large volumes of the effluent water from the aspii*ators each time they were used, the total capacity of each aspirator was accurately determined in the first instance, and, the aspirators being chosen of such a size that their capacity exceeded by only a little the volume required for each determination, the actual volume of air drawn into them was ascertained by difference, i.e. by measuring the volume of water — a few litres only — remaining in the aspirator and deducting it from the previously ascertained total capacity. Suitably chosen carboys, fitted with rubber plugs and connexions of glass tubing, served as the aspirators, and in addition to the total W. J. A. lilJTTERFIELD 493 capacity being determined and niaiko<l <.n each, for convenience of controlling the rate of flow each was provided with a litre scale, which enabled the number of litres of air drawn in to be approximately read off at any moment. Tiie order in which the component portions of the complete train of apparatus were set up was— reckoning from the place from which the sample of air was drawn— as follows : (1) The bacteria arresting tube, which was unsealed and attached at the moment of commencing a determination. (2) The length of lead or "composition" gas piping leading from the sample intake to the bench on which the absorption tubes and aspirator were set up. (.S) The double-limbed absorption tube, charged with pumice saturated with sulphuric acid, for the absorption of moisture. (4) The first or principal double absorption tube, containing in one limb soda-lime, and in the other sulphuric acid pumice, for the absorption of the carbonic acid. (.5) The second or guard tube, similar to the last, for the absorption of traces of carbonic acid which might escape absorption in the preceding tube. (6) The aspirator, arranged to give a flow at a rate of about one litre per minute. Five of these sets of apparatus were used simultaneously on four occasions, i.e. twice on each of two evenings. There were therefore required for carrying out the determinations (1) five double absorption tubes for the absorption of moisture, and one tube similarly prepared and charged, against which each of the five tubes Wiis weighed ; (2) five principal double absorption tubes for the absorption of the carbonic acid, and five similar guard tubes, as well as a similarly prepared and charged tube against which each of these ten tubes was weighed. A covered box, with numbered places for the reception of the tubes, was used for carrying them to and from the laboratory and the House of Commons. The three absorption tubes in each set were connected up shortly before the commencement of a determination bv means of short lengths of sound well-fitting flexible tubing, and coni- munication between them and the inlet pipe and aspirator was cut oti' for the time being by means of clips. The whole of the five sets being thus in readiness, the clips were opened, and the aspirators started, all virtually simultaneously, at the moment when the germ filters had been attached to the inlets of the pipes at a signal preconcerted with the i\I embers who had charge of the filters in the Chamber. The filters were removed and plugged, and the aspirators stopped simultaneously, after running from 30 to 40 minutes, on another pre- 494 Air in the House of Commons concerted signal being given. The whole was carried out so that veiy few Members in the Chamber except those who were co-operating were aware that the tests were in progress. After the aspirators had been stopped, the absorption tubes were disconnected, and returned to their places in the box, which was then taken to the laboratory for the weighings to be made, while the volumes of air aspirated were accurately ascertained in the manner already described. The tests were carried out on the 7th and 21st July, 1902, when the attendance of members in the Chamber was quite up to the average. From 200 to a little over 300 persons were present on these occasions in the body of the Chamber and galleries. The first set of determina- tions on each date terminated shortlj^ before 7.30 p.m. (when the House adjourned for dinner), and the second set about 11.15 p.m. Each set covered a period of from 30 to 40 minutes, as already stated. The outside air was clear on both occasions, and the cotton-wool filter was, therefore, not in action. The following details of one set of determinations will indicate the magnitude of the actual weighings and measurements, and the degree of accuracy attained in working : Volume of air aspirated. (Corrected to nor- mal temp, and pressure) litres Increase in weight of Moisture. Grammes per litre of air Carbonic Position No. Moisture tube grammes No. 1 CO2 tube grammes No. 2 CO2 tube grammes Volumes per 10,000 volumes of air 1 2 3 4 5 39-32 38-55 41-35 43-40 42-28 0-3152 0-3106 0-33U7 0-3510 0-3526 0-0262 0-0357 0-0335 0-0305 0-0448 + 0-0005 + 0-0001 -t- 0-0002 + 0-0002 + 0-0005 0-00802 0-00806 0-00821 0-00809 0-00834 3-39 4-71 4-12 3-58 5-39 It will be seen that the alteration in weight of the second or guard tube for absorbing carbonic acid was so small as to be within the possible error in weighing. In other sets the alteration was occasionally in the oppf)site direction, i.e. the tube had apparently lost in weight by 0"0002 gramme. The changes in weight of this second or guard tube, tlie primary object of which was merely to indicate whether the first tube had absorbed the whole of the carbonic acid in the aspirated air, were tiieref<jre disregarded in calculating the results shown in the last column. The connexions had to be made in the equalizing chamber, whicii dii'cctly communicates with the l)el)ating Chamber b}- gratings. W. J. A. I5UTTERFIKLD 495 rapidly, while the House was sitting, without disturbing the Members either by noise or reHection from a strong light. The time between the two sets of determinations on one evening was none too much for finishing the one set and being ready for the next, as the author deemed it expedient in order to avoid possible confusion to make uU the weighings himself. There was less than three hours available for disconnecting the absorption tubes, one set of which was on the ceiling of the Chamber apart from the others, conveying them to the laboratory ^ mile away, making the fifteen weighings, returning with them to the House and connecting them up in the proper order. Results of Determinations. Volumes of Carbonic Acid in 10,000 volumes of Air. 7th July, 1902 21st July, 1902 Position First Period 6.30 Xo 7.10 p.m. Second Period 10.35 to 11.5 p.m. First Period 6,48 to 7.30 p.m. Second Period 10.32 to 11.18 p.m. 1. Centre of Equalizing Chamber, representing the air before it passes into the Debating Chamber 2. Against the wall on Ministerial Side of Debating Chamber 3. Ministerial Side, over empty seat in middle row of benches, near gangway 4. Opposition Side, over empty seat in middle row of benches, near gangway 5. About 6 inches below ceiling of Debating Chamber, near Bar end 3-74 5-22 5-17 5-23 5-60 3-21 4-21 4-79 5 04 4-82 3-14 4-72 3-35 4-96 5-29 3-39 4-71 4 12 3-58 5-39 The results obtained, which are shown in the accompanying table, may now be referred to. Position 1, from which air was drawn for analysis, was in the centre of the equalizing chamber. The air here represented the average condition of the air supplied to the Debating Chamber. The mean of the four sets of determinations showed that there was present on the average 3'37 volumes of carbonic acid in 10,000 volumes of air. The maximum figure obtained was 374 ; the minimum 314. As pure country air contains on the average 3 volumes, and the air of towns — in the absence of fog — from 3 to 4 volumes of carbonic acid per 10,000 of air, it will be obvious that the air supplied to the Chamber was, in this respect, commcndably good. 496 Air in the House of Commons Positions 2, 3 and 4 were, as already indicated, in tlie body of the Chamber, one being against the wall on one side, and the other two in coiTesponding positions among the benches on opposite sides of the House. The positions were altered slightly for the different sets of determinations, and one very low result is explained by the fact that the air was drawn in close to one of the gangways, to which it would pass almost directly from the equalizing chamber. The results obtained at these three positions in the four sets of determinations may be summarized as follows: The mean was 4<.59 volumes of carbonic acid per 10,000 volumes of air — an excess of 122 volumes over the mean for the incoming air. The maximum results obtained in the 12 determina- tions showed an excess of 1'83 volumes, and the minimum an excess of 0'19 volume over the result for the incoming air (Position 1) at the same time. Position 5, near tlie ceiling of the Chamber, served to indicate the condition of the vitiated air passing away from the Chamber. The mean result for this position was o"27 volumes, or an excess of 1'90 volumes over the mean result for the air about to enter the Chamber. The maximum result showed an excess of 2'15 volumes, and the minimum an excess of I'd volumes, over the result for the incoming air at the same time. It will thus be seen that the air supply to the Chamber was adequate to avoid a rise of 2 volumes of carbonic acid over that present in the incoming air, except close to the ceiling, where the rise was on one occasion slightly more than 2 volumes. The highest absolute figure obtained was 5"60 volumes close to the ceiling. In order to indicate how excellent is the renewal of the air of the Chamber which these figures prove, some suggested standards of ventila- tion and results obtained in other buildings may be quoted. Petten- kofer held that 10 volumes of carbonic acid per 10,000 volumes of air (or an excess of about 6 volumes over the proportion he found in the air of towns) should not be exceeded in the air of rooms, etc. But the observations of Carnelley, Haldane and Anderson on the air in crowded elementary schools showed that a lower limit than 13 volumes per 10,000 could not be fixed for such buildings in 1887, though now improved means of mechanical ventilation might lead to a revision of this limit. Finally the Departmental Committee which reported to the Home Secretary on the Ventilation of Factories and Workshops in August, 1902, concluded that it was reasonable to expect that under ordinary ciicumstances 10 volumes should not be exceeded in such W. J. A. BlTTTKIlFIRT.D 497 places unless o'as was burning-. This conimittoo recommenclod that a niaxininm limit of 12 volumes should be prescribed as a standard of ventilation for factories and woikshops when gas was not burning, and that compliance with it should be ultimately enforced on employers. It will be seen that the ventilation of the Debating Chamber of the House of Commons was shown b}- the author's determinations of carbonic acid to be exceptionally good, when judged by the standards of ventilation which have received authoritative recognition. Journ. of Hyg. iii 33 498 THE MICKOORGANISMS IN THE AIR OF THE HOUSE OF COMMONS. By G. S. GRAHAM-SMITH, M.A., D.P.H., M.B. (Camb.). [From the Pathological Lahoratorij of the University of Camhridye.) CONTENTS. Method of collecting and cultivating organisms. Experiments on the outside air .... Comparison of above with results of other observers Ventilating apjjaratus of the House Experiments in the House ..... Results of other observers in comparable situations Identification of bacteria ..... Summary of results of experiments p. 498 p. 500 p. 501 p. 504 p. 504-505 p. 508 p. 51-2 p. 513 The investigations described in the present paper were undertaken during the summer of 1902, at the request of the Select Committee on the Ventilation of the House of Commons. Methods of collecting and cultivatiiig the organisms in the air. As a i-esult of certain preliminary experiments, it was decided to adopt a .slight modification of the method described by Frankland'^' in 1887. 'J'he principle of the method is to entangle the micro- organisms in plugs of tightly packed glass wool by drawing known volumes of air through them. An air pump of known capacity, or under ceitain conditions automatic aspirators, wei'c u.sed for the aspiration of the air through gluss collecting tubes fitted with glass wool plugs. Gr. S. Graham-Smith 499 TJie collecting tubes. The collectinor tubes Avei-e made fiom strong glass tubing -5 cm. in internal diameter and 12 ems. in length. Each was provided with three plugs of Hnely divided glass wool {A, B, G) kept in position by con- strictions m the tubes. The constriction behind G was first made and the plug inserted, next that behind B, and finally the one behind A. The tube was then marked at the end nearest G with a blue cross, and was placed inside a stout glass test-tube, whose open end was plugged with cotton-wool, to act as a sterile case when the collecting tube^'was not actually being used. The blue-marked end of the collecting tube was placed nearest the open end of the test tube, so that when the latter was opened this end should first drop into the hand. In all subsequent proceedings this end was alone handled, and fixed to the tube of the air pump or aspirator, and at the end of the experiment the collecting tube was again placed inside its case in the same position. ^ Blue Cross Case M P.^<-K+ 2cm. "^S 4cm. ^ 4cm. ^ %^^"" ^M) Cotton 1 Wool Plug ^ B i- A COTTPM WCOL A1T0W.S mark direction of air current. Before use the collecting tube in its case was sterilised at 160" C. in hot air on these occasions. During the collection of the sample the air passes through the collecting tube from A to G and the majority of the organisms are entangled in the i)lug A. On a few occasions a small number passed through to plug B, which is used as a control to ascertain what propor- tions of organisms are carried through A. Plug G is to prevent contamination of the other plugs when the collecting tube is being handled. For the aspiration of the air through these collecting tubes an air- pump was used in the majority of examinations connecteil to the collecting tube by a rubber pipe about 10 feet in length, so that the disturbance caused by the working of the pump should not influence the air at the place where the samples were being collected. For experiments in the chamber during a sitting such a method was found to be inconvenient. In this case a known volume of air was aspirated by connecting the collecting tube by means of a length of 33—2 500 Air of the House of Commons lead piping to a graduated carboy from which water was being siphoned into another vessel. Cultivation of Samples. After removing the collecting tube from its case, it was cut through half wa}' between A and B. The free and cut ends were sterilised b}^ passing quickly through a flame, and the plug A pushed by means of a sterile wire into a Petri dish containing melted sterile gelatin. The plugs were then broken up and evenly spread out Vv'ith a sterile platinum needle. The samples were cultivated for 5 days or longer at 20" C. At the end of this time the colonies were counted under a lens, and subcultures made to determine the species of the organisms found. In this way numerical estimations of the numbers of the organisms per litre were made of the outside air at various places, the Debating Chamber before, and during, debates, the ventilating shaft leading to it, and various Committee, Smoking, and Dining Rooms. Results of Experiments. Table I. Experiments on outside air, July I8th. 4*5 litres of air aspirated in each case. No. of exp. Place No. of bacterial colonies No. of mould colonies Total colonies No. of organisms per litre I Terrace (ground level) 14 5 19 4-2* (l-l)t n ,, (10 ft. from ground) 8 5 18 2 9 (11) III ,, (20 ft. from ground) 6 9 15 3-3 (2'0) IV Clock Tower (half-way up) 0 1 7 1-5 (0-2) V „ (top) 8 3 6 13 (0-6) VI Peers' Inner Court 16 3 19 4-2 (0-6) VII Star Court 21 6 27 6-0 (1-3) * indicates number per litre of bacteria and moulds in this and other tables, t Moulds per litre in brackets ( ) in this and all other tables. The figures just quoted show that very few bacteria were present in the air at the top of the clock tower (1'3)* and that the numbers were about the same half-way up (lo). At 20 and 10 feet above the ground level there was however a considerable increase, 3*3 and 29 respectively, and at the ground level (Terrace) the number was still greater, 4-2. ' All figures, here and elsewhere in the text, record the number of microorganisms per litre. G. S. Graham-Smith 601 Two closed courts were also examined and showed in one case the same number as on the Terrace and in another an increase of 2 per litre (60). At the time when these experiments were conducted there was a slight west wind and the day was bright and moderately sunny. No smoke zone was observed in ascending the clock tower and consecjuently no experiments were made to ascertain whether greater, or lesser, numbers of micro-organisms are present amongst these floating particles. Comparison ivith the observations of other experimenters. The observations of several investigators^ have shown that the numbeis of the micro-organisms in the outside air are dependent on various factors, such as the time of year, condition of the weather, time of day, and the locality, especially with regard to the height of the latter, and the free circulation of air about it. Influence of the time of year. The experiments of Frankland ^^\ Griffiths '^', and others show that the numbers are least during the winter months and greatest during the summer, reaching a maximum during August. Frankland records the following results from observations on the roof of the Science School, Kensington. January "4 August 10"5 March 2-6 September 4-3 May 3-1 October 3-5 June 5'4 November 1"3 July 6-3 December 2 0 Griffiths**' found in two situations in Lincoln that the maximum was reached in August and that the mean number from November to March was about half that from April to October. Lincoln. Top of Hill. November to March Mean 5 April to October ,, 16 Base of Hill. November to March ,, 1'5 April to October „ 3-4 ' Although much work has been done by Petri, Miqucl and other continental bac- teiiologists on this subject, the observations here quoted are mostly those of English investigators, as being most suitable for comparison with the present experiments. The method adopted by each is given with the references to the literature at the end. No figures obtained by the simple exposure of plates have been quoted. 502 Air of the House of Coimno7is Miquel '"' found iu the centre of Paris, in Winter 2"8, Spring 8"9, Summer 12"2, Autumn 6"8. Injiuence of weather. Carnelley, Haldane and Anderson'^' found the proportion of bacteria to moulds in the outside air considerably inHuenced by the condition of the weather : On still, damp days this ratio was 1 On windy days, ,, „ 1'3 On still, dry days ,, „ 2 6 On windy, dry days „ „ 14'1. They conclude that moulds are not so much affected as bacteria by changes in dampness. Influence of altitude. Numerous observations have established the fact that the numbers in the outside air rapidly decrease with the height of the place iu which the observation is made. The results of Griffiths''®' experiments at Lincoln have just been quoted. They show that in winter there are three times as many bacteria at the bottom as at the top of the Hill, and in summer twice as many. Frankland '"' has made several observations on this point. His figures are : — Primrose Hill (top)... ... ... ... "9 (bottom) 2-4 Norwich Cathedral (top of spire, 300 ft.) 7 (tower, 180 ft.) ... •!) (close) 1-8 St Paul's Golden Gallery ... 1-1 ... l-Oi'i Stone „ ... 3-4 ... 3-7 Churchyard ... 7-0 ... 4-G Influence of locality. It has been found, howevii-, that th(- luinibeis present in a locality under observation are influenced to a still greater extent by its surrounding, than by any of the factors yet given, the numbers being greatest in crowded districts, and least in more open spaces. Cr. S. Graham-Smith 503 As instances of this, Frankland -dvcs the t'ullowinj; figures*^'. Kensington Gardens TH ''^' 2 1 Jind 5 Hyde Park IS iS „ 3 8 Exhibition Boad 55'4 On this point Griffiths'**' als^o made a series of experiments in Litndoii. July August Forest Hill ... 4-2 5-3 City (near Bank) ... 5-6 7-3 Piccadilly ... 5-3 6-4 Near Monument ... 5 "8 7'0 In Dundee town, in quiet places, Carnelley, Haldane, and Anderson'^* found a mean of '8, as against 1 in the suburbs. Influence of Divj and Niglit. The same observers arrived at the conchision that open spaces give lower results during the night, and that even clo^e places by night give a lower average than open spaces by day, the moulds particularly show- ing a large reduction. Day Night Open places Open places Close places x^ J ,.„ bacteria •?/ i „ bacteria "15) .,,- bacteria "49/ .-q Dundee '"^i ,, ^J =1'2 u n t = ly ii nti = oo. moulds -Sj moulds "0 \ moulds -04 j They also made certain experiments illustrating the same point in the courts of the Houses of Parliament (j). oO-i). Numbers found in the outside air during the present experiments. The present experiments were made during the month of July, and from a consideration of the observations just c[Uoted the figures might have been expected to be rather high. The weather was line and sunny (19^ C. in shade and 28° C. in sun). Experiments I — V correspond closely to the results of Frank- land '^•'"'"'' at St Paul's, showing a gradual increase from 1'3 at the top of the Clock Tower to 42 on the Terrace level. It has been shown that the numbers lu open spaces are not great even in London, and the latter figure may probably be taken as a fair estimate of the numbers near the ground level in the open space about the Houses of Parliaiuent, Samples taken at 1 }).m. from two closed courts, the Peers' Inner 504 Air of the House of Commons Court (VI) and the Star Court (VII), give 4-2 and 6-0 respectively. Carnelley, Haldane and Anderson''^' made an examination of the central court of the Houses of Parliament in 1887, finding on April 19th, 20th 8.30 p.m.. .. 9-2 1.0 a.m.. 4-4 May 18th, 19th 6 p.m.. .. 22-0 12.30 a.m.. .. 4-5 They state that during the earlier experiments the traffic in the streets was very great, and quote these results as showing the great diminution in the numbers of organisms found in the night as compared with the da}'. Experiments VI, VII give numbers only slightly higher than those above quoted in tlie night, but the places in which they were made would not be much influenced by traffic in the streets. Experiments ivithin the House. The arrangements for the ventilation of the Debating Chamber have been fully described and figured in the preceding paper by Mr Butterfield. It will therefore be sufficient to remark here that the air passes upwards from the equalising chamber to the Debating Chamber through a perforated grating covered with string matting and extending over the whole of the free space on the flour, including the gangways. Part also enters by openings under the seats. The outlet is through openings in the roof As has previously been mentioned, automatic aspirators were made use of in the investigations in the Chamber during sittings. In each of the four series of observations made at 7 and 7.15 p.m., 10.30 and 10.45 p.m. respectively, five aspirators Avere simultaneously in use — four situated in the equalising chamber and one on the roof One of the former was connected with a collecting tube placed in the equalising chamber under the central grid of the floor of the House, and three by means of long lead tubes passing through the floor of the Debating Chamber with collecting tubes fixed to the backs of the Members' seats. One of these collecting tubes was placed on the third seat on the Govern- ment side at the breathing level, and one in a similar situation on the Opposition side. A third was fixed at a high level behind the Govern- ment seats. A collecting tube coimected with a similar aspirator was projected through an opening in the roof over the entrance door. In taking these samples the collecting tubes were attached to their pipes at a detinile time by certain Members, and the aspirators in the (I. S. Graham-Smith 505 equalising chamber then turned on. After five minutes the aspirators were stopped, tlie tubes removed, and the vohimes of air drawn through the collecting tubes read off. In the other mechanically ventilated rooms the air is extracted by propeller lans placed in the windows. The inlets are through flues coimected with gratings on the walls. TAIiLE 11. Experiments in Ventilalin;/ Shaft of chamber, etc., July ISth. 4-5 litres of air aspirated in each case. No. of exp. Place No. of bacterial colonies No. of inoulfl colonies Total colonies No. of organisra.s per litre VIII Air inlet at Terrace 4 1 5 11 (O 2) IX End of first passage 4 0 4 O 8 X In front of scrim cloth 9 0 9 2-0 XI Behind scrim cloth 6 1 7 1-5 (o-a) XII Inside cotton wool filter (working) 3 1 4 O 8 (O 2) XIII Equalising chamber 4 0 4 O 8 XIV Debating Chamber over central grid 6 6 12 2-6 (1-3) The results of the examination of the air at various points in the ventilating passages to the Cliauiber itself are given in the above table and show that but few organisms were present in the entering air, at any rate on the day of the examination. When no debate was in pro- gress very few bacteria were present in the equalising chamber below the central grid (-8), and on the floor level of the chamber itself over the central grid only 2-6 were found under these conditions. During debates the mean of four experiments in the equalising chamber (XXI, XXII, XXXI and XXXII) shows that there was a considerable increase (8-3) over the number found in the incoming air when no debate was in progress ("8). The position selected below the central grid is, however, the one in the eejualising chamber most likely to be contaminated by the dust fldling through from the Chamber above. Though the increase is considerable, yet even during debates, the number is low for such a position, and about the same as the average found by Frankland in the outside air of London in summer. Four sets of experiments were conducted within the Chamber itself during debates, two at 7 p.m. when the House had been sitting 5 hours, and two at lO.oO p.m. when the sitting had lasted 8i hours (including the dinner interval). The results of these experiments are given 111 Tables 111 and IV. 506 Air of the House of Commons Table III. Experiments in the Chamber during a debate, Jidij \L\st, 7 — 7.15 p.m. Temperature 1 8° C No. of exp. XV XVI XVII xvni XIX XX XXI XXII XXIII XXIV Government side, third seat Government side, back seat * Opposition side, third seat Eijualising chamber, under ^ central grid \ Eoof over entrance door No. of bacterial colonies No. of nioulil colonics Total colonies Litres of air aspirated No. of organisms per litre 34 14 48 4-5 lO 6 (3 1) 18 3 21 4 0 5-2 (0-7) 26 6 31 6 0 5-1 (0-8) 17 7 24 5o 4-4 (1-2) 18 10 28 4-5 6-2 (2-2) 25 15 40 5-0 SO (3 O) 27 10 37 4 0 9-2 (2-5) 30 14 44 5 0 8-8 (2 8) 26 15 41 5 0 8-2 (3-0) * Aspirator failed to work. XV, XVII, XIX, XXI, XXIII, were carried out simultaneously at 7 p.m. and XVI, XVIII, XX, XXII, XXIV simultaneously at 7.15 p.m. The day was windy and damp. 282 persons were present, namely 176 Members, 66 strangers, 28 reporters, and 12 ladies. A division took place at 6.30, 393 Members being present. Table IV. Experiments in the Chamber duriv<j a debate., July 'l\st. 10.30 — 10.45 p.t)i. No. of exp. XXV XXVI XXVII XXVIII XXIX XXX XXXI XXXII XXXIII XXXIV Place Government side, third seat Government side, back seat Opposition side, third seat Equalising chamber under) central grid Roof over entrance door No. of bacterial colonies No. of mould colonies Total colonies Litres of air aspirated No. of organisms per litre 17 11 28 4 0 7 (2-7) 14 10 24 4-0 6 (2-4) 15 7 22 5-0 4 4 (1-4) 11 2 13 2-5 5 2 (0-8) 23 6 29 5-5 5 2 (i-o) 13 10 26 4-5 5 7 (2-2) 26 12 38 4-5 8 4 (2-6) 22 13 35 4-5 7 7 (2-8) 30 5 35 5 0 7 O (l-O) 2() 6 32 5-0 6 4 (1-2) XXV, XXVII, XXIX, XXXI, XXXIII were carried out simultaneously at 10.30 p.m. and XXVI, XXVIII, XXX, XXXII, XXXIV at 10.45. 305 persons were present, namely 152 Members, 108 strangers, 26 reporters, and 19 ladies. They indicate that the organisms are most numerous in the equalis- ing chamber. The numbers near the roof are nearly as great. Within the Chamber itsell", the greatest number was fouml, as would be ex- O. S. Oraham-Smith .-)(»7 pected, on tlic most crowded side, namely the Government third seat (7-2), next must numerous on the Opposition third seat (5'4), and h-ast at a high level behind the Government benches (4<-8). By taking the highest numbers obtained, namely those in the e(iualising chamber, as 1007o the following ratio is obtained, yp/o at the roof, 87"/o third Government seat, 6a"/o third Opp(jsition seat, and 57"/o above Government back seat. Although the actual numbers were excessive, the ratio obtained from the earlier experiments is, with the exception of the third Government seat, almost identical, namely equalising chamber lUO'Yo, roof 96 Vo, Government third seat 1237o, Opposition third seat 57 7o, and above Government back seat 53 "/o- The results of the experiments within the Chamber are given shortly in the annexed table. Table V. Sunimavij of prperimeats in Chuiaber durliuj debnteti, J ^^^ >J '^\st. Organisms per litre Mean of all experiments Position of Tube Early Series Late Series Ratio 7 p.m. 7.15 p.m. 5-2 (0-7) 4-4 (1-2) 6-2 (2-2) y-2 (2-5) 8-2 (3-0) 10.30 p.m. 10.45 p.m. Government side, third seat Government side, above j back seat \ Opposition side, third) seat \ Equaliising chamber Roof 10-6 (3-1) 5-1 (0-8) 8-0 (3-0) 8-8 ('2 -8) 7-0 (2-7) 4-4 (1-4) 5-2 (1-0) 8-4 (2-6) 70 (1-0) 6-0 (2-4) 5-2 (0-8) 5-7 (2-2) 7-7 (2-8) G-4 (1-2) 7 2 (2-2) 4-8 (10) 5-4 (1-8) 8-3 (2-7) 7-6 (2 0) 87 -Vo 57,, 65 „ 100,, 91 „ It is interesting also to observe that the numbers were in most cases remarkably uniform, and that there was no increase at the later time. During the experiments at (j.3(), 282 persons were present in the Chamber and Galleries, and at 10.30, 305 persons. When the experiment in (Committee Room No. 9 was made the lans were working, and 150 persons were present. The result showed 209 organisms per litre. In Committee Room No. 1 with only 41 persons present, the windows open but no fans working, the mean of two experiments (XXXVII, XXXVIII) gave 346. In these rooms therefore three and five times as many bacteria were discovered respectively as in the Chamber itself. 508 Air of the House of Commons No. of exp. XXXV* XXXVI XXXVII XXXVIII XXXIX XL XLI XLn* Table VI. Experiments in Committee, Dining, and Smoking Rooms. 4'5 litres of air aspirated in each case. Place Committee Room No. 9. Fans working, 150 persons present. 1.45 p.m. Committee Koom No. 1. Fans not working, windows open, 41 persons ijresent. 1.30 p.m. Central Dining Room. 36 per- sons present. 8 p.m. Members' Smoking Room. 24 persons present. 9 p.m. No. of bacterial colonies No. of nioulr] colonies Total colonie-s No. of organisms per litre 42 18 60 13 3 (4-0) 73 21 94 20 9 (4-6) 136 24 160 35 5 (5-3) 133 19 152 33 7 (4-2) 153 33 186 41 3 {8-4) 145 54 199 44 2 (12-0) 90 48 138 30 6 (10-6) 19 20 39 8-6 (4-4) * In each of these cases part of the phig was loosened during transit and the result is therefore not reliable. Samples from the JMembers' Smoking Rooms showed 30 G per litre (XLI), being about the same number as found in Committee Room No. 1, but from the Central Dining Room still higher figures were obtained, namely, 4r3 and 44"2, mean 432. In certain samples of dust enormous numbers of micro-organisms were present. These samples were obtained from the Ways and Means Corridor, the Chamber itself, and the corridor outside the Lavatory. That from the Ways and Means Corridor gave in "01 gi'ammes 18,944 colonies or about 1,900,000 per gramme. Comparison of the abuve fgures ivitli the results of other investigations 0)1 air within rooms. It is probably most advantageous to compare the numbers of organ- isms found in the Debating Chamber, Committee, and other rooms witli those found in schools. It has already been shown (p. 502) that to some extent the numbers, and proportion of bacteria to moulds, depend in such situations on conditions of the weather. There are, however, other factors which influence the numbers in a much greater degi'ee, namely the locality, cleanliness, age, and ventilation of the building, and the amount of disturbance of the atmosphere. (j. S. CiJlUHAM-SMITII 509 Influence of Locality. Carnelley'" has demonstrated that even within bnihlings the altitude exerts some influence. He found on the average the following numbers in schools situated at various altitudes. No. of schools Organisms Situation examined per litre Higli ... ... 25 ... ... 95 Medium ... ... 20 ... ... 106 Low ... ... 19 ... ... 164 Even the slight difference caused by tiie flat on which the room is situated causes an appreciable difference according to this observer. No, of schools Organisms Situation examined per litre Downstairs ... ... 28 ... ... 122 Upstairs ... ... 28 ... ... 62 The same investigator also gives figures to illustrate the influence of open, and closed, situations. No. of schools Organisms situation examined per litre Most open ... ... 18 ... ... 66 Medium ... ... 18 .. ... 84 Least open ... ... 17 ... 135 (These figures have been inserted to show that some differences have been found to prevail under the conditions mentioned. It is evident, however, that the more highly, and more openly situated, schools are probably the more recent, and cleaner. Upper and lower rooms also may not be occupied to the same extent. In consequence of these considerations too much stress should not be laid on these results.) Influence of the Age of the Building. It has been shown by Carnelley '■» and by Carnelley, Haldane, and Anderson'-'' that the age of the building has a most striking influence on the numbers found in the school rooms. Years opened No. of cases Organisms / more than 22 years ... 24 ... 81 (1) Country Schools ... j between 17—13 ,, ... IG 65 y within 1 year ... 3 ... 3(3 a . , . , , i more than 22 years 4 IQii Schools in suburbs » •' '■ •• ^^^ and county towns ) between 15-9 ,, ... 41 ... 97 within 1 year ... (i (j.5 ,„,,,,,. / I''uilt before 1860 .. 7 qii (2) Schools m 1 , ^ , „. , ■' Dundee i " between 1875—1880 20 ... 1.50 I ,, „ 1880—1885 .r, 38 (Experiments made in 1886.) 510 Air of the Hoiise of Commons Influence of Cleanliness. The two sets of observers from ^vllom the last figures were quoted have also demonsti-ated that the cleanliness, or otherwise, of the rooms of schools and dwelling houses is a factor of some importance in determining the numbers present. Natural Mechanical Schools ventilation ventilation Cleaner ... ... 91 ... ... 3 Average ... ... 125 ... ... 16 Dirtier ... ... 198 ... ... 30 Influence of Ventilation. Of all the various factors which have a bearing on the number of micro-organisms present in the air of rooms, probably ventilation is the most important. It has been found, however, that mechanical ventilation at the time of the experiment is of little importance, but the following tables from Carnelley ''* show that the effect of habitual mechanical ventilation is well marked. No. of schools examined Organ isms Towu schools (Aberdeen). Natural ventilation 17 136 ,, ,, (Dundee). 