48

REPORT OF

The Lancet Sanitary CommissionON THE

VENTILATION OF THEATRES ANDPLACES OF PUBLIC ASSEMBLY.

PART II. -THE PARIS SORBONNE.

WE will now describe’ the ventilation of the great amphi-#theatre of the Paris Sorbonne, which contains 3000 seats,and is the most recent application of the principles we haveattempted to explain. We have already remarked that the<Paris Sorbonne was the latest application of the principles’of ventilation so successfully employed at the Vienna OperaHouse. Of course we allude to the new Sorbonne, themagnificent edifice that abuts on the Rue des Ecoles,which was inaugurated in 1889, but which, nevertheless,,has not yet come fully into use. Within this structurethere is an immense amphitheatre, where all the greatceremonies connected with the Paris University take

place. Here the problem of warming and ventilatingds as difficult as in a theatre, for SOOO seats have tobe provided ; while that of the form of structure is

even more difficult, for the seats should be all equallygood. The building, however, differs from a theatre inas-much as there is a platform instead of a stage. The form

adopted is that of most Parliament houses-namely, thesemicircle, with a platform instead of the tribune. Thepresident’s seat is of course in the centre of the platform,facing the half-circle. The pit or floor is about the size ofthe platform-namely, only half the width of the amphi-theatre. On each side and all round rise tiers of seats,while on the floors above there are two galleries. Even thesectional drawing, which we give, will at least partially<show that the seats are all equally good and command an- equal view of the platform. It will be observed how under<every seat there is an air inlet. In fact, the seats in thegalleries, as in the body of the hall, are all suspended overair chambers, and these air chambers form the third of theseries-namely, the mixing chambers similar to what we- have seen at the Vienna theatre. Yet the ventilation onlyresembles that of the Vienna Opera House in general princi-ple ; there is a difference in detail. The air is propelledinto the amphitheatre by the force of three fans that standside by side in the inlet passages or air shafts.. A portionof the air is conducted into a furnace, where it is warmed,the other portion travels upwards towards the mixing room.The two shafts, however, meet together just below the floorof the mixing room. Here a very simple apparatus enablesthe attendants to open more or less widely the door or valveof the cold air shafo. The wider it is opened the greater thecurrent of cold air as compared with that of the warmed air,and thus by moving these valves the temperature of themixing chamber is easily regulated.The three fans propel each 20,000 cubic metres of air per

hour. This is, therffore, a total of 60,000 cubic metres.But if they were made to revolve with exceptional velocitythe supply of air could be raised to 72,000 cubic metres perhour. These fans are unusually large in diameter, morethan six feet, and they only make about 150 revolutions inthe minute. They were designed especially to produce alentiful but slow current of air. When a shaft is verylong and force is required to send the air forward a

great diatance, as in the ventilation of coal mines, then theSer ventilator would, with its great centrifugal force,render better service. But at the Sorbonne the object was thereverse-namely, that of moving a large volume of air overa wide space at a slow rate. The power is provided by agas motor engine of 15 horse-power. As the air enters theunderground passages it can be moistened in summer bya spray of water. This spray is produced in the samemanner as that which exists at the House of Commons,whence the idea was derived.When tenders’were invited for the ventilation of the

Sorbonne, the condition stipulated was that each personshould be supplied with 20 cubic metres of air per hour.

A well-known firm of French sanitary engineers, Messrs.Geneste and Her?cher, were successful in the competitionthat ensued, and we have seen that the screw fans whichthey provided, by propelling 60,000 cubic metres of air perhour, supply precisely the 20 cubic metres required for eachof the 3000 persons who can be seated in the amphitheatre.But with mechanical force it is easy enough to give anyamount of air ; the difficulty is to ensure its even distribution,and this in so slow and gradual a manner as to be imper-ceptible. To moderate the current, the air inlets, which arecut out in the floor under every seat, are covered over withtwo perforated iron plates, placed about an inch one abovethe other. The perforations in the plates a!every smallnamely, four millimebres in diameter. These iron perforatedplates measure about 8 in. by 14 in., but the total usefulsurface for air inlet amounts throughout the whole amphi.theatre to 80 metres square. The rapidity at which theair enters is equal to 25 centimetres per second. The out.lets measure in all 45 metres square; they are situated inthe roof of the ball and under the galleries. Here the airpasses out at the rate of 50 centimetres per second. Gas-burners help to draw upwards the vitiated air till it reachesthe final outlet shaft, which measures 14 metres square;and in this shaft the air travels at the rate of 1 metre20 centimetres per second. It has not been found neces-sary to place an exhaust fan in this outlet shaft; the air,being warm and forced in from below, naturally goesupwards.Thus we find realised at the Sorbonne what had already

been done at the Vienna Opera House. In the screw

fans and the 15 horse-power engine are the mechanicalmeans of providing with mathematical exactitude theamount of air required. Then there is the large mixingchamber, where, by means of nicely adjusted valves, theattendants can regulate the inlet of hot air and of cold airso as to make an atmosphere which they generally warm to65&deg; F. The inlets are so numerous and large that the air canonly travel through them slowly, and, being subdivided bythe minute perforations in the iron plates placed over theinlets, occasions no draught;. All this, we repeat, is a copyof what we have seen at Vienna; but Messrs. Geneste andHerscber were determined to go a step further, and attemptto realise for the Sorbonne M. Emile Trelat’s highest con-ception or good ventilation.M. Trelat’s ideal of well-being is a fine autumnal day,

when the air is cold and crisp, but the rays of the sun arestill warm. The colder the air, the greater the internaloxidation in breathing, and therefore the greater the in-ternal warmth. If while breathing cold air the bodycan be preserved from external cold by the radiationof heat from the sun or other sources, then the mosthealthy and the most enjoyable state of physical exist-ence results. We know that the atmosphere takes uplittle or none of the heat that passes through it by radia-tion. To realise this ideal the walls surrounding theamphitheatre are hollowed, and inside there is a canalisationby which heat can be imparted to the substaace of which theyare built. Also the flat wall facing the amphitheatre, byreason of its size and the coldness of the stones with which itis built, would chill the air in the body of the hall anddetermine a down current. This would strike the heads of theprofessors sitting on the platform. To obviate such a danger,at a height of about ten feet above the platform, and for thewhole length of the wall, there is an emission of especiallyheated air, which counteracts the down current and thechill created by this broad surface of cold wall. Thus thecold produced by the material of the building itself isneutralised. This is not all. Though, as already explained,there are ample means of providing warmed air throughoutthe whole of the amphitheatre, it can also be ventilatedwith cold external air in the midst of radiated heat. Tosecure this imitation of M. Trelat’s ideal autumnal, cold,bright, sunny day, the air-mixing chambers of the amphi-theatre are closed about an hour before the public are

admitted. The batteries in the heating furnace are raisedto about 300&deg; to 400&deg; C. The air passing over these veryhot warming batteries is allowed to escape up all the hotair shafts built inside the walls of the amphitheatre. Itenters the amphitheatre by the openings such as thatsituated ten feet above the platform, and travels upwardsalong the cold surface of the walls, which are soon warmed.As this is proceeding the air in the mixing chamber, by itsproximity with the furnace that is in the chamber below,becomes slightly warmed. It therefore expands and travels

49

upwards through the multitudinous openings into the bodyof the hall. In a very short time the temperature ofthe whole amphitheatre is raised to about 160&deg; F. Theplace is therefore absolutely untenantable. The walls,the furniture, everything in the amphitheatre is thoroughlyheated, and soon absorbs and husbands a large stock ofcaloric. Then about a quarter of an hour before the publicare admitted all the hot-air supply is cut off, and the warm-ing of the amphitheatre entirely stopped. The air-pro-

’’

pelling screw fans are now set in motion. They pnmp intothe amphitheatre pure cold air from the street. The over.heated air is soon driven out, and by the time the publicenter they find in the amphitheatre exactly similar air tothat they were breathing in the street. This air has not

magnificent agsembly hall. Thus the Sorbonne amphi.theatre can be warmed and ventilated as is the Vienna.Opera House, with a carefully prepared mixture of hot andcold air; it may be ventilated with pure cold outside air,and warmed by radiation from its heated walls, or the twosystems may be combined if desired.There is something especially fibting in the fact that this,

the great centre, where honours and rewards are distributedto those who have distinguished themselves in learning andscience, should in itself be an example of what science can)achieve for the comfort and health of the audiences privi-leged to assist at any of the meetings held in this amphi.theatre. At the Sorbonne will be crowned the laureates ofthe Paris University, but crowns should also be reserved for

THE NEW SORBONNE, PARIS.

A, Pure air inlet. B, Engine house. C, Inlet ventilating fan. D, Furnace for warming the air. E E, Hot air shaft. F F F ir, Cold air shafts.g g g g, Valve regulating amount of cold air, which here joins the hot air shaft. H H H, Hot and cold air mixing chambers. ii, Hot air pipe-to counteract cold down draught caused by the wall. J, Burners above glass reflecting roof, serving to light the amphitheatre and drawoff the foul air. ’

been warmed or mixed with warmed air in any way ;it is a pure and, so to speak, an unadulteratedout-of-door atmosphere. But through this cold airis radiated the heat given off by the hot walls and fur-niture of the amphitheatre. Also the cold incomingair as it strikes the hot walls is warmed. It therefore be-comes lighter, expands, and travels upwards towards theoutlets in the ceiling. If, on the contrary, as is usually thecase, the walls were cold and the incoming air was warmed,then the air on striking the walls would be cooled, wouldcondense, would become heavier, and therefore would fallas a cold draught on the heads of the people below. Thewalls of the amphitheatre retain their heat for a few hours ;that is long enough for the ordinary meetings held in this

those who have made its amphitheatre an example to theworld of what can be done to secure the due observation ofNature’s laws by continuing the provision of pure air, evenwhen 3000 persons have to assemble under one roof andin one single hall.

NEW INFIRMARY BUILDINGS, ST. OLAVE’S UNION.-Recently the opening ceremony took place of the newpavilions at the infirmary, Lower-road, Rotherhithe. Theyhave been erected by the guardians of the poor of theSt. Olave’s Union, and will provide room for 280 beds, rais-ing the total accommodation to 650 beds. The outlay hasamounted to about &pound;36.000.