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New Zealand Times, Volume XXX, Issue 4493, 13 August 1875, Page 2

Ix will be remembered that some time since we reprinted an article, furnished to us by the Government Printer, on a new system of ventilation designed by a Mr. Tobin. We also commented on Mr. Town's discovery in the most favorable terms. Tn a few days the colony was informed from Dunedin that Mr. George Bell, the present proprietor of the Evening Star there, had, so long as eighteen years ago, made a similar discovery to that made by Mr. Tobin, and applied it with the most complete success to the ventilation of a small, and previously uncomfortable, Independent chapel at Kew, in the colony of Victoria. From Dunedin papers to hand we find that in this colony also Mr. Bell has been equally successful, and not only this, but that his plan was in some respects an improvement on that of Mr. Tobin. According to the Evening Star, it occurred to Mr. Bell that, although the plan adopted at rural Kew succeeded in supplying fresh and probably pure air, it was quite possible that, being drawn from atmospheric strata nearest the earth, miasma or even foetid smells might be admitted with it. In order to obviate this, he determined that should the opportunity occur of applying his invention, air should be conducted downwards and beneath the floor through tubes, drawing their supplies from the level of the highest part of the outer walls. By this arrangement the danger of supplying vitiated air would, under ordinary circumstances, be avoided ; and if there were any special conditions rendering it undesirable, special adaptation would be necessary. No opportunity of applying the plan offered itself until Mr. John Sibbald altered the Princess Theatre, Dunedin, some three years ago. The great drawback to that elegantly designed place of amusement was that with a full house it was almost impossible to breathe, for it was supposed the architect had made no provision for supplying fresh air. We do not know his name—we believe ho was a German —but, injustice to him, it should be stated that he had to a certain extent mot the difficulty by introducing two ventilating tubes under the platform of the dress circle, with perforations for diffusing the air through the panelling in front ; but these had been ignorantly boxed up and rendered useless during some scenic or other alterations. To a certain extent, therefore, ho had forestalled the system ; but his knowledge was rendered abortive by ignorant meddling. When'

the alterations were projected a few years since, Mr. Sibbald consulted Mr. Bell, and, after having the plan explained, requested liim to supervise carrying it out. This was really no enviable task, but it was undertaken ; and it would amuse were all told of the difficulties thrown in the way of its completion by workmen, who did not like to be directed by one who was an outsider, being neither an architect, nor a joiner, nor a carpenter. Most unwillingly, and sometimes contrarily, was every direction adopted, and the result is a somewhat imperfect, but at the same time, as far as it goes, a very successful application of the plan. In some respects the Princess Theatre afforded unusual facilities for the experiment. Beneath the floor of the pit, and extending twothirds of the distance towards the stage, is an excellent air-tight floor. The floor of the pit being raised some feet above this at one end, a vast triangularly - shaped chamber was formed, having no connection with the outer air. Into this chamber air is poured by means of six large perpendicular tubes supplied by openings in the wall about eighteen feet above the street. There is thus beneath the feet a chamber of pure air, which is diffused through the theatre by openings covered with perforated zinc, placed under the back part of each row of seats at intervals through the whole area of the pit. The same number of perpendicular tubes'communicating with horizontal distributors ventilate the boxes, the air being diffused through perforations under each tier of seats. An upward movement of the air within the theatre is secured through the one outlet for foul air being heated by the gasalier. Mr. Tobin does not consider such an outlet necessary, but (says the Star) our experience differs altogether from his on that point. Practically it has been found, where facilities for getting rid of foul air are defective, all plans for supplying pure air are comparatively neutralised. The opening for expulsion of vitiated air, however, requires to be very small compared with that for admission of fresh air, for rapid draught outward at the height of a ceiling is of no consequence to health, and is necessary to prevent the impure air being condensed and falling back into the apartment; while small openings for admission of air below would induce draughts that must produce colds, rheumatism, or other kindred disorders. The principle must be born in mind, therefore : free and full admission —rapid expulsion. Although there are many parts of the Princess Theatre that could not be reached without outlay almost equivalent to building it afresh, the fact that as many persons as can find room can enjoy an evening's performance without experiencing inconvenience is quite sufficient to convince the most sceptical that the plan has succeeded. Those who have access to the article from The Times circulated by the General Government, will at once recognise the general similarity of the plans of ventilation, but that Mr. Bell's has advantages not claimed for tho other. It has been shown that it is applicable to the ventilation of public buildings.