462 REPORTS ON THE STATE OF SCIENCE. 



that mechanical ventilation removed most of the microbes contributed 

 from the bodies and clothing of the occupants. 



These observations indicated that in mechanical ventilation a steady 

 movement of the air was maintained throughout the room, tending to 

 prevent the microbes from settling on surfaces and to convey them out 

 of the room. 



It is desirable that similar investigations should be carried out with 

 the aid of the more complete methods of bacteriological investigation 

 now at our command. 



Comparison of Mechanical and Natural Ventilation. 



On comparing together mechanical and natural ventilation it is seen 

 that they each have their advantages and disadvantages. By means 

 of mechanical ventilation the air-supply can be better controlled, 

 washed and filtered from dust, heated or cooled ; the disturbing in- 

 fluence of variation in the force and direction of wind can be more 

 easily overcome ; the required temperature of the room more steadily 

 maintained. 



On the other hand, mechanical ventilation is far more costly : the 

 process is placed almost entirely in the hands of one individual, generally 

 remote from the schoolroom, whilst at the same time both teachers and 

 scholars are deprived of the salutary object-lesson afforded by 'natural 

 ventilation ' in the desirability of admitting fresh air into all occupied 

 rooms and dwellings. 



Recommendations. 



From the foregoing statements it will be seen that the Committee are 

 of opinion that a large number of investigations will have to be made 

 before a final opinion can be formed with regard to many points in 

 connection with the problems involved in practical ventilation ; for 

 insta-nce, the position and size of inlets and outlets, the best means 

 for the impartial distribution of the fresh air supplied, the relative 

 advantages of mechanical as compared with ' natural ventilation,' the 

 best mode of conveying heat. 



Until such final opinion is formed, the best systems of ventilation will 

 suffer discredit owing to faulty and defective methods of carrying them 

 out ; great expenses may be needlessly incurred in the construction of 

 ventilation installations, whilst those who are responsible for the manage- 

 ment of schools will be constantly harassed by new regulations and 

 uncalled-for expenditure without obtaining any real improvement in the 

 ventilation. 



The Committee have endeavoured to make investigations on some of 

 the points mentioned above, but have not the means or authority for 

 carrying them out. They suggest that inquirers well versed in the 

 scientific aspect of the question, and acquainted with the practical 

 methods employed for ventilation, as well as with the requirements and 

 practical business management of schools, should be commissioned to 

 carry out such investigations ; that schoolrooms, some provided with 

 mechanical, others with ' natural ' systems of ventilation, be put at. 

 their disposal for this purpose ; that the time is ripe for a carefully 

 conducted investigation on scientific lines of the whole subject of school 

 \entilation. 



