WARMING AND VENTILATION. 21 



smaller or larger operations, whereby, as well as on account 

 of the form of the furnace and the mode of blast, great 

 economy of fuel is attained. They are accompanied by a 

 table with cast-iron top, beneath which is a bellows worked by 

 the foot, and through which three jets rise which can be 

 adapted to the twyers of any of the furnaces. We give this 

 detailed description, because our practical acquaintance with 

 them in the operations of the laboratory enables us to give a 

 most favourable opinion of their excellence ; and, having seen 

 them in operation in the hands of practical melters, for fusing, 

 soldering, &c., we can speak of their general practical value 

 in the arts. The enterprising originators of these furnaces 

 are about applying the same principles to larger cupola fur- 

 naces for melting iron, and to other furnaces, large and small, 

 for^arious metallurgic operations. They are made by Barron 

 Brothers, No. G Piatt street, New York. 



2. Warming and Ventilation. 

 Little has been added to our stock of knowledge on these 

 subjects during the last few years; but, if we were to apply 

 what we already know, doubtless general health would be 

 greatly benefited. Our public places of assemblage and our 

 dwellings are heated to a tropical temperature, by air, the 

 dust of which has been subjected to dry distillation by passing 

 over a red-hot iron surface, and produced fumes of empyreu- 

 matic oils and tarry matters, which we endeavour most se- 

 dulously to prevent escaping, by barring up all avenues and 

 chinks communicating with the external air, except those 

 accidentally produced. In ventilation, there is still less at- 

 tempted. It may be that masons and carpenters design to 

 leave behind them, when their work is completed, a generally 

 diffused system t)f ventilation, by half-filling the places in 

 walls with mortar, and putting in green wood, which shrinks 

 and cracks in every direction ; but it is hardly necessary to say 

 that this fanciful kind of ventilation is not based on very sound 

 principles. It is sad to reflect on the badly heated and not 

 ventilated school-rooms in the now widely diffused public- 



