Dr. Ure 07i iVarming a7id Ve.ntilating. B5 



rapidly over the scorching deserts of Arabia and Africa, constitute 

 the Simoom of those regions, and are well known by their injurious 

 effects on animal and vegetable life. To these noxious qualities is 

 superadded, as in the air of all rooms heated through the medium 

 of cast-iron pipes or stoves, an offensive smell, arising partly from 

 the partial combustion of animal and vegetable matters always 

 floating in the atmosphere of a town, and perhaps also from minute 

 impregnations of carbon, sulphur, phosphorus, or even arsenic, de- 

 rived from the metal itself. The Author expresses his surprise that 

 in the recent report of the Parliamentary Committee on the subject 

 of ventilation, no reference is made to the methods employed for 

 that object in factories, although they afford the best models for imi- 

 tation, being the results of innumerable experiments made on a 

 magnificent scale, with all the lights of science, and all the resources 

 of the ablest engineers. He proceeds to describe these methods ; 

 and is then led to investigate the comparative efficiency, with a 

 view to ventilation, of a draught of air resultiiig from a fire and 

 chimney, and that produced by the rotation of a fan -ventilator. 

 He shows that a given quantity of coal employed to impart motion 

 to the latter, by means of a steam-engine, produces a ventilating 

 effect 38 times greater than can be obtained by the consumption of 

 the same fuel in the ordinary mode of chimney ventilation. Accord-^ 

 ingly, he strongly advises the adoption of the former in preference 

 to the latter : and inveighs against the stove-doctors of the present 

 day, who, on pretence of economy and convenience, recommend 

 the slow combustion of a large body of coke, by means of a slow 

 circulation of air ; under which circumstances, it is well known to 

 chemists that much carbonic oxide, a gas highly pernicious to all 

 who respire it, is generated ; accompanied, at the same time, by a 

 comparatively small evolution of heat. In order to obtain the 

 maximum quantity of heat from a given mass of fuel, its combus- 

 tion, he observes, should be very vivid, and the evolved caloric 

 should be diffused over the largest possible surface of conducting 

 materials ; a principle which has been judiciously applied in several 

 French factories. It has been proved that work-people employed 

 in calico-drying rooms, heated according to the plan here repro- 

 bated, become wan, emaciated, and diseased ; while in rooms in 

 which the air is more highly heated by means of steam-pipes, they 

 preserve their health and florid complexion. 



16. *' An Experimental Inquiry into the Relative Merits of Mag- 

 netic Electrical Machines and Voltaic Batteries, as Implements of 

 Philosophical Research." By William Sturgeon, Esq., Lecturer 

 on Natural and Experimental Philosophy at the Honourable East 

 India Company's Military Academy at Addiscombe. Communicated 

 by P. M. Roget, M.D., Sec. R.S. 



The first part of this paper is occupied by a description of two 

 forms of constructing the magnetic electrical machine, which the 

 author has adopted ; and the second, with the particulars of some 

 experiments made with a view to determine the respective powers 

 of these machines as com pared, with the common voltaic battery. 

 In the first form of the instrument, a reel, round the periphery of 



Third Series. Vol.10. No. 58. Jr/??. 1837. K 



