5G SCIENCE IN SHORT CHAPTERS. 



the Society of Arts, December 9th, 1881, and contains some 

 curious fallacies, probably due to its extemporaneous character ; 

 but as they have been quoted and adopted not only in political 

 and literary journals, but also by a magazine of such high 

 scientific standing as Nature (see editorial article, January 

 5th, 1882, p. 219), they are likely to mislead many. 



Having already, in my " History of Modern Invention, 

 etc.," and in other places, expressed my great respect for Dr. 

 Siemens and his benefactions to British industry, the spirit in 

 which the following plain-spoken criticism is made will not, I 

 hope, be misunderstood either by the readers of Knowledge or 

 by Dr. Siemens himself. 



I may further add that I am animated by a deadly hatred of 

 our barbarous practice of wasting precious coal by burning it 

 in iron fire-baskets half buried in holes within brick walls, and 

 under shafts that carry 80 or 90 per cent, of its heat to the 

 clouds ; that pollute the atmosphere of our towns, and make 

 all their architecture hideous ; that render scientific and effi- 

 cient ventilation of our houses impossible ; that promote rheuma- 

 tism, neuralgia, chilblains, pulmonary diseases, bronchitis, and 

 all the other " ills that flesh is heir to" when roasted on one 

 side and cold-blasted on the other ; that I am so rabid on this 

 subject, that if Dr. Siemens, Sir F. Bramwell, and all others 

 who defend this English abomination, were giant windmills in 

 full rotation, I would emulate the valor of my chivalric pred- 

 ecessor, whatever might be the personal consequences. 



Dr. Siemens stated that the open fireplace " communicates 

 absolutely no heat to the air of the room, because air, being a 

 perfectly transparent medium, the rays of heat pass clean 

 through it." 



Here is an initial mistake. It is true that air which has 

 been artificially deprived of all its aqueous vapor is thus com- 

 pletely permeable by heat rays, but such is far from being the 

 case with the water it contains. This absorbs a notable amount 

 even of bright solar rays, and a far greater proportion of the 

 heat rays from a comparatively obscure source, such as the red- 

 hot coals and flame of a common fire. Tyndall has proved that 

 8 to 10 per cent, of all the heat radiating from such a source as 

 a common fire is absorbed in passing through only 5 feet of air 

 in its ordinary condition, the variation depending upon its 

 degree of saturation with aqueous vapor. 



Starting with the erroneous assumption that the rays of heat 

 pass " clean through" the air of the room, Dr. Siemens went 



