OS SCIENCE IN SHORT CHAPTERS. 



escape. It would, in fact, correspond to the action of our 

 open fireplaces in rendering effective ventilation impossible. 



The following, from the report of the Lords' Committee 

 on Accidents in Coal Mines, 1849, illustrates the magnitude 

 of the ventilation arrangements then at work. In the Helton 

 Colliery there were two downcast shafts and one upcast, the 

 former about 12 feet and the latter 14 feet diameter. There 

 wore three furnaces at the bottom of the upcast, each about 9 

 feet wide with about 4 feet length of grate-bars ; the depth 

 of the upcast and one downcast 900 feet, and of the other 

 downcast 1056 feet. The quantity of air introduced by the 

 action of these furnaces was 168,560 cubic feet per minute, at 

 a cost of about eight tons of coal per day. The rate of motion 

 of the air was 1097 feet per minute (above 12 miles per hour). 

 This whole current was divided by splitting into 16 currents of 

 about 11,000 cubic feet each per minute, having, on an aver- 

 age, a course of 4J miles each. This distance was, however, 

 very irregular the greatest length of a course being 9^ miles ; 

 total length, 70 miles. Thus, 168,560 cubic feet of air were 

 driven through these great distances at the rate of 12 miles per 

 hour, and at a cost of 8 tons of coal per day. 



All these magnitudes are greatly increased in coal-mines of 

 the present time. As much as 250,000 cubic feet of air per 

 minute are now passed through the shafts of one mine. 



The problem of domestic ventilation as compared with coal- 

 pit ventilation involves an additional requirement, that of 

 warming, but this does not at all increase the difficulty, and I 

 even go so far as to believe that cooling in summer may be 

 added to warming in winter by one and the same ventilating 

 arrangement. As I am not a builder, and claim no patent 

 rights, the following must be regarded as a general indication, 

 not as a working specification, of my scheme for domestic 

 ventilation and the regulation of home climate. 



The model house must have an upcast shaft, placed as 

 nearly in the middle of the building as possible, with which 

 every room must communicate either by a direct opening or 

 through a lateral shaft. An ordinary chimney built in the 

 usual manner is all that is required to form such a main shaft. 



There must be no stoves nor any fireplaces in any room 

 excepting the kitchen, of which anon. All the windows must 

 be made to fit closely, as nearly air-tight as possible. No 

 downcast shaft is required, the pressure of the surrounding 

 outer atmosphere being sufficient. Outside of the house, or 



