BRITISH ASSOCIATION. 33 



fuel, there appears to be no limit to the temperature attainable, except the powers 

 of resistance in the materials of which the furnace is composed. 



With regard to smoke, which is at once a waste and a nuisance, having myself 

 taken part with Dr. Richardson and ^r. Longridge in a series of experiments 

 made in this neighbourhood in the years 185*7-58 for the purpose of testing the 

 practicability of preventing smoke in the combustion of bituminous coal in steam 

 engine boilers, I can state with perfect confidence that, so far as the raising of 

 steam is concerned, the production of smoke is unnecessary and inexcusable. 

 The experiments to which I refer proved beyond a doubt, that by an easy method 

 of firing, combined with a due admission of air and a proper arrangement of fire- 

 grate, not involving any complexity, the emission of smoke might be perfectly 

 avoided, and that the prevention of the smoke increased the economic value of 

 the fuel and the evaporative power of the boiler. As a rule, there is more smoke 

 evolved from the fires of steam-engines than from any others, and it is in these 

 fires that it may be most easily prevented. But in the furnaees used for most 

 manufacturing operations the prevention of smoke is much more difficult, and will 

 probably not be effected until a radical change is made in the system of applying 

 fuel for such operations. 



Not less wasteful and extravagant is our mode of employing coal for domestic 

 purposes. It is computed that the consumption of coal in dwelling-houses 

 amounts in this country to a ton per head per annum of the entire population ; so 

 that upwards of twenty-nine millions of tons are annually expended in Great 

 Britain alone for domestic use. If any one will consider that one pound of coal 

 applied to a well-constructed steam-engine boiler evaporates 10 lb., or one gallon 

 of water, and if he will compare this effect with the insignificant quantity of 

 water which can be boiled off in steam by a pound of coal consumed in an ordi- 

 nary kitchen fire, he will be able to appreciate the enormous waste which takes 

 place by the common method of burning coal for culinary purposes. The simplest 

 arrangements to confine the heat and concentrate it upon the operation to be 

 performed would suffice to obviate this reprehensible waste. So also in warming 

 houses we consume in our open fires about five times as much coal as will produce 

 the same heating effect when burnt in a close and properly constructed stove. 

 Without sacrificing the luxury of a visible fire, it would be easy, by attending to 

 the principles of radiation and convection, to render available the greater part of 

 the heat which is now so improvidently discharged into the chimney. These are 

 homely considerations — too much so, perhaps, for an assembly like this ; but I 

 trust that an abuse involving a useless expenditure exceeding in amount our 

 income-tax, and capable of being rectified by attention to scientific principles, 

 may not be deemed unworthy of the notice of some of those whom I have the 

 honour of addressing. 



The increase of the earth's temperature as we descend below the surface is a 

 subject which has been discussed at previous Meetings of the British Association. 

 It possesses great scientific interest as affecting the computed thickness of the 

 crust which covers the molten mass assumed to constitute the interior portions of 

 the earth, and it is also of great practical importance as determining the depth at 

 which it would be possible to pursue the working of coal and other minerals 

 Vol. IX. c 



