MECHANICS AND USEFUL ARTS. 93 



most if not all the difficulties heretofore experienced in this de- 

 partment. 



The use of gas as fuel has been tried to a considerable extent 

 in France and other countries, but the progress has neither been 

 rapid nor very satisfactory ; one reason of this lies, perhaps, in 

 the imperfection of the modes of combustion, although something 

 has been done of late to remedv this : another is the natural hesi- 

 tation of the directors of gas works to keep pressure of their 

 gasometers all day for a small supply. 



Still enough has been done to supply a certain amount of infor- 

 mation on the economical part of the question, both as regards 

 gas-cooking apparatus and stoves for churches and other large 

 buildings. The average consumption of the cooking-stoves in 

 use in France, which consume a mixture of gas and air, is found 

 to be as follows: For a large fire, 260 litres per hour; for a 

 moderate fire, 140 litres per hour; for a small fire, 50 litres per 

 hour. AVhen the stove is used, what the French caWpot-au-feu, it is 

 found that it is sufficient to keep up a large fire for about 20 min- 

 utes only, after which the gas may be turned down, and the cook- 

 ing completed with a very small fire. Taking the average duration 

 of this kind of cooking at 4 hours, and the cost of gas at 30c. per cubic 

 metre, — tlie present price in Paris, — the consumption amounts 

 to 1,050.20 litres, the expense of which is 31.20c., or little more 

 than 14d. The cleanliness and handiness of gas as fuel, and 

 the great economy arising from its instantaneous lighting and ex- 

 tinction, give it, in the hands of careful persons, a great advantage 

 over charcoal, with few of its inconveniences, — one of which is 

 the impossibility of using it for broiling with a special arrange- 

 ment, as the smallest quantity of fat falling upon heated charcoal 

 fills the house with stifling fumes. 



In a coal-using country, however, like England, the use of gas 

 for the heating of apartments, and especially large buildings like 

 churches, is of more imjDortance than its aj)plication to cooking ; 

 and considerable improvement has been made of late in France 

 in apparatus for the warming of ordinary rooms, to which we 

 shall shortly have to refer more particularl}'. 



The most imiDortant results yet produced refer to the heating 

 of churches, which has been essayed on a large scale at Berlin. 

 The metiiod generally adopted is that of placing a horizontal gas- 

 pipe with 3 jets within a stove made of sheet iron, and over the gas- 

 jets a piece of brass wirework, of which the openings are not more 

 than one-twenty -fifth of an inch in diameter. The cathedral at Ber- 

 lin has a cubical contents of about 13,300 metres, and it is heated by 

 means of 8 of these stoves, each of which has 22 of these brass 

 gratings, 11^ inches in length by 1^ inches in width, making in 

 all about half an inch square of grating for each cubic metre to 

 be warmed. The consumption of gas in raising the air within 

 the edifice to the required temperature — an operation which 

 takes 3 hours — is 83,400 litres, or 4.82 litres per cubic metre ; 

 to maintain the same heat afterwards requires only seven-tenths 

 of a litre of gas per cubic metre. 



The parish church of Berlin, whose cubic contents is 13,800 



