192 



JHE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Junk, 



fail to be biglily appreciated by the engineer; the following calcula- 

 tion of the cost, outlay and income of a small gas work is useful, as it 

 shows at what a comparatively trifling expense villages might be 

 lighted. 



If tlie number of lamps required is known, the materials necessary for the 

 production of the gas to supply those lamps are known also. The profit and 

 loss of such establishments in actual operation may as surely be relied upon 

 as that given upon paper. 



Upon a well-regulated system the cost of producing every 1000 cubic feet 

 of gas with the sanie coal will not vary one penny the whole year round ; the 

 quantity of gas made will be adequate to the demand, and no more. The 

 ^ear and tear of the machinery will be exactly that which was anticipated, 

 and therefore the annual outlay will be known ; the sale of the products of 

 the establishment may be depended upon with equal certainty, and the in- 

 come known ; the profit arising from the difference is thus ascertained. I 

 will give as an example the results of a small gas estabhshment erected in 

 the country. 



Apparatus for the supply of 70 pubhc and 7j private 

 lamps cost ..... 



Retort-house and chinmey .... 

 400 yards of -1 -inch pipe . . . . 



740 do. 3-inch do. . 



266 do. do. .... 



500 



130 



101 13 4 



129 



39 13 



£900 G 4 



Outlay in- 



Coal carbonized 



Do. as fuel 



240 bushels of lime 



One man by day and one by night 



Carried forward 



1838 



204 17 11 



54 15 



6 



62 8 



X328 11 



1839. 



204 19 



54 14 



6 



62 8 



£328 1 2 



Leaving a Profit of £136 7 9 £191 7 10 



The equal results of these two years is not peculiar to this estabhshment ; 

 there are many of much greater extent that can compare with it. 



The chapter on "Retorts," describes the different plans that have 

 been adopted, their faults and advantages, their mode of setting, con- 

 struction and cost, and is illustrated with some beautiful engravings 

 and wood cuts. The annexed engraving shows the construction of a 

 retort, and the manner in which it is set, when a small quantity of gas 

 is required. 



In country towns, where the quantity of gas made during the winter sea- 

 sons does not exceed 10,000 cubic feet in twenty-four hours, the retorts must 

 be set singly, as represented in Figs. 1 & 2., the flue passing beneath and over 

 the retort, which rests upon a half-brick arch, cut flat at the top to receive 

 it ; the end is guarded by a thick fire-tile. 



Mr. Croll, the superintendent of the Chartered Gas Company's works, 

 (Brick Lane station), has introduced a system of using the coke as fuel while 

 red-hot. The charge from the retorts is drawn into a wrought-iron carriage, 

 and immediately taken to those furnaces which require feeding. He informs 

 me, that the saving efl"ected by this simple process is equal to 10 or 12 per 

 cent. ; 1 should conceive it to be fully that. The reason is evident ; because 

 when a qiiantity of black coke is thrown on the previously heated mass of 

 fuel, the flues will to a certain extent become cool, since the heated air is 

 absorbed. When hot coke is thrown on, no absorption takes place, and the 

 flues are kept up at a uniform temperature. 



Mr. Clegg speaks very highly of Mr. Grafton's fire clay retort. 



In England and Scotland the fire-clay retort has superseded the use of 

 metal in no less than forty towns ; in some instances it has lasted for the ex- 

 traordinary period of twelve years ; while, during this time, at all other 

 works where the invention is not yet used, it may be asserted that iron re- 

 torts have been renewed as many times. The oven or D-shajied retorts are 

 found to be the most advantageous, being made with a capacity to carbonize 

 one cwt. of coal every hour. They can be constructed either to be heated by 

 coke ovens, or coke furnaces, or by the burning of tar : with coke ovens they 

 are more durable. It appears that clay retorts, when constructed upon such 



a scale as that given in the plate, have great power to retain their heat when 

 brought to the proper temperati:re for decomposing the coal, viz. 27° of 

 Wedgewood. 



This power of retaining heat is proved by constant practice to produce 

 1000 cubic feet of gas per ton from the same coal more than the average of 

 the London produce, and the consumption of fuel is not more than 22 or 

 23 lb. of coke to carbonize 100 lb. of Newcastle coal, taking the average of 

 six months' working ; it is even less with the Staffordshire or Lancashire 

 coal. 



We have now shown bv our extracts the value of this excellent 

 work, and in the next nuniber we shall proceed to notice the remain- 

 ing part of Mr. Clegg's book ; in the mean time we hope that both the 

 volumes will be in the hands of all those who are desirous of obtaining 

 information on the subject of gas works. 



Before we close the present notice, we must oft'er a just tribute of 

 praise to Mr. Gladwin the engraver, for the very clear manner in which 

 he has executed the plates in Mr, Clegg's work, which are so beauti- 

 fully delineated, that they cannot fail to convey, even to the non-pro- 

 fessional observer, an accurate knowledge of the construction of the 

 apparatus which they delineate. 



