2 14 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[August, 



land) gains in bnlk nearly 30 per cent., and loses in weight 25 per 

 cent.; Carlisle co.il nearly the same; wliile Cannel and Cardiff coals 

 gain in bulk 30, and lose in weight 30-5 per cent. Bewick's Wallsend 

 coal loses 30, and Russell's Wallsend 307 per cent, by the larae 

 process. 



General Characters of Bituminous Coals. 

 In specific gravity, coals of the free-burning class fall a little below 

 the anthracites, ranging from 1'2S to 1-44. Their mean weight per 

 cubic foot is, however, only two-thirds of a pound less than that of the 

 first class. As they contain liut a small portion of matter to be vapor- 

 ized, they soon come to the temperature of full ignition. The con- 

 siderable increase of volume which thi'V take in coking, favours the 

 subsequent rapid and effective combustion of their fixed carbon. In 

 some cases, especially when brought very gradually to ignition, their 



masses of coke scarcely cohere, and the original forms of their lumpi 

 are in a measure preserved. 



In many respects, this class of coals bears a strong analogy to the 

 preceding. The ratio of the fixed to the volatile combuslihle m.itter 

 is, however, something less. The exterior presents often a resinous 

 lustre. The surfaces of deposition are easily developed by fracture. 

 Great facility of ignition, and a high degree of activity in the com- 

 bustion of their volatile constituents, are also general properties of 

 this class. Their high proportion of volatile combustible matter ren- 

 ders these coals, when nearly free from sulphur, eminently suitable 

 for the production of illuminating gas; and the tendency of their 

 cokes, with few exceptions, to inturaesce strongly, renders them, in 

 common with the preceding class, highly serviceable in forming large 

 hollow fires for smithing purposes. 



SIX TABLES, 

 Exhiliting the Relative Value of Coals aceordiug to their Various Qualities. 



Names of coals, arranged in 

 the order of their Relative 

 Weights. 



Beaver Meadow, slope No. 5 

 Atkinson and Tenipleman's. . 



Scotch 



Newoasllc 



Pictou. (Cunard's) 



Liverpool 



Cannclton. (Indiana) .. 



Dry pine wood 



Mamea, in the order of Ra 

 pidity ot IgDition. 



Cannelton, (Indiana) .. 

 Newcastle 

 Pictou, (Cunard's) 

 Liverpool 



Scotch . , 



Atkinson and Tenipleinnn*s. 

 Beavur Aleadow, slops No. b 



Pictou, (Canard's) .. 

 Atkinson and Templeman's.. 



Scotch 



Cannelton, (Indiana) .. 



Newcastle 



Liverpool 



Beaver Meadow, slope No. 5 



Names, in thcorder of Evapo- 

 rative Power lor Kqual 

 Weights. 



Atkinson and Templeman's . . 

 Beaver flieadow, slope No. 5 



Pictou, (Cunard's) 



(averpool 



Cannelton, (.Ittdlana) . . 



Scotch 



Dry pine wood 



James of coals, \a the order 

 of Kvaporative I'ower undi 

 Kqual Bulks. 



Atkinson and Templeman's., 

 Heiivor Meadow, slope No. 5 

 Newcastle 

 Pictou, i.Cuiiard*s) 

 Liverpool 



Cannelton, (Indiana), 

 Dry pine wood.. 



Dry pine wood.. 

 Liverpool 

 Cannelton, (Indii 



Beavor Meadow, slope No. 5 

 Atkinson and 'rempleman'a.. 



Scjtch 



Pictou (Cunard's) 



Rt view. 



The tables here presented, containing, first, a general synoptical 

 view of the character and efficiency of the several coals, and, seeondiv, 

 a number of distinct classifications in reference to different characters 

 considered to be of the most practical importance, and based, in every 

 instance, on the numerical lesults of experiment, will, I trust, be found 

 highly serviceable in guiding those whose duly it may be to n.ake 

 choic^ of fuel for the naval or other public service, to the selection of 

 such as will answer the specific object for which they may be pro- 

 cured. 



If an equal importance could be attached to every one of the qua- 

 lities of coals w hich form the bases of the ten ranks above given, then 

 the sum of the ratios or relative values found in the last columns 

 would, for any sample, give nearly its true relative value in the 

 market. Such equality does not, however, exist. Nor is it easy to 

 assign the exact relative weight oi importance of the several qualities 

 indicated. For different purposes they must be differently estimated. 

 Thus, when sold by weight and used on shore, the weight per cubic 

 foot, as givfn in the first rank, is a point of little moment. Space fur 

 stowage IS easily obtained. But in steam navigation, bulk, as well as 

 weight, demands attention; and a diflerence of Iwtnlyper cent., which 

 experimi-nt shows to exist between the highest and the lowest ave- 

 rage weight of a cubic foot of diftorent coals, assumes a value of no 

 little magnitude. 



For the purposes of steam navigation, therefore, the rank most 



important to be considered is that in which the names of coals stand 

 in the order of their cca^ora^U'e power, under given bulks. This is 

 obviously true, since, if other things be equal, the length of a voyage 

 must depend on the amount of evaporative power aH'urded by the fuel 

 which can be stowed in the bunkers of a steamer, always of limited 

 capacity. 



As every sample of coal has been allowed a fair opportunity to 

 exhibit its own distinctive character, it would be useless to attempt to 

 substitute for the results of practical experiments, on such a scale as 

 is here presented, any mere ojjinions or conjectures derived from ob- 

 servations made at random, with no standards of time, weight, or 

 magnitude ; or even any theoretical conclusions drawn from tests, how- 

 ever skilfully applied, merely to single hand specimens. It lias been 

 my aim in all these researches to avoid matters extraneous to the ex- 

 periments themselves and to their legitimate interpretation. It has 

 not been deemed expedient to swell this report by the introduction of 

 matters not within my own cognizance. 



Comparison nilh British Coal. 



It will not fail to be remarked, that the justly celebrated foreign 

 bituminous coals of Newcastle, Liverpool, Scotland, Pictou, and Sid- 

 ney — coals which constitute the present reliance of the great lines of 

 Atlantic steamers — are fully equalled, or rather surpassed in strength, 

 by the analagous coals of eastern Virginia ; that they are decidedly 

 surpassed by all the free-burning coals of Maryland and Pennsylvania; 

 and that an equally decided advantage in steam-generating power is 



