100 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[M. 



On llii: Fossil Fishes iif the Yorkshire and Lancashire Coal-Fiehls. by Mr- 

 AV. C. 'Williamson. 



AVithiu the last four years tlio coal measures of tliese countries Ijave as- 

 Miiued a zoological inii>orlance. wliicli previously they were not sup|ioseil to 

 ])Ossess. In Lancasliiru ictliyolites have been lately found to jicrvadc the 

 whole of the series from the Anhvick limestone to the uiillstone grit, and in 

 Yorkshire they liave also been obtained in great abundance. On comparing 

 the specimens procured at Middleton colliery, near Leeds, with the fossil 

 fishes of Lancasliire, the author detected the following as common to both 

 coal-fields, viz. ; — Viplothia f/ihhosus, Ctenoptyehits pectinatits, Mfijalicfhys, 

 lUbberlii, Gi/rardiilhiis fornwsiis : also, remains of api)arentl)' species of 

 Holoptycliub and Platysomus ; but he has obtained some ictliyolites in the 

 Yorkshire field which he has not seen in the Lancashire, and he is of npini(m 

 that tlie latter deposits are characterised by the greater prevalence of lepidoid 

 fishes, and the former by sauroid. These remains, excejit in the case of the 

 Ardwiek limestone, always occur in highly bitundnous shale, anil they are 

 most abundant where it is finely grained, and in general where jilants are 

 least numerous. This distinction in the relative abundance of ictliyolites and 

 vegetables, Mr. AVilliainson conceives may throw some additional liglit upon 

 the circumstances under which the coal formations were aeeumidated. The 

 tislies are found chiefly in the roof of the coal, rarely in the seam itself, and 

 not often in its floor. .Mr. Williamson, in conclusion, makes some remarks 

 on the manner in which ictliyolites are associated with the otlier fossils of 

 the coal measures. .\.t Burdiehouse they occur in the midst of freshwater 

 shells and Cypris ; at Coalbrook Dale with marine testacea ; in the lov\ er coal 

 measure of Lancashire, not far from the beds containing Gonialites IJsteri, 

 and Pecten popiiraceiis ; higher in the same field, and in Yorkshire, they are 

 associated with freshwater shells ; at Middleton with Lingula; ; and at the top 

 of the series in Lancasliire and Derbyshire with Mytili and Melaniic. 



-'/ paper on the Geoloffi/ around the Shores of Waterford Iluren, by T. 

 Austin, Esq. 



As the object of this communication is to describe topogra])hically the 

 structure of the shores of Waterford Haven, its details do not admit of 

 abridgment. The formation composing the district are mountain limestone, 

 a conglomerate, clay-slate, and trap, the limestone and conglomerate consti- 

 tuting the greater portion of the east side of the Haven, and the conglom- 

 erate the opposite. 



REVIE'tVS. 



On Steam- Boilers and Stiam-E7ighits. By Josiah Parkes. Trans- 

 actions of the Institution of Civil Engineers, vol 3. London : J. 

 Weale. 1840. 



PART II. . — ON STEAM-ENGINES, PRINCIPALLY WITH REFEREKCE TO 

 THEIR CONSUMPTION OF STEAM AND FUEL. 



In our Number for July last vpe noticed the part of tliis investiga- 

 tion, which treated of the cjualities of steam-boilers, and of the influ- 

 ence exercised over evaporation by their proportions and practical 

 nianagemenf. Of that part we considered the only value to consist in 

 the/acts therein recorded. 



In the introduction to this part the autlior makes the following very 

 sensible observation : 



" The generation and application of steam are distinct jiroblems; 

 they rerpiire to be separately treated, and their results to be separately 

 stated. It is the economy of steam whicli constitutes the dynamic 

 perfection of an engine ; it is the ecunomy of heat in supplying 

 steam to an engine ; which constitutes the evaporative Derfection of 

 a boiler ; and it is only by distinguishing the effects of e cli, that the 

 valui- of any change of |u-actice, in cither department, can be correctly 

 ascertained." 



Now, although there may be few, if any practical e ineers, who 

 would be disposed to doubt the truth of this remark, yet we are per- 

 suaded that it is not in general duly appreciated, or at least, that very 

 little attention is paid to it by them. 



The author has divided this part into two ])ortions : in the first, 

 which occupies about one-fourth of the whole, he has mvestigated the 

 atmospheric, the stationary non-condensing, or the high-pressure, 

 the low-pressure condensing, and the Cornish high-pressure expan- 

 sive pumping etigines. The facts established on these four varieties 

 are collected and exhibited in a comprehensive table, (table i>.) The 

 last three-fourths of the work are dedicated solely to the locomotive 

 engine, the chief part tending to prove the inaccuracy of all the esti- 

 mations which have hitherto been made of the several resistances 

 which have to be overcome by that variety of engine. Tlie author 

 has, liowever, also developed ■.I'ncw Ihury «/ Ik hcomotirc (iigim, the 

 fallacy of which will be at once evident to the scientific reader; but 

 its plausibility might induce the practical man (who has not the 

 means of detecting theoretical errors,) to put implicit faith in its cor- 



rectness. For his sake, therefore, we shall feel it necessary to take 

 more notice of this new theory than we sliould otherwise have done. 



The two sections in which the author treats of the methods e m- 

 plot/id til diltrniine Ihe j-vKer of ingints, and »/ the mdinnren of ijf'tcl, 

 present nothing worthy of notice ; but in the next section, which 

 treats nf l/ie expendtlnre ti/pon'er, we have to ])oint out an error, which 

 we thought to be already so thoroughly eradicated, that it could 

 never more find its way into any work having the slightest ])retensions 

 to science. This section coniniences thus: 



" Tile ponderable element of steam is water: its consnnijjtion by an 

 engine is appreciable ; and it is now assumed, almost universally, that 

 the sum of its imponderable element, heat, is a constant quantity, in 

 steann of all specific gravities. The elastic force of steam is also ge- 

 nerally assumed to be proportional to its density ; thus, ei)ual amounts 

 of heat and water are expended in the generation of equal power, at 

 wdiatever pressure steam be used by an engine." 



We adtnit the first assumption, that the quantity of heat contained 

 in a given weight of steam is a constant quantity, whatever may be 

 its density ; but it is not a fact, as Mr. Parkes assests, that the elastic 

 force of steam is also generally assumed to be proportional to its den- 

 sity : indeed a comparison of the numbers given in the table, (page 

 122,) which he himself took from M. de Pamhour's Ki/r T lieu nj of tlie 

 SUetm Engine, would have convinced him at once that that assertion 

 was not well founded. For we there find the volume of steam formed 

 from a volume of water equal to unify is equal to 2427, when gene- 

 rated under a pressure of lUlbs. on the square inch ; and G"?, when 

 generated under a pressure of 4(Jlb. We ought, therefore, to have , 

 since these volume are inversely proportional to the density of the 

 steatn, 



10 : 40 : : G77 : 2427, 



which would give, by making the product of the means equal to that 

 of the extremes, 



24270 = 27080, 

 which is absurd. The conclusion drawn from this law is therefore 

 also false ; wherefore equal amounts of heat and water are not ex- 

 pended in the generation of equal power, when the steam is used 

 at different pressures. 



In tliis same section, (page f),"!,) the author tells us that 



" By knowing the evaporation from the boilers, and consequeutly, 

 the weight of water as steam which passes through an engine, we 

 grasp the principal fact of practical consequence to the engineer ; a 



fact which is free from all uncertainty in its nature ; 



and the weight of water, which has passed from the boiler in that 

 state, and produced a given effect, appeals conclusively to the under- 

 standing as indicative, in a comparison of engines, of their respective 

 economy in the expenditure of power." 



This does not seem very consistent with what he says on the sub- 

 ject in the first section, (page .■J2,) where, speaking of this method 

 of determining the power of engines, he observes, that " as its 

 value deiiends on a perfect accordance between the results of experi- 

 mental and practical seience — an accordance yet unascertained, — and 

 since many precautions are requisite to secure true results from this 

 test, it has been seldom resorted to by practical tnen." 



The discordance between these two cjuotations is most remarkable, 

 and the ivaragraph which follows the latter leaves no room to doubt 

 that the basis of the method there alluded to is the identical fact 

 which he says is/ree/roni all uncertainty in its natnn, Ike. 



In the table already alluded to, (table G,) will be found many results 

 computed from the data furuisheil by experiment, which, if correct, 

 will be of great jjractical utility to the engineer. Among these may 

 be mentioned the weight of water as steam equivalent to the produc- 

 tion of a horse power in each engine, and also, the duty effected by 

 one pound of steam. " These sums, (cohnnns U and IG,") the author 

 observes denote the positive and relative efficiency of sleam in the 

 different " engines ;" and here we recognize the pen of Mr. Parkes in 

 the signification he gives to the word relative, it being liere used to 

 express the inverse of positive. Thus the relatirc efficiency of the 

 steam decreases in ]irecisely the same ratio as its yjos//;r£ efficiency 

 increases, which we finddillicult to comprehend with our ])reconceived 

 notions of the meaning of the word relatin. We should have thought, 

 for instaifce, that ii' lUe jjostli re eflicieucy of the steam in a given 

 engine were equal to a, and in a second engine to b, its relative effi- 

 ciency in the first in comparison with the second would be -, and 



that if, the positive efficiency b, remaining the same, that if the 

 engine were increased from a to 2 a, its relative efficiency would also, 



be increased from - to 

 b 



, or in the same ratio as its 2}osilive effici- 



ency, The true nlative efficiency both of the steam and of the fuel is 



