1841.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



38.5 



lated erroneously the pressure aud volume of the steam in the cylinder, as 

 veil as the press\u-e due to the blast-pipe ; that he has tested the experiments 

 by a false principle, grounded upon his confusion of the vaporization for the 

 same distance with the vaporization in the same time ; and we shall see very 

 soon that in calculating what he calls the mommtum generated by the en- 

 gines, he has wrongly considered the whole weight of the train as raised up 

 in the air by the engine, instead of being dragged or rolled along the rails ; 

 idl points established upon the very talles and words of Mr. Parkes, so that 

 he cannot say that his sentiments have been misrepresented ; consequently, 

 we were justified also in adding that he heaps errors on errors, combining 

 and complicating them unawares, till be arrives at a point where he does not 

 produce a single result that is not erroneous. 



8th. After having shown the material errors and general misreasoning 

 which pervades the whole of the strictures of Mr. Parkes against our re- 

 searches and those of others, we come to the Critic's own conception, that is 

 to the calculation of the mechanical effect of locomotive engines, by what 

 he calls the momentum generated. He says, (page 128), " Column 2 exhibits 

 the momentum, or product of the mass, in tons, of the engine, tender and 

 train, multiplied into its velocity in feet per second ; and the sums thus re- 

 present the respective mechanical effect produced per second by each engine." 

 And (page 130), " Four means are derived from these results. Mean I. in- 

 forms us, Ist, That when the velocity is increased in the ratio of 1'52 to 1, an 

 increased consumption of power is required for the production of equal me- 

 chanical effects, or of equal momenta, in the ratio of 1'43 to 1, being some- 

 what less than in the direct ratio of the velocities. 2nd. That power is ex- 

 pended in the ratio of 2-43 to 1, or in about that of the square of the velocities 

 to produce equal gross commercial results. 3rd. That power is expended in 

 the ratio of 3-11 to 1, or in not much less than that of the cubes of the 

 velocities, to realize equal useful commercial results." 



So, in our former paper, we have properly cited Mr. Parkes, and therefore 

 cur conclusion is correct, that what he calls momentttm is nothing more or 

 less than the common useful effect (weight of engine included), as explained 

 in every work upon that subject j with the exception that, here it is wrongly 

 calculated ; and to be convinced that it is wrongly calculated, it suffices to 

 give a glance at table XVI., page 143, of Mr. Parkes's paper. There we see 

 that the Atlas, in experiment I, produced a momentum equal to 206'90 tons, 

 gross load of the engine (column 5), multiplied by 14-263 feet per second, 

 mean velocity of the engines per second (column 9), equal to 2951*01 tons 

 moved one foot per second (column 11). This momentum or mechanical 

 effect, reduced in pounds, is equal to 6,610,262 lb. moved one foot per second, 

 or to 396,615,744 lb. moved one foot per minute. Now, if we observe that a 

 horse power is expressed by 33,000 lb. moved one foot per minute, we shall see 

 that the momentum produced by the Atlas, in that experiment was equal to 



296,615,744 



—33^00- = 12,019 horses. 



Experiment II. exhibits a momentum equal to 12,504 horses, experiment III. 

 a momentum equal to 5,862 horses, and so of the others. The North Star 

 alone produced a momentum or mechanical e^ec^ equal to 21,668 horses. 

 These extraordinary results proceed from Mr. Parkes taking erroneously the 

 total weight in tons, for the resistance moved, as if the whole train were 

 carried up in the air by the engine ,- whereas the true resistance overcome in 

 rolUng the train along the rails, is only at the rate of about 6 lb. per ton of 

 weight ; besides the friction of the engine, the gravity, the resistance of the 

 air, &c., neglected by Mr. Parkes. 



Certainly, then, we were quite right to say that calculations like these do 

 not tend to the progress of science, but that they would rather lead it back 

 to its first nidiments ; and if we have added, besides, that Mr. Parkes has 

 not made one ej.periment on locomotive engines, it is a fact that can easily be 

 verified in looking at bis table XVI., from which he has drawn his momenta. 

 In column I. of that table, the name of every one of the experimenters is 

 given, and there is not one experiment in the name of Mr. Parkes. So that 

 a man so fertile in strictures against the experiments of others, has not made 

 a single one, himself. 



I must now say a few words on the letter of Mr. Parkes, lately inserted in 

 several perioilicals, in support of his former strictures against my experiments 

 on locomotive engines. It would seem from that letter, that I have attacked 

 ^Ir. Parkes, but mere dates will easily settle that point. The attacks of Mr. 

 Parkes against me will be found in his paper. On Steam-loilers and Steam- 

 engines, inserted in the Transactions of the Institution of Civil Engineers, 

 Tol. III., with the date, London, 1839, given (page 162) at the end of the 

 paper. In this writing I am attacked almost without interruption, from page 

 77 to the end. The alleged inaccuracy of my experiments is presented under 

 all possible forms, as the necessary consequence of the results obtained by 

 Mr. Parkes in his tables. It was then incumbent upon me to protest against 

 any conclusions drawn from these tables, and to prove that they are, as well 

 as the reasonings of the Critic, an uninterrupted series of mistakes. There- 

 fore I published an answer in the introduction to the second edition of my 

 Treatise on Locomotive Engines, Weale, 1840, and afterwards printed it again 

 with more details and full references, in the Civil Engineer and Architect's 

 Jonmal, September 1841. This date, and the whole subject of the paper 

 itself, show sufficiently that it is but an answer to the unfounded strictures 

 of Mr. Parkes. 



Now that I have e tablished that, in my refutation of the criticisms of Mr. 

 Partes, I have not m'srepresented hi» sentiments, it would be very easy, and 



completely justifiable, to add some observations upon the expressions used 

 by Mr. Parkes in bis letter, to support by words what he could not support 

 by arguments. But, as it is my decided intention to keep distinct from any 

 discussion foreign to the scientific question, I shall abstain from presenting 

 any remark on the subject, begging only the persons who want to form a 

 precise judgment of this controversy, to read the letter of Mr- Parkes again, 

 after having perused this paper, and then to make their own observations. 



G. De Pamboir. 



GREAT WESTERN STEAM SHIP COMPANY. 



The question about the legality of the Great Western Steam Ship 

 Company carrying on a marine engine factory has now been decided, 

 the supporters of sucli an absurd plan have at last been compelled to 

 come forward and concur in their own defeat, a circumstance not to be 

 regretted, when it is considered with how much pertinacity they 

 stuck to their bantling, and how determined they were in their endea- 

 vours to foist it upon the unwilling shareholders. As it is, a great 

 loss must be incurred in the disposal of the property, independently 

 of the waste which must have been caused by the maintenance of the 

 establishment, ami the victimized shareholders remain without any 

 remedy against those who have so grossly abused their trust. When 

 individuals embarked their property in the Great Western Steam 

 Ship Company, marine engineers especially, they never contemplated 

 that the funds of the Company were to be applied to any purpose but 

 the legitimate one of engaging in the carrying trade, they did not ex- 

 pect that their money was to be wasted in rivalry against themselves, 

 or that the company was to go to the expense of hazardous experi- 

 ments. Yet scarcely had one ship been launched, before the directors, 

 who had barely capital enough to fit out another ship, set up a large 

 building yard and an engine factory, intended for executing machinery 

 on the greatest scale. The result it wanted but little sagacity to fore- 

 see ; it was a sad destruction of the Company's prospects, and a 

 serious injury to their revenue, for while these experiments have been 

 going on, the North American apd West Indian Mail Companies have 

 launched each half-a-dozen steamers, and have set them to work. 

 Where, however, is the Mammoth ? she has not even her hull Bnished, 

 and when she will be launched no one can tell. As to the propriety 

 of any company, except one with a fleet of vessels, like the General 

 Steam Navigation Company, engaging in ship-building or engineering, 

 it is preposterous, and still more so where there is only a paltry 

 amount of capital available for the purpose. 



The next question is whether it is at all proper for a joint-stock 

 company to engage in such a business as marine engineering, and we 

 have no hesitation in saying that no company is justified in under- 

 taking any thing of the kind. We think it more necessary to dwell 

 upon this' point, as some ambitious individuals are endeavouring to 

 form a separate company for the purpose of carrying on the rejected 

 steam factory, which will as certainly prove a loss to its new proprie- 

 tors as it has to the Great Western Company. There is no rule laid 

 down which applies more clearly to this case than that which governs 

 the constitution of joint-stock companies; it is expressly defined that 

 a joint-stock company can only safely engage in such pursuits as are 

 beyond the capital or credit of a private individual, and that any 

 company, endeavouring to compete with private enterprise in its own 

 proper sphere, must sustain a loss. Now, surely, with regard to steam 

 ship building, it cannot be said that there is any call for a company to 

 engage in it, as the private parties who now carry it on have proved 

 themselves fully competent, having, during the present year, supplied 

 not only the English government, but other governments with steam 

 frigates, and having turned out of their yards a fleet of first-class ves- 

 sels for the North American and West Indian stations. There is no 

 call for a company, every one is satisfied with the present system, and 

 the Great Western Steam Ship Company, or the Steam Ship Factory 

 Company, must lose largely in a ridiculous contest with a small capital 

 against the Maudslays, Seawards, Millers, Lairds, Napiers, aud Acra- 

 mans, of the great steam ports. We therefore conjure the Bristolians 

 to beware of the snare which a few ambitious men are getting ready 

 for their downfall. 



il/«//a.— It has been determined by the Admiralty to erect at Malta a bis- 

 cuit baking apparatus on the plan of Mr. T. T. Grant ; it wdl be situated 

 over the galley arches. We have heard also that a dock is forthwith to be 

 constructed in the dock-yard there, on a site pointed out by Captain Bran- 

 dreth, and for that purpose a contract has been made in Calanea for stone 

 of an admirable quality, equal to granite, but in reality lava, which is to be 

 delivered on the spot, ready worked for use, at 2s. 9d. only the cubic foot. 



