1842.1 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



1.3.3 



and his 0-93 ton per horse power would then amount pretty nearly to what 

 is known to be the actual weight of beam engines afloat, namely, about 1 

 ton. 



As a inoof that this weight is not over-rated, I cannot do better than 

 again tabulate some known engines of the best makers, giving their weights 

 as compared with the Gorgon. 



Name of 

 Vessel. 



Gorgou 



Hecia 



Stromboli 



Monarch 



Medea 



Makers of Engines. 



Seaward 

 Scott & Sinclair 

 R. Napier & Co. 

 Boulton & Watt 

 Maudslav 



These weights include water in the boilers, spare gear, and coal boxes 

 complete. 



A word perhaps may be added upon another of Vulcan's " astounding 

 facts," which he parades with mucli pomp and circumstance, namely, the 

 incorrectness of the weight given by Messrs. Seaward to the .\drairalty.* 

 The estimated weight of the Gorgon engine (for the engine i/self is all we 

 have at present to do with, no alteration being proposed in the other portions 

 of the whole weight,) was 121 tons : the aciua/ weight, when manufactured, 

 was found to be, adopting "Vulcan's" own statement, 123 tons, 3 cwt. 1 

 That is, the ac/ual weight was 2 tons, 3 cwt. greater than the estimate ; an 

 estimate, be it remembered, formed entirely by calculation, before a single 

 part of the engine was put in hand, and while no other engine of the kind 

 was in existence from whicli to obtain data. And this is the flagrant error, 

 or something worse, with which Jlessrs. Seaward are charged, from which 

 " your readers are desired to form their own conclusions," &c., and which 

 " calls so loudly for explanation '." 



The following facts, with which I have been furnished by a friend on whom 

 I can rely, are I think, pretty conclusive as to the saving both of weight and 

 space. 



The Gorgon steam frigate of 1050 tons was built in 1837, and was origi- 

 nally intended to receive beam engines of 220 horse power, the bulk heads 

 being placed 62 feet apart, the ordinarj- distance allowed for engines of that 

 size. The estimated weight of these engines was given as 2 70 tons, including 

 the coal boxes and the water in the boilers ; and space was proposed to be 

 allotted for 300 tons of coal. 



This same vessel is now, without any alteration of her engine-room, fitted 

 with engines upon the direct action principle, of 320 horse power, weighing 

 less than 300 tons, and has provision for 420 tons of coal in store. Why the 

 change was made, I do not know ; but I believe the beam engines originally 

 intended for the Gorgon are now in the Hydra, a smaller vessel but an 

 excellent sailer. 



Again, I may instance two vessels in the navy, now afloat. The Stromboli, 

 with beam engines of 280 horse power, has an engine-room of oS feet in 

 length, and carries only seven days' supply of fuel in the engine-room, draw- 

 ing, with her stores on board, 14 feet of water. The Driver, a sister vessel, 

 built from the same lines, has clirecl engines, also of 280 horse power, in an 

 engine-room of only 52 feet long, in which she carries 14 days' fuel, and the 

 same quantity of stores, at the same draught of water. 



The second division of your correspondent's critique is upon th ! fric/ion 

 of the engine. Your readers mil observe, however, that there is no mention 

 of any material advantage from lessened friction, in the quotation I have 

 introduced from the Gorgon pamphlet, and I can add that m such pretemion 

 is made throughout the whole of the work ; the object for which this subject 

 is introduced there, being only to defend the engine from the char-es brought 

 agamst it by those who asserted that the loss bv friction was\-»«/eW(./'y 

 inc-eased by the use of the shortened connecting rod. "Vulcan" misht, 

 therefore, have spared himself pen and ink on this head, and had he con- 

 tented himself with merely insisting that no very- material gain arose from 



As a proof that errors m computing the weights of engines may easily 



u^r!',„ f**" o'"?,"''V °V •'''"," ,"' ^V^ engines, of 280 horse po«er eacli. 



ere made m Scotland «iih,n the ast throe years, for the Governmen! ; each 



pa r He shed about 60 tons more than the ttdght given by the makers to Ihe 



this cause, his remarks might have passed unnoticed ; hut he has not been 

 satisfied with simply chasing away the phantom he himself had conjured up ; 

 he has gone further, and, presuming I suppose upon his newly-acquired valour, 

 he has levelled a heavy charge against the Gorgon engine, viz. that " the 

 enormous friction caused by the short connecting rod is so great as to equal 

 J of the power of the engine passing through them." This renders a few 

 words to him necessary. 



He has thought proper to pay us, the readers of your valuable periodical, 

 a ver>- had compliment, by telling us that we cannot understand an investiga- 

 tion of the subject, wherefore he " avoids all scientific observation as to the 

 laws of friction," &c. ; but I am sure that you, Mr. Editor, will join with me 

 in removing the screen behind which he would thus shield himself from the 

 liability of being caUed upon to prove his daring assertions. He must, or 

 ought to know, that the majority of your readers are not " casual" but "pro- 

 fessional" readers, who are perhaps as well skilled in investigation as "Vulcan" 

 himself, and who are not accustomed to take statements for granted, because 

 the person making them " fears his inability to make himself fuUv understood 

 by casual readers." The case is simply stated ; we have the force transferred 

 from the piston rod to the crank pin by two different arrangements of ma- 

 chinerj-, tlie transfer in each case being attended with some loss, from the 

 friction caused isy the strain or pressure upon the gudgeons. The question 

 is, then, what proportion does this loss bear, celcrh paribus, in the case of 

 the Gorgon to that in the other or beam engine ? This is perfectly ascer- 

 tainable by mathematical analysis, and, in fact, in no other way, from' the all 

 but impossibility of having in practice other things alike in the two cases, 

 which they must be, or extraneous causes will so affect the results as to render 

 them perfectly inconclusive for the object in question. I will, therefore, 

 with your permission, Mr. Editor, call upon " Vulcan" to show what ground 

 he has for bis assertion, by giving an investigation of this friction case; or if 

 his " inability to make himself understood" arises from his ignorance of 

 mathematics, he must get those by whom " he was assured" of the truth of 

 his fact to help him out of his difficulty. If " Vulcan" does not furnish you 

 with this statement, I will. 



The third matter animadverted upon by " Vulcan" is wljat he calls Messrs. 

 Seaward's slatemeni, "that the consumption of fuel does not exceed GJlb. 

 per nominal horse power per hour." Now this statement is an entire and 

 gratuitous fabrication. " Vulcan" must surely have been thinking of his 

 ancient occupation in " Etna's fiery glow," and must have forged it for the 

 occasion ; for there is not a syllable about the Gorgon's consumption of fuel 

 in the whole pamphlet, nor is the subject even alluded to throughout the 

 work, except in one passage, page 24, where the saving of fuel is mentioned 

 as one of the " great and paramount objects to be aimed at in the construc- 

 tion of steam engines for navigation." It is, indeed, added that "this system 

 of engines is far superior in all the quahties above enumerated," biit the 

 saving of fuel named in the first paragraph seems to have been included in 

 the other more by accident than design, for it is not even hinted at in aav 

 other portion of the work. Indeed, to have claimed for the direct system 

 any material advantage over the common one on this score, would have been 

 a downright absurdity ; for what connection can a different arrangement of 

 the rods and levers have with the consumption of fuel, except as regards the 

 insignificant amount in which the difference of friction would affect it ? and 

 who, in their senses, would pretend that such was the fact ? That the Gor- 

 gon engines do work with a much smaller proportionate consumption of fuel 

 than many others, I can very readily believe ; but whatever gain there is in this 

 respect must be, of course, owing to improvements in the construction, which 

 are independent of the direct action principle, and which Messrs. Seaward 

 could just as well apply to beam engines as to the Gorgon's. 



The introduction of the fuel question is, therefore, irrelevant, and only 

 shows that "Vulcan" either can never have seen the pamphlet be pretends 

 to re\iew, or must be fixed in a much more discreditable alternative, which 

 your readers will easily supply. 



The remainder of " Vulcan's" paper consists of a series of statements 

 which only show the limited information he bad obtained upon the subjects 

 he professed to treat of, and which will be sufficiently answered by noting 

 down the following facts. 



The speed of the Gorgon's engines, with 420 tons of coal on board and 

 provisions for six months, is 19 strokes per minute; with 200 tons of coal, 

 21 strokes. 



When the " Styx" was tried in the river, " with my lords and a large parly 

 on hoard," she had 260 Ions of coal in the boxes, and 30 tons of water in 

 the tanks, and the speed of her engines was 20 strokes per minute. " Vnlcaa" 

 should, therefore, have placed less " confidence" in the information which led 



