160 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Mat, 



sumption as under six pounds. The onus lies with the Messrs. Sea- 

 ward, to prove this upon scientific and practical data ; and until they 

 do so, I must conclude, with Vulcan, that they have been carried away 

 by enthusiasm. 



The following data and dimensions on which the Gorgon was con- 

 structed, may be relied on : — 



Dimensions. ft. in. 



Length between perpendiculars . . . 178 



Keel for tonnage 152 3 



Moulded breadth 36 4 



Extreme ditto 37 6 



Depth in hold 23 



Tonnage ] 108. 



Data. 



25 tons. 

 . 50 " 



Weight of masts and rigging 

 Anchors and chain 



1000 men 



Engines and water 



Coals 



Hull 



Provisions and stores 



Total . 



133 



270 



300 



630 



78 



1486 



Displacement at load line . . , 1412 tons. 

 Load line 12 tons to an inch immersion. 

 I give you this, that I may put a few questions to Mr. Pole. He 

 says "the speed of the Gorgon's engines, with 400 tons of coal, is 19 

 strokes per minute ; with 200 tons, 21 strokes per minute." One or 

 the other appears incorrect; thus 420— 200=220 tons difference. 

 The Gorgon at her load line is 12 tons per inch ; we have -^"=18i 

 inches decreased draught, with the 200 tons on board. It w'ould be 

 more than this, for at 18 inches below her load line, she is probably 

 not more than lOi or 11 tons per inch. But say 18 inches ; does Mr. 

 Pole assert that the paddle wheel (26 feet 10 inches working diameter 

 by 7 feet 2 inches long,) relieved of IS inches dip, would only make 

 a difference of tno strokes in the engines ? Again, with reference to 

 the Styx, he says "she had 260 tons of coal on board, and went 21 

 strokes." Where did she get them ? I allude to experiment, Gth 

 May, 1S41 (see, as referred by you, p. 210, vol. iv.), on which occasion 

 she started horn the Canal Iron Works; and I believe the Government 

 are not in the habit of sending coals to their ships away from the 

 dockyards, especially so large a quantity as 260 tons. With regard 

 to the speed of the engines, you. Sir, setttle that— it was 17 strokes; 

 so we must have these questions answered before we finally convict 

 Vulcan of falsehood. 



By the bye, allow me to lecture yourself for two very important 

 errors in the paragraph p. 210, vol. iv. First, you sav the Styx's en- 

 gines are 560 horse power, cylinder 62 inches, 5 feet' 3 inches stroke. 

 According to iMr. Watt, this gives 1-10 horses each engine, or 280 only 

 for both. Secondly, you say the Styx is fitted with Mr. Seaward's 

 patent engines. This controversy has already shown there is nothing 

 of the sort. There are other points which I would wish to go into, 

 especially relating to the evaporative power of the boilers, and their 

 incapability of producing steam equal to the supply of cylinders of 

 66-inch diameter, 5 feet 6 inches stroke, and 20 strokes per minute, 

 at a cojitumptwn of " under six pounds" .- but fear I have already 

 transgressed too much on your space ; I therefore reserve this for a 

 future communication. 



I refer to the statement of Vulcan that one-third of the power is 

 absorbed by the friction of the piston rod, merely to say that I do not 

 understand it. Verily it appears in its present shape to be nonsense, 

 and IS either a misprint, or error in expression. Let Vulcan explain ; 

 and perhaps iu the mean time Mr. Pole will give us his version of the 

 subject. 



1 have heard, and I have read, not only in the Journat, but in a 

 talented Glasgow contemporary, "dark and mysterious hints" of 

 collusion between public officers and private establishments. How far 

 this is correct I am not prepared to say, but hope, for the honour of 

 the profession, that it is not true. However, it behoves the principals 

 of all our large establishments to come forward, and remove this 

 aspersion upon their honour. " Competition" is a glorious thing for 

 the advancement of both theoretical and practical science; let us have 

 it to repletion, but let that competition be fair and honest. Possessing, 

 I am proud to say, a somewhat extensive acquaintance among the 

 members of the profession, I am sure there is not one but would em- 

 phatically agree with me in this sentiment; but I am sure they will 

 eqnally "grieve " with me at the following:— The Mechanic's Mag., 

 (No. 974J, has a continuation of the olla podrida species of advertise- 

 ment. It states " the Admiralty have given instructions to build a 



large frigate, the Penelope, of 650 horse-power — that it is the propo- 

 sition of Mr. John Edye, and that the commission for building the en- 

 gines has been given to the inventors of the Gorgon plan, the Messrs. 

 Seaward and Co." 



Those who know Mr. Edye are well aware that his talents and ac- 

 complishments are great and various, and that the natural modesty of 

 his disposition, added to the dignity of his official situation, would 

 not allow him willingly to have his name thus brought forward for 

 others' uses. But has the executive of the Admiralty acted with 

 their usual fairness in this case ? They have given unto the Messrs. 

 Seaward this large order to the amount of perhaps £25,000, lotthout 

 consulting any otiier establishment — is this fair or honest? Is it a 

 proper compliment to the profession generally, when it is known that 

 others have improved upon what is termed the Gorgon engine even 

 to a moiety, as it regards space. To what are we to ascribe this par- 

 tiality ? is a question I decline to answer. 



I am. Sir, 



Your's very truly, 

 London, 12th jipril, 1842. " Perseus. 



Sir — I should not again have troubled your readers with any further 

 remarks on " Direct and Beam Action Engines," had not an article 

 appeared in your April number under the signature of Wm. Pole, in 

 which an investigation of the relative amounts of friction in the two 

 descriptions of engines is imperiously and confidently demanded. 



I am glad of the opportunity thus afforded me of correcting an am- 

 biguity in one of the sentences upon that subject, which unfortunately 

 escaped my notice until it appeared in print in your January number. 

 It might, indeed, seem that I had wished to convey the impression 

 that the friction on the parallel motion of the Gorgon engine equalled 

 one-third of the power exerted — but far was it from my intention to 

 express so palpable an absurdity : when comparing the amount of 

 friction upon the parallel motion in the beam and direct engine, 1 

 might well call it relatively enormous in the latter case, " upon those 

 parts the strain on nhich, caused by the short connecting rod, is so 

 great as to equal one-third of the power of the engine passing through 

 them to compel the piston rod to move in a vertical line " ; the un- 

 certainty as to my meaning arising from the accidental omission of 

 the words "the strain on which," 1 much regret, as it has caused me 

 thus in explanation to trespass on your valuable space, and gave your 

 correspondent an opportunity which, in his desperation, he seized 

 upon with avidity, of proclaiming a transient triumph. 



That the lateral strain does amount to one-third of the power 

 exerted is simply shown : 



Let a be the angle which the connecting rod makes with the ver- 

 tical, and let P represent the effective force on the piston ; then, 

 P secant a =: strain along the connecting rod, 



P tangent a = the horizontal thrust; and when the connecting rod 

 is three times the length of the crank, the greatest value of a = 

 19" 28', in which case the lateral thrust equals P 3534; this pressure 

 has to be sustained by the parallel motion or guides whichever may 

 be adopted, and in practice causes great wear and tear on those parts, 

 nor has any combination been found effectually to resist the strain for 

 a length of time. 



Having already far exceeded the limits between which I had hoped 

 to have confined my remarks, I shall defer, for the present, making 

 any allusion to the subtleties and the assumed knowledge of facts 

 with which Wm. Pole has filled his communication, but shall not fail 

 to do so on an early occasion, unless, indeed, some of your readers, 

 with a readier pen and more time at their disposal than I have, should 

 be roused by indignation to expose the fallacies with which that paper 

 abounds. 



Sir, I am, 

 London, 19M April. Yours, obediently, 



Vulcan. 



Inlaid Marbles. — A beautiful mode of ornamenting marbles has recently 

 been brought into use in Paris. It consists in etching, by acids, deeply into 

 the marble, various designs upon a properly prepared bituminous ground. 

 When the corrosion has gone sufficiently deep, the cavities are filled up with 

 hard coloured wax, prepared so as to take a polish equal to that of the marble 

 when cleaned off. Drawings thus made on black marble, and filled in with 

 scarlet wax, after the manner of Etruscan, and certain Egyptian designs, are 

 said to have a very noble effect, and are applied to tables, panelling, stoves. 

 &c. — Repertory of Patent Inventions. 



