158 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Mat, 



pounds," and 33,0001b. lifted oue foot. My calculations are made on the 

 same basis. Referring to Weale's Tredgold, vol. ii, plates 33 and 34, 

 engines of tlie Kile, (being exactly similar to the Hydra's,) plate 34 

 on the plan, shows the distance between the inds o/t/ie main levers to be 

 a feet 4 inches, consequently there is room for a cylinder of that dimen- 

 sion over the flanges. Taking Mr. Watt's data, a 5-feet stroke should 

 make 2Ustrokesper minute,or215 feet. This at 33,000 lb. is equal to 

 a 67-inch cylinder to produce 160 horses, and if we allow 4 inches each 

 side for the joints and flanges, we have G7-(-8;=7a=;6 ft. 3, or an ample 

 clearance of half an inch on each side. Plate 33 is a longitudinal 

 section of the engine, and its extreme length from steam pipe flanch 

 to fore end of engine frame is 23 feet 6 inches, its extreme width 

 over the main gudgeons being 8 feet 3 inches only ; and be it observed, 

 this length includes an extended head stock framing, which (with all 

 respect be it spoken,) I cannot conceive necessary, at least to so great 

 an extent ; but there it is, and as I wish to adhere to facts, what 

 have we ? — The Hydra's beam engine of 160 horses, requiring 23 feet 

 6 inches in length, and 8 feet 3 inches in breadth; the Gorgon engine 

 of 160 horses, requiring 20 feet 6 inches in length, and 7 feet 10 inches 

 in breadth — a saving of 3 feet on 23 feet 6 inches, or about one-eighth ! 

 I must call on Mr. Pole to show how this agrees with the first item of 

 the Gorgon advantage, as quoted by himself from the pamphlet, viz. 

 that the saving in space is very nearly one-half. 



It may be said such an engine has not been made, and is merely 

 hypothetical. I apprehend one thing only is necessary to produce it 

 •^un order.* And here I beg to maintain, the question is between 

 the beam and Gorgon engine, and we have not only to prove what has 

 been done, but what can be done, on the principle of the former. Let 

 us take the Medea, by Maudslay. I refer your readers to Tredgold, 

 plates 37 and 38. The former is a plan of the engines of the Phoenix 

 (same as the Medea) ; the distance between the main levers is 5 feet 

 10 inches. Here we require a lateral extension to 6 feet 4 inches, as 

 in the Hydra, to make room for a cylinder of 67 inches. This done, 

 the Medea's engine is 1 feet 9 inchts over all athwart, or one inch less 

 than the Gorgon ! Plate 38 is a longitudinal view of the same ; the 

 length of the engine is, as it regards space occupied, only 19 feet, but 

 as in the Hydra, I'll take in the additional piece of frame, and call it 

 21 feet 6 inches, and what have we? — ^Medea beam engine, requiring 

 21 feet G inches in length, and 7 feet 9 inches in breadth ; tlie Gorgon 

 engine, requiring 20 feet 6 inches in length, and 7 feet 10 inches in 

 breath — a saving by the latter of -^ part in length, and an increase in 

 breadth of one inch. Sir, let your readers examine and judge for 

 themselves. 



Having, I hope, shovfn that what may be called engines of some 

 standing can be increased to 320 horses without additional space, I 

 now fulfil my promise, to explain that engines having the same stroke 

 as the Gorgon, viz. 5 feet 6 inches, may be made under these restric- 

 tions. In fact, I shall do no more than prove the correctness of Vulcan's 

 " sketch." And here. Sir, I have recourse to the useful table published 

 in your April number, viz. the proportions used by Maudslay, Son, and 

 Field. You state their 100 horse 5-feet stroke is 14 feet 2| inches from 

 centre of cylinder to centre of crank (see table, the 42nd and 43rd line) . 

 Having 6 inches more stroke, say 5 feet 6 inches, we will take this 

 proportion, and find the same distance to be 15 feet 6 inches as near 

 as may be. By Mr. Watt's formula a stroke of 5 feet 6 inches 

 should make 20-130 strokes, or say 22 li feet per minute, to produce 

 a power of 160 horses. At this speed we recjuire a cylinder of 66 

 inches, the same as in the Gorgon : then for a beam engine on these 

 proportions, we have — ft. in. 



Distance from crank to centre of cylinder . . . 15 6 

 Half diam. of cylinder, plus flanges, joints, &c.=33-|-9= 3 6 

 Half projection of headstock : in this we take Messrs. 

 Seawards' own practice, as in the Mcegara, taking propor- 

 tion as length of crank, the true guide. The Sloegara's 

 stroke is 4 feet 3 inches ; width of headstock 4 feet 3 inches. 

 (See Tredgold, plate 49.) In this case the stroke is 5 feet 

 6 inches: take 5 feet 6 inches-;- 2=: . . . .29 



For the whole length of the engine 



21 9 



The nidlh of such an engine would be as that of the Hydra, viz. 

 8 feet 3 inches. Thus, what have we here? — A beam engine, as the 

 Gorgon, 21 feet 9 inches in length and 8 feet 3 inches in breadth; 

 Gorgon engine 20 feet 6 inches in length, and 7 feet 10 inches in 

 breadth — a saving of 15 inches upon 21 feet 9 inches, or just one- 

 seventeenth part, and in breadth a saving of 5 inches upon 8 feet 3 

 inches, or about one-nineteenth part. Does not this call for explana- 



* Since writing this, 1 have been crediljly informed that a pair of beam 

 tHjjines of this power, or nearly so, are constructing by Boultoa and Watt. 



tion ? I have not done yet, but fear being prolix, although I hope you 

 will bear with me, as it is of great importance to the profession that 

 this matter should be set straight. 



Let your readers consult Tredgold, plate 49, being a longitudinal 

 section of the Mcegara's engines. "They are stated to be seventy horses, 

 having a 44-inch cylinder, and 4 feet 3 inches stroke ; according to 

 Mr. Watt, this should travel 206 feet per minute, giving a power of 

 06 horses. Now this engine occupies 17 feet 6 inches in length for 

 this small power; and if the Gorgon engine is compared with such 

 beam engines, perhaps a better case might be made ; but that, I humbly 

 submit, is not the point in dispute. 



Having given your readers comparisons of Boulton and Watt's 

 and Maudslays' practice, let us go north, and show what our Scotch 

 friends can do. Let them look at Tredgold, p. 41 — a section of the 

 Don Juan's engines, by Claud, Girdwood and Co. (I am now speaking 

 of space only). This is an engine of 6 feet stroke, and 68-inch cylin- 

 der, at 7 1b. equal to a power of 176 horses x '-=352 horses, or 32 

 more than Gorgon ; and what have we here ? — ft. in. 



A Clyde beam engine, over all . . . . . 23 3 



Gorgon engine 20 G 



— A s;iving of 2 feet 9 inches upon 23 feet 3 inches, or about one- 

 eighth. No plan of this engine is given, so I cannot compare as 

 it regards lateral space, be it observed this scheme is like Vul- 

 can's sketch, particularly in the way the longitudinal pressure of 

 the shaft is resisted by large deck beams; and is there any reason 

 why this should not answer in a beam as well as in a Gorgon engine? 

 Should it not even be better from the greater length of the connecting 

 rod? 



In concluding the subject of space, I will draw attention to the facts 

 that I have shown : — 



1. That the Hydra's and Medea's engines maybe increased to 320 

 horses, without material additional space. 



2. 'That a beam engine of the Gorgon's proportions may be con- 

 structed as sketched by Vulcan. 



3. That the Don Juan's engines are 32 horses larger than the 

 Gorgon's, and only 23 feet 3 inches long. 



4. That the saving in No. 1 is about one-twelfth, in No. 2 one- 

 seventeenth, and in No. 3 about one-eighth, this latter beirg of larger 

 power. 



Mr. Pole assumes an argument in favour of the Gorgon engine, upon 

 the number made by the Messrs. Seaward. Let me repeat Vulcan's 

 assertion, that with two foreign exceptions, the "British Government 

 is the only patron of the Gorgon engine." No commercial man 

 connected with steam navigation will look at them. 



I do not think Vulcan political in reflecting on the judgment of 

 navy engineers : they are notoriously behind, and have great lee way 

 to gain. Mr. Pole will recollect that, not long ago, we had a highly 

 favourable report on Hall's condensers; that thousands were expended 

 on Morgan's wheels ; still the first invention did not extend beyond 

 the Mcegara, the latter is now exploded ; may we not suppose a 

 similar fate awaits the Gorgon engine ? I think Vulcan's prophecy 

 most reasonable and probable. It may be said, the Government are 

 the persons to make experiments. True; but should they not be 

 guided by discrimination and judgment in the selection of subjects? 



But other firms are making "direct engines." Government say "We 

 will have no other: what are they to do? They must comply, or lose 

 royal favour, shut up their shops, or find work for their people. Is 

 the course diflicult to decide ? 'Tis what is vulgarly called » Hobson's 

 choice." But if we are to have " direct engines," let us have them 

 in a shape that offers compensation for their acknowledged disadvan- 

 tage. If credit is to be given to the Messrs. Seaward for a reduction 

 of one-eighth, or one-twelfth, or one-seventeenth, what amount of 

 admiration is due to Maudslay, to Boulton and Watt, who, in the 

 Devastation and Virago, have annihilated space to one-half that of 

 the Gorgon engine I Could those gentlemen have stooped to such 

 species of advertisement, with what propriety could they have pub- 

 lished a pamphlet, and with all the "pomp and circumstance" of 

 success, have said — 1st. "A great saving (nearly one-half) of the 

 space usually occupied by the engine in the vessel." 



I now advert to the important subject of the weight of marine 

 engines. Vulcan states " the assumed weight of the Gorgon's ma- 

 chinery was 257 tons, and that it really weighed 298J tons." This 

 has not been contradicted, and I presume it to be correct, as great 

 care was taken ; Government appointed a special officer to see each 

 portion weighed. Now I am fully aware of the difliculty in assuming 

 weights of machinery, especially that of a new design, and do not 

 think much of the Surveyor of the Navy's annoyance at finding some 

 40 tons more on board than he had displacement for ; but that is not 

 the point of difference. It is, what proportion does this 2981 tons 

 bear to the weight of a pair of beam engines of 320 horse power ? 



