lO^t.J 



inri x^iviL, arNuiiMiiiU AI\L» ARCHITECT'S JOURNAL. 



9S 



STEAM NAVIGATION. 



THE GOVERNMENT STEAM VESSEL CONTRACT. 



Since the publication by us of the Specification and Condilions is- 

 sued to engineers for constructing engines for four second class and 

 two first class vessels, Government have extended the space allowed 

 for the engine room 6 feet in length for both class vessels ; this is still 

 too little : if the beam engine is to be introduced, it onght to have 

 been extended to at least 12 feet, otherwise engineers v/ill not be able 

 to carry out their own ideas as to the most effective mode of con- 

 struction ; they will be obliged to cramp their ideas to make the en- 

 gine suitable tu tl]e Goveriiment dictates as to space. We believe 

 the limitation originated in a great mistake, as it is supposed by many 

 persons that the tubular boiler, which is now being very generally in- 

 troduced, occupies less space; this is true as to bulk, but not superfi- 

 cially,for it is requisite to construct tubular boilers witli as large a fire 

 grate and back flue as for the flue boiler, for if a given quantity of 

 steam is to be generated, tlie same quantity of fuel will be required 

 for a tubular boiler as for a well constructed flue boiler. We consider 

 that Government was most decidedly wrong in limiting the space at 

 all; it ought to have been left entirely to the judgment of the engineer 

 to make their own designs, and it would tlien have been the duty of 

 the Government officers, to have compared each design, and decided 

 upon that engine which appeared to them to be the most effective for 

 permanent service, for a few feet in length in such large vessels, as 

 irom 180 to 220 feet in length, cannot be of such consequence as the 

 eftec live working of the engine. 



We have before alluded to the necessity of Government making a 

 rigid enquiry as to the comparative duty, expense of working and 

 repairs of each description of engines, whether beam or direct action 

 of the several descriptions that have been introduced within the last 

 10 years ; we trust this will be no longer delayed : and there is one 

 other enquiry that ought also to be made, that is, as to the length of 

 the Government steamers ; in our opinion the second and first class 

 vessels are too short, they would be better if built from 10 to 20 feet 

 longer, which would give that space which is so essentially re(iuisUe 

 to make a comfortable engine room, the most important part of a 

 steamer. 



THE SCREW AND PADDLE WHEEL TRIAL. 



In page 85, of last week's Journal, we gave the particulars of the Govern- 

 ment trial of the screw propeller and the paddle wheel, with her Majesty's 

 steana shijis the Ra//ie,- and Promethms, the former vessel was fitted with the 

 screw, and the latter the paddle wheel ; as the experiment is one of im- 

 portance, we have taken the trouble to obtain the proportions of the Rattler 

 We understand that as far as the build of the vessel, the proportions of the 

 Prometheus are nearly the same. 



Dimensions of H.BI.S. RBttler. Feet. Inchei. 



Length, extreme .. ., 195 q 



Ditto on decks .. .. 170 g 



Ditto on keel for tonnage .. .. 157 91 



Breadth, extreme .. .. 32 8i 



Ditto moulded .. .. 31 jq 



Depth of hold .. .. jg 71 

 Burthen in tons 888^ 



Draught of water (mean) . . . . H 3 



Area of midship section at 11 ft. Sin. . . 280 



Engines — Maudslay's 4 cyUnders, aggregate 

 power 200 horses : — 



Diameter of cylinders . . . . 40 



Length of stroke . . . . 4 q 



Diameter of screw . . . . 9 



Pitch of ditto. . ., .. 11 Q 



Length originally . . • • 5 g 



Do. as reduced on the occasion of the trial 3 

 Number of threads two. 



The gearing at present consists of two motions, which gives a velocity of 

 four to one of the engine. The first motion of two to one consists of a 

 large spur wheel and pinion, the cogs of which are divided into three parts 

 thus — "^ 



those of the larger wheel being made of hard wood, and the smaller one of 



iron ; this sub-division of the wheels, prevents that very disagreeable raftlinc' 

 which is so nuich complained of. 



The second motion consists of a large and small drum, with their surfaces 

 divided into seven convex parts, thus — 



upon which seven leather straps, of live inches in width, are kept ti^ht hv a 

 suitable pulley or drum for that purpose. The drum and straps have merely 

 been put in to try their efficiency, and to allow the multiple to be diminished 

 or increased as circumstances may require. It is inl<-nded, when the experi- 

 ments have been completed, to remove the drums .i,nd straps, which will be 

 replaced by a single wheel and pinion of requisite proportions 



It is estimated that from 18 to 20 im'. is absorbed in transmitting the 

 power of the engine through the medium of straps at so great a velocity as 

 IS required to drive the screw. 



Diameter of Gearing. 



Diameter of spur wheel 



M'idth .. 



Pitch .. .. .. \\ 



Diameter of pinion 

 Ditto large drum . . 

 Dittoof small drum 



The boilers are upon the ordinary llue principle. 



The boilers of the Promet/ieus are upon the new tubular principle, the dia- 

 meter of her two cylinders 52Jin., length of stroke 4 ft. Gin. 



LAUNCH OF THE "QUEEN" NEW FERRY STEAMER. 



On Saturday, 12th inst., a fine iron steam boat, the property of the Biiken- 

 liead Comra.ssioners, and intended to plv between Woodside Ferry and 

 Georges pier, was launched from the yard of Mr. John Laird, the builder 

 ^orth Birkenhead— amidst a large concourse of spectators, the occasion 

 having excited considerable local interest, the vessel being of a new and pe- 

 culiar construction, which it is fully expected will greatly expedite the trip 

 across the Mersey, particularly from the Cheshire side. " She is somewhat 

 arger than the ^un, (the largest boat now on the station,) being 110ft 

 long by 22 It. beam ; her plates and ribs are of extra strength ; and she is 

 put together with that tidelity, firmness, and improved fastenings, for which 

 the constructor (who has had greater experience than any other iron ship, 

 builder) has long been justly celebrated. Iler deck is flush, and uninter- 

 rupted liyunwieldly erections, from end to end, her paddle frame-work beine 

 carried along her whole length, dying into her extremities, and enclosed by 

 continuous bulwarks, so that the full length and breadth, including the over- 

 hangings, IS rendered available for the accommodation of passengers She 

 IS moreover finely moulded, and will doubtless prove herself very speedv 

 Her peculiarity consists in her being constructed that she may be pronelled 

 with either end foremost, so that the delay of backing out, and then running 

 a-head from the shore, especially from the Woodside shp, and which occu- 

 pies on an average from four to five minutes each trip, (or nearly half the 

 time of crossing,) will be altogether avoided— itself a great desideratum not 

 only as regards passengers, but expenditure of fuel. This is accomplished 

 by a rudder at each end, so contrived that it may be fixed firmly amidships, 

 forming a cutwater when that end (which was before the stern) is required 

 to become the bow. So far the plan has before been in operation, though 

 with but partial success, from the difficulty of securing the respective rud- 

 ders to form a stem, and their habUity, even on slight contact at their outer 

 edge, to be carried away or deranged. Mr. Laird has, however, contrived a 

 remedy for this liability to damage by an outward and standing guard of iron, 

 forming a cutwater outside the rudder when that end is the bow, and within 

 and just clear of which the rudder works, when it becomes the stern, in 

 which case, from its comparative thinness, it oflers little or no resistance to 

 the speed of the vessel as a stopwater. This guard is secured, below, to the 

 keel, and above to the stern. The rudders do not rise, as in ordinary vessels, 

 to the top of the external part of the stern post, but occupy the space only 

 between the bne of the keel and the water or dranght-mark of the vessel. 

 When not in use it is not perceptible to the eye, forming, as it were, a secret 

 door. It is secured, when forming part of 'the stern below, by dropping a 

 strong bolt, which firmly attaches its outer edge to the guard, so that the 

 whole becomes as one piece, forming a deep ho!ding-on fore-foot. A steam 

 frigate for the navy has recently been built, having two rudders, with the 

 object here sought, on the suggestion of Lord Dundonald. How she will 

 succeed we have not yet ascertained; but we doubt not but additional 

 strength and safety would be secured by the adoption of Mr. Laird's " patent 

 guard." Another steamer of precisely the same size and construction, and 

 for the same proprietary, is in a forward state iu Mr. Laird's yard . The 

 Queen will be propelled by engines of 60 H.f ., with oscillating cylinders, by 

 Messrs. George Forrester & Co. (See Journal for last November, p. 367, 

 and Plate XIII.) The engines and boilers will occupy a space of only 21 ft.', 

 leaving a large space forward and aft for cabin accommodation. 



