330 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Oct. 



the usual methods ; tlie upper edge of the periphi'ry of tlic friction 

 rollers or wheels, M, heing, the whole of tlieiu, in tlie sami> hcriz. ntal 

 plane. The object of tlie arrangement and invention the |iatentee 

 states to be, to allow any lateral motion of the upper or revolving 

 plate of the turn-table to take place, without in any way atiecling the 

 pressure or position of the said revolving plate upou the friction 

 rollers or wheels. 



The patentee also states, the third part of his improvements to be, 

 the arrangement of the rails ujion the turn-plates, and the arrange- 

 ment of turn-plates upon parallel lines of railway, to facilitate the re- 

 moval or transit of carriages from one rail to another. This improve- 

 ment simply consists in placing tlie turn-plates in such a position that 

 a line passing through the centres of such turn-plates shall be at such 

 an angle as shall divide the circle. The patentee giving two exam- 

 ples, thus: one in which the line passing through the centre of the 

 turn-plate is at an angle of 60° to the line of rails; by their being 

 placed in this position the patentee fixes upon the turn-table three 

 lines of rails, and a carriage placed thereon has to be moved twice 

 tlirougli 60° only, or one-sixth of a circle, instead of by the usual ar- 

 rangement 90° or one-fourth of a circle. In the other example of the 

 patentee's, the said lines passing through the said centre of tne turn- 

 plates are placed at an angle of 45^: in this example the patentee 

 arranges upou the turn-plates four lines of rails; and a carriage re- 

 quires to be moved through one-eighth of a circle, or 45°, twice, to 

 place it upon another and parallel line of rails. By these arrange- 

 ments, the patentee states, the turn-table is in a position to receive a 

 carriage upon it, whether from the inclined line between the parallel 

 or main lines, or from the main or parallel lines themselves. 



The patentee, after specifying and describing his invention and im- 

 provements, states his claim to be; 1st. The construction and appli- 

 aalion of moveable tongue rails of railway switches, as hereinbefore 

 described. 2nd. The construction and arrangement of railway turn- 

 tables, by which the upper edges of the peripheries of all the revolv- 

 ing friction rollers or wheels are in one and the same plane, that plane 

 being horizontal, oi at right angles, to the centre line of the axes of 

 motion of the upper or moveable plate of the turn-table, and thereby 

 allowing lateral motion of the said upper or moveable plate upon the 

 said revolving friction rollers or wheels, without injuriously affecting 

 or deranging the perfect action of the said arrangement and apparatus. 

 And the patentee also claims the construction and application of the 

 lever balancing apparatus to the said turn-tables, as hereinbefore de- 

 scribed. 3rd. The arranging and fixing the rails upon turn-tables, 

 and the arrangement of the relative positions of the said turn-tables to 

 facilitate the removal of carriages from oue to another line of rails, as 

 hereinbefore described. 



HIGH-PRESSURE MARINE BOILERS. 



The explosion of the boiler of the Cricket steamboat has given promi- 

 nence to the question, whether high-pressure steam can be used with 

 safely for the purpose of navigatioa. In consideriog the subject, however, 

 at such a time, there is some danger that the judgment may be prejudiced, 

 and a too-hasty decision given against the principle, when only the mode 

 of carrying it into practice has been defective. It is most desirable to 

 view ihe matter as freely as possible from the ioSueoce which such a 

 disaster is calculated to produce, and to consider all the circumstances 

 attending it, fur the purpose of ascertaining whether they disclose any 

 inherent danger in the use of high-pressure steam that no precaution can 

 remove, or whether the accident was the result of recklessness on the part 

 «f those employed, or of want of care in the manufacturing engineer ; — 

 casualties altogether independent of the safety of high-pressure steam. 

 We will in the first place compile a brief narrative of the event, collected 

 from the evidence of those who witnessed the explosion. 



The Cricket was one of three steamboats built on the same principle, 

 and employed in conveying passengers to and from the Adelphi-pier and 

 London-bridge, at the low fare of one halfpenny. On Ihe morning of the 

 'J7th of August, the Cricket was at the Adelphi-pier, waiting for passen- 

 gers. She had been waiting for ten minutes after having come from Lon- 

 don bridge, with the steam up; yet, during that time, nearly all the wit- 

 nesses declare that there was no steam blowing olf. The captain had gone 

 luhoie, and the person in whose charge the engine was for the day — not 

 the regular engineer— was standing on deck near the funnel talking to Ihe 

 ttsker. The call-boy was in the after-cabin, and not one of Ihe persons 

 belonging to the boat was in the engine-room. The number of passengers 

 ua bokrd is variously utated at from 100 to 200. Suddenly a load ouis. 



was beard, which is described by some of the passengers to have resem- 

 bled the sound of rushing steam and rending iron, rather than a sudden 

 explosion ; others, indeed, compare the noise to the discharge of a cannon. 

 The boiler casing was projected with great force through the after part of 

 the boat, which was completely destroyed. The whole flooring of Ihe 

 deck was blown up, the cabin was stripped bare, and the iron sides of the 

 vessel, where it narrowed at the run, were laid flat, and the boiler casing 

 was carried into the water. The steam chest was projected upwards, 

 carrying with it the funnel and the outer case of Ihe boiler, and shattering 

 the bridge which connected the two paddle-boxes. The front plate of the 

 boiler and the tubes were driven against the frame of the engine, which 

 was much injured, but it forlunately arrested Ihe progress of that portioD 

 of the boiler, and thus preserved the fore part of the boat. 



An explosion attended with such destruction on Ihe vessel must, of 

 necessity, have told with disastrous ellect on Ihe numerous passengers. 

 Those on the after deck were blown into Ihe air : some fell into the water, 

 and others descended among the ruins of Ihe vessel. The number killed, 

 however, is wonderfully small considering Ihe destructive elfecis of the 

 explosion. The lives lost were only five, and among them was the call- 

 boy, who was boiling coffee in the afler-cabin when the boiler casing swept 

 through it. Even he, continued to live sometime after the explosion. It 

 is a remarkable circumstance, also, to which we shall subsequently direct 

 attention, that not one of those who were killed had been injured by scald- 

 ing, and among the many who have sustained injuries by the explosion, 

 very few have been scalded, and none of them seriously. 



The foregoing is a brief resume of the principal facts given in evidence 

 before the coroner, respecting the explosion of Ihe boiler and its effects ; 

 we have now to inquire for the cause of the disaster. The engine was 

 constructed in accordance with a plan (patented by Mr. Smith, one of the 

 proprietors of the boat,) in which the principles of high-pressure and of 

 condensing engines are combined, and Ihe result is reported to have been 

 a great saving of fuel. The engines were made by Mr. Joyce. The 

 boilers were tubular, having the fire contained in a tube three feet diame- 

 ter within them. The boiler casing, which was cylindrical, was about 

 five feet diameter and six feet long, with a hemispherical end at ihe after 

 part, and it was made of f -inch iron. The steam chest was cylindrical, 

 with a hemispherical top, and was composed of iron y^ths of an inch 

 thick. There were CO tubes of 2 J inches diameter inside and 4 ft. U in. 

 long. The safety-valves were if^ inches in diameter, being flat and rest- 

 ing on flat seats. The length of the levers was 27 inches, and the fulcrum 

 2f inches. Of these valves there was one on each of the two boilers, 

 which freely communicated by steam and water passages ; and besides 

 these lever-valves, each boiler had a Salter's spriug-valve supposed to 

 indicate 45 lb. on the index : there was also a mercurial gauge, for the 

 additional guidance of the engineer as to the pressure of the steam. 

 Neither of the boilers bad any stays above the tubes, nor in the steam 

 chest. With respect to the boat itself, the following specification for its 

 construction, as agreed between Mr. Smith and Mr. Joyce, shows that it 

 was intended to be put together in the best manner : — 

 " Specification o/ an Iron Steamboat. 



Length on deck . . 120 feet 



Breadth of btam . . 13 feet 



Depth of hoM . . 7 feet 



Draft of water 2 ft. 6 in., with machinery aud coals on board. Is to be 

 built of the best plates, flush jointed, aud countersunk rivttted. 

 Plating of bottom lower streak, one-fourth thick ; 

 Second, third, and fourth streaks, three-sixteenths thick ; 

 Fifth streak, one-eighth full ; sixth streak, one-eighth. 

 Angle iron frames 2 in. by 2 in., and 18 inches apart in centre of vessel, 

 and towards the ends the angle iron to be lighter, and 24 inches apart. 



Sleepers about 12 inches deep and one quarter thick, and of suSicieot 

 length to distribute the weight of engines and boiler over 3U feet length »{ 

 vessel. 



Keel and stems 6 inches by ^-inch. 

 Bulkheads and coal bunkers J full,i bare. 



Suitable half-round iron all round tiiat portion of the boat desiguatitti 

 the plank shear or gunwale streak, including sponsons. 

 Wood Work. 

 Shelf piece of best red pine . . 6 in. by 24 in. 

 Beams, 24 inches apart . . . 34 " 2i 



Plankshear of Quebec oak . . 7 " 24 



Deck, best yellow pine . . . 5 " 14 



^ Shear streak of best red pine . . fi 8 " 14 



Paddle beams, spring beams, aud rim pieces of tjuebec oak. 

 Cabin floors of good yellow battens, one inch thick, on suitable bearers 

 of red pine. 



Cabiui t« be fitted up aimilar to the Ant and Bee, and the joiners' nark 



