52 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Feb. 



about tlie boiler when pulled out of the canal ; the back end of the boiler is 

 protruded about six inches, owing to the stay rod having given way ; the 

 slay rod has lately been found, from which he was satisfied that the boiler 

 had flat ends. Such a boiler is not so strong as one with egged ends, but 

 still it was sufficient for a seven or eight horse power engine. 



Ceorge Brnnsoii, of Manchester, engineer, stated that lie was on Messrs. 

 Elce k Cottam's premises on the 8th of October, and observed the same so as 

 to be able to speak particularly to the whole of the machinery. He saw the 

 boiler at the same time, and has seen it since the e.iiplosion. He thought it 

 a good one, and he is still of the same opinion, and the body of it has not 

 gone out of circle the eighth of an inch. He thinks the accident was not 

 owing to pressure from steam, but the hydrogen and c.xygen gases coming 

 into contact with the red hot plates of the boiler ; if the water was boiled 

 down lower than where the fire acts upon the boiler, the plates of the boiler 

 would then become red hot, and would change the water into hydrogen and 

 oxygen, the iron would take up a poriion of the oxygen, and the hydrogen 

 •would then be in the space of the boiler, and explosion would take place 

 without the presence of atmospheric air from without. I come to this 

 opinion, not from my own experiments, but from having seen the electric 

 spark applied when the vessel has been hermetically sealed, by means of a 

 wire being passed into it, and in this case the heat from the fire would, in 

 like manner, pass through the iron plate, but it could not have passed if 

 there had been watei' inside. He has known explosions to take place from 

 low as well as high pressure boilers, where parties had professed to work 

 with only four pounds to the square inch ; we very frequently work low pres- 

 sure boilers with only three pounds to the inch, but not where explosions 

 have taken place. I think such a stay rod was sufficient for this boiler, and 

 that there was no more than five and a half horses power on the engine 

 when all the machinery was at work in the usual way ; there were on the 

 premises thirteen common lathes, which would take two and three-fifths 

 horse power ; two slide lathes, half horse power ; one large grindstone, which 

 was worn down, one half horsepower; two small ones, a third of a horse 

 power ; one upright drill, one fifth of a horse poH er ; a planing machine four 

 feet upon the bed, one fifth of a horse power ; a centring machine and cut- 

 ting engine, a fifth of ahorse power, because both could not be employed 

 together ; a roving frame with 72 spindles, a fifth of a horse power ; and an 

 eccentric machine for blowing a smith's bellows, a tenth of a horse power, or 

 half a man. He has had much experience in fitting up mills for the last H 

 years, and he has always proceeded and disposed of the power in this ratio. 

 If the gauges were defective, the water m'ght get too low without the engi- 

 neer observing it, but it was more likely to be owing to the negligence of the 

 engineer, as he has often found them negligent, even when they have been 

 short of water, and water could not be forced into the boiler, the steam being 

 so high. The machine and tool work were all light. 



Robert Armstrong, of .Salford, engineer, was examined. He stated that he 

 Lad examined the boiler since it was found, and should not like to have 

 trusted it with a pressure of 401b. to the square inch, but for the quantity of 

 machinery to be turned, there was no occasion for any such weight ; he knew 

 of many in the town egg-ended without stays, to work with 401b. This 

 might be worked with 301b. without danger ; such a boiler was sufficient to 

 work an engine of from 6 to 10 horse power. He considered the accident 

 arose from the water getting too low, and too much steam rising too rapidly, 

 the water rising over the heated plates, and being suddenly flushed into 

 steam with great pressure ; there are marks inside the boiler which show 

 that the water had frequently been allowed to get too low, so as to allow the 

 plates to get overheated above the surface of the water, but could not speak 

 positively to this having been the case in this instance ; had it been so, and 

 had the boiler been ten times the strength it was, it would have exploded. 

 All high pressure engines, from the mode in which they are fed with water, 

 are liable to such accidents. This boiler was too little for 10, but it would 

 drive from 6 to 8 horse power very well. 



Tliomss Banks, of Manchester, engineer, stated he did not make either the 

 engine or the boiler. About 16 months ago he put a Salter's spring to the 

 boiler and weighed it to forty pounds. Mr. Elce was very anxious to prevent 

 accidents, and since this Mr. Elce has got a waterfloat, which he always con- 

 sidered the most dangerous thing about boilers, more accidents having hap- 

 pened through them than anything ever appended to boilers, as I have proved 

 from an experience of near fifty years ; they are very useful if attended to, 

 but the engineer must not depend upon them too long ; tliey cause the engi- 

 neer to be over confident. Two good gauge cocks, a Salter's spring, and a 

 safety valve, which this boiler had, were sufficient in any case. He had no 

 doubt if Mr. Elce had never got the w aterfloat, the accident would never have 

 happened ; he also put up a steam gauge. He thinks if the engine had been 

 weighted for nine or ten horse power it would have broken down, but the 

 boiler would have stood. He thinks the explosion was owing to the boiler 

 being short of water. He has known of many explosions, all of which he 

 attributed to the same cause. 



Ci'orge IValion Buck, of Ardwick, and }yi!liam fairiairn, and Richard 



Roberts, of Manchester, engineers, gave their evidence jointly ; they stated 

 that they had examined Messrs. Elce and Co.'s premises, for the purpose of 

 endeavouring to ascertain the origin of the bursting of their steam boiler. 

 The engiue was on the high pressure now condensing principle, and called a 

 six horse power ; the boiler was cylindrical, measuring 3ft. lOlin. internal 

 diameter, and 9ft. 4iin. long, with fiat ends ; each end was composed of two 

 semicircular plates rivetted together in the centre, in the direction of its 

 horizontal diameter; the ends being of this weak form were sustained or 

 strengthened by a tie bar passed through the centre of the boiler, and con- 

 nected by cotters or keys to staples or stay bar straps of iron rivetted to the 

 centre of each end ; the part which first gave way, we think, on close examina- 

 tion, was the staple to which the tie bar was keyed at the end next the fur- 

 nace ; that the key or cotter had been driven until its larger end was in con- 

 fact with only one inch in length of the staple, and that the pressure of the 

 steam was then sufficient to draw the cotter through the plate of which the 

 staple was made ; the staple and the cotter indicate that this efi'ect must have 

 taken place after the fie bar was thus liberated, either end of the boiler might 

 next give way, but it appeared that the opposite end being accidentally the 

 weaker of the two, which it must have been, (probably from its being more 

 subjected to the action of the hot air of the flue), then gave way. being torn 

 asunder horizontally at the rivets ; the two halves of the end then flew open 

 like folding doors, and detached themselves from the boiler by breaking the 

 angle iron to which they were rivetted ; at the same moment the cylindrical 

 part of the boiler, with its other end, was projected horizontally with prodi- 

 gious force, its end came in contact with a heap of coals and the earth, which 

 was scooped out to the depth of two feet, lying in its path, by which the 

 other flat end of the boiler was driven into the cylindrical part where it was 

 afterwards found. This obstruction of the coal and brick wall against which 

 it was lying, and also of the earth, changed the direction of the motion of 

 the boiler, and deflected it into the canal where it was afterwards recovered. 

 The boiler did not appear to have suffered injury in any other part from the 

 explosion ; we observed that the safety valve was loaded by means of a verti- 

 cal rod passing through a stuffing box, and this rod we were informed was 

 acted upon by a lever and spring balance of Salter's construction, and that it 

 was capable of being screwed down to a pressure of 451b. to the square inch, 

 and no more ; on examining the vertical rod attached to the valve, they were 

 led to conclude that it appeared to have been set fast, or that it must have 

 offered much resistance to the rise of the valve independently of the pressure 

 of the lever, from the following considerations. If at the moment of the ex- 

 plosion the pressure of the steam had exerted a force of only 451b. to the 

 square inch, or the maximum according to the spring balance, the strain upon 

 the tie bar >»ould have been about 25,5001b , but the force exerted to draw 

 the cotter through the staple, on the supposition that the metal was of average 

 strength, must have been about 57,0001b., which indicates that the expansive 

 force of the steam must have amounted to not less than lOOlb. per square 

 inch ; this they believe was the real cause of the accident, but whether the 

 valve was held down accidentally or intentionally, in all probability can never 

 be known. They think that the ends of boilers of this description for high 

 pressure steam should be convex instead of flat, and that the safety valve 

 should be so constructed as to be acted upon by the weight or spring without 

 the intervention of a stuffing box or any other obstruction, between it and 

 the lever spring or weight acting upon it, and that although injudiciously 

 loaded, the boiler would not give way for steam at a pressure of not more 

 than 45 lb. to the square inch, but that it would have been better had there 

 been several stay rods or tie bars instead of one, and that no accident would 

 have happened had the above precautions been adopted ; that they could see 

 nothing in connexion with the death of the deceased for which any one could 

 be chargeable with blame, except only that it was injudicious to depend upon 

 one tie bar, and they have no reason to believe that there was an insuflSciency 

 of water ; and that from 5 to 5^ horse power would turn all the machinery 

 except the jack frame, which we cannot speak to; the accident we attributed 

 to the valve, which they consider did not act from some cause unknown, al- 

 though it might be in good working condition. 



The Hannibal. — The keel of a 90 gun ship, to be named the Hannibal, has 

 been laid in the same spot where the Trafalgar was built in Woolwich Dock- 

 yard, and a number of workmen are actively employed in preparing the tim- 

 ber for her constauclion. The Hannibal will be a splendid vessel on Sir Wil- 

 liam Symond's plan, and have a great breailth of beam, for which vessels 

 designed by the present surveyors of the navy are distinguished. 

 The following are the dimensions of the Hannibal :— 



ft. in. 



Length on the gun-deck , , , 204 



Breadth extreme 60 



Ditto for tonnage 39 2 



Ditto moulded 38 4 



Depth in hold 23 8 



