an autobiography-第56节
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g an important part of their contract。 Happily； I had already given some attention to this application of the powers of the steam hammer。 In fact； I had secured a patent for it。 I had the drawings for the steam hammer pile…driving machine with me。 I submitted them to Mr。 Baker； and he saw its importance in a moment。 〃That；〃 he 'said； 〃is the very thing that I want to enable me to complete my contract satisfactorily。〃 Thousands of enormous piles had to be driven down into the deep silt of the Shore； and to have driven them down by the old system of pile…driving would have occupied a long time； and would also have been very expensive。
The drawings were of course submitted to Captain Brandreth。 He was delighted with my design。 The steam pile…driver would be； in his opinion； the prime agent for effecting the commencement of the great work originated by himself。 At first the feat of damming out such a high tide as that of the Hamoaze seemed very doubtful； because the stiff slate silt was a treacherous and difficult material to penetrate。 But now； he thought； the driving would be rendered comparatively easy。 With Captain Brandreth's consent the contractors ordered of me two of my steam hammer pile…drivers。 They were to be capable of driving 18…inch square piles of 70 feet in length into the silt of the Hamoaze。
＇Image＇ Space to be enclosed at the Hamoaze
This first order for my pile…driver was a source of great pleasure to me。 I had long contemplated this application of the power of the steam hammer。 The machine had long been in full action in my 〃mind's eye；〃 and now I was to see it in actual reality。 I wrote down to my partner by that night's post informing him of the happy circumstance。 The order was for two grand steam hammer pile…drivers； each with four…ton hammer…blocks。The wrought…iron guide case and the steam cylinder were to weigh in all seven tons。 All this weight was to rest on the shoulders of the pile。 The blows were to be about eighty in the minute。 This； I thought； would prove thoroughly effective in rapidly driving the piles down into the earth。
I have said that the steam pile…driver was in my mind's eye long before I saw it in action。 It is one of the most delightful results of the possession of the constructive faculty； that one can build up in the mind mechanical structures and set them to work in imagination； and observe beforehand the various details performing their respective functions； as if they were in absolute material form and action。 Unless this happy faculty exists ab initio in the brain of the mechanical engineer； he will have a hard and disappointing life before him。 It is the early cultivation of the imagination which gives the right flexibility to the thinking faculties。 Thus business； commerce； and mechanics are all the better for a little healthy imagination。
So soon as I had returned home； I set to work and prepared the working drawings of the steam pile…drivers。 They were soon completed； conveyed to Devonport； and erected on the spot where they were to be used。 They were ready on the 3d of July 1845。 Some preliminary pile…driving had been done in the usual way； in order to make a stage or elevated way for my pile…driver to travel along the space where the permanent piles were to be driven。 I arranged my machines so that they might travel by their own locomotive powers along the whole length of the coffer dam； and also that they should hoist up the great logs of Baltic timber which formed the Piles into their proper places before being driven。
The entire apparatus of the machine was erected on a strong timber platform； and was placed on wheels； so that it might move along the rails laid down upon the timber way。 The same boiler that supplied the steam hammer part of the apparatus served to work the small steam…engine fixed to the platform for its locomotion； and also to perform the duty of rearing the next pile which had to be driven。 The steam was conveyed to the hammer cylinder by the jointed pipe seen in the annexed engraving。 The pipe accommodated itself to any elevation or descent of the hammer。 The whole weight of the cylinder； hammer…block； and guide box； supported by the shoulders of the pile； amounting to seven tons in all； rested upon the shoulders of the pile as a 〃persuader；〃 and the eighty blows per minute of the four…ton hammer came down with tremendous energy upon the top of the pile head。 No soil； that piles could penetrate； could resist such effective agencies。
＇Image＇ Diagram of the Steam Pile…Driver
Explanation of the Diagram of the Steam Pile…Driver。The chief feature of novelty of this pile…driving machine consists in the employment of the direct action of the Steam Hammer as the blow giving agent； and also in the manner in which the dead weight of the entire apparatus； consisting of the hammer…block C； the steam cylinder A； and its guide…case B； is employed to importantly aid the effect of the rapid and energetic blows of the steam hammer。 These ponderous parts rest on the shoulders of the pile H all the while it is being driven； the pile in this respect being the only support of the apparatus A B C。 So that； besides the eighty blows per minute that the four…ton steam hammer energetically deals out to the head of the pile from a four foot fall the dead weight of the apparatus constantly acts as a most effective 〃predisposer〃 to the sinking of the pile into the ground； the hoisting chain D being let slack the while； so as to allow A B C to 〃follow down〃 the pile H； while the eighty blows per minute are incessantly showered on its head。 The upward stroke of the piston； with its attached hammer…block C； is arrested at the proper height not only by allowing the steam that raised it to escape； but as soon as the piston passes the escape holes X X； the confined air above the piston at O rebounds； and so aids most effectively in increasing the energy of the fall of the hammer…block C on the pile head。
There was a great deal of curiosity in the dockyard as to the action of the new machine。 The pile…driving machine…men gave me a good…natured challenge to vie with them in driving down a pile。 They adopted the old method； while I adopted the new one。 The resident managers sought out two great pile logs of equal size and length70 feet long and 18 inches square。 At a given signal we started together。 I let in the steam； and the hammer at once began to work。 The four…ton block showered down blows at the rate of eighty a minute； and in the course of four and a half minutes my pile was driven down to the required depth。 The men working at the ordinary machine had only begun to drive。 It took them upwards of twelve hours to complete the driving of their pile！
Such a saving of time in the performance of similar workby steam versus manual labourhad never before been witnessed。 The energetic action of the steam hammer； sitting on the shoulders of the pile high up aloft； and following it suddenly down； the rapidly hammered blows keeping time with the flashing out of 〃the waste steam at the end of each stroke； was indeed a remarkable sight。 When my pile was driven； the hammer…block and guide case were speedily re…hoisted by the small engine that did all the labouring and locomotive work of the machine； the steam hammer portion of which was then lowered on to the shoulders of the next pile in succession。 Again it set to work。 At this the spectators crowding about in boats； pronounced their approval in the usual British style of 〃three cheers！〃 My new pile…driver was thus acknowledged as another triumphant proof of the power of steam。
The whole of the piles for this great work were speedily driven in。 The wall was constructed； and the docks were completed in an unusually short time。 The success of my pile…driver was followed by numerous orders。 It was used for driving the immense piles required for the High Level Bridge at Newcastle； the great Border Bridge at Berwick…upon…tweed； the Docks at Tynemouth； the Docks at Birkenhead； the Docks at Grimsby； the new Westminster Bridge； the great bridge at Kief in Russia； the bridge at Petersburg； the forts at Cronstadt； the Embarrage of the Nile； at Yokohama in Japan； and at other places。 It enabled a solid foundation to be laid for the enormous superstructures erected over them； and thus contributed to the permanence of many important undertakings。
The mechanical principles on which the efficiency of the steam pile…driver chiefly depends are as simple as I believe they are entirely novel and original。 The shoulder of the pile acts as the sole supporter of the ponderous mass of the hammer…block； cylinder； and guide…box。 This heavy weight acts as a predisposing agency to force the pile down； while the momentum given by the repeated fall of the hammer； at eighty blows the minute； brings the constant dead weight into full action。 I am not aware of any other machine in which such a combination of mechanical forces is employed。
Another very effective detail consisted in employing the waste steam in the upper part of the cylinder for the purpose of acting as a buffer to resist any undue length of the upward stroke of the piston。 But for this the cylinder covers might have been knocked off。 The
