an autobiography-第64章
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the upward stroke of the piston。 But for this the cylinder covers might have been knocked off。 The elastic buffer of waste steam also acted as a help to the downward blow of the hammer…block。 The simplicity and effectiveness of these arrangements formif I may be allowed to say soa happy illustration of my 〃Definition of Engineering；〃 the application of common sense in the use of materials。
The folding…up steam pipe with which the steam was conveyed from the boiler to the cylinder at all heights； and the way in which the folding joints accommodated themselves to the varying height of the cylinder； was another of my happy thoughts。 In fact； this invention； like most others； was the result of a succession of happy thoughts。 The machine in its entirety was the result of a number of common…sense contrivances； such as I generally delight in。 At all events； this most effective and novel machine was a special favourite with me。
I may mention； before concluding this branch of my subject； that pile…driving had before been conducted on what I might term the artillery or cannon…ball principle。 A small mass of iron was drawn slowly up； and suddenly let down on the head of the pile at a high velocity。 This was destructive； not impulsive action。 Sometimes the pile was shivered into splinters； without driving it into the soil； in many cases the head of the pile was shattered into matches； and this in spite of a hoop of iron about it to keep the layers of wood together。 Yet the whole was soon beat into a sort of brush。 Indeed； a great portion of the men's time was consumed in 〃reheading〃 the piles。 On the contrary； I employed great mass and moderate velocity。 The fall of the steam hammer…block was only three or four feet； but it went on at eighty blows the minute； and the soil into which the pile was driven never had time to grip or thrust it up an impediment well known to ordinary pile…drivers。 At the end of the driving by my steam hammer； the top of the pile was always found neat and smooth； indeed more so than when the driving began。
I may again revert to my interview with the Lords of the Admiralty on the occasion of my first meeting them at Devonport。 I was residing at the hotel where they usually took up their quarters while making their annual visitation of the dockyard。 I was honoured with an invitation to confer with Sir George Cockburn； Mr。 Sidney Herbert； and Captain Brandreth on a subject of considerable importance； namely； the proving of chain cables and anchors required for the Royal Navy。 The question was mooted as to whether or not some permanent injury was done to both by the test strains to which they were submitted before being put on board ship。 This was a subject of vital importance。 The members of the Board requested me to act as one of a committee to inquire into the subject。 I felt much gratified by the invitation and gladly accepted it。
On discussing the subject with these gentlemen that evening； I found that Sir George Cockburn entertained an ingenious theory in support of his apprehensions as the effect of 〃over…proof〃 straining of cables and anchors。 It was that they were originally in the condition of a strong man who had to lift some heavy weight； requiring him to exert his muscular strength to the utmost； and； although he might perform the feat； it was at the cost of a permanent injury； and that he might never be able to lift the same weight again。 This； however true it might be with regard to flesh and bone structures； was scarcely true with respect to mechanical agencies。 I proposed a simple experiment with chain cables； which； it occurred to me； would show quite a different resultnamely； that the capability of resisting the severest proof…strain would rise rather than fall at each successive proof of the same chain cable。
To test the correctness of my supposition； we had a first…class chain cable put into the proof machine；and subjected it to such a strain as to break it again and again； until at last it was divided almost into single links。 As I expected； the proof or breaking strain kept rising and rising as each successive remaining portion of the cable was torn asunder； thus showing that no injury to the natural tenacity of the chain had resulted from the increased proofs to which it had been subjected； and that the last broken links had been much more resisting than the first。 The same class of demonstrative experiments was made with anchors； and other wrought…iron work used in the service。 The Admiralty officers were much gratified with the result； as removing a groundless but very natural apprehension； heightened； no doubt； by the suggestions that had been made to the Admiralty； that their standard proof strain was not only too high in itself； but produced permanent damage to what at the outset was of the toughest iron。 My system of continued proof…straining was； in fact； another exemplification of the 〃Survival of the Fittest〃！
A very interesting truth came out in the course of our experiments。 It was that the chief cause of failure in the links of chain cables arose； not so much from their want of tenacity； or from the quality of the iron； but from some defective welding in the making of the links。 To get at this truth； many excellent cables as received from the contractors； as well as veteran ones that had held great ships riding at anchor in terrible gales； were pulled asunder link by link by an intentional destructive strain by the proving machine。 An exact account was taken of the nature of the fracture of each。 The result was that in eight cases out of ten； the fracture was found to result from a defectively welded part of the chain…link。 The practically trained eye could see the scoria which indicates the defective welding。 Though long unseen； it was betrayed at once when the link was torn open by the proof strain。
My services on this committee proved a source of great enjoyment to me。 I had frequent occasion to visit the dockyards and workshops； accompanied by Captain Brandreth； surveyor…general of the Admiralty landworks；Mr。 Thomas Lloyd； engineer…in…chief of the Admiralty； and Mr。 Jeremiah Owen； chief of the metal material required in the equipment of the navy I was requested to suggest any improvement in the workshops that I thought would add to the efficiency of the department； and I trust that my recommendations proved of practical good to the service。 At the same time； I have reason to know that many of the recommendations of the committee； though cordially acknowledged by the higher powers； were by a sort of passive resistance practically shelved。
I was much amused； when I first went to Devonport dockyard； to notice the punctilious observance of forms and ceremonies with respect to the various positions of officialsfrom the admiral…superintendent down the official grades of dignity； to the foremen of departments； and so on。 I did not care for all this panjandrum of punctiliousness； but was； I hope； civil and chatty with everybody。 I had a good word for the man as well as for the foreman。 I received some kind and good…natured hints as to the relative official superiority that prevailed in the departments； and made out a scale or list of the various strata accordingly。 This gamut of eminence was of use to me in my dealings with dockyard officials。 I was enabled to mind my p's and q's in communicating with them。
The first Sunday that I spent at Devonport I went to the dockyard churchthe church appointed for officials and men employed by the Government。 The seats were appointed in the order of rank； employments； and rate of pay。 The rows of seats were all marked with the class of employers that were expected to sit in them。 Labourers were near the door。 The others were in successive rows forward； until the pew of the 〃Admiral Superintendent；〃 next the Altar rails； was reached。 I took my seat among the 〃artificers；〃 being of that order。 On coming out of church the master…attendant； next in dignity to the admiral…superintendent； came up to me to say how distressed he was to see me 〃among the artificers；〃 and begged me in future to use his seat。 No doubt this was kindly intended； and I thanked him for his courtesy。 Nevertheless I kept to my
