an autobiography-第26节
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atus was then plunged into a vessel of boiling water； or heated to boiling point； when the total expansion of the bar was measured by a graduated scale； as seen in the annexed engraving。 By this simple means the expansion of any material might be ascertained under various increments of heat； say from 60deg to 2l2deg。 It was simply a thermometer； the mass marking its own expansion。 Dr。 Brewster was so much pleased with the apparatus that he described it and figured it in the Edinburgh Philosophical Journal； of which he was then editor。
＇Image＇ The road steam…carriage。 By James Nasmyth。
About the year 1827； when I was nineteen years old； the subject of steam carriages to run upon common roads occupied considerable attention。 Several engineers and mechanical schemers had tried their hands； but as yet no substantial results had come of their attempts to solve the problem。 Like others； I tried my hand。 Having made a small working model of a steam…carriage； I exhibited it before the members of the Scottish Society of Arts。 The performance of this active little machine was so gratifying to the Society that they requested me to construct one of such power as to enable four or six persons to be conveyed along the ordinary roads。 The members of the Society； in their individual capacity； subscribed #60； which they placed in my hands as the means for carrying out their project。
I accordingly set to work at once。 I had the heavy parts of the engine and carriage done at Anderson's foundry at Leith。 There was in Anderson's employment a most able general mechanic named Robert Maclaughlan； who had served his time at Carmichaels' of Dundee。 Anderson possessed some excellent tools； which enabled me to proceed rapidly with the work。 Besides； he was most friendly； and took much delight in being concerned in my enterprise。 This 〃big job〃 was executed in about four months。 The steam…carriage was completed and exhibited before the members of the Society of Arts。 Many successful trials were made with it on the queensferry Road； near Edinburgh。 The runs were generally of four or five miles； with a load of eight passengers sitting on benches about three feet from the ground。
The experiments were continued for nearly three months； to the great satisfaction of the members。 I may mention that in my steam…carriage I employed the waste steam to create a blast or draught by discharging it into the short chimney of the boiler at its lowest part； and found it most effective。 I was not at that time aware that George Stephenson and others had adopted the same method； but it was afterwards gratifying to me to find that I had been correct as regards the important uses of the steam blast in the chimney。 In fact； it is to this use of the waste steam that we owe the practical success of the locomotive…engine as a tractive power on railways； especially at high speeds。
The Society of Arts did not attach any commercial value to my steam road…carriage。 It was merely as a matter of experiment that they had invited me to construct it。 When it proved successful they made me a present of the entire apparatus。 As I was anxious to get on with my studies； and to prepare for the work of practical engineering； I proceeded no further。 I broke up the steam…carriage and sold the two small high…pressure engines； provided with a compact and strong boiler； for #67； a sum which more than defrayed all the expenses of the construction and working of the machine。
I still continued to make investigations as to the powers and capabilities of the steam…engine。 There were numerous breweries； distilleries； and other establishments； near Edinburgh； where such engines were at work。 As they were made by different engineers； I was desirous of seeing them and making sketches of them； especially when there was any special peculiarity in their construction。 I found this a most favourite and instructive occupation。 The engine tenters became very friendly with me； and they we re always glad to see me interested in them and their engines。 They were especially delighted to see me make 〃drafts；〃 as they called my sketches； of the engines under their charge。
My father sometimes feared that my too close and zealous application to engineering work might have a bad effect upon my health。 My bedroom work at brass casting； my foundry work at the making of steam…engines； and my studies at the University classes； were perhaps too much for a lad of my age； just when I was in the hobbledehoy statebetween a boy and a man。 Whether his apprehensions were warranted or not； it did so happen that I was attacked with typhus fever in 1828； a disease that was then prevalent in Edinburgh。 I had a narrow escape from its fatal influence。 But thanks to my good constitution； and to careful nursing； I succeeded in throwing off the fever； and after due time recovered my usual health and strength。
In the course of my inspection of the engines made by different makers； I was impressed with the superiority of those made by the Carmichaels of Dundee。 They were excellent both in design and in execution。 I afterwards found that the Carmichaels were among the first of the Scottish engine makers who gave due attention to the employment of improved mechanical tools； with the object of producing accurate work with greater ease； rapidity； and economy； than could possibly be effected by the hand labour of even the most skilful workmen。 I was told that the cause of the excellence of the Carmichaels' work was not only in the ability of the heads of the firm； but in their employment of the best engineers' tools。 Some of their leading men had worked at Maudslay's machine shop in London； the fame of which had already reached Dundee； and Maudslay's system of employing machine tools had been imported into the northern steam factory。
I had on many occasions； when visiting the works where steam…engines were employed； heard of the name and fame of Maudslay。 I was told that his works were the very centre and climax of all that was excellent in mechanical workmanship。 These reports built up in my mind； at this early period of my aspirations； an earnest and hopeful desire that I might some day get a sight of Maudslay's celebrated works in London。 In course of time it developed into a passion。 I will now proceed to show how my inmost desires were satisfied。
CHAPTER 7。 Henry Maudslay； London
The chief object of my ambition was now to be taken on at Henry Maudslay's works in London。 I had heard so much of his engineering work； of his assortment of machine…making tools； and of the admirable organisation of his manufactory； that I longed to obtain employment there。 I was willing to labour； in however humble a capacity； in that far…famed workshop。
I was aware that my father had not the means of paying the large premium required for placing me as an apprentice at Maudslay's works。 I was also informed that Maudslay had ceased to take pupils。 After experience； he found that the premium apprentices caused him much annoyance and irritation。 They came in 〃gloves；〃 their attendance was irregular； they spread a bad example amongst the regular apprentices and workmen； and on the whole they were found to be very disturbing elements in the work of the factory。
It therefore occurred to me that； by showing some specimens of my work and drawings； I might be able to satisfy Mr。 Maudslay that I was not an amateur； but a regular working engineer。 With this object I set to work； and made with special care a most complete working model of a high…pressure engine。 The cylinder was 2 inches diameter； and the stroke 6 inches。 Every part of the engine； including the patterns； the castings； the forgings； were the results of my own individual handiwork。 I turned out this sample of my ability as an engineer workman in such a style as even now I should be proud to own。
In like manner I executed several specimens of my ability as a mechanical draughtsman； for I knew that Maudslay would thoroughly understand my ability to work after a plan。 Mechanical drawing is the alphabet of the engineer。 Without this the workman is merely a 〃hand。〃 With it he indicates the possession of 〃a head〃 I also made some samples of my skill in hand…sketching of machines； and parts of machines； in perspectivethat is； as such objects really appear when set before us in their natural aspect。 I was the more desirous of exhibiting the ability which I possessed in mechanical draughtsmanship； as I knew it to be a somewhat rare and much…valued acquirement。 It was a branch of delineative art that my father had carefully taught me。 Throughout my professional life I have found this art to be of the utmost practical value。
Having thus provided myself with such visible and tangible evidences of my capabilities as a young engineer； I carefully packed up my working model and drawings； and prepared to start for London。 On the 19th of May 1829； accompanied by my father； I set sail by the Leith smack Edinburgh Castle； Captain Orr； master。 After a pleasant voyage of four days we reached the mouth of the Thames。 We sailed up from the Nore on Saturday afternoon； lifted up； as it were； by the tide； for it was almost a dead calm the whole way。
The si
