industrial biography-第60章
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industry; the King might have made from 40s。 to 50s。 a…week as a hard
wood and ivory turner。 Lord John Hay; though one…armed; was an adept
at the latter; and Lord Gray was another capital turner。 Indeed the
late Mr。 Holtzapffel's elaborately illustrated treatise was written
quite as much for amateurs as for working mechanics。 Among other
noble handicraftsmen we may mention the late Lord Douglas; who
cultivated bookbinding。 Lord Traquair's fancy was cutlery; and one
could not come to him in a more welcome fashion than with a pair of
old razors to set up。
。。。'
There was at that time a great passion for automata in France; which
gave rise to many highly ingenious devices; such as Camus's miniature
carriage (made for Louis XIV。 when a child); Degennes' mechanical
peacock; Vancanson's duck; and Maillardet's conjuror。 It had the
effect of introducing among the higher order of artists habits of
nice and accurate workmanship in executing delicate pieces of
machinery; and the same combination of mechanical powers which made
the steel spider crawl; the duck quack; or waved the tiny rod of the
magician; contributed in future years to purposes of higher
import;the wheels and pinions; which in these automata almost
eluded the human senses by their minuteness; reappearing in modern
times in the stupendous mechanism of our self…acting lathes;
spinning…mules; and steam…engines。
〃In our own country;〃 says Professor Willis; 〃the literature of this
subject is so defective that it is very difficult to discover what
progress we were making during the seventeenth and eighteenth
centuries。〃*
'footnote。。。
Professor WILLIS; Lectures on the Results of the Great Exhibition of
1851; lst series; p。 306。
。。。'
We believe the fact to be; that the progress made in England down to
the end of last century had been very small indeed; and that the
lathe had experienced little or no improvement until Maudslay took it
in hand。 Nothing seems to have been known of the slide rest until he
re…invented it and applied it to the production of machinery of a far
more elaborate character than had ever before been contemplated as
possible。 Professor Willis says that Bramah's; in other words
Maudslay's; slide rest of 1794 is so different from that described in
the French 'Encyclopedie in 1772; that the two could not have had a
common origin。 We are therefore led to the conclusion that Maudslay's
invention was entirely independent of all that had gone before; and
that he contrived it for the special purpose of overcoming the
difficulties which he himself experienced in turning out duplicate
parts in large numbers。 At all events; he was so early and zealous a
promoter of its use; that we think he may; in the eyes of all
practical mechanics; stand as the parent of its introduction to the
workshops of England。
It is unquestionable that at the time when Maudslay began the
improvement of machine…tools; the methods of working in wood and
metals were exceedingly imperfect。 Mr。 William Fairbairn has stated
that when he first became acquainted with mechanical engineering;
about sixty years ago; there were no self…acting tools; everything
was executed by hand。 There were neither planing; slotting; nor
shaping machines; and the whole stock of an engineering or machine
establishment might be summed up in a few ill…constructed lathes; and
a few drills and boring machines of rude construction。*
'footnote。。。
Address delivered before the British Association at Manchester in
1861; and Useful Information for Engineers; 1st series; p。 22。
。。。'
Our mechanics were equally backward in contrivances for working in
wood。 Thus; when Sir Samuel Bentham made a tour through the
manufacturing districts of England in 1791; he was surprised to find
how little had been done to substitute the invariable accuracy of
machinery for the uncertain dexterity of the human hand。 Steam…power
was as yet only employed in driving spinning…machines; rolling
metals; pumping water; and such like purposes。 In the working of wood
no machinery had been introduced beyond the common turning…lathe and
some saws; and a few boring tools used in making blocks for the navy。
Even saws worked by inanimate force for slitting timber; though in
extensive use in foreign countries; were nowhere to be found in Great
Britain。*
'footnote。。。
Life of Sir Samuel Bentham; 97…8。
。。。'
As everything depended on the dexterity of hand and correctness of
eye of the workmen; the work turned out was of very unequal merit;
besides being exceedingly costly。 Even in the construction of
comparatively simple machines; the expense was so great as to present
a formidable obstacle to their introduction and extensive use; and
but for the invention of machine…making tools; the use of the
steam…engine in the various forms in which it is now applied for the
production of power could never have become general。
In turning a piece of work on the old…fashioned lathe; the workman
applied and guided his tool by means of muscular strength。 The work
was made to revolve; and the turner; holding the cutting tool firmly
upon the long; straight; guiding edge of the rest; along which he
carried it; and pressing its point firmly against the article to be
turned; was thus enabled to reduce its surface to the required size
and shape。 Some dexterous turners were able; with practice and
carefulness; to execute very clever pieces of work by this simple
means。 But when the article to be turned was of considerable size;
and especially when it was of metal; the expenditure of muscular
strength was so great that the workman soon became exhausted。 The
slightest variation in the pressure of the tool led to an
irregularity of surface; and with the utmost care on the workman's
part; he could not avoid occasionally cutting a little too deep; in
consequence of which he must necessarily go over the surface again;
to reduce the whole to the level of that accidentally cut too deep;
and thus possibly the job would be altogether spoiled by the diameter
of the article under operation being made too small for its intended
purpose。
The introduction of the slide rest furnished a complete remedy for
this source of imperfection。 The principle of the invention consists
in constructing and fitting the rest so that; instead of being
screwed down to one place; and the tool in the hands of the workman
travelling over it; the rest shall itself hold the cutting tool
firmly fixed in it; and slide along the surface of the bench in a
direction exactly parallel with the axis of the work。 Before its
invention various methods had been tried with the object of enabling
the work to be turned true independent of the dexterity of the
workman。 Thus; a square steel cutter used to be firmly fixed in a
bed; along which it was wedged from point to point of the work; and
tolerable accuracy was in this way secured。 But the slide rest was
much more easily managed; and the result was much more satisfactory。
All that the workman had to do; after the tool was firmly fitted into
the rest; was merely to turn a screw…handle; and thus advance the
cutter along the face of the work as required; with an expenditure of
strength so slight as scarcely to be appreciable。 And even this
labour has now been got rid of; for; by an arrangement of the
gearing; the slide itself has been made self…acting; and advances
with the revolution of the work in the lathe; which thus supplies the
place of the workman's hand。 The accuracy of the turning done by this
beautiful yet simple arrangement is as mechanically perfect as work
can be。 The pair of steel fingers which hold the cutting tool firmly
in their grasp never tire; and it moves along the metal to be cut
with an accuracy and precision which the human hand; however skilled;
could never equal。
The effects of the introduction of the slide rest were very shortly
felt in all dep