the commercial
faculty. He has helped others in their difficulties, but forgotten
himself. Many have profited by his inventions, without even
acknowledging the obligations which they owed to him. They have used
his brains and copied his tools, and the "sucked orange" is all but
forgotten. There may have been a want of worldly wisdom on his part,
but it is lamentable to think that one of the most prolific and useful
inventors of his time should in his old age be left to fight with
poverty.

Mr. Whitworth is another of the first-class tool-makers of Manchester
who has turned to excellent account his training in the workshops of
Maudslay and Clement. He has carried fully out the system of
uniformity in Screw Threads which they initiated; and he has still
further improved the mechanism of the planing machine, enabling it to
work both backwards and forwards by means of a screw and roller motion.
His "Jim Crow Machine," so called from its peculiar motion in reversing
itself and working both ways, is an extremely beautiful tool, adapted
alike for horizontal, vertical, or angular motions. The minute
accuracy of Mr. Whitworth's machines is not the least of their merits;
and nothing will satisfy him short of perfect truth. At the meeting of
the Institute of Mechanical Engineers at Glasgow in 1856 he read a
paper on the essential importance of possessing a true plane as a
standard of reference in mechanical constructions, and he described
elaborately the true method of securing it,--namely, by scraping,
instead of by the ordinary process of grinding. At the same meeting he
exhibited a machine of his invention by which he stated that a
difference of the millionth part of an inch in length could at once be
detected. He also there urged his favourite idea of uniformity, and
proper gradations of size of parts, in all the various branches of the
mechanical arts, as a chief means towards economy of production--a
principle, as he showed, capable of very extensive application. To
show the progress of tools and machinery in his own time, Mr. Whitworth
cited the fact that thirty years since the cost of labour for making a
surface of cast-iron true--one of the most important operations in
mechanics--by chipping and filing by the hand, was 12s. a square foot;
whereas it is now done by the planing machine at a cost for labour of
less than a penny. Then in machinery, pieces of 74 reed
printing-cotton cloth of 29 yards each could no