men of invention and industry-第70节
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discovery by Dollond; in 1758; of the relation between the
refractive and dispersive powers of different kinds of glass; and
the invention by that distinguished optician of the achromatic
telescope; the manufacture of that instrument had been confined
to England; where the best flint glass was made。 But through the
short…sighted policy of the Government; an exorbitant duty was
placed upon the manufacture of flint glass; and the English trade
was almost entirely stamped out。 We had accordingly to look to
foreign countries for the further improvement of the achromatic
telescope; which Dollond had so much advanced。
A humble mechanic of Brenetz; in the Canton of Neufchatel;
Switzerland; named Guinaud; having directed his attention to the
manufacture of flint glass towards the close of last century; at
length succeeded; after persevering efforts; in producing masses
of that substance perfectly free from stain; and therefore
adapted for the construction of the object…glasses of telescopes。
Frauenhofer; the Bavarian optician; having just begun business;
heard of the wonderful success of Guinaud; and induced the Swiss
mechanic to leave Brenetz and enter into partnership with him at
Munich in 1805。
The result was perfectly successful; and the new firm turned out
some of the largest object…glasses which had until then been
made。 With one of these instruments; having an aperture of 9。9
inches; Struve; the Russian astronomer; made some of his greatest
discoveries。 Frauenhofer was succeeded by Merz and Mahler; who
carried out his views; and turned out the famous refractors of
Pulkowa Observatory in Russia; and of Harvard University in the
United States。 These last two telescopes contained
object…glasses of fifteen inches aperture。
The pernicious impost upon flint glass having at length been
removed by the English Government; an opportunity was afforded to
our native opticians to recover the supremacy which they had so
long lost。 It is to Thomas Cooke; more than to any other person;
that we owe the recovery of this manufacture。 Mr。 Lockyer;
writing in 1878; says: 〃The two largest and most perfectly
mounted refractors on the German form at present in existence are
those at Gateshead and Washington; U。S。 The former belongs to
Mr。 Newall; a gentleman who; connected with those who were among
the first to recognise the genius of our great English optician;
Cooke; did not hesitate to risk thousands of pounds in one great
experiment; the success of which will have a most important
bearing upon the astronomy of the future。〃'7'
The progress which Mr。 Cooke made in his enterprise was slow but
steady。 Shortly after he began business as an optician; he
became dissatisfied with the method of hand…polishing; and made
arrangements to polish the object…glasses by machinery worked by
steam power。 By this means he secured perfect accuracy of
figure。 He was also able to turn out a large quantity of
glasses; so as to furnish astronomers in all parts of the world
with telescopes of admirable defining power; at a comparatively
moderate price。 In all his works he endeavoured to introduce
simplicity。 He left his mark on nearly every astronomical
instrument。 He found the equatorial comparatively clumsy; he
left it nearly perfect。 His beautiful 〃dividing machine;〃 for
marking divisions on the circles; four feet in diameter and
altogether self…actingwhich divides to five minutes and reads
off to five seconds is not the least of his triumphs。
The following are some of his more important achromatic
telescopes。 In 1850; when he had been fourteen years in
business; he furnished his earliest patron; Professor Phillips;
with an equatorial telescope of 6 1/4 inches aperture。 His
second (of 6 1/8) was supplied two years later; to James
Wigglesworth of Wakefield。 William Gray; Solicitor; of York; one
of his earliest friends; bought a 6 1/2…inch telescope in 1853。
In the following year; Professor Pritchard of Oxford was supplied
with a 6 1/2…inch。 The other important instruments were as
follows: in 1854; Dr。 Fisher; Liverpool; 6 inches; in 1855; H。 L。
Patterson; Gateshead; 7 1/4 inches; in 1858; J。 G。 Barclay;
Layton; Essex; 7 1/4 inches; in 1857; Isaac Fletcher;
Cockermouth; 9 1/4 inches; in l858; Sir W。 Keith Murray;
Ochtertyre; Crieff; 9 inches; in 1859; Captain Jacob; 9 inches;
in 1860; James Nasmyth; Penshurst; 8 inches; in 1861; another
telescope to J。 G。 Barclay; 10 inches; in 1864; the Rev。 W。 R。
Dawes; Haddenham; Berks; 8 inches; and in 1867; Edward Crossley;
Bermerside; Halifax; 9 3/8 inches。
In 1855 Mr。 Cooke obtained a silver medal at the first Paris
Exhibition for a six…inch equatorial telescope。'8' This was the
highest prize awarded。 A few years later he was invited to
Osborne by the late Prince Albert; to discuss with his Royal
Highness the particulars of an equatorial mounting with a clock
movement; for which he subsequently received the order。 On its
completion he superintended the erection of the telescope; and
had the honour of directing it to several of the celestial
objects for the Queen and the Princess Alice; and answered their
many interesting questions as to the stars and planets within
sight。
Mr。 Cooke was put to his mettle towards the close of his life。 A
contest had long prevailed among telescope makers as to who
should turn out the largest refracting instrument。 The two
telescopes of fifteen inches aperture; prepared by Merz and
Mahler; of Munich; were the largest then in existence。 Their
size was thought quite extraordinary。 But in 1846; Mr。 Alvan
Clark; of Cambridgeport; Massachusetts; U。S。; spent his leisure
hour's in constructing small telescopes。'9' He was not an
optician; nor a mathematician; but a portrait painter。 He
possessed; however; enough knowledge of optics and of mechanics;
to enable him to make and judge a telescope。 He spent some ten
years in grinding lenses; and was at length enabled to produce
objectives equal in quality to any ever made。
In 1853; the Rev。 W。 E。 Dawesone of Mr。 Cooke's customers
purchased an object…glass from Mr。 Clark。 It was so satisfactory
that he ordered several others; and finally an entire telescope。
The American artist then began to be appreciated in his own
country。 In 1860 he received an order for a refractor of
eighteen inches aperture; three inches greater than the largest
which had up to that time been made。 This telescope was intended
for the Observatory of Mississippi; but the Civil War prevented
its being removed to the South; and the telescope was sold to the
Astronomical Society of Chicago and mounted in the Observatory of
that city。
And now comes in the rivalry of Mr。 Cooke of York; or rather of
his patron; Mr。 Newall of Gateshead。 At the Great Exhibition of
London; in 1862; two large circular blocks of glass; about two
inches thick and twenty…six inches in diameter; were shown by the
manufacturers; Messrs。 Chance of Birmingham。 These discs were
found to be of perfect quality; and suitable for object…glasses
of the best kind。 At the close of the Exhibition; they were
purchased by Mr。 Newall; and transferred to the workshops of
Messrs。 Cooke and Sons at York。 To grind and polish and mount
these discs was found a work of great labour and difficulty。 Mr。
Lockyer says; 〃such an achievement marks an epoch in telescopic
astronomy; and the skill of Mr。 Cooke and the munificence of Mr。
Newall will long be remembered。〃
When finished; the object…glass had an aperture of nearly
twenty…five inches; and was of much greater power than the
eighteen…inch Chicago instrument。 The length of the tube was
about thirty…two feet。 The cast…iron pillar supporting the whole
was nineteen feet in height from the ground; and the weight of
the whole instrument was about six tons。 In preparing this
telescope; nearly everything; from its extraordinary size; had to
be specially arranged。'10' The great anxiety involved in these
arrangements; and the constant study and application told heavily
upon Mr。 Cooke; and though the instrument wanted only a few
touches to make it complete; his health broke down; and he died
on the l9th of October; 1868; at the comparatively early age of
sixty…two。
Mr。 Cooke's death was felt; in a measure; to be a national loss。
His science and skill had restored to England the prominent
position she had held in the time of Dollond; and; had he lived;
even more might have been expected from him。 We believe that the
Gold Medal and Fellowship of the Royal Society were waiting for
him; but; as one of his friends said to his widow; 〃neither worth
nor talent avails when the great ordeal is presented to us。〃 In
a letter from Professor Pritchard; he said: 〃Your husband has
left his mark upon his age。 No optician of modern times has
gained a higher reputation; and I for one do not hesitate to call
h