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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

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