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 9.9inches, 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."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. Acontest 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.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. Dawes--one 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.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.
