THE ENGLISH OBSERVATORIES. 



535 



Herschel died at Hanover, her native city, in 1849, at the age of 

 ninety-eight. Sir John Herschel, the only son of the great astronomer, 

 worthily continued these illustrious traditions. He resumed and com- 

 pleted the exploration of the heavens commenced by his father, at first 

 at Slough, then at the Cape of Good Hope, where he transported a 

 telescope of twenty feet. He died in 1871, after having contributed, 

 by labors of the highest order, to the progress of science. One of his 

 sons, Alexander Herschel, is equally devoted to astronomical pursuits. 



The gigantic telescope of Lord Rosse, which was finished in 1845, 

 the same year when the noble lord was elected representative peer of 

 Ireland, is fifty-five feet in length, and has six feet of aperture. The 

 mirror weighs over four tons, the tube seven tons, and the total weight 

 exceeds eleven tons. The Leviathan, as this giant telescope is called, 

 is suspended between two stone walls at Birr Castle, the hereditary 

 residence of Lord Rosse, in King's County, Ireland. When, in 1826, 

 the young Lord Oxmantown the title that he then bore turned his 

 attention toward practical astronomy, there was no constructor capa- 

 ble of furnishing instruments such as he desired. William Herschel 

 had kept the secret of the alloy he used for his mirrors, and the pro- 

 cess by which he constructed them. James Short, the greatest con- 

 structor of the eighteenth century, so skillful in casting and polishing 

 mirrors, had burned and destroyed before his death his whole stock 

 of tools, in order to remain without a rival. Every thing was then to 

 be discovered anew, and it took Lord Rosse twenty years before he 

 attained the construction of a mirror by means of which he could 

 sound the depths of space and resolve into a mass of stars the most 

 of the nebulae toward which he directed his gigantic instrument. All 

 the nebulas, however, are not resolvable ; some of them are decidedly 

 agglomerations of cosmical matter not yet condensed. Lord Rosse 

 was the first to demonstrate that the great nebula of Orion, one of the 

 finest in the heavens that belongs to the last category, has within a 

 few years changed its appearance in consequence of the concentration 

 of the matter of which it is formed. This celebrated observer died in 

 1867 ; his son worthily continues the labors commenced by the father 

 with such brilliant success. 



Lord Rosse preferred mirrors to objectives, on account of the diffi- 

 culty that attends the manufacture of objectives of large dimensions. 

 But great improvements have since been made; Mr. Clark, an Ameri- 

 can, constructed in 1862 a powerful instrument, with an object-glass 

 of eighteen and a half inches of aperture. Messrs. Cooke & Son, cele- 

 brated constructors of York, finished in 1868 an equatorial of twenty- 

 five inches of aperture, and twenty-nine feet of focal length. The 

 telescope of this gigantic apparatus is mounted on an iron column 350 

 feet high, and weighs nearly ten tons. This equatorial was constructed 

 for Mr. Newall, proprietor of the submarine cable-works at Gateshead, 

 near Newcastle ; it is destined for the island of Madeira, where it will 



