A high-school astronomy: in which the descriptive, physical, and practical are combined .. (1859)
Mattison, Hiram, 1811-1868 · New York, Mason brothers · leaf 238
aced. 535. The first telescope constructed upon this plan wasthat by Sir William Herschel, in 1782. This was calledhis 20 feet reflector, and was the instrument with whichhe made many of his observations upon the double stars.In 1789, he completed his forty feet reflector, untilrecently the largest… … SIR WILLIAM HERSCHELS FORTY FEET REFLECTOR. 536. The speculum of this instrument is 4 feet indiameter, 3^ inches thick, and weighed, before beingground, 2,118 pounds. The tube is made of sheet ironriveted together, and painted within and without. The length of the tube is 39 feet 4 inches, and its…
Astronomy
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