100 ' THE HISTORY OF THE TELESCOPE. 



1723, which was found to be e(j[ual to the Huygheus refractor of 123 

 feet in length. From this time we may date the l)eginuiug of the 

 superiority of reflectors, A few years kiter Short commenced his 

 career as a practical optician, and for thirty years he was unapi)roached 

 in the excellence of his instruments. During this time many telescopes, 

 more powerful than the best of the previous century and infinitely more 

 convenient in use, had been made and scattered throughout Europe, 

 but during this period also there was a singular dearth of telescopic 

 discovery. Perhaps men thought that the harvest had already been 

 gathered ; or, perhaps, we may find the explanation in that the great 

 cost of telescopes so restricted their use that the impulse to discovery 

 by their means was confined to a very small class. In view of the 

 remarkable manner in which the standstill in this branch of science 

 was finally followed by a brilliant period of discovery, rivalled alone 

 by that of Galileo, we might well regard the latter cause as the chief 

 one. 



William Ilerschel was born in 1738 in Hanover. In 1755 he left his 

 native country, and going to England, secured a i)osition as organist 

 in Octagon Chapel, Bath, where we find him in 1700. Here he became 

 so profoundly interested in the views of the heavens which a borrowed 

 telescope of moderate power yielded, that he tried to purchase one in 

 London. The cost of a satisfactory instrument proving beyond his 

 command, he determined to construct one with his own hands. Thus 

 he entered upon a course which was to reflect honor upon himself, his 

 country, and his age, and which was to add more to physical astronomy 

 than any other one man has added before or since. With almost 

 inconceivable industry and perseverance he cast, ground, and polished 

 more than four hundred mirrors for telescopes, varying in diameter 

 from 6 to 48 inches. This in itself would imply a busy life in any arti- 

 san, but when we remember that all this was merely subsidiary to his 

 main work of astronomical discovery, we can not withhold our admira- 

 tion. 



Fortunately for science as well as for himself, he made early in his 

 career a discovery of the xevy first importance which attached the at- 

 tention of all Christendom. On the night of March 13, 1781, Herschel 

 was examining small stars in the constellation of Gemini with one of 

 his telescopes of a little more than G inches in diameter, when he per- 

 ceived one that ai)peared "visibly larger than the rest." This proved 

 to be a new world, now known as Uranus. The discovery led in the 

 following year to his ai>pointment as astronomer to the king, George 

 III, with a salary sufficient to enable him to devote his whole time to 

 astronomy. 



One of the fruits of this increased leisure was the construction of a 

 telescope far more powerful than had been dreamed of by his prede- 

 cessors, namely, a telescope 4 feet in diameter and 40 feet in length. 

 Commenced in 1785, Herschel dated its completion as August 28, 1789, 



