PROPHECY OF HERSCHEL in 



He conceived the idea of a 40-feet reflector, with a 

 4-feet mirror at the bottom of the tube, cast and 

 polished by himself. His own account of the begin- 

 ning of this magnificent work is this : " In the year 

 1783 I finished a very good 20-feet reflector with a 

 large aperture, and mounted it upon the plan of my 

 present telescope. After two years' observation with 

 it, the great advantage of such apertures appeared so 

 clearly to me, that I recurred to my former intention 

 of increasing them still farther ; and being now suffi- 

 ciently provided with experience in the work I wished 

 to undertake, the President of our Royal Society, who 

 is always ready to promote useful undertakings, had 

 the goodness to lay my design before the King. His 

 Majesty was graciously pleased to approve of it, and 

 with his usual liberality to support it with his Royal 

 bounty." There is this to be said on the departure 

 now made, that the great telescope, from the difficulty 

 of handling it. cannot be considered to have altogether 

 answered his expectations, for the 20-feet continued 

 to be his favourite in studying the heavens. But he 

 was full of hope. " By applying ourselves," he wrote 

 in April 1784, " with all our powers to the improve- 

 ment of telescopes, which I look upon as yet in their 

 infant state, and turning them with assiduity to the 

 study of the heavens, we shall in time obtain some faint 

 knowledge of, and perhaps be able partly to delineate, 

 The Interior Construction of the Universe!' 



Herschel himself devised and superintended every- 

 thing about this great telescope. None but " common 

 workmen " were employed, as was also the case with 

 the greater reflector built by Lord Rosse, sixty years 

 later. The woodwork of the stand, and machines for 



