MIRRORS FOR TELESCOPES MADE 37 



" At Bath in my leisure hours," he says, " by way of 

 amusement, I made for myself several 2-feet, 5-feet, 

 7-feet, 10-feet, and 20-feet Newtonian telescopes; 

 besides others of the Gregorian form of 8 inches, 

 12 inches, 18 inches, 2 feet, 3 feet, 5 feet, and 10 feet 

 focal length. My way was ... to have many mirrors 

 of each sort cast ; and to finish them all as well as I 

 could ; then to select by trial the best of them, which 

 I preserved ; the rest were put by to be repolished. In 

 this manner I made not less than 200, 7-feet; 150, 

 10-feet ; and about 80, 20-feet mirrors, not to mention 

 those of the Gregorian form, or of the construction of 

 Dr. Smith's reflecting microscope, of which I also made 

 a great number. . . . The number of stands I invented 

 for these telescopes it would not be easy to assign." * 

 The story he tells of this magnificent " amusement," if 

 less racy than his sister's, is far more wonderful. Could 

 these mirrors have been sold at the prices then ruling 

 the market, a large fortune would have rewarded the 

 maker, as it ultimately did. 



In June 1773 the new departure of Herschel com- 

 menced. Some of his pupils had left Bath ; concerts, 

 oratorios, and the theatre were at an end for five or 

 six months. " To my sorrow," his sister writes, " I saw 

 almost every room turned into a workshop." A 

 cabinetmaker was making a tube and stands of all 

 kinds in the drawing-room; her brother Alexander 

 was "turning patterns, grinding glasses, and turning 

 eye-pieces " in a bedroom ; and while this manufactory 

 was in its busiest whirl, William Herschel was besides 

 composing glees, catches, anthems for winter consump- 

 tion in the public rooms and the chapel, or holding 



1 Phil. Trans., 1795, pp. 347-48. 



