134 WATSON. 



Mr. Troughton's larger works, such as his equatorial instruments, 

 circles, transits, &c., are as well known in the astronomical world 

 as those of Wren in the architectural ; they are too numerous to 

 mention here, and are distributed in various parts of the world. 

 The gigantic zenith tube at Greenwich was about the last work on 

 which he was engaged, and he had just time to finish it before his 

 strength failed. The only astronomical instrument which is not 

 greatly indebted to Mr. Troughton is the telescope, and he was de- 

 terred from making any attempt in this branch of his art by the 

 curious physical defect of colour blindness, which existed in many 

 members of his family. Like Dalton he could not distinguish 

 colours, and had little idea of them, except generally as they con- 

 veyed the impression of greater or less light. The ripe cherry and 

 its leaf were to him of one hue, only to be distinguished by their 

 form. With this defect in his vision he never attempted any expe- 

 riments in which colour was concerned ; and it is difficult to see 

 how he could have done so with success. 



The most remarkable of Troughton's writings are, ' An account 

 of a method of dividing astronomical and other instruments by 

 ocular inspection,' &c. Phil. Trans., 1809, which was awarded with 

 the Copley medal ; ' A comparison of the repeating circle of Borda, 

 with the altitude and Azimuth Circle ' Memoirs E. Ast. Soc. ; and 

 several articles in Brewster's ' Edinburgh Cyclopedia,' such as 

 * Circle,' ' Graduations,' &c. 



In the year 1825 Mr. Troughton paid a visit to Paris, and in 1830 

 he received an honorary gold medal from the King of Denmark. 

 During the latter portion of his life he became almost entirely deaf, 

 only hearing by the aid of a powerful trumpet. He died at his 

 house in Fleet Street, June 12, 1835, in the eighty-second year of 

 his age, and was buried at the Cemetery, Kensal Green. Me 

 Notices of the Royal Astronomical Society, vol. 3, February, 1836. 



RICHARD WATSON, BISHOP OF LLANDAFF, 

 D.D., F.R.S., &c. 



Born August, 1737. Died June 4, 1816. 



Eichard Watson, celebrated both as an able theologian, and as a 

 professor of chemistry, was born at Haversham, near Kendal in 

 Westmoreland. His ancestors had been farmers of their own estates 

 for several generations, and his father, a younger son, was for forty 

 years the head master of the Grammar-school at Haversham, but 



