i jz Mr. herschel’s Defcription of a Lamp-Micrometer 
with 460 : therefore, without laying much ftrefs upon the 
exaftnefs of the obfervation, I (hall only report it to exemplify 
the ufe of the micrometer. My radius was ^5 feet 1 1 inches. 
The diameter of the ftar, by the diftance of the lucid points, 
was 2,4 inches, and the power I ufed 227 : hence the magni- 
fied angle is found 19', and the real diameter of the ftar 
5'', 02 2. The fcale of this meafure ,474 m-illefimals of an 
inch, or almoft half an inch to a fecond. 
