264. Mr. Herschel on the 



fouth preceding the fame ftar ; very exa£l, and by the fame 

 kind of illumination. Od. 17, 1783, Diilance 6' 55^'' 7'^' ; 

 a fecond meafure 6'' 56^^ ii^^^ as exacl: as pofTible. Od. 23, 

 1783, l^olition 42^ 57^ ; a fecond meafure 42° 45' ; fingle lens ; 

 power '^'i; opaque-microfcopic-illumination. Nov. 14, 1783, 

 Diftance 7' 4^' 35^'^ Nov. 12, 1784, DilTiance 7' 22'' 35^''" ; 

 Pofition 38^ 39^ Its diameter is about loor 15^''. I haveexa- 

 mined it with the powers of 71, 227, 278, 460, and 932 ; 

 and it follows the lav\^s of magnifying, fo that its hody is no 

 illuiion of light. It is a little oval, and in the 7-feet refle6lor 

 pretty well defined, but not fl'iarp on the edges. In the 20 -feet, 

 of 18,7 Inch, aperture, it is much better defined, and has much 

 of a planetary appearance, being all over of an uniform bright- 

 nefs, in which it differs from nebulae : its light fecms however 

 to be of tiie ftarry nature, which fuffers not nearly fo much as 

 the planetary difks are known to do, when much magnified. 



T'he fecond of thefe bodies precedes the 13th of Flam- 

 steed's Andromeda about 1^6 in time, and is 22^ more fouth. 

 It has a round, bright, pretty well defined planetary difk of 

 about \2^^ diameter, and is a little elliptical. When it is viewed 

 with a 7-feet refle6i:or, or other inferior inftruments, it is not 

 nearly fo well defined as with the 20-feet. Its fituation with 

 regard to a pretty confiderable ftar is, Diflance (with a com- 

 pound glafs of a low power) f 51'^ 34^^^ Pofition i2°o^ f. 

 preceding. Diameter taken with 278, 14^^ 42''''''. 



The third follows B (Fl. 44.) Ophiuchi 4^,1 in time, and 

 is 23^ more north. It is round, tolerably well defined, and 

 pretty bright ; its diameter is about 30^^ 



piece, that may throw it back upon the wires. By this means none of the direft 

 rays can reach the eye, and thofe iew which are refleded again from the wires do 

 not interfere fenfibly with the fainteft objects, which may thus be fecn undif- 

 turbed. 



The 



