598 BIBLIOGRAPHY OF HEKSCHEL's WRITINGS. 



Herschel, W.: Synopsis of the Writixgs of— Continiied. 



A. n. Vol. p. 



1812 102 113 Tlte apparent and real Magnitude of the Planetary Bodij. I call its ap- 

 parent diameter 0".775 ; that is, its real diameter was about 428 

 miles. 



118 The EccentricUii and Color of the planetary Body. 

 The jilanetary body was eccentric in the head. 



119 The color was of a pale ruddy tint like that of such equally small 



stars as are inclined to red. 

 119 The Illumination of the Planetary Body. 



We may infer [from observations] that it was visible by rays emitted 

 from its own body. 



119 The Read of the Comet. 



120 [Descrii^tion of the head.] 



120 The Color and Eccentricity of the Head. 



The color in everyone of my telescopes was greenish or bluish green. 



121 The head was eccentric ; it deviated towards the sun. 



121 The Apparent and Real Magnitudes of the Head. 



The real diameter of the head was about 127,000 miles. 



122 A Transparent and Elastic Atmosphere about the Head. 



I saw stars through it ; it was thus transparent. Its elasticity may 

 be inferred from its circular form. 

 122 The extenc of the Cometic Atmosphere. 



It was more than 507,000 miles in diameter; its real extent far ex- 

 ceeds this. 



122 The Bright Envelope of the Cometic Atmosphere. 



123 The Figure, Color, and Magnitude of the Atmosphere. 



Its shai)e was circular; it reached nearly half way round the head 

 of the comet, and divided into two streams, one on each side of 

 the head. The color had a strong yellowish cast. Its real diame- 

 ter must have exceeded 643,000 miles. 



123 The Tail of the Comet. It was, Oct. 15, 23^° long. 



124 The greatest real length of the Tail. 



It must have been upwards of 100,000,000 miles. 



124 The Breadth of the Tail. It was, Oct. 12, nearly 15,000,000 miles. 



125 The Curvature of the Tail. 

 This was subject to variations. 



125 The general appearance of the Tail. 



126 The tail had two branches. [See observations.] November 9 the 



tail of the comet being near the Milky Way, the appearance of one 

 compared to the other was perfectly alike. 



127 Tlie return of the Comet to the Nebulous Appearance. 



As the comet went further from the earth I had reason to suppose 

 that all the still visible phenomena of body, head, atmosphere, 

 envelope, and tail would soon be reduced to the semblance of a 

 common globular nebula. And this, not only from its increasing 

 distance but by the actual physical changes which I observed in 

 the construction of the comet. 



127 The gradual vanishing of the Planetary Body. 



128 The disappearance of the transparent part of the Atmosphere under the 



cover of the scattered light of the contracted Envelope. 



129 Uncommon Appearances in the Dissolution of the Envelope. 

 One, two, and three streams seen in it at different times. 



130 Uncommon Variations in the Length of the Streams. 



131 Alterations in the Angle of the Direction of the Envelope. 



