

The Planets of the Month — Occultations. 455 



is the same, and the acme of perfection is always accidental, 

 and not to be attained with undeviating certainty by any 

 rules f but still there are considerations which lead us to 

 think that some rules may be more conducive than others 

 to the attainment of that accidental perfection. After all, the 

 perfection of which we speak is, like all other earthly excel- 

 lence, only comparative ; an inherent peculiarity in the con- 

 stitution of light, as consisting of successive vibrations inca- 

 pable of being collected without mutual interference, must for 

 ever bar our advance beyond a certain boundary. Airy has 

 taught us that under the most favourable circumstances " the 

 image of a star will not be a point, but a bright circle, 

 surrounded by a series of bright rings." Only, therefore, 

 so long as the magnifying power is insufficient to render 

 this phenomenon visible, a limit which of course varies with 

 the size of the telescope, can the focal image assume the 

 deceptive appearance of perfection. And this is equally 

 true, whatever construction of instrument, reflecting or re- 

 fracting, may be employed. 



THE PLANETS OF THE MONTH. 



Maes is now rapidly leaving us. His diameter, 13"'2 at the 

 beginning of the month, will be only 9"'6 at its close, while 

 in opposition it was 16"'6. During the most favourable posi- 

 tion there was fortunately much clear sky, and definition has 

 been more sharp, for the most part, than in 1862 ; and the 

 evidence is quite satisfactory, both as to the general per- 

 manency and occasional variation of the spots. 



Uranus may be recognized at present with great ease, from 

 his position about 3° p 35 M, the cluster near Propus, No. 8 of 

 our list (Intellectual Observer, Feb. 1864, p. 54) ; somewhat 

 s, however, of its centre. He is still nearer the star Propus 

 itself, bearing np from it. - He may readily be distinguished 

 with a moderate power from the neighbouring stars by his 

 visible diameter (4'' - 2) and his soft, tranquil, planetary light. 

 I see the minute disc even with 65, but of course better with 

 higher magnifiers. 



OCCULTATIONS. 

 The Moon will pass over several considerable stars during 

 the present month at convenient hours. January 4th, e 

 Piscium, 4 mag., will be concealed from 5h. 53m. till 6h. 59m. 

 — 6th. a- Arietis, 6 mag., from 4h. 44m. till 5h. 51m. — 8th. 

 B. A. C, 1468, 6 mag., from 5h. 47m. till 6h. 37m.— i Tauri, 

 5| mag., from 8h. 45m. till 9h. 24m. — 31st. 60 Piscium, 6 mag., 

 from 6h. lm. to 6h. 52m. 



