Existence of an Atmosphere surrounding the Sun. 447 

 Table I. {h=l). 



As a first series of observations for discussion, I have selected 

 that of a small and well-defined spot observed in August and 

 September 1854, under favourable circumstances, which m both 

 its passages over the disc passed very near to the centre, and 

 which, from August 8 to August 20, exhibited no marked devia- 

 tion of its nucleus from a circular form. On its second appear- 

 ance, it formed one of a small group ; and after September 10 

 ceased to be distinguishable. In the Table which follows are 

 given in the first column the fractions of the days of observation 

 (in civil reckoning) ; in the second and third, p the angles of po- 

 sition and p the angles from centre of apparent photosphere ; 

 in the fourth and fifth / and X the hehographical longitudes 

 (fi-om node) and latitudes, deduced from the elements (for 1854-0) 

 N = 74° 30', 1 = 7° 10', as adopted provisionally at Redhill. 



From comparison of the longitudes of the two passages at and 

 about the dates at which the spot passed the centre, it was found 

 that 25'i-240 was the period of sidereal rotation for this spot. 

 This value has accordingly been used in computing the dates in 

 the sixth and last column, which are those of the spot's passing 

 the meridian through node given by each day's observation. 



