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Ordinary Meeting, March 5th, 1861. 

 Dr. Joule, President; in the Chair. 



Mr. Joseph Sidebotham read a Paper " On the Structure 

 of the Luminous Eiwelope of the Sun," being a communication 

 to him from James Nasmyth, Esq., of Penshurst. 



Mr. Nasmyth has made the discovery, that the entire 

 surface of the sun is composed of objects of the shape of a 

 willow leaf; these objects average about 1,000 miles in length, 

 and 100 in breadth, and cross each other in all directions, 

 forming a network ; the thickness of this does not appear to 

 be very great, as through the interstices the dark or penumbral 

 stratum is seen, and it is this which gives to the sun that peculiar 

 mottled appearance so familiar to observers. These willow 

 leaf-shaped objects are best seen at the edges of a solar ' spot 

 where they appear luminous, on a dark ground, and also com- 

 pose the bridges which are formed across a spot ' when it is 

 mending up ; the only approach to symmetrical arrangement 

 is in the filaments bordering the spot, and those composing 

 the penumbra, which appears to be a true secondary stratum 

 of the sun's luminous atmosphere ; here these bodies show a 

 tendency to a radial arrangement. Although carefully 

 watched for, no trace of a spiral or vortical arrangement has 

 been observed in these filaments; thus setting aside the 

 likelihood of any whirlwind-like action being an agent in the 

 formation of the spots, as has been conjectured to be the case. 

 The writer does not feel warranted at present in hazarding 

 any conjectures as to the nature and functions of these 

 remarkable willow leaf-shaped objects, but intends pursuing 

 the investigation of the subject this summer, and hopes to lay 

 the results before the British Association during their meeting 

 in this city. The Paper was illustrated by three beautiful 

 drawings. No. 1 represented one of the willow leaf-shaped 

 objects ; No. 2 the luminous surface of the sun as being entirely 

 Proceedings— Lit. & Phil. Society— No. 11.— Session, 1860-61. 



