308 Notices respecting New Booh. 



oblique to the direction of the parallels of latitude on the sun's sur- 

 face, and converging on both sides of the equator to the preceding 

 side of the disc. Penumbra? of great spots also were sometimes 

 observed to be rounded and well-terminated on the preceding side, 

 but rugged and extensively diffused on the following, where they 

 would often take the form of great trains, and ultimately affect the 

 form of pretty long, straight parallel bands, having the same obli- 

 quity to the parallels of latitude as the lines and spots above-men- 

 tioned. Sir John is of opinion that these bands and lines, having a 

 transverse direction to the course of the currents which the dyna- 

 mical theory supposes, " must be assimilated rather to ripple-marks 

 which are transverse to the direction of the general movement in 

 which they have their origin than to trails drawn out by a current 

 in its own direction, if indeed the appearances in question be any- 

 thing more than accidental." 



A very remarkable character of the solar spots is the intense 

 blackness of the spot " nucleus," or " opening," as it has been termed, 

 as contrasted with the penumbra or " shallow " surrounding it. 

 " This want of graduation — this sharply marked suddenness of trans- 

 ition, is altogether opposed to the conception of a susceptibility of 

 indefinite and easy mixture in the luminous, non-luminous, and 



semi-luminous constituents of the solar envelope There is no 



gradual melting of the one shade into the other — spot into penumbra 

 — penumbra into full light. The idea conveyed is more that of the 

 successive withdrawal of veils, — the partial removal of definite films, 

 than the melting away of a mist, or the mutual dilution of gaseous 

 media. Films of immiscible liquids having a certain cohesion, float- 

 ing on a dark or transparent ocean and liable to temporary removal 

 by winds, would rather seem suggested by the general tenour of the 

 appearances, though they are far from being wholly explicable by 

 this conception, at least if any considerable degree of transparency 

 be allowed to the luminous matter." — P. 436. 



The chapter concludes with the remark, that during the months 

 embraced by the observations the state of the sun seemed evidently 

 undergoing a gradual alteration in the nature of a subsidence from 

 violent agitation to comparative tranquillity. 



There are five appendices to the work, the contents of which are 

 as follows : — 



A. " On the numerical magnitudes of certain stars, as obtained by 

 subsequent observation on the principle of sequences, in the northern 

 hemisphere, compared and combined with the same stars as observed 

 in the southern ; and of some others whose places in the scale of 

 magnitudes are directly deducible from these by interpolation of the 

 sequences." 



B. " On the difference of level between the Royal Observatory, 

 Cape of Good Hope, and Feldhausen." The result is 1 12*23 feet 

 for the difference of level between the cisterns of the barometers, that 

 at Feldhausen being the higher. 



C. " On the temperature required by the surface-soil under ex- 

 posure to clear sunshine, and some other effects of accumulated 



