NOTICES AND ABSTRACTS 



OF 



MISCELLANEOUS COMMUNICATIONS TO THE SECTIONS. 



MATHEMATICS AND PHYSICS. 



Address of W. Spottiswoode, F.R.S., President of the Section. 



The great range of subjects comprised in this section, and the multiplicity of papers 

 submitted to it, have doubtless contributed to deter my predecessors in this chair 

 from preparing addresses so elaborate and comprehensive as those delivered to other 

 sections. The custom, however, of prefacing the business proper by a short sum- 

 mary of subjects which have engaged the attention of philosophers during the past 

 year, and which may therefore be expected to come before us during our present 

 sittings, appears to be sanctioned by the wishes of our members, and may perhaps 

 be followed without materially departing from that brevity which is here both 

 customary and desirable. Foremost among the astronomical subjects in which we 

 may hope to receive communications are the researches of Messrs. Be la Rue, 

 Stewart, and Loewy, in solar physics. Without attempting to anticipate what they 

 may have to state, it may be as well to remind the section that it seems now to be 

 established that solar spots are at a lower level than the penumbrre, the facuhe at a 

 higher ; that the photosphere is gaseous ; and that the behaviour of the spots, as to 

 appearance and disappearance, is connected with the position of the planets, and 

 principally with that of Venus. The objection to this view of the nature of sun- 

 spots which has been raised on the ground of the unbroken curvature of the sun's 

 limb, notwithstanding the elevation of the faculre and depression of the spots, has 

 been answered by Professor Phillips in a paper read before the Royal Society. That 

 the central mass is of less brilliancy than the photosphere is also ascertained ; but 

 whether this arises from solid matter at a lower temperature, or otherwise, is still a 

 question. M. Faye, in an elaborate memoir presented to the French Academy, 

 suggests that it may consist of transparent gas. 



The moon continues to be the subject ot careful investigation, both theoretical 

 and observational. M. Delaunay explains that the delay in completing the second 

 part of his lunar theory arises from his having to carry his developments beyond 

 the order originally contemplated, viz. the seventh — in some cases as far as the 

 ninth. M. Allegret states that the terms involving the cube of the time became im- 

 portant when determining the secular variations. Under this head mention must 

 not be omitted of Professor Cayley's valuable contributions to the lunar theory. 



The Lunar Committee of this Association have been most actively engaged 

 during the past year, and will state the results of their labours in their report. 



The planet Mars has been the object of much telescopic research on the part of 

 our President, Messrs. Dawes, Lockyer, and others. The supposition that the 



1865. 1 



