British Association. 389 



his meritorious career by obtaining a First Class at this University 

 and has, as you know, spent large sums of money and displayed 

 considerable mechanical genius in erecting, near his own castle 

 in Ireland, an instrument of far greater power than any other in 

 the world ; and with it he has observed these nebulae, and em- 

 ployed skilful artists to delineate their forms : and he has more- 

 over made the very curious discovery, that some of them are ar- 

 ranged in a spiral form, a fact which gives rise to much inter- 

 esting speculation on the kind of forces by which their parts are 

 held together. It were much to be wished that observations sim- 

 ilar to these, and with instruments of nearly the same power, should 

 be made of the Southern nebulae also ; that this generation might 

 be able to leave to posterity a record of their present configur- 

 ations. The distinguished Astronomer, Mr. W. Lassell, the dis- 

 coverer of Neptune's satellite, has just finished at his own cost, 

 an instrument equal to the task, mounted equatorial ly ; and I am 

 not without hope that it may, at perhaps no very distant 

 period, be devoted to its accomplishment. A recent communi- 

 cation from him to the Astronomical Society expresses satisfaction 

 with the mounting of his instrument, and after many trials its 

 great speculum has at last come forth nearly perfect from his la- 

 boratory. 



Comets, 



Of all the phenomena of the heavens, there are none which ex- 

 cite more general interest than comets — those vagrant strangers, 

 the gipsies as they have been termed of our solar system, 

 which often come we know not whence, and at periods when we 

 least expect them : and such is the eftect produced by the strange- 

 ness and suddenness of their appearance, and the mysterious nature 

 of some of the facts connected with them, that while in ignorant 

 times they excite alarm, they now sometimes seduce men to leave 

 other employments and become astronomers. Now, though 

 the larger and brighter comets naturally excite most general pub- 

 lic interest, and are really valuable to astronomers, as exhibiting 

 appearances which tend to throw light on the internal structure 

 of these bodies, and the nature of the forces which must be in 

 operation to produce the extraordinary phenomena observed, yet 

 some of the smaller telescopic comets are, perhaps, more interest- 

 ing in a physical point of view. Thus the six periodical comets, 

 the orbits of which have been determined with tolerable accuracy, 



