ON THE SOLAR ECLIPSE OT DEC. 12, 1871. 327 



The accompanying Table (p. 326) is merely intended as an attempt roughly 

 to indicate (according to our present knowledge of the earliest appearance in 

 time of the several orders of Crustacea) the most probable manner in which the 

 various groups were evolved from a common pre-Cambrian parent-stock. I 

 have specially distinguished those which are merely persistent types, but 

 incapable of modification, from those which were capable both of persistence 

 and modification ; and these again from the inadaptive types which have died 

 out. The aberrant and highly speciahzed parasitic types appear last in time, 

 and mark the culminating point of the Crustacea when conditions prevailed 

 more highly favourable to the class than at any earlier period. 



Report of the Committee appointed to organize an Expedition for 

 observing the Solar Eclipse of Dec. \2, 1871. 



At their Meeting in Edinburgh in August last, the General Committee of the 

 British Association for the Advancement of Science having had under their 

 consideration the great importance of observing the ecUpse of 12th of De- 

 cember, 1871, authorized their President, Sir W. Thomson, E.E.S., to bring 

 the matter to the notice of the Treasury, which he did in a letter dated 9th 

 August, 1871, stating fully how desirable it was in the interest of science 

 that advantage should be taken of this opportunity to advance solar physics, 

 and explaining in general terms the best methods of carrying them out. 



It was suggested in the President's letter that Mr. J. Norman Lockyer, 

 F.R.S., who had long devoted himself to spectroscopic investigations, should 

 form a member of the expedition. 



The President was authorized by Sir E. Sabine, K.C.B., President of the 

 Eoyal Society, and Mr. Lassell, President of the Eoyal Astronomical Society, 

 to state to the Treasury their cordial concurrence in the request of the 

 British Association. 



A most prompt reply was received to their communication, the Treasury, 

 by a letter dated 16th August, 1871, acceding at once to the request of the 

 President, and granting a sum not exceeding £2000 for the purpose. 



In the hope of a favourable reply being received from the Treasury, the 

 General Committee had, by a resolution at their last Meeting in Edinburgh, 

 authorized the General Officers to take such steps as they might deem advisable 

 as soon as possible after the receipt of the Treasury letter. The General 

 Officers held a meeting on the 22nd of August; and having in the first 

 instance requested Mr. Norman Lockyer, F.E.S., to join them in consulta- 

 tion, they resolved to appoint a Committee to direct all the necessary 

 arrangements. 



To this Committee, as originally constitiited, additional members were from 

 time to time added. It now consists of the following names : — The President 

 and General Officers of the Association, Prof. J. C. Adams, Sir G. B. Airy 

 (Astronomer Eoyal), Prof. Clifton, Mr. De La Rue, Dr. Frankland, Mr. Hind, 

 Mr. .Lassell (President E.A.S.), Lord Lindsay, Mr. Lockyer, General Sabine, 

 General Strachey, Colonel Strange, and Prof. Stokes. 



The Treasury having been good enough to address the Admiralty and the 

 War Office requesting their cooperation, the Committee entered into com- 



