38 REPORT — 1 884. 



these two sets of tidal curves has progressed satisfactorily, and will be 

 shortly completed. 



It is hoped also that a like reduction will be soon commenced with 

 other self-registering tidal cnrves during the same period at several other 

 points, both on the English and the French coasts. 



The Committee request to be allowed to transmit to the Board of 

 Trade, and to the Belgian Government respectively, the thanks of the 

 Association for their assistance and donations in furtherance of this 

 inquiry. 



The Committee request to be reappointed, with a grant of ten pounds 

 to defray the expenses of reduction, &c. 



Fourth Report of the Committee, consisting of Professor Schuster 

 (Secretary), Sir William Thomson, Professor Sir H. E. Eoscoe, 

 Professor A. S Herschel, Captain W. de W. Abney, Mr. K. H. 

 Scott, and Dr. J. H. Gladstone, appointed for the purpose of 

 investigating the practicability of collecting and identifying 

 Meteoric Dust, and of considering the question of undertaking 

 regular observations in various localities. 



During the past year a grant of 20Z. has been spent in constructing a 

 new instrument for collecting continuously any cosmic dust, volcanic 

 dust, or other impurities mechanically suspended in the atmosphere. The 

 essential part of the instrument consists in a series of filters of fine 

 platinum wires through which the air is continuously drawn by an 

 aspirator. 



This instrument is being experimented with at the Marine Station for 

 Scientific Research at Grantou, and a complete description of the instru- 

 ment and dust collected will be given in next year's Report. Large 

 carboys furnished with glass filters, fourteen inches in diameter, have been 

 arranged for collecting the dust carried down by rain on the top of Ben 

 Nevis, Lord MacLaren's residence in Rossshire, Inch Mickry in the Firth 

 of Forth, and at the Scottish Marine Station. 



The dust from these different points and elevations will be carefully 

 compared with that collected by the new instrument, by Messrs. Murray 

 and Renard and by members of the Committee. 



A full report will be furnished to the next meeting. 



^he Committee also consider it to be of great importance to collect 

 dust on the island of Bermuda and on another coral island in the Pacific, 

 say Longalubon, and hope to obtain a sufficient grant of money to enable 

 them to carry out their intention. 



