Proceedings of the British Association, 151 



their internal motions if any, the number of strata which may be 

 detected, and the number and direction of the currents which 

 their motion may indicate, will also form interesting objects of 

 observation in conjunction with the preceding. Cotemporaneous 

 observations will of course be made on the earth, during the time 

 of the aerostatic voyage, which will possess a greatly increased 

 interest if circumstances shall permit it to take place on the day 

 when hourly meteorological observations are made at all the prin- 

 cipal observatories of Europe, according to the plan laid down by 

 Sir J. Herschel, Portions of the air should be brought down, 

 for examination, from the highest elevations ; and this may prob- 

 ably be best effected by taking up several glass balloons or bottles 

 carefully gauged, fitted with stop-cocks, and filled with water. 

 The water should be allowed to run out at the proper station, and 

 the stop-cocks closed. Experiments upon the radiation of heat 

 would be interesting, although there are probably no known 

 means of instituting them with all the accuracy which could be 

 desired. To these observations might be added, others of great 

 interest upon the electricity of the atmosphere, by dropping wires 

 into clouds, or from stratum to stratum of cloudless air, and ex- 

 amining the nature of the electricity of their extremity by means 

 of a very delicate electroscope, but the observer's attention must 

 not be distracted by a great variety of objects. It would be de- 

 sirable that two observers, stationed at the extremities of an accu- 

 rately measured base, should take the altitudes of the balloon, at 

 the instants the observations of pressure and temperature were 

 made. 



The committee, of which Sir J. Herschel is chairman, for su- 

 perintending 4he scientific cooperation of the British Association 

 in the system of simultaneous observations in Terrestrial Mag- 

 netism and Meteorology, made a report, of which the following 

 is the principal part : 



Your committee, referring to their last report for the history of 

 the magnetic operations in progress up to that time, have to state, 

 in continuation, that the magnetic observatory at St. Helena was 

 finished, and the instruments established in August, 1840, — at 

 Toronto in September, and at Van Diemen's Land in October of 

 the same year. The observatory at the Cape of Good Hope was 

 completed and in activity at the commencement of March in the 

 current year, under the superintendence of Lieut. Eardley Wil- 



