to the Antarctic Regions. 187 



shortly after the establishment of the Van Diemen's Land observatory. 

 The observations there will have especial interest, since, taken in con- 

 junction with those simultaneously making in Van Diemen's Land, 

 they will decide the important question, how far that exact cor- 

 respondence of the momentary magnetic perturbations which has 

 been observed in Europe, obtains in so remote a region, between 

 places separated by a distance equal to that between the most widely 

 distant European stations. 



In the interval between quitting Van Diemen's Land and return- 

 ing to it again, opportunities will no doubt occur of performing 

 more than one other series of magnetometer observations, the lo- 

 cality of which may be conveniently left to the judgement of Cap- 

 tain Ross, bearing in mind the advantage of observing at stations 

 as remote as possible from both Van Diemen's Land and New Zea- 

 land. 



The research for the southern magnetic pole and the exploration 

 of the antarctic seas will afford, it may be presumed, many oppor- 

 tunities of instituting on land hitherto unknown, or on firm ice when 

 the vessel may be for a time blockaded, observations of this descrip- 

 tion ; and in the progress of the circumnavigation, the line of coast 

 observed or supposed to exist under the name of Graham's Land, or 

 those of the islands in that vicinity, South Shetland, Sandwich Land, 

 and finally on the homeward voyage the Island of Tristan d'Acunha, 

 will afford stations each of its own particular interest. 



A programme will be furnished of the days selected for simulta- 

 neous observations at the fixed observatories, and of the details to 

 be attended to in the observations themselves as above alluded to. 

 These days will include the terms or stated days of the German Mag- 

 netic Association, in which, by arrangements already existing, every 

 European magnetic observatory is sure to be in full activity. These 

 latter days, which occur four times in the year, will be especially 

 interesting, as jieriods of magnetometrical observations by the Expe- 

 dition, when the circumstances of the voyage will permit. For the 

 determination of the existence and progress of the diurnal oscillation, 

 in so far as that important element can be ascertained in periods of 

 brief duration, it will be necessary to continue the observations hourly 

 during the twenty-four for not less than one complete week. At 

 every station where the magnetometers are observed, the absolute 

 values of the dip, horizontal direction, and intensity will require to 

 be ascertained. 



Sydney, for a station of absolute determinations, would be with 

 great propriety selected, as there can be no doubt of its becoming 

 at no distant period a centre of reference for every species of local 

 determination. 



The meteorological particulars to be chiefly attended to, as a part 

 of the magnetic observations, are those of the barometer, thermo- 

 meter, wind, and especially auroras, if any. In case of the occur- 

 rence of the latter indeed, the hourly should at once be exchanged 

 for uninterrupted observation, should that not be actually in opera- 

 tion. The affections of the magnetometers during thunder-storms. 



