106 ATMOSPHERIC ELECTRICITY. 



possess a greater number of observations in those little accessible parts 

 of the earth's surface, many important problems can not be satisfac- 

 torily solved. Arctic and antarctic expeditions are of interest to scien- 

 tific men, not because they care much whether we get a few miles 

 nearer the pole, but because a well-conducted party collects invaluable 

 information on its journey. Although much remains to be done in the 

 regions surrounding the north magnetic pole, our knowledge in the 

 southern hemisphere is almost disgracefully inadequate, and it is to be 

 hoped that before long a well-equipped expedition may fill up to a cer- 

 tain extent the large gaps in our electrical, and magnetical knowledge 

 which at present stop so many of our researches. 



But although investigations to be conducted in the arctic regions are 

 of primary importance, we may do much nearer home in extending and 

 completing existing information. Instrumental appliances and meth- 

 ods of observation, originally put into a satisfactory state by Lord 

 Kelvin, have been improved, especially by Mascart, Exner, Elster, and 

 Geitel. One of our most crying wants at present is a series of contin- 

 uous observations by means of self-registering instruments in places 

 where the neighborhood of a town or other local circumstances do not 

 interfere with the normal changes. The Greenwich Observatory, to 

 which we look for help in such matters, is placed in the difficulty that 

 the daily variations there observed are markedly different from those 

 in the majority of places, and it is probable that the nearness of Lon- 

 don is fatal to any generally useful series of observations of atmospheric 

 electricity being conducted in our national observatory. 



