1903] THE ELECTROMETER 139 



over a range of nearly an inch, and the thermometer rose at 

 one time to + 17^°. Last night the floor of the entrance 

 porch was a swamp, whilst water was dripping from the sides 

 and roof. It has never been in this state before during the 

 winter. In many respects the gale has been the worst we have 

 had, and yet, thanks to experience, we have weathered it with- 

 out any of the minor mishaps of last year, except the temporary 

 loss of our stove-pipe exhaust. From without the ship looks 

 to be completely buried in snow. 



1 We are still at a loss for any warning of our approaching 

 blizzards. The barometer only commences its vagaries after 

 the storm is on us. There has been a suggestion that strong 

 mirage is a sign of bad weather to come, but this fortunately is 

 not the case, as very extraordinary mirage effects are constantly 

 seen. At one time we had an idea that the electrometer might 

 be taken as a guide, but this, again, seems to show little until 

 the gale has actually begun. 



1 But although the electrometer may not serve us in this 

 way, it has yielded some extremely interesting results. 

 Bernacchi has continued to take regular observations with 

 this instrument ; he mounts it on a tripod and takes observa- 

 tions with the match conductor just above it, or hoisted on a 

 pole fifteen feet high. He is thus able to discover the electrical 

 potential at both these heights, though the task is not always a 

 pleasing one, as the small screws of the instrument have to be 

 manipulated with bared fingers. Once or twice Skelton has 

 assisted Bernacchi in taking hourly observations over a con- 

 siderable period. Perhaps the most interesting point is that 

 there is almost continuously a negative potential in our regions, 

 whereas in temperate regions the air is generally electro-positive 

 to the earth. 



'The observations at four feet and fifteen feet show that the 

 difference of potential increases considerably with the altitude. 

 During the summer months there is a perceptible daily range, 

 with a maximum at midnight and a minimum at noon, and the 

 potential is higher than in winter when there is no measurable 

 range. When the air is filled with falling or drifting snow the 



