ATMOSPHERIC ELECTRICITY. 69 
made three times a day at intervals of six hours; for example, at 
8 am., 2 p.m., and 8 p.m, or at 7.30 am., 1.30 p.m., and 7.30 p.m. 
Whatever times are most convenient may be chosen, provided they 
be separated by intervals of six hours. 
(3) It is very desirable that hourly observations should be made, 
if only for a few days, in winter and in summer. If possible, arrange- 
ments to do so, at least for six consecutive days in winter and for six 
consecutive days in summer, should be made. The results will be 
very interesting as showing whether there is a diurnal or semi- 
diurnal period in either the Antarctic winter or summer. 
(4+) Make occasionally special observations when there is any- 
thing peculiar in the weather, especially with reference to wind. 
V. Special precautions: 
(1) In the Antarctic climate more care may be necessary than in 
ordinary climates as to earth connections. Therefore put a piece of 
metal on the stand on which the electrometer is placed during an 
observation on board ship, and keep this in metallic communication 
with the ship’s coppers. If the electrometer is held in the hand 
with a glove on, a piece of the fine wire supplied with the instrument 
ought to be tied round the brass projection which carries the lens, or 
otherwise attached to the outer case of the electrometer, and by this 
wire sufficient connection maintained with the earth during an obser- 
vation. The connection will probably be sufficient if a short length 
of the wire is laid on the ice and the observer stands on it. Enough, 
however, is not yet known as to electric conductivity of ice: and to 
make sure, it may be necessary to have a wire or chain let down to 
the water through a hole in the ice, and metallic connection kept up 
by a fine wire between this and the electrometer case during an 
observation. 
(2) The observer’s cap (particularly if of fur) and his woollen 
clothing, and even his hair if not completely covered by his cap, will 
be apt in the Antarctic climate to become electrified by the slightest 
friction, and so to give false results when the object to be observed is 
atmospheric electricity. A tin foil cover for cap and arms, kept in 
metallic communication by a fine wire with the hand or hands applied 
to the case of the electrometer or to the micrometer screw head, should 
therefore be used by the observer (and assistant, if he has an assistant 
to carry lantern, or for any other purpose), unless he has made sure 
that there is no sensible disturbance from those causes, without the 
precaution. Tin foil for this purpose is supplied with the instrument. 
VI. Instruments, stores, and appliances for observation of atmo- 
spheric electricity sent with the Expedition : 
