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Chap. V.]
MAGNETOMETRICAL OBSERVATIONS.
125
1840
accuracy; the result has most fully justified my confident expectations. Mr. Scott, mate of the Terror, and Mr. Dayman, of the Erebus, were appointed as his assistants, and a marine from each ship completed the establishment of the observatory.
In order that a more complete comparison might be instituted between the observations at Hobart-town and those to be made in more southern stations to be visited by the Expedition, the expanded system of observation we had hitherto used was to be continued by Lieutenant Kay; but as these periods of exact comparison occurred so seldom, and seemed to me scarcely sufficient to detect many of the curious phenomena that might be expected to present themselves on more frequent comparisons of even shorter intervals, I considered it advisable to arrange that one additional hour of continued observation should be made every night; and the time selected for this purpose was that most favourable for seeing the aurora, which has been known to exercise so powerful an influence on the magnetometers, and most suited for watching its several phases. I especially directed the attention of Lieutenant Kay and his assistants, during our absence, to notice the frequency, direction, form, altitude, and all the changes in the appearance of auroræ, as they would also have formed, had we been so fortunate as to have found a place in which to pass a winter in the Antarctic regions, circumstances of corresponding and continual observation, and perhaps serve to account for many irregularities that might appear in the summer