OBSERVATORY AT KELBURN

Dominion, Volume 19, Issue 93, 14 January 1926, Page 8

OBSERVATORY AT KELBURN

EXTENSION OF BUILDING Additions are about to be made to the Government Observatory at Kelburn, where much valuable recording lias been done in astronomy and seis- . inology for some time past, under cramped and altogether disadvantageous conditions. The proposed addition, tenders for which have been called, consists of four rooms on the one floor, to be erected in red brick with concrete facings, in precisely the style of the little building which has for so long done duty as both observatory and offices. Foundations were built a year ago, solid enough to carry a building three stories in height. The new building will be divided into four offices, and when completed the existing office will serve as a. library. The seismograph, which records Wellington’s tremors and shakes, is deep, down in the earth, on a shaft of 'concrete. Curiously enough the entrance cellar, and the one in which the seismograph is housed, were there for many years before: their existence was suspected, being oart of the gunpit of the old Kelburn battery,' the entrance to which had been sealed up with 18 inches of concrete. The original plans showed some sort of a subterranean structure by a series of dots, but it was never clear that the dotted areas represented work actually carried out. At last it was decided to ascertain what lay beyond that wall of concrete, and two fine cellars were found,’ admirably adapted for seismological purposes. There the machine, with its electrical apparatus, carries out its work in Stygian darkness. Indeed, the only light that can be per-' mitted is a thin line which is reflected by small mirrors on to the centre of the revolving drum of bromide paper. When there is no movement of the earth the line appears straight on the paper, but as soon as the delicatelypoised floating bar of aluminium becomes agitated in the slightest degree the line begins to move from side to side. The extent of its movement is a fair guide to the intensity of the disturbance. save that being only adapted for the recording of lateral movement, vertical action is not recorded. New Zealand is one of the known oscillating countries of the world. It is for ever on the move, though the tremors may be too Winy to be felt. Whilst visiting the Observatory yes-

terday, the Government Seismologist (Dr. C. E. Adams) took up a sheet of ’ ■ sensitised paper which had been developed some hours previously—a record of the preceding 24 hours. Apparently it showed no movement, but on a closer examination of the line it was found to be of minute zigzag formation, showing that there was earth movement practically continuously throughout the day. Foundations have been prepared in the cellar for a vertical seismograph, but at present the cost of the only instruments for measuring the intensity of vertical movement is rather bevond the resources of the Observatory. English inventors have not troubled very much about it, for the reason that ' England knows not the vertical earthquake.