142 Transactions. 



and below that a shell of still greater density about 630 miles thick (BBB). 

 Below the last-named shell there seems to be a marked change of physical 

 condition — either the density is much less (which is hardly conceivable) or 

 the centrosphere (CCC) is viscous. I have drawn hypothetically the possible 

 paths of preliminary waves reaching the San Fernando Observatory from the 

 origin : (a) They may have been transmitted along a path approximating 

 to the chord 111, but with greatly reduced speed through the central 

 portion ; or (b) they may have been transmitted along, or nearly along, 

 the path 2 2 2, as internal surface waves for the middle portion of the 

 path — that is, along the surface of the centrosphere ; or (c) they may have 

 been transmitted along a path 3 r 3 — that is, along the chords Or, r S.F., 

 being reflected at r. 



I put this forward as a mere trial hypothesis, based upon the examina- 

 tion of the records of one earthquake, and examined only partially by other 

 records. It is, however, I think, worth careful examination in the light 

 of all the available data of other earthquakes. I propose to make such an 

 examination (which may last months, or even years), and hope to place 

 the results, whether positive or negative, before you on a future occasion. 



I should like to express my appreciation of the kindness of the observers 

 in charge of the Milne seismographs at Sydney, Adelaide, Perth, and Christ- 

 church in sending me copies of their records and seismograms. I regret 

 that I have been unable to obtain any of the records of the instrument at 

 the Melbourne Observatory. 



Art. XIV. — Fluctuations in the Level of the Water in some Artesian Wells 



in the Christchurch Area. 



By F. W. Hilgendorf, M.A., D.Sc. 



[Read before the Philosophical Institute of Canterbury, 6th December, Wll.\ 



As part of the activities of the Artesian Wells Committee of the Canter- 

 bury Philosophical Institute, observations on fluctuations in the static 

 height of the water in some flowing wells in the Christchurch artesian area 

 were undertaken early in January, 1910. The records of the wells will be 

 dealt with separately. 



(1.) Lincoln College Well. 



This well is 341 ft. deep from the ground-level, which is 38 ft. above 

 sea-level. It is a 2 in. pipe, and was sunk in 1893. The water rises to 

 about 8 ft. above ground-level. 



There are in the district four other wells of approximately the same 

 depth. The nearest of these is about three-quarters of a mile away, and 

 the next nearest over a mile away. 



The observations were taken by means of a glass tube attached to a tap 

 bored into the well-pipe, and the tube was backed by a wooden scale 

 marked in centimetres. The hydraulic rams worked by the well were shut 

 off for the purpose of taking the observations, and the water in the tube 



