Marriner. — The Mokoia Aerolite. 185 



quite large pieces of the meteorite, and the mineral is perfectly opaque, so 

 I have little doubt as to its nature." 



In conclusion, I should like to express my indebtedness to all those 

 who have so willingly assisted me, especially Mr. C. Hawken, Mokoia ; 

 Mr. J. L. Fletcher, British Museum, London ; Mr. A. Hamilton, Welling- 

 ton ; Mr. J. T. Ward, Wanganui ; Mr. R. Speight. M.A., Christchurch ; 

 Dr. P. Marshall, Dunedin ; Mr. B. C. Aston, Wellington ; and Mr. W. Syme, 

 Wanganui. 



EXPLANATION OF PLATES XXR^ AND XXV. 



Plate XXR^. 



Fig. 1. Fragment A of Mokoia meteorite ; \ of natural size. Weight, 5 lb. 3 oz. 

 Fig. 2. Fragment B of IMokoia meteorite ; J of natural size. Weight, 5 lb. 2 oz. 

 Fig. 3. Portion of the root of fir-tree (Pinus insignis), showing where it was struck by a 

 portion of tlie meteorit^. 



Plate XXV. 



Fig. -1. General structure of meteorite, showing chondri in base, x 15. 

 Fig. 2. Chondrus composed of olivine and enstatite separated by a circular crack from 

 the surroundins, base, x 36. 



Art. XV. — On the Radio-activity of the Artesian-water System of Christ- 

 church, New Zealand, and the Evidence of its Effect on Fish-life. 



By C. Coleridge Farr, D.Sc, &c., and D. C. H. Florance, M.A., M.Sc. 



[Read before the Philosophical histitute of Canterbury, 13th July, 1609.] 



Some time ago a committee was set up by the Philosophical Institute of 

 Canterbury to examine the various problems suggested by the artesian system 

 of Christchurch ; and, though the committee is in no way responsible for 

 the opinions which will be expressed, and, indeed, may not agree with them, 

 yet this paper may be regarded as a first result of its labours, as it fell to the 

 authors to examine the water with regard to its radio-active condition, 

 whilst others are undertaking other investigations. 



The method of examining the water for radio-activity was that adopted 

 by others, notably by Strutt. The water was collected in a flask holding 

 approximately half a litre. This was immediately corked, with, a piece of 

 glass tube passing through the cork, on the outer, end of which was a short 

 piece of rubber tubing which was closed by a pinch-cock. The same time 

 (twenty minutes) was allowed to elapse between the collection of each 

 sample of water and the commencement of operations for its testing. To 

 test the gas the indiarubber tube was connected to a Liebig condenser, and 

 the water boiled so as to drive off the gases contained in the water. These, 

 together with the air left in the top of the flask, which was never quite filled 

 with water, were collected over water, and, to insure their all passing over 

 into the collecting-vessel, at the close of the boiling the condensing-water 

 was stopped, and steam was sent through the apparatus. The boiling 



