PHESIDENt'sI ADDKBSS SECTION A. 41 



Specific conductivity of the air at Sydney, so determined, is only about 

 ontvtenth of the value just stated. Here again, there is a considerable 

 discrepancy between my own and other measures which has yet to be 

 invest ig-ated. 



With increasing knowleilge we can look forward to developments 

 of importance to meteorology in connection with ionic observations; 

 just now it is doubtfid, I tliink, if valuable efiort. is not being wasted 

 as a i-esult of over-confidence in the present state of the art. 



Such is a sketch of our present knowledge of the ions of the 

 almosj)liere. With the pidjlication of Mr. Wellisch's and Mi'. Suther- 

 l;;nd"s investigations we liave reached a definite idea of the small ion 

 in air — a molecule, which, as the attraction of its charge brings about 

 collisions which would otherwise not occur, acts as if it were one of 

 more than the normal size — the conception enabling our experience to 

 bo not only simply but exactly described. Of the larger ions, no such 

 definite pictiu'c can as yet be drawn. Ions similar in character have 

 been obsen^ed in gases from flames and in other cases, and it is to 

 be hoped that the material which is now being collected ma}' soon 

 prove siifficient, in the hands of those specially skilled in the methods 

 of the Kinetic Theory of Gases, for a discussion of the life history of 

 these molecular clusters. The study of the natural ions has a special 

 interest, as a wider determination of the facts of the ionisation of the 

 aiv means ,ih advance towards a more comprehensive knowledge of 

 atmosphei-ic electricitv. 



REPORT OF THE COMMITTEE ON SEISMOLOGY. 



Bn fh>- Secrefarij, P. BAnACCHl. F.R.A.S. 



To THE President of Section A — 



SiK, — I have the honour to present the attached reports from the 

 Observatories of Sydney, Adelaide, Perth, and Melbourne, showing 

 what had been done in Australia, in regard to Seismology, during the 

 period, 1st January, 1907, to olst December, 1908 : and to direct 

 attention ti> two important matters, as follows, viz.: — 



(a) At present no organised sei-vice exists in Australia for 



obtaining earthquake records from localities outside of 

 the capitals. It would not be difficult to recruit in each 

 State a large number of voluntary observers, not neces- 

 sarily to be jirovided with any special instrumental equip- 

 ment, to report seismic phenomena in accordance with 

 some uniform plan. 



I would suggest that the Council be asked to bring 

 this matter before the State Governments, recommending 

 that the existing oljservatories be given facilities and 

 some little extra means (say, £100 per annum) for the 

 purpose. 



(b) Professor Milne, as secretary of the Seismological Com- 



mittee of the British Association, collects and publishes 

 the seismic records obtained at many observatories in 

 every part of the world, including Australia and New 

 Zealand, and an International Seismological Association 

 also deals with similar seismic records. There appears to 

 be an unnecessary complexity and some doubt as to the 



