364 Froceedij^gs of tlie Royal Society of Victoria. 



vations taken during a journey across Australia, the isobaric 

 charts published by the Observatory would give the probable 

 sea-level reading at each point, from which and the actual reading 

 the height is determined. Work of this sort, however, though 

 by no means without value, cannot possibly approach in precision 

 that done under more favourable conditions. 



In compiling the above notes, use has been made of Bulletin 

 No. 8 of the Department of Mines of Victoria, by Professoi- 

 Gregory, F.R.S., and valuaV)le hints have been received from 

 Mr. T. W. Fowler, M.C.E., Lecturer on Surveying, Melbourne 

 University. To these gentlemen thanks are accordingly given. 



Note. — Whymper and others have called attention to the 

 mechanical hysteresis, or fatigue of the aneroid spring, as a 

 source of serious error, and a special instrument has bren devised 

 to obviate it. This trouble, which was serious at high altitudes 

 in the Andes, does not appear to be of practical importance on 

 the very moderate elevations found in Australia. 



An aneroid with optical instead of mechanical magnification 

 has been brought out by Goldschmidt, to eliminate friction errors, 

 but, so far, does not appear to have gained much favour. 



