ANNIVERSARY ADDRESS. 25 
The general result was to show that real hysteresial losses always 
occur, and that the properties of a particular sample are perfectly 
definite in this respect, though different samples of the same 
dielectric may have widely different properties. Since the com- 
mencement of the year he has had the advantage of Miss Martin’s 
assistance, and an investigation similar to the foregoing, but 
referring to the magnetic properties of substances like sulphur, 
bismuth, etc., is nearly completed. Professor Threlfall has also 
devoted much time to the phenomenon of the electrolytic deposition 
of metals, with the object of ascertaining the cause of the differ- 
ence in the nature of the deposits which occur under varying 
circumstances, So far the results of this investigation have been 
entirely negative. 
In hydrodynamics Mr. G. H. Knibbs, Lecturer in Surveying in 
the Sydney University, has continued, in the Engineering 
Laboratory, his examination of the determination of the viscosity — 
constant for water. He has shewn that the corrections for end 
Conditions used in even the most recent evaluations require 
amendment. The very extended results available have now been 
entirely re-reduced from the original data, and exhaustively com- 
pared, the more rigorous corrections being applied throughout. 
Mr. Knibbs concludes that the discrepancies between the results 
of different investigators are not satisfactorily accounted for by 
merely dimensional differences in the apparatus used, and if a 
higher order of precision is sought, it will be necessary to consider 
the sources of the discrepancies. In geodetical astronomy Mr. 
Knibbs has fully discussed the method of determining the direction 
of the astronomical meridian by means of solar observations, and 
has obtained expressions for the errors of the methods usually 
employed. The series of tables supplied in his paper greatly 
facilitate the discussion and reduction of such observations. - 
_ 1. Eneteerine anp Pusric Works.—Our Engineering Section 
18 One of which we as a Society are justly proud, and the papers 
of the Section published in our Journal by no means represent 
_ the whole of the scientific work dealt with at the monthly meet- 
