GLACIAL DEPOSITS OF BACCHUS MARSH. 
321 
4.— MODELS TO SHOW THE AXES OF CRYSTALS. 
By A. LIVERSIDGE , M.A., F.R.S., Professor of Chemistry, University of Sydney, 
N.S. W. 
These models have been used by me for teaching purposes since 
1875, and have been shown at the International Exhibitions of Phila- 
delphia, London, Melbourne, and Chicago ; but, up to the present, no 
account has been published of them. 
The two models show the relationship of the axes in the 
tetragonal, rhombic, oblique, and doubly oblique systems of Crystals. 
The edges of the Crystals are represented by elastic cords, so as 
to permit of the extension of the axes. 
Model No. 1 shows the relationship of the axes in the tetragonal, 
rhombic, oblique, and doubly oblique systems. Plate, Pig. 1. 
(a) By extending the vertical axis, acute tetragonal pyramids 
are obtained. Pig. 2 shows the device for the axial joints. 
( [b ) By extending one or both of the horizontal axes, the 
rhombic system is shown. Pig. 3 shows details of L and X. 
( c ) The oblique or monoclinic system is obtained by inclining 
one axis. Pig. 4 gives details of intersection of axes. 
(d) The doubly oblique or anorthic system is shown by inclining 
two axes. Pig. 5. 
(e) Each axis can be extended by regular increments indepen- 
dently of the others. 
All three of the axes can be extended to represent various 
pyramids; the different forms of brachy and macro pyramids are 
shown by extending the lateral axes. 
Model No. 2 shows how the domes and horizontal prisms are 
produced from the pyramids by extending the axes to infinity. Pig 6. 
All of the axes cau be extended by regular increments, as in the 
first model. 
5.— THE GLACIAL DEPOSITS OP BACCHUS MARSH. 
By GRAHAM OFFICER , B.Sc., and LEWIS BALFOUR, B.A. 
At the last meeting of this Association, held at Adelaide, a paper 
was read by Mr. G. Sweet, prepared by himself and Mr. Brit.tlebank, 
on the glacial deposits of Bacchus Marsh, containing statements to 
which, through our unavoidable absence, we regret we were unable to 
reply at the time. As their paper is in great part a criticism of a 
former one by us, read before the Royal Society of Victoria — and as 
Messrs. Sweet and Britt! ebank chose to read their paper before this 
Association — we feel that we cannot, in duty to ourselves, allow this 
present meeting of the Association to pass without a justification of 
our position. 
The first point that we would direct attention to is that Messrs. 
Sweet and Brittlebank, by implication at least, if not directly, would 
have it appear that we had trespassed on their prior claim to the work- 
ing of the district, as surely must appear to anyone who will read the 
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