ABSTRACT OF PROCEEDINGS. XXXVIl. 
Ridley; Oncosperma fasciculata, Thwaites; Oveodoxa oleracea, 
Martius; Pinanga acaulis; Rhopaloblaste hexandva, Scheft.; 
Adiantum dolabriforme, Hook.; Dracaena Sandenana, Hort.; 
D. Goldteana, Hort.: Rhododendyon amaenum, Planch. var. 
Magnet; R. indicum, Linn. var. Phryne; Tydaea pandora. 
Mr. J. Naneave, F.I.A.— 
“Astronomical Micrometer and Position Circle with dark 
field illumination. Microscopes with specimens of rock 
and diatoms.” 
Mr. Epwarp F. Pirrman. A.R.S.M., Under Secretary for Mines 
and Government Geologist, assisted by Mr. GrorceE S. 
Carp, A.R.S.M., Curator of the Mining and Geological 
Museum— 
“ Recently Discovered Minerals and Fossils,” including 
Ordovician graptolites from new localities, fish from St. 
Peters, Native Arsenic, Fluorite, Emery, etc., etc. 
“‘ Photographs of scenes of Geological and Geographical 
interest in New South Wales. A large and specially 
important collection. 
Prof. J. A. Pottocx, D.Sc., and Mr. U. VonwiL__er, B.Sc., 
Physical Laboratory of the University— 
1. “ Magnetic Model” of an atom on the corpuscular theory 
of matter. First described by Professor Mayer. 
A number of small bar magnets, held vertically with their south 
poles upwards by corks floating in water, represent the electrons or 
corpuscles, while a large bar magnet is placed above the water with its 
north pole pointing downwards, this representing the positive electricity 
distributed through the atom. The small magnets are attached by the 
large one but mutually repel one another, and as a result take up 
definite positions of equilibrium, arranging themselves in some sym- 
metrical manner depending onthe number present. If they are all 
removed and put in the water near the side of the dish, one by one, 
they are seen to move rapidly towards the centre and take up their 
positions of rest. Three arrange themselves so as to form a triangle, 
four a square, five a pentagon (generally), six a pentagon with one 
inside, and so on; a series of concentric rings being formed as the 
number increases. It is interesting to remove the centre magnet when 
seven are present, the ring of six cannot remain long without a magnet 
inside, one very soon moving to the centre leaving an outer ring of five. 
