president's address. 867 



antiquity, and the density of the population which was in 

 occupation of that district at the time of their formation, p. 49. 



Mr, Lawrence Hargrave (August 6) read a paper upon " The 

 Trochoided Plane," deiined as a flat surface, the centre of which 

 moves at _ uniform speed in a circle, the plane being normal 

 to the surface of a Trochoidal Wave, having a period equal to 

 one revolution of the said centre. In this arrangement he finds 

 the key to the flight of birds, and the consti'uction of flying 

 machines, p. 61. 



Mr. H. C. Russell, B.A., F.R.A.S., describes (Nov. .5) anew 

 form of actinometer, depending on the conversion of water into 

 steam by solar heat, p. 73. Also (Dec. 17.), on a new self- 

 registering Anemometer and Pluviometer for the Sydney Obser- 

 vatory, p. 118. 



Mr. D. A. Porter, of Tamworth, read a paper (November 5) on 

 Varieties and Localities in New South Wales of Quartz, Tour- 

 maline, Topaz, Corundum, Beryl, Diamond, Idocrase. Axinite, 

 and Wolfram, p. 75. 



Mr. C. Moore, F.L.S., Director of the Botanic Garden, read 

 (December 3) Notes on the Genus Doryanthes (Giant Lily), with 

 an account of D. Excelsa, D. Palmeri and a new species D. 

 Larkini, p. 81, 



Mr. W. K. Abbott, of Abbottsford, Wingen, contributes 

 (December 3) a long, elaborate, and highly interesting paper on 

 The Water Supply in the Interior, in which, among other matters, 

 he discusses the Geological Formation of the Plains, which he 

 ascribes to the ancient existence of Salt or Bitter Lakes, com- 

 parable to the Caspian, and explains the modes in which water 

 may be advantageously obtained or preserved in various districts, 

 p. 85. 



Mr. W. H. Caldwell, M. A., Balfour-Student in the University, 

 and Fellow of Gonville and Caius' College, Cambridge, gave 

 (December 17) an extempore account of his work in ascertaining 

 the mode of development of the embryos of Marsupials, 

 Monotremes, and the Ceratodus. He gave a description of the 



