ABSTRACT OF PROCEEDINGS. XXI. 



of Mr. Dearie's solution and of the nature of the problem were 

 discussed. The laws of permeable flow, and the relation of these 

 to the ascertainment of the amount flowing off from soil — a 

 question of some importance to engineers — and that absorbed for 

 any given rate of rainfall were pointed out. The physical cir- 

 cumstances which affect percolation, it was stated, must be 

 considered in the general question, and formulae were given for 

 obtaining the necessary constants for the soil. Evaporation, the 

 effect of solar radiation, the law of diffusion, the effect of air 

 temperature, humidity, and of atmospheric motion and drainage 

 had to be considered in estimating losses ; and the complexity of 

 the general expression for the degree of saturation showed that 

 the exact solution would be difficult. The study of elementary 

 cases might afford some indication of a practical solution for 

 various conditions naturally occurring. The paper closed with 

 some remarks on graphs representing natural phenomena, the 

 phenomena to be observed, and the mode of shewing them. 



3. "Divisions of Some Aboriginal Tribes, Queensland," by. R. H. 

 Mathews, l.s. 

 Mr. R. H. Mathews read a short paper dealing with the 

 social organisation of some native tribes of Queensland. He 

 illustrated the different types of divisional systems adopted by 

 the aborigines for the purpose of regulating the intersexual rela- 

 tions. In some tracts of country the community is segregated 

 into two intermarrying groups ; in other geographic areas there 

 are four divisions of the inhabitants ; whilst in other districts 

 there are eight intermarrying divisions. In these several types 

 of social structure the men of a certain section or group marry 

 the women of another prescribed section, and the resulting off- 

 spring inherit a section name which is in all cases determined 

 through the mother. The author drew attention to the great 

 value of a knowledge of these social divisions in all ethnological 

 investigations among the native tribes of Australia. 



EXHIBIT. 



Examples of the Joly natural-colour Photographs, by Mr. P. 

 Caro, exhibited by Mr. S. H. Barraclough, m.m.e., Assoc, m. Inst. c.e. 



