SECTIONAL TRANSACTIONS.—J. 439 
nomical, meteorological, terrestrial, in range-finding, &c. And more recently 
persistent attempts have been made to find a possible and practicable means of 
exhibiting motion pictures in full relief to public audiences. 
In this communication the basic principles of successful stereoscopy will be 
discussed and the main methods that have been tried in connection with motion 
pictures will be reviewed. In the new method to be presented a return is made 
in part to the original principles which Brewster used for the viewing of small 
pictures in three dimensions, but with modifications necessitated by the use of 
large pictures that may be exhibited in public. Types of stereoscopes adapted 
for this purpose will be shown, and during the meetings a demonstration will 
be arranged for those who may be more particularly interested. 
The stereoscopy of projected pictures raises a number of new and significant 
problems in visual science, a few of which will be touched upon in the concluding 
part of the paper. 
Saturday, August 9. 
Informal Conference of Experimentalists on Laboratory and Applied 
Researches. 
Chairman: Dr. C. S. Myers, C.B.E., F.R.S. 
Monday, August 11. 
14, Joint Discussion with Section L (q.v.) on Tests for Scholarships 
and Promotions. (Page 456.) 
15. Joint Discussion with Section H on Racial Mental Differences. 
Prof. W. McDoueatt, F.R.S., Dr. C. S. Myzrs, C.B.E., F.R.S. 
Prof. W. McDovaatu, F.R.S.— 
It is a matter for rejoicing that anthropologists are now becoming interested 
in the question of mental peculiarities of races and the differences of innate 
_ mental constitution between races. Unfortunately there is no approximation 
to agreement on these questions among psychologists. The majority of them, 
perhaps, under the influence of the dogma that man is nothing more than a 
bundle of mechanical reflexes, adheres to the popular view (determined by 
humanitarian sentiment and religious beliefs) that there are no such differences. 
This popular superficial view is also in part a reaction against an older popular 
view to the effect that the difference of knowledge and culture between civilised 
man and a savage expresses or corresponds to a similar difference of innate 
mental endowment. ‘hose who examine this question, impartially and un- 
influenced by any of these popular beliefs and dogmas, agree that there are 
differences of innate mental constitution between races; but they differ widely 
as to the nature of these differences and as to their importance in determining 
the differences of nature and level of the cultures attained by the several divi- 
sions of the human race. 
The exacter methods of observation furnished by experimental psychology 
have attained two conclusions which may be regarded as well founded. 
First, the Cambridge Anthropological Expeditions of 1899 showed that two 
of the coloured races, Oceanic negro and Malayo-polynesian, differ from the 
white race in respect of sensory capacities hardly at all; the differences found 
were so small as to furnish no ground or explanation for differences of cultural 
achievement. Later work has but confirmed this conclusion, and it may be 
regarded as established that most, and probably all, branches of the human 
race enjoy sensory capacities which natively are extremely similar in range 
and culture. 
Secondly, the methods of intelligence testing seem to have revealed certain 
racial differences in respect of ‘general intelligence’ or innate capacity to 
develop ‘general intelligence.’ Whether ‘general intelligence’ is a true unit 
character in the Mendelian sense or in the psychological functional sense 
