126 



Miss M. A. Whiteley and Prof. Karl Pearson. 



Journey 1. Mean of Sydney — Hornsby and Hornsby — Sydney. 



Difference 18*5 sextant minutes. 



Journey 2. Mean of Sydney — Hornsby and Hornsby — Sydney. 



Difference 18'1 sextant minutes. 



Journey 3. — Mean of Sydney — Hornsby and Hornsby — Sydney. 



Difference 18'1 sextant minutes. 



The maximum difference is thus 0'4 sextant minute, and corresponds 

 to an uncertainty in the value to be assigned to the acceleration of 

 gravity at Hornsby as compared with that at Sydney taken as known 

 of one part in 500,000. This we believe to fairly represent the accu- 

 racy attainable by the instrument in actual field work. It is about 

 double of the outside accuracy attainable by invariable pendulums, not 

 connected by telegraph, and the observation takes about half an hour, 

 but the time depends on the time required for the temperature to 

 become steady. The observations quoted took about three hours each. 

 Packing and unpacking takes about an hour and a half, and the actual 

 observing about five minutes, but the temperature must be watched to 

 the maximum or minimum before the observations begin. 



The weight of the instrument and of appliances taken directly from 

 the laboratory and packed in strong boxes is 226 lbs. ; by making 

 special appliances with a view to lightness this weight might be reduced 

 to one-half. 



The paper is illustrated by working drawings, &c. 



" Data for the Problem of Evolution in Man. I. A First Study 

 of the Variability and Correlation of the Hand." By Miss 

 M. A. Whiteley, B.Sc., and Karl Pearson, F.K.S. Eeceived 

 April 6 — Bead April 27, 1899. 



1. In a more purely theoretical discussion of the influence of natural 

 selection on the variability and correlation of species, which one of the. 

 present writers hopes shortly to publish, a number of theorems are 

 proved which it is desirable to illustrate numerically. But the quanti- 

 tative measures of the variability and correlation hitherto published 

 are comparatively few in number, especially when, as in the present 

 case, we desire to have their values for a number of local races of the 

 same species. When we have once realised that neither variability nor 

 correlation are constant for local races but are modified in a determi- 

 nate manner by natural selection, and further that their differences are 

 the sure key to the problem of how selection has differentiated local 

 races, then the nnportance of putting on record all the quantitative 

 measures we can possibly ascertain of variability and correlation 

 becomes apparent. For some five years past various members of the 



