SCIENCE. 



[Vol. TO., No. 156 



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English feet, while the formerly admitted height 

 was 66 feet. Such a great difference from the 

 formerly admitted height is startling, yet the new 

 figures are the result of so accurate and well- 

 checked operations and calculations that their re- 

 sult cannot be doubted. According to the new 

 determination, the slope of the Neva is about the 

 same as that of the Volga in its middle course, 

 while the formerly admitted heights made it four 

 times greater. To have another check on the 

 height of Lake Ladoga, the barometric means of 

 H. Schlusselburg were compared with those of St. 

 Petersburg for a mean of eight years. The differ- 

 ence of level of the Ladoga and Gulf of Finland, 

 determined barometrically, is but 8.6 feet ; that is, 

 less by 7.7 feet than that determined by levelling. 

 If we suppose both series of observations to be 

 equally accurate, and the instrumental error de- 

 termined with the greatest precision, this would 

 prove that the mean pressure rises toward the 

 east, — a result quite consistent with the general 

 course of the isobars in Russia ; but the difference 

 is rather too large for so small a distance. 



Lakes Husen and Onega have also been levelled, 

 and the figures for them will shortly be published. 

 Their height was also found to be smaller than 

 formerly admitted. A. Woeikof. 



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POPULAR PSYCHOLOGY. 



Socrates, Cicero tells us, called down philos- 

 ophy from heaven to earth, and introduced it 

 into the cities and houses of men. In each stage 

 of the development of a science an essential step 

 is the diffusion of the general tendencies and 

 results obtained amongst the intelligent public. 

 Nowadays, when each branch of study must 

 make good its claim to a place on the curriculum, 

 it is more than ever necessary to acquaint the 

 cultured and powerful public with the general 

 problems and broad outlines of your science. 

 Thus it has come about that a certain class of 

 scientific men have almost made themselves 

 specialists on the topic of popular science. It 

 is hugely to them that the public looks for their 

 scientific enlightenment. A larger and more im- 

 portant class of popular scientists, very fortu- 

 nately, are the masters of science themselves. 

 When such men as Huxley and Helmholtz pre- 

 pare with their own hands the scientific food for 

 the public mind, there really must be an inade- 

 quate power of reception of such knowledge, if 

 healthful, wide-spread activity in science is not 

 the result. 



Psychology j since it has received the impulse 

 which has made 'physiological psychology' a 

 common description of it, has made sufficient 



