232 LEISURE-TIME STUDIES. 



part to the varying rates at which nervous impulses are 

 transmitted through the nerves, and to or from the brain, 

 and the variations in the rate of nerve-impulse are of course 

 referable to inherited peculiarities, and to ancestral and 

 transmitted qualities of mind. The difference between a 

 person of phlegmatic disposition and a person of sanguine 

 temperament, may thus be properly enough referred to the 

 varying rates with which sensations and feelings are appre- 

 ciated and acted upon. Disposition or temperament thus 

 becomes referred, secondarily, to the manner in which and 

 aptitude with which nerves receive and transmit impressions. 

 Primarily, of course, we must refer the exact causes of the 

 quicker or slower transmission of impulses to the consti- 

 tution of the individual who exhibits them. 



Mr. Galton gives a very interesting example of the differ- 

 ences to be observed between various individuals in the 

 respects just noted, by a reference to a practice common 

 amongst astronomers. He says : " It is a well-known fact 

 that different observers make different estimates of the exact 

 moment of the occurrence of any event. There is," he con- 

 tinues, " a common astronomical observation in which the 

 moment has to be recorded at which a star that is travelling 

 athwart the field of view of a fixed telescope, crosses the 

 fine vertical wire by which that field of view is intersected. 

 In making this observation it is found that some observers 

 are over-sanguine and anticipate the event, whilst others are 

 sluggish, and allow the event to pass by before they succeed 

 in noting it." This tendency of each individual is clearly 

 not the result either of inexperience or carelessness, since, as 

 astronomers well know, " it is a persistent characteristic of 

 each individual, however practised in the art of making 

 observations or however attentive he may be." And so 

 accustomed, indeed, are astronomers to these differences in 

 observers, that a definite and standing phrase that of the 

 "personal equation" is used in that science to express the 

 difference between the time of a man's noting the event and 

 that of its actual occurrence. Every assistant in an observa- 



