7 o THE POPULAR SCIENCE MONTHLY. 



some of them become mathematicians like Gauss and Ampere, 

 while others continue all their lives what they were in the begin- 

 ning, simply specialists in figures. We do not know whether 

 this distinction arises in the nature of things, or simply results 

 from the chances of life. Very good minds think there is a rela- 

 tion between the calculating faculty and mathematical talent, 

 and believe that, if these prodigies were intelligently given a 

 special education, they might most of them become remarkable 

 mathematicians. Experiment has not given a definite result on 

 this point. M. Inaudi has determined not to go to the mathe- 

 matical school, but will preserve and develop his natural gifts. 

 Another question arises as to the influence of heredity in these 

 cases. For a long time physicians have been accustomed, when 

 an abnormal combination of talents appears in a particular per- 

 son, to find a number of special characteristics in his family. 

 Sometimes these have appeared through several generations, as 

 in certain noted families of musicians and naturalists. Some- 

 times the peculiarity appears in the shape of eccentricity. No 

 such peculiar family traits have been found associated with M. 

 Inaudi, nor any special antecedents in himself. He has never 

 been ill, and his development has been normal. 



The study of M. Inaudi has been fruitful for psychology. On 

 one side it has brought a remarkable confirmation to the theory of 

 partial memories ; and on another side it has made us familiar 

 with a new form of mental calculation, the auditive form. It 

 may also have taught us something else. We have found that it 

 is possible for some faculties, like memory, to acquire an extent 

 double and triple that of the normal. The fact permits us to 

 descry in how large a measure the human mind is still capable of 

 improvement. — Translated for The Popular Science Monthly from 

 the Revue des Deux Mondes. 



The polished stone hatchet, according to Mr. Thomas Wilson's report on an- 

 thropology at the Paris Exhibition in 1889, is recognized almost all over Europe 

 as an amulet protective against lightning. It is called in many languages "the 

 stone of lightning " or "thunder-stone." The hatchets are drilled for suspension, 

 or are put over the fireplace or in the stones of it, or are inserted in a crack. The 

 general belief is that they come from the heavens in a flash of lightning; and one 

 peasant declared that he had seen such a stone fall, and, going for it, had found it 

 and extracted it from the hole still hot. Elint arrow-heads are also regarded in 

 the same way. A common amulet, of great power, in Brittany is what is called 

 there the pierre du croix, a mineral, staurolite, which crystallizes in the form of 

 a cross. It is regarded as a token from God in favor of the religion of the coun- 

 try, and is given to these his chosen people in recognition of their piety and re- 

 ligious fervor. In Italy the coral is an amulet supposed to guard its owner against 

 the evil eye. These are the principal objects of regard ; but there are many others 

 of less importance, which are, however, much relied upon. 



