LONGEVITY OF ASTRONOMERS. 61 



persons having reached the age of eighteen years, there die 944 before 

 they are seventy years old ; 42 between seventy and seventy-nine ; 13 

 between eighty and eighty-nine ; and one between ninety and ninety- 

 nine. The divergencies between the two groups are very evident. 



If we limit our investigations to a purely intellectual domain — that 

 is, if we confine the examination to scientific and literary men and 

 artists — we shall find that the chances of life are greatest with the first 

 and least with the last. A. Quetelet has, in his " Anthropometrie," 

 made a comparison on this point between the most famous men of 

 antiquity and of modern times, and has found that the mean life of 

 fourteen most illustrious artists was fifty-nine years and four months ; 

 of twenty-four literary men, sixty-five years and six months ; and of 

 twenty-two scientific men and philosophers, seventy-three years and 

 eleven months. On our own side, we have made a selection of the 

 twenty-three most celebrated astronomers, and have found their aver- 

 age term of life to be seventy-one years and eleven months. The 

 duration of life among these different classes of men of intellectual 

 life varies, as we have seen, when we pass from one to the other. The 

 variations depend both on external conditions peculiar to each of them, 

 and upon the objects of their labors and studies. The two causes are 

 in fact connected, the first proceeding naturally from the second. 



Professor P. Riccardi, in his "Biblioteca Matematica Italiana," gives 

 a table of the average life of the mathematicians of Italy, in the order 

 of their fame. He has arranged his mathematicians in four catego- 

 ries, comprising : 1. The three most illustrious names (Archimedes, 

 Galileo, and Lagrange). 2. Forty-seven mathematicians of great repu- 

 tation. 3. Fifty of the second rank. 4. Three hundred and eighty of 

 the third rank. The average duration of life in these categories of 

 mathematicians was — 1. Seventy-six years and eight months. 2. Six- 

 ty-nine years and five months. 3. Sixty-six years and four months. 

 4. Sixty-five years and ten months. 



The fame of a scientific man being generally in proportion to the 

 industry with which he works, we may draw our inferences from these 

 facts as to the relations between activity and duration of life. 



Another interesting fact has been brought out in our researches for 

 this article. The excitement of the life of our age and the consequent 

 diminution of its length have been frequently spoken of. We do not 

 live as long as formerly, it is said, but Ave live more rapidly. The 

 latter hypothesis may be true, but the former one is certainly false, as 

 statistics have demonstrated for the present century. In Belgium, 

 among other countries, the mean of life, which, during the period from 

 1841 to 184.5, was thirty-one years and three months, was lengthened 

 to thirty-three years in the lustrum from 1871 to 1875. A similar dif- 

 ference has been observed in other countries. Data for comparison 

 are scarce for centuries previous to the present one, but our statistics 

 of the lives of astronomers may give us some information on this point. 



