# Popular Science Monthly/Volume 25/May 1884/Longevity in Astronomers

THE average length of human life in civilized countries is calculated to be about thirty-three years. This mean applies to the whole of the population of a country. But certain distinctions may be made, between different professions for example, among which considerable variations are observable. It is easy to believe that some professions would have the general effect of increasing the probable duration of life, while others would abridge it. It is generally admitted that men devoted to scientific pursuits enjoy the expectation of a considerably longer life than the average. We have been curious enough to inquire how much foundation for this opinion there is in the case of astronomers, whose observations, calculations, and studies imperiously require a quiet, sedentary, and regular life. Our investigation has been facilitated by MM. Houzeau and Lancaster's "Bibliographie Générale de l'Astronomie," in the biographical chapter of which we found all the information we needed. In this chapter are given the date of birth and death of 1,741 astronomers, of periods reaching from the most ancient times to our own days. Calculating the mean length of life of the whole 1,741, we have found it to be sixty-four years and three months. Fully to appreciate the value of this figure, we must compare it with that representing the average expectation of life at the age at which the astronomer may be supposed to have begun his career. If we fix this age at eighteen years, the person enjoys an average expectation, according to the mortality-tables, of living to sixty-one years. The astronomer, then, enjoys an advantage equivalent to an additional expectation of three years and three months. If we examine the ages to which they actually lived, we find that, out of a thousand astronomers, 596 lived to be seventy years old; 260 to between seventy and seventy-nine; 126 to between eighty and eighty-nine; 15 to between ninety and ninety-nine; and three to be over a hundred years old.

Taking a population in mass, say that of Belgium, of a thousand 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 "Anthropometric," 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 average 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 categories, comprising : 1. The three most illustrious names (Archimedes, Galileo, and Lagrange). 2. Forty-seven mathematicians of great reputation. 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. Sixty-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 we 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 1845, was thirty-one years and three months, was lengthened to thirty-three years in the lustrum from 1871 to 1875. A similar difference 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. We have determined the average length of life of the adepts of the science of the sky who died before 1780 and of those who have died since that year. We have obtained sixty-three years and six months for the former, and sixty-four years and eleven months for the latter. The advantage in favor of these is not to be despised.

Taking a hundred individuals in each of these categories, there died at different ages:

Before 1870. | After 1870. | |

Before seventy years of age | 62 | 57 |

Between seventy and seventy-nine | 23 | 28 |

Between eighty and eighty-nine | 12 | 13 |

Between ninety and ninety-nine | 2 | 2 |

Over a hundred | 1 | 0 |

The conclusion at which we arrive has already probably occurred to more than one reader. Become an astronomer, if you wish to live long. We will add, whoever follows this counsel will not only see the limits of his life far removed, but he will also find in the study and contemplation of the heavenly bodies a satisfaction more durable than any earthly pleasures.—*Translated for the Popular Science Monthly from Ciel et Terre.*