EULOGY ON QHETELET. 173 



tism, electricity, light, &c. lu 1828 be published a review of the lectures 

 given at the museum upon the calculus of probabilities, as an introduc- 

 tion to his course of physics and astronomy. 



The public lectures of Quetelet were such a success that the govern- 

 ment considered it advisable to institute other courses of the same kind, 

 and on the third of March, 1827, was installed the Museum of Science 

 and Letters, with a corps of efficient professors in the various branches 

 of science and literature. In the review of the lecture with which, three 

 days later, Quetelet opened his course, we find one of his favorite ideas: 

 " The more progress physical sciences make, the more they tend to 

 enter the domain of mathematics, which is a kind of centre to which 

 they all converge. We may even judge of the degree of perfection to 

 which a science has arrived by the facility with which it may be sub- 

 mitted to calculatiou." The museum continued to exist for eight years. 

 After suffering with all the other educational establishments of the 

 country from the effects of the revolution, it was absorbed into the free 

 university in 1834, and Quetelet ceased his public instruction after 

 twenty years of service. He soon commenced again, however, having 

 been appointed professor of astronomy and geodesy to the military 

 school, by a royal decree, on the Gth of January, 183G. Among his pu- 

 pils at the Athenaeum were the Duke of Saxe Coburg Gotha and the 

 late Prince Consort of England, who always retained a warm affection 

 for his preceptor. 



We have said that Quetelet was only twenty-four years of age when 

 made a member of the Brussels Academy. His first contribution, 

 "A memoir upon a general formula for determining the surface of a polygon, 

 formed on a sphere, hy the arcs of great or little circles, disposed in any man- 

 ner whatever,^'' was an admirable production. Garnier said of it, that 

 its elejrant simplicity and the symmetry of the formula lent interest to 

 a subject which would otherwise have appeared very dry. His second 

 menioir, "A new theory of conic sections considered in the solid,'''' did him 

 great honor. His third paper was upon tlie paths followed hy light 

 and elastic bodies. We have now come to a subject which occupied much 

 of his attention, to which he devoted three memoirs presented to the 

 academy, and numerous articles in the Correspondance Mathematique et 

 Physique — that is, caustic curves. In one of those articles he gives the 

 following theorem, which in importance is worthy to be ranked with the 

 discovery of the focale: "The caustic by reflexion, or by refraction for 

 any cm ve whatever, illuminated by a radiant point, is the development 

 of another curve, which has the property of being the envelope of all 

 the circles, which have their centers upon the reflecting or directing 

 curve, and of which the radii are equal to the distances of the centers 

 from the radiant point in the first case, and proportional to these same 

 distances in the second case ; the constant relation being that of the 

 sine of incidence to the sine of refraction." It was easy to extend this 

 theorem to surfaces, considering spheres enveloped instead of circles. 



