WOMEIT IN ASTRONOMY. 535 



with astronomy after the death of their mother, and made the calcula- 

 tions, for the Academy of Sciences of Berlin, of the " Ephemeris " and 

 the " Almanac " which were sources of revenue to that learned body. 

 In the same period a number of French and Italian astronomers had 

 female collaborators in their own families. Celsius, the celebrated pro- 

 fessor at TJpsala, and a pupil of Kirch the son, was entertained, while pass- 

 ing through Paris to Bologna, by De I'lsle, whose sister was devoting 

 herself to astronomy. Reaching Italy, he found liliewise that his new 

 master, Manfredi, had two learned sisters, engaged, like their brother, 

 rn the study of the stars. This caused Celsius to say, in a letter to 

 Kirch : " I begin to believe that it is fated for all the astronomers whom 

 I have had the honor of becoming acquainted with during my journey 

 to have learned sisters ; I have a sister, too, but not a very learned 

 lady. To keep up the coincidence, we must make an astronomer 

 of her." 



Other women, whose names are less well known, wrote on astronomy 

 during the seventeenth century. We may cite Maria Cunitz, daugh- 

 ter of a Silesian doctor, who published astronomical tables in 1650 ; 

 Jeanne Dume, who in 1650 wrote a book defending the Copernican 

 system against "scientific" attacks upon it. Of more modern date 

 was Madame Gabrielle Emilie de Breteuil, Marquise du Chatelet, 

 who was for fifteen years the constant friend of Voltaire, and in her 

 retreat at Cirey devoted her whole life to the sciences. She it was 

 who first made known to France, then devoted to scientific Cartesian- 

 ism and the doctrine of elementary vortices, the masterly work of 

 Newton. This was a title to glory which might have made the 

 fortune of more than one scientific man, and it fell upon a woman. 

 Mademoiselle de Breteuil had received a very careful education, but 

 her natural taste for study and serious occupations did not prevent her 

 from shining brilliantly in the society of the courts of the Regency 

 for some years after her marriage with M. du Chatelet. One of the 

 best evidences of her genius that we have is in the bearing toward her 

 of Voltaire, who had no respect for any but mental gifts. He had 

 returned from Great Britain full of enthusiasm for English science 

 and philosophy, and occupied with the dream of making Newton 

 known to his countrymen and dethroning Descartes at the Academy. 

 It may appear singular that he selected Madame du Chatelet for this 

 work ; but the choice was not extraordinary after all. She had already 

 made some progress in mathematical studies under the direction of 

 Maupertuis and Clairaut, and Voltaire was looking for the assistance 

 he needed to some one outside of the oflicial scientific circle. The 

 translation of Newton's " Principia " would be the best means of 

 making known in France the great English geometrician and the ad- 

 mirable simplicity which his theory of attraction lent to the study of 

 the movements of the stars. This work Madame du Chatelet did well. 

 But she did more than make a simple translation. The algebraic com- 



