In the preface to the collected works of I. P. Dolbnya, published in French by resolution of the Council of the Mining Institute of Empress Catherine II under the title "Oeuvres mathématiques de Jean Dolbnia," the famous French mathematician Gaston Darboux, in particular, wrote: "The distinguished geometer, whose works I have the honor to present to the Academy, was during his lifetime Professor of Analysis at the St. Petersburg Mining Academy, of which he had been a brilliant student; but the majority of his works were published in French in our mathematical collections and principally in the Bulletin of Mathematical Sciences. By deciding to gather them into a single volume and thus present them as a whole, the Mining Academy has rendered a real service to mathematical studies. The works of Dolbnya do honor to his country."