=963.= Two of his [Euler’s] pupils having computed to the 17th term, a complicated converging series, their results differed one unit in the fiftieth cipher; and an appeal being made to Euler, he went over the calculation in his mind, and his decision was found correct.--BREWSTER, DAVID. _Letters of Euler (New York, 1872), Vol. 2, p. 22._ =964.= In 1735 the solving of an astronomical problem, proposed by the Academy, for which several eminent mathematicians had demanded several months’ time, was achieved in three days by Euler with aid of improved methods of his own.... With still superior methods this same problem was solved by the illustrious Gauss in one hour.--CAJORI, F. _History of Mathematics (New York, 1897), p. 248._ =965.= Euler’s _Tentamen novae theorae musicae_ had no great success, as it contained too much geometry for musicians, and too much music for geometers.--FUSS, N. _Quoted by Brewster: Letters of Euler (New York, 1872), Vol. 1, p. 26._ =966.= Euler was a believer in God, downright and straight-forward. The following story is told by Thiebault, in his _Souvenirs de vingt ans de séjour à Berlin_, .... Thiebault says that he has no personal knowledge of the truth of the story, but that it was believed throughout the whole of the north of Europe. Diderot paid a visit to the Russian Court at the invitation of the Empress. He conversed very freely, and gave the younger members of the Court circle a good deal of lively atheism. The Empress was much amused, but some of her counsellors suggested that it might be desirable to check these expositions of doctrine. The Empress did not like to put a direct muzzle on her guest’s tongue, so the following plot was contrived. Diderot was informed that a learned mathematician was in possession of an algebraical demonstration of the existence of God, and would give it him before all the Court, if he desired to hear it. Diderot gladly consented: though the name of the mathematician is not given, it was Euler. He advanced toward Diderot, and said gravely, and in a tone of perfect conviction: a + b^n _Monsieur_, ------- = x, _donc Dieu existe; repondez!_ n Diderot, to whom algebra was Hebrew, was embarrassed and disconcerted; while peals of laughter rose on all sides. He asked permission to return to France at once, which was granted. --DE MORGAN, A. _Budget of Paradoxes (London, 1872), p. 251._