402 Biographical Account of {Dec. 
time news of your progress. I have a feeling which informs me 
that you will go far; but I cannot live long enough to enjoy your 
success.” 
Nothing more was necessary to induce Bossut to go to Paris. 
Fontenelle received him kindly, and recommended him to Clairaut 
and d’Alembert, who were prodigal in their encouragements. 
D’Alembert in particular chose him more especially for his pupil, 
and took a pleasure in removing the difficulties which might have 
retarded his progress. ‘Time cemented this union, founded on the 
one hand on the attachment which results from benefits conferred, 
and on the~other from-the justest and most lively gratitude. This 
friendship subsisted, without interruption, till the death of d’Alem- 
bert. Bossut had particularly studied the writings of his master ; 
and when any person applied to d’Alembert for explanations of a 
difficult passage, which would have obliged him to read over again 
his memoir with attention, he sent him to his disciple and confi- 
dent, saying to him, “ Call upon Bossut.” 
Camus, another academician, Examiner of the Pupils of Artil- 
lery and Engineers, conceived for him the same affection, and in- 
troduced him to Comte d’Argenson, Minister at War, who named 
him Professor of Mathematics in the School of Engineers at 
Mezieres. This was in 1752, when Bossut was scarcely 22 years 
of age. 
About the end of the same year the Academy admitted him into 
the number of its Correspondents. A memoir of his had been 
read, entitled, Uses of the Differentiation of Parameters for the 
Solution of different Problems in the inverse Method of Tangents. 
in giving an account of this memoir, inserted in the second volume 
of the Savans Etrangers, the historian of the Academy says, that 
we find in it the solution of divers problems proposed by John 
Bernoulli, the first of which had not hitherto been resolved by any 
person. In speaking of the methods of Bossut, he adds, that they 
appear short and elegant. He gives the same opinion of two other 
problems, constituting a second memoir published in the same 
volume. 
The Leipsic Acts had in 1752 announced a theorem of Euler on 
the rectifiable difference of certain elliptic arcs, Bossut, in demon- 
strating it, joined a simple and direct method for discovering this 
theorem a priori. In the same volume (iii.) he applied to different 
problems concerning the cycloid, a method which was then judged 
so much the more ingenious that it is not confined to problems alone, 
Lut may serve likewise on many other occasions. 
The duty of Professor of Mathematics, to which he devoted 
himself for 16 years, without interruption, and with a success 
always increasing, at the school of Mezieres, did not prevent him 
from making himself known by a number of works, the subjects of 
which were either pointed out to him by his lectures, or by the 
labours of contemporary mathematicians, or by the prizes of the 
Academy. Thus he drew ‘up at first his Elements of Mechanics, 
