EULER 
ther, who was thén a widow, and to conduct her to Euler, 
Berlin, where she remained till the time of her death in, Leonard, 
that_ it would occupy of our: to give 
remain teiahiattonnion of debi. We i ddeotove: 
content ourselves with referring the reader to the articles 
Acuromatic TeLescopes, ALGrpra, ARITHMETIC of 
many of his memoirs have no value whatever, except in 
so far as they exhibit fine of the resources of 
matic Telescopes, on Naval Architecture, and on Gun- 
', are among the number of those which are liable 
tothe om 
matical class of the y, and in the same year he 
obtained the piece ps Sp Anatomy of Sciences 
of Paris, for the best work on the theory of magnetism. 
About this time Robin’s Treatise on Gunnery had ap- 
peared in England, and though our cou had 
treated Euler with great severity, this act of injustice 
did not. prevent him from recommending it to the 
king of Prussia, as the best book on the subject. He 
seentennalatonl tis 00 in chee ome which he made, 
ve a comp! motion of projec- 
tiles. M Turgot pope gh work to be transla. 
tillery; and about the same time there appeared a 
splendid edition of it in England. 
In 1746, he published his new Theory of t and 
rs and in 1759, va memoir oath ack Hake 
at angaper gained. ize © rench 
Academy of Sciences. - ee 5 
In 1750, Euler went to Frankfort to receive his mos 
229 
1761 ; having enjoyed for 11 yearsthe assiduous atten- 
tions ofa favourite son, and the high’pleasure of seeing 
him universally esteemed and admired. 
When Euler remained at Berlin, he formed an in- 
timate acquaintance with M. De M is, the learn- 
ed President of the Prussian Academy of Sciences, and 
he defended Maupertuis’s celebrated and favourite-prin- 
ciple of the least action, by resolving by means of it 
some of the most difficult problems in mechanics. In 
the dispute into which he was thus led with Koenig; 
who had attacked Maupertuis in 1751, he lost for a 
while his usual serenity, and became one of the ene< 
mies of that unfortunate individual. 
Al h the number of foreign associates in the 
French Academy of Sciences was limited to eight, yet 
- Euler was appointed to the ninth place in 1755, on the 
condition that no appointment should take place at the 
first vacancy. 
In the year 1760, the Russian army under General 
Tottleben into the Marche of Brandenburg, 
and a farm which Euler possessed near Char: 
lottenberg. As soon as the Russian was in 
. formed of the event, he immediately repaired the loss 
bya large sum; and upon giving notice of the 
aimee to the Empress Elizabeth she added to 
this indemnity a present of four thousand florins. This 
act of ity, no doubt, had a powerful effect in 
attaching Euler to the Russian government, which, 
in spite of his absence, had always paid him the pen- 
sion which it at him in 1742, _ Having received 
an invitation the Empress Catherine, he obtained 
ission from the King of Prussia to return to St 
etersburg to spend the remainder of his days; but his 
eldest son was not allowed to accompany him. When 
Euler-was on the eve of his re, Prince Czartorisky 
invited him, in the name of the king of Poland, to take 
the road of Warsaw, where, | with kindness, he 
spent 10 days with Stanislaus, who afterwards honours 
ed him with his correspondence. 
Shortly after his arrival in St Petersburg, on the 17th 
July 1766, he lost the sight of his other eye, having 
been for a considerable time obliged to his 
calculations with characters, traced with chalk 
upon a slate. His pupils and his children copied his 
calculations, and wrote sithig.tmapanlentediotaieias 
dictated to them. To one of his servants, who was 
quite i t of mathematical knowledge, he dicta~ 
ted his Elements of Algebra, a work of v 
merit, which has been translated. into. the lish 
ey 2 other languages. .Euler now ired the 
rare ky of greys oni ot Tenens mioaticoes. 
prose analytical arithmetical calculations ; and. 
. d'Alembert, when he saw him at Berlin, was asto- 
nished at some examples of this kind which occurred 
in their conversation. With the design. of instructin 
his dchildren in the extraction of roots, he formed 
a table of the six first powers of all numbers, from 1 
to 100, and he recollected them with -the utmost ac- 
. Two of his pupils having computed -to the 
17th term, a complicated Cia: pp their results 
differed one unit in the fiftieth cypher ; and an appeal 
being made to Euler, he went over the calculation in 
his mind, and his decision was found correct. 
His principal amusement, after he lost his sight, was 
to make artificial loadstones, and to, give lessons on ma~ 
thematics to one of his grand-children, who seemed to 
evince a taste for the science, 
In 1771, a dreadful fire broke out in St Petersburg, 
