"Would you not like to have for the use of the Library a good air-pump, with all the apparatus belonging to it, and the improvements invented by members of the Royal Society? I will send you shortly the books about it, the price and a list of everything belonging to it. Three have been sent to Russia; for there are many Russians here. They mostly study mathematics and navigation, adapting themselves to the taste of their chief, who took a wonderful interest in these subjects during his visit here. The Czar purchased, also, from Mr. Edmund Halley, for eighty pounds, his 'incomparable quadrant,' which he used in discovering the southern stars at St. Helena; and with which he took pretty good observations of the moon and the planets in 1683, 1684, and other years.
"I visit daily the best mathematicians here in town. I have been with Flamsteed, who is considered the best astronomer in England, and who is constantly taking observations, which, together with the Paris observations, will give us some day a correct theory respecting the motion of the moon and of its appulse to the fixed stars; and with its help there may be found a true longitude at sea. He has found that the motion of the moon has as yet by no means been well determined; that all theoretical lunar tables are very imperfect; and that the same errors or deviations which are noticed in an earlier period of eighteen years and eleven days, occur again afterwards."
In view of Swedenborg's later career, as a student and teacher of theological science,—upon which his earlier studies must be presumed to have had their influence,—it may not be without profit to read the observations of one of his eminent French contemporaries, upon the judgment passed upon mathematical studies, in which Swedenborg was so proficient, by two of the most popular and illustrious theological teachers of the preceding generation. D'Alembert, in his Eloge of Bossuet, says:
"Of all the profane studies, that of mathematics was the only one which the young ecclesiastic believed he
- Œuvres de D'Alembert, vol. 2, p. 247.