Note 4 — Chapter II

In 1754 D'Alembert (1717-1783) published an article in the famous old Encyclopedia edited by Diderot and himself on Dimension. In this article the idea of the fourth dimension is dwelt upon at length. The view which he expressed in this article, of course, served greatly to popularize the conception among the learned men of the day, and owing to the close relationship existing between D'Alembert and La Grange, it is not surprising that the latter should have been very much enamored of the idea.