Lectures on Elementary Mathematics is an 1898 translation by Thomas J. McCormack of lectures delivered in 1795 at the École Normale by Joseph Louis Lagrange. The book covers fractions and logarithms, solutions of quadratic, cubic, and quartic polynomials in radicals, numerical solutions of polynomial equations, and graphical methods.
The book is of historic interest for both content and context, yet also of mathematical interest for its perspectives on school algebra and coordinate geometry. Discussion of interpolation polynomials starts on page 131.
From the translator’s preface: The originality, elegance, and symmetrical character of these lectures have been pointed out by De Morgan, and notably by Dühring, who places them in the front rank of elementary expositions, as an exemplar of their kind. Coming, as they do, from one of the greatest mathematicians of modern times, and with all the excellencies which such a source implies, unique in their character as a reading-book in mathematics, and interwoven with historical and philosophical remarks of great helpfulness, they cannot fail to have a beneficent and stimulating influence.