It proved superior to anything which had preceded it, and was at once ‘autorisé par le conseil de l'instruction publique’, 3 July 1846.
The twenty-ninth edition, in two volumes, appeared in 1884 (remodelled by H. Witcomb, Spiers's successor at the École des Ponts et Chaussées), and it remained for a long time a standard dictionary.
[1] In November 1857 he brought an action against Léon Contanseau and his publishers, Longmans & Co., for violating the copyright of his dictionaries in a work entitled A Practical Dictionary of the French and English Languages’ but Vice-chancellor Sir William Page Wood (afterwards Lord Hatherley), in his decision on 25 February 1858, said that, although great use of Spiers's books had been made without due acknowledgement, yet in regard to such publications, which were not entirely original, a charge of piracy could not be sustained.
Besides his Dictionary, Spiers's chief publications were:[1] All these works were issued in both English and French editions in London, Paris, and America (New York or Philadelphia).
Spiers also printed and edited for French students Sheridan's The School for Scandal and The Essays of F. Bacon, Viscount St. Albans (1851).