_Clarke's Essay on the Usefulness of Mathematical Learning._--Can any of
the readers of "N. & Q." assist me in obtaining a copy of this work? In the
same author's _Rationale of Circulating Numbers_ (Murray, London, 1778) it
is stated that the demonstrations of all the theorems and problems at the
end of the Rev. John Lawson's _Dissertation on the Geometrical Analysis of
the Ancients_ "will be given at the latter end of _An Essay on the
Usefulness of Mathematical Learning_, which will soon be published." In a
subsequent portion of the work, a sketch of the contents of the _Essay_ is
given, which include "a Treatise on Magic Squares, translated from the
French of Frenicle, as published in _Les Ouvrages de Mathématique par
Messieurs de l'Académie Royale des Sciences_, with several Additions and
Remarks." And in a list of "Tracts and Translations _written and published_
by H. Clarke, LL.D.," which occurs at the end of my copy of the first
volume of Leybourn's _Mathematical Repository_ (London, 1805), the _Essay_
appears as No. 10, and is stated to have been published in 8vo. at six
shillings. None of my friends are acquainted with the work; but if the
preceding description will enable any reader to help me to a copy, I shall
esteem it a great favour.