advantageous direction to national education, by making our young artist
familiar with the application of descriptive geometry, to the graphic
constructions which are necessary in the greater number of the arts, and
in making use of this geometry in the representation and determination
of the elements of machinery, by means of which, man by the aid of the
forces of nature, reserves for himself, in a manner, in his operations
no other labour than that of his intellects. It is no less advantageous
to extend the knowledge of those phenomena of nature which may be turned
to the profit of the arts. The charm which accompanies them will
overcome the repugnance that men have in general for manual operations,
(which most regard as painful and laborious,) as it will make them find
pleasure in the exercise of their intellect; thus there ought to be in
the formal school a course of descriptive geometry.

As yet we have no well compiled elementary work on that art, because
till this time learned men have taken too little interest in it, or it
has only been practised in an obscure manner by persons whose education
had not been sufficiently extended, and were unable to communicate the
result of their lucubrations. A course simply oral would be absolutely
without effect. It is necessary then, for the course of descriptive
geometry, that practice and execution be joined to the hearing of
methods; thus pupils will be exercised in graphic construction of
descriptive geometry. The graphic arts have general methods with which
we can only become familiar by the use of the rule and compass. Among
the different applications that may be made of descriptive geometry,
there are _two_ which are remarkable, both for their universality and
their ingenuity; these are the constructions of _perspective_ and the
strict determination of the _shadows_. These two parts may finally be
considered as the completion of the art of describing objects.