equable temperature and extremely dry. The roofs of
magnificent buildings should be of materials not likely to be dissolved
by water or changed by air. Many electrical conductors should be placed
so as to prevent the slow or the rapid effects of atmospheric
electricity. In painting, lapis lazuli or coloured hard glasses, in
which the oxides are not liable to change, should be used, and should be
laid on marble or stucco encased in stone, and no animal or vegetable
substances, except pure carbonaceous matter, should be used in the
pigments, and none should be mixed with the varnishes.

_Eub_.--Yet, when all is done that can be done in the work of
conservation, it is only producing a difference in the degree of
duration. And from the statements that our friend has made it is evident
that none of the works of a mortal being can be eternal, as none of the
combinations of a limited intellect can be infinite. The operations of
Nature, when slow, are no less sure; however man may for a time usurp
dominion over her, she is certain of recovering her empire. He converts
her rocks, her stones, her trees, into forms of palaces, houses, and
ships; he employs the metals found in the bosom of the earth as
instruments of power, and the sands and clays which constitute its
surface as ornaments and resources of luxury; he imprisons air by water,
and tortures water by fire to change or modify or destroy the natural
forms of things. But, in some lustrums his works begin to change, and in
a few centuries they decay and are in ruins; and his mighty temples,
framed as it were for immortal and divine purposes, and his bridges
formed of granite and ribbed with iron, and his walls for defence, and
the splendid monuments by which he has endeavoured to give eternity even
to his perishable remains, are gradually destroyed; and these structures,
which have resisted the waves of the ocean, the tempests of the sky, and
the stroke of the lightning, shall yield to the operation of the dews of
heaven, of frost, rain, vapour, and imperceptible atmospheric influences;
and, as the worm devours the lineaments of his mortal beauty, so the
lichens and the moss and the most insignificant plants shall feed upon
his columns and his pyramids, and the most humble and insignificant
insects shall undermine and sap the foundations of his colossal works,
and make their habitations amongst the ruins of his palaces and the
falling seats of his earthly glory.

_Ph