vapour, and that the pond will always be filled with vapour to the
level of the top of the dam. The only question is, how far this vapour
is entitled to be called _malaria_. We have the misfortune to be able
to answer that question experimentally.... A man must be something
less or more than a king, to keep his health in that palace for any
length of time."

On the subject of _malaria_, an Italian term for the produce of marshy
lands, the attention of the public has lately been powerfully excited
by a series of essays by Dr. Macculloch, an abstract of which will be
found at page 252, of our accompanying Number, under the head "Arcana
of Science." Dr. M. is supported in his opinion by Lord Bacon and
other philosophers; and he shows, that though it is commonly supposed
that standing waters, when clear and free from smell, and all running
waters, are perfectly salubrious, they may, in fact, be nearly as
injurious as those that are putrid and stagnant; "that, besides proper
marshes, fresh and salt meadows, and wet pasture lands generally, all
woods, coppices, thickets, rivers, lakes, ponds, _ornamental waters_,
pools, ditches--_plashy_ and _limited spots of ground generally_, &c.,
send forth more or less of this noxious vapour; that wherever, in
short, any chemical compound of the vegetable elements is wetted, or
held in solution by water, there the poison in question may be or will
be produced, _provided the temperature be sufficiently high_; that the
smallest spot coming under any of the above denominations is
sufficient to produce _malaria_, and _a single inspiration of that
malaria to produce disease_."

Such is the theory of Dr. Macculloch; but, as observed by a
contemporary, Why should he have observed any delicacy on this
subject?--why not have, long since, denounced the whole of the ponds