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 in St. James's, the Green, and Hyde Parks, Kensington Gardens, and the Regent's Park, as pestilential nuisances to all around them? Besides, he states that _malaria_ is only generated in _hot weather_; so that the palace, being intended as a _winter_ residence, the health of our gracious sovereign will, we hope, not be endangered by his residence. That there is much show of reason in this objection, cannot be denied; at the same time it should be remembered, that in all great undertakings the conflicting prejudices and caprices of private interests generally work too prominent a part: hence, opinions should be entertained with caution.