I shall only take notice of one assertion more, it being both tedious and unnecessary to follow him through the whole. “From _every_ record of epidemic and pestilential diseases, it would appear, that they have their stated periods of recurrence; that these periods are such months as are most remarkable for vicissitudes of the atmosphere; that they become general only in those years in which these vicissitudes are extreme; that they do not occur in seasons when the heats or colds, however intense, are equable; nor in years when the state of the atmosphere is tempered throughout; and that they uniformly cease with the establishment of an equable state of the atmosphere, whether the weather be cold or hot.... In Aleppo, according to Dr. Russel, the Europeans regularly shut themselves up in their houses _every year_, at some period between April and July; and the rich natives begin to adopt the same plan, &c.... From this fact it appears, that the plague occurs at Aleppo, in a state more or less mild, almost annually, and _that it commences and ceases at certain known periods_. But it has been remarked that, in its most severe state, this disease recurs only at periods of ten years, or _thereabouts_: a regularity which cannot, upon any known principle, be attributed to a power of such casual application as contagious matter.” In the beginning of this paragraph our author makes a bold appeal to _every_ record of epidemic and pestilential disorders; but here we may ask, Has he consulted _every_ record of these disorders? That he has not, we may readily believe; but even those which are hinted at seem either to have been very inaccurately consulted, or wilfully misrepresented. To evince this I subjoin the following abstract of what Dr. Alexander Russel says of the plague in general, with the annotations of his brother, Dr. Patrick, taken from Russel’s Natural History of Aleppo. The inhabitants of Aleppo suppose that the plague visits them once in ten years, and that it is always imported; and the most severe plagues are thought by some to come from Damascus, while others contend that they come from the northward. Dr. Alexander Russel thinks this popular opinion of the return of the plague not altogether unfounded; and he thinks it also probable that it never invades Aleppo without having previously attacked either Damascus or Khillis, Aintab, Marash or Uufa. He thinks that its appearance always is in one of the maritime towns of Syria; if in Sidon, Byroot or Tripoli, Damascus is commonly the channel by which it reaches Aleppo; but, if it shows itself first at Scanderoon or Byass, its approach is by the way of Khillis or Aintab.