If the site of Rome with its other concomitants be considered, we shall readily understand why pestilences were there so rife. It is situated in a level country on the low banks of the Tiber, surrounded by the extensive Ostiensian and Pontine marshes, exposed to the powerful rays of the sun, and subject to inundations and other commotions of the elements; further the inhabitants having been constantly engaged in war, did not cultivate their lands sufficiently to produce food for half the population, nor had they any established commercial intercourse with other countries, from which they could be supplied in times of scarcity. From their perpetual inroads agriculture was also interrupted among all the adjoining nations, and the far-famed Romans were often reduced to the necessity of feeding upon grass, leaves, and unwholesome roots, or of consuming the provender stored for their cattle, till men and beasts, and, it is said, birds and fish, perished together, so pestilential were the seasons; “vulgato per omne genus animalium morbo.” I might go on multiplying authorities _ad infinitum_ to show that previously to the middle of the seventeenth century those ages were full of physical and political miseries, sufficient to account for the frequent outbreak of fatal maladies; and we shall also find that subsequently to that period all those countries that have adopted judicious regulations in the construction of their dwellings, in widening their streets, improving the drainage, and securing an adequate supply of the three grand essentials to vitality,--light, air, and water, have proportionately experienced a corresponding immunity from pestilence, a notable exemplification of which we have in this our own country, although we are far, very far, in this the nineteenth century, from the improved condition that our wealth and the repeated warnings of disease which have been vouchsafed us, especially since the year 1832,--now nearly twenty years,--should have given rise to.