The importance of cleanliness in cities, and of purity in the waters by which they are supplied, will more properly fall under consideration in another division of our subject; but we may here generally observe, that no circumstance contributes in a greater degree to the public health than an attention to this branch of medical jurisprudence. The deleterious influence of stagnant waters is too apparent to admit controversy, in which are to be included moats, where the water has no motion, and meadows which are occasionally overflowed; it has accordingly been the policy of every enlightened country to provide adequate resources for its drainage, and those liberal individuals who have encouraged the plans for its accomplishment have ever been distinguished by the gratitude of the people. It has been conjectured, and not without probability, that the patriotism of _Marcus Curtius_ is thus handed down to us in a figurative allusion, and that he probably filled up, at his own cost, some stagnant pools which affected the health of his fellow citizens. _Empedocles_, a disciple of _Pythagoras_, delivered the Salentines from the dangerous exhalations with which they were infested, by conducting two neighbouring rivers through their marshes, by which the stagnant waters were carried off; the air was therefore no longer infected, and the diseases which had flowed from this source immediately subsided. In ancient Rome, the physical evils which have since so materially contributed to deprive it of its former salubrity and splendour, were obviated by magnificent aqueducts. The slaughtering of cattle is another very important object in relation to the public health of a great city, and we cannot but wish that some police regulations were established that might mitigate the serious evils so often experienced from this circumstance, in most of the large towns of the British empire.