The existing calendar of diseases, studied in connection with the classical history of the diseases written for us by the longest unbroken line of authorities in the world of letters, shows, in unmistakable language, that the imposition of every known malady of man is coeval with every phase of his recorded life on the planet.  No malady, once originated, has ever actually died out; many remain as potent as ever.  That wasting fatal scourge, pulmonary consumption, is the same in character as when Coelius Aurelianus gave it description.  The cancer of to-day is the cancer known to Paulus Eginaeta.  The Black Death, though its name is gone, lingers in malignant typhus.  The great plague of Athens is the modern great plague of England, scarlet fever.  The dancing mania of the Middle Ages and the convulsionary epidemic of Montmartre, subdued in their violence, are still to be seen in some American communities, and even at this hour in the New Forest of England.  Small-pox, when the blessed protection of vaccination is withdrawn, is the same virulent destroyer as it was when the Arabian Rhazes defined it.  Ague lurks yet in our own island, and, albeit the physician is not enriched by it, is in no symptom changed from the ague that Celsus knew so well.  Cholera, in its modern representation is more terrible a malady than its ancient type, in so far as we have knowledge of it from ancient learning.  And that fearful scourge, the great plague of Constantinople, the plague of hallucination and convulsion which raged in the Fifth Century of our era, has in our time, under the new names of tetanoid fever and cerebro-spinal meningitis, been met with here and in France, and in Massachusetts has, in the year 1873, laid 747 victims in the dust.

I must cease these illustrations, though I could extend them fairly over the whole chapter of disease, past and present.  Suffice it if I have proved the general propositions, that disease is now as it was in the beginning, except that in some examples of it it is less virulent; that the science for extinguishing any one disease has yet to be learned; that, as the bases of disease exist, untouched by civilisation, so the danger of disease is ever imminent, unless we specially provide against it; that the development of disease may occur with original virulence and fatality, and may at any moment be made active under accidental or systematic ignorance.

A CITY OF HEALTH.

I now come to the design I have in hand.  Mr. Chadwick has many times told us that he could build a city that would give any stated mortality, from fifty, or any number more, to five, or perhaps some number less, in the thousand annually.  I believe Mr. Chadwick to be correct to the letter in this statement, and for that reason I have projected a city that shall show the lowest mortality.  I need not say that no such city exists, and you must pardon me for drawing upon your imaginations as I describe it.  Depicting