What was the result of this simple proceeding? Why, the mortality fell, from seventeen in a hundred, down to between five and six; and Dr. Collins gives us the result up to his time in these words, "Thus, by his valuable suggestions, 16,371 lives have been saved, as, had the mortality of infants continued one in six to this day (1833), the number of children dying of the 131,227 (which is the total number born in the hospital) would be 21,871, as the hospital registry now shows." In the battle of Waterloo, the British and their allies lost 16,186 men; that is, 185 less than the great army of very light infantry saved from death by letting out the smoke of the battle of life, and letting in the sweet air of heaven, through the walls of the Dublin hospital. So much for what air alone can do for children. Now, it is not the "nine-day fits" of that hospital in its unventilated condition which kills our poor children in the hot months, but that other disease of infancy, which to name is like sounding a funeral knell in the ears of many a parent. This one malady, more than any other, gives Boston its place on the black list of unhealthy towns. All parents having young children leave the city during the worst part of the sickly season, if they have the means of so doing. Our best streets look as DEFOE tells us London streets looked during the Great Plague. But thousands of families must remain; and we are bound to do what we can for them in their dearest interests,--the lives of their children. With regard to cholera-infantum,--the deadly scourge of which I have spoken,--the testimony of experience shows that change of air, even temporary, often effects the cure of which the apothecary, who "pestles a poisoned poison behind his crimson lights," cannot bring about with his drugs, though the wisest of physicians had written the prescription. This point is so important, and bears so directly, not only on the necessity of park-spaces, but upon their distribution so as to bring them within reach of all the crowded and unhealthy districts as far as possible, that I shall borrow a few sentences, enforcing it, from writers recognized as authorities on the diseases of children.