"Even in cases in which a removal to a healthy and airy situation in the country is impracticable," says Dr. CONDIE of Philadelphia, long and well known by his writings, "much benefit may be derived from carrying the patient frequently into the open air in a carriage, or in the arms, or, when its residence is near a large river, sailing it daily in an open boat." And Dr. JOHN BELL of the same city says, "The restorative effects of fresh air in cholera-infantum are strikingly evinced in the relief procured by many hundreds of children every summer in Philadelphia, by their simply crossing and recrossing the River Delaware in steamboats once or twice a day. New life is restored to the little beings, who, on leaving their homes in the city, seemed almost exanimate, and in the last stage of incurable exhaustion." Dr. JAMES STEWART of New York, in his treatise on the diseases of children, and our own honored patriarch of the profession, the late Dr. JAMES JACKSON, in his letters to a young physician, speak in similar terms of the great advantage of change of place and of air. The "aquatic jaunts" recommended by Dr. STEWART, and spoken of as so efficacious by Dr. BELL, are among the advantages to be secured by the plan proposed by our Park Commissioners. I wish twenty tons of little children could be shipped every fine summer day for a good sail. There is one particular region which I will mention as like to be specially benefited by the plan referred to,--a region which would get the advantages of the fresh air coming over the wide estuary of Charles River without the expense and trouble of taking boats. The narrow and crowded streets of the northern slope of Beacon Hill, and a wide region extending northward from it, are inhabited by the very class most exposed to cholera-infantum and diseases of that nature. Having lived for many years in Charles Street, where I am no longer an owner, I had occasion to learn the incomparable comfort and delight to be got in a hot summer's day, when the wind is from the southwest, by turning the corner of Charles and Cambridge Streets, and getting into the current of air cooled by passing over the water. Some of the poor mothers with sick children had found out where to bring them for relief; and I often thought, if there were an open green filling up that corner, with shade trees and seats, what a priceless _sanatorium_ it would be to all that suffering quarter of the city! The proposed green margin, beginning at Leverett Street, and extending along the river, will meet this very want; and this is only one locality of many which will thus turn its natural advantages to account.