To perform such service satisfactorily, skilled labor must be employed. No student of general science, much less a common artisan, was qualified to undertake this investigation into the causes of disease; however patent these causes might be, he had no power to appreciate their real significance. Minds trained by education, and long experience in observing and treating the diseases of the laboring classes, could alone thoroughly and properly accomplish the work proposed. [Sidenote: The Medical Experts] Happily, experts were at hand and prepared to enter upon the task, viz.: the dispensary physicians. The daily duties of these practitioners have been for years to practice among the poor, and study minutely their diseases; and thus they have gained an extensive and accurate knowledge of the sanitary and social condition of the mass of the people. Many of these practitioners have been engaged in dispensary service, and in a single district, for ten to twenty years. They have thus become so familiar with the poor of their district, though often numbering 40,000 to 50,000, that they know the peculiarities of each house, the class of disease prevalent each month of the year, and to a large extent the habits, character, etc., of the families which occupy them. From this class of medical men the Council selected, as far as possible, its corps of Inspectors. As a body, they represent the best medical talent of the junior portion of the profession of New York. Many occupy high social positions, and all were men of refinement, education, and devotion to duty. They entered upon the work with the utmost enthusiasm; engaging in it as a purely scientific study. Everywhere the people welcomed the Inspectors, invited them to examine their homes, and gave them the most ample details. [Sidenote: Plan of Inspection] The plan of inspection adopted by the Council was as follows: The city was divided into thirty-one districts and an Inspector selected for each, care being taken to assign to each inspector a district with which he was most familiar. The Inspector was directed to commence his inspection by first traversing the whole district, to learn its general and topographical peculiarities. He was then to take up the squares in detail, examining them consecutively as they lie in belts. Commencing at a given corner of his district, he was first to go around the square and note: 1. Nature of the ground. 2. Drainage and sewerage. 3. Number of houses in the square. 4. Vacant lots and their sanitary condition. 5. Courts and alleys. 6. Rear buildings. 7. Number of tenement houses. 11. Drinking shops, brothels, gambling saloons, etc. 12. Stores and markets. 13. Factories, schools, crowded buildings. 14. Slaughter-houses (describe particularly). 15. Bone and offal nuisances. 16. Stables, etc. 17. Churches and school edifices.