In connection with this subject, attention is called to the following extract from the Author’s Report on the Drainage, which accompanies the "Third Annual Report of the Board of Commissioners of the Central Park:" "In order to test the efficiency of the system of drainage employed on the Park, I have caused daily observations to be taken of the amount of water discharged from the principal drain of ’the Green,’ and have compared it with the amount of rain-fall. A portion of the record of those observations is herewith presented. "In the column headed ’Rain-Fall,’ the amount of water falling on one acre during the entire storm, is given in gallons. This is computed from the record of a rain-gauge kept on the Park. "Under the head of ’Discharge,’ the number of gallons of water drained from one acre during 24 hours is given. This is computed from observations taken, once a day or oftener, and supposes the discharge during the entire day to be the same as at the time of taking the observations. It is, consequently, but approximately correct: Date. Hour. Rain-fall. Discharge. Remarks. July 13. 10 a.m. 49,916 184 galls. Ground dry. galls. No rain since 3d inst.; 2 inches rain fell between 5.15 and 5.45 p.m. and 1-5th of an inch between 5.45 and 7.15. July 14. 6-1/2 " 4,968 " July 15. 6-1/2 " 1,325 " July 16. 8 " 1,104 " July 16. 6 p.m. 33,398 " 7,764 " Ground saturated at a depth of 2 feet when this rain commenced. July 17. 4,319 " July 18. 9 a.m. 2,208 " July 19. 7 " 1,325 " July 20. 6-1/2 " 993 " July 21. 11 " 662 " July 22. 6-1/2 " 560 " July 23. 10 " 1,698 " 515 " This slight rain only affected the ratio of decrease.