by Douglass' successor, Chief Engineer John B. Jervis. The Croton River was dammed, aqueducts were built, tunnels dug, piping laid, and reservoirs created. The gravity-fed aqueduct dropped 13 inches per mile, 1/4" per 100' (~0.02%). An elliptical tube, 8.5 feet (2.6m) high by 7.5 feet (2.3m) wide, of iron piping encased in brick masonry was laid, sometimes in cuts, with conical ventilating towers every mile or so, to relieve pressure and keep the water fresh. Hydraulic cement was added where the aqueduct crossed rivers. It extended from the Old Croton Dam in northern Westchester County to the Harlem River, where it continued over the High Bridge at 173rd Street and down the West Side of Manhattan and finally into a Receiving Reservoir located between 79th and 86th streets and Sixth and Seventh Avenues; the site is now the Great Lawn and Turtle Pond in Central Park. The Receiving Reservoir was a rectangular tank within fortress-like rusticated retaining walls, long and wide; it held up to of water. flowed into it daily from northern Westchester. The Full Flow, Design capacity, of the elliptical tube: 8201 CFM, or 88 MGD. From the Receiving Reservoir, water flowed down to the Croton Distributing Reservoir, better known simply as the Croton Reservoir, a similar fortified tank located on Fifth Avenue between 40th Street and 42nd Street, where the New York Public Library Main Branch and Bryant Park are located today. This reservoir was built to resemble ancient Egyptian architecture. New Yorkers came uptown for the fine view of the city obtained from atop its walls. The aqueduct opened to public use with great fanfare on October 14, 1842. The day-long celebration culminated in a fountain of water that spouted to a height of 50 feet (15 m) from the beautifully decorated cast iron Croton Fountain in City Hall Park. Among those present was James Renwick, Jr., who went on to design Grace Church in New York, the Smithsonian Institution Building in Washington, D.C., and St. Patrick's Cathedral in New York, and was involved in the architectural and engineering work on the aqueduct as an up-and-coming 18-year-old. Impact on the city Water started flowing through the aqueduct on June 22, 1842, taking 22 hours for gravity to take the water the 41 miles (66 km) (at a velocity of ) to reach Manhattan. Even though only 6,175 houses had been connected to the system by 1844,