and Walnut Sts after the American Civil War. This hospital consisted of 35 beds and a dispensary. The second hospital was the site of the first surgery at CHOP which was first performed by 1870. In addition, the first resident physician at CHOP was appointed in 1873 and formal medical teaching in medical and surgical clinics began in 1877. Early on in CHOP's history, a long-term care ("convalescent") facility was opened as a County Branch near Overbrook. In 1899 the County Branch convalescent facility was closed and the program and patients transferred to the Seashore House near Atlantic City, New Jersey. CHOP later underwent an expansion and capacity was increased to 94 beds by 1892. A nursing school, the Ingersoll Training School, was opened in 1894. In 1900 the Catherwood Milk Laboratory was established. In 1914 the first Department for the Prevention of Disease in the nation was established. Third hospital 1916–74 Construction adjacent to the second hospital began in 1913 and the first unit was opened in 1916 extending toward 18th and Bainbridge Streets. In 1919 the hospital became affiliated with the University of Pennsylvania School of Medicine. The affiliation became steadily closer over the next 17 years, with the Children's Hospital becoming identical to the pediatric department of the school of medicine, with most of the attending physicians appointed jointly to both institutions. In 1925 the hospital became affiliated with the Philadelphia Child Guidance Clinic. Whooping cough (pertussis) vaccine was first developed. The first formal allocation of funds to research was recorded in 1937. The first closed incubator for newborns was used. The nursing school was disbanded in 1945 and converted into an affiliate training center. A six-story research building next to the hospital was dedicated in 1954. In 1962 under Dr. C. Everett Koop (later to be Surgeon General), the first neonatal intensive care unit (NICU) in the nation was opened, along with a new neonatal surgical unit. In 1965 the first home care program for children was established. A Clinical Research Center under the auspices of the National Institutes of Health was opened in 1965. In 1967, after years of lobbying hospital physician and anesthesiologist, Dr. John Downes finally opened up a pediatric intensive care unit (PICU) at CHOP, the first of its kind in the United States. Downes was inspired by pediatric and adult intensive care units in Europe and wanted to open a state-of-the-art