The steam boilers and machinery for the ironclad USS Monitor were built in DeLamater's Iron Works foundry during the American Civil War (1861-1865).[1] Swedish immigrants marine engineer and inventor John Ericsson considered DeLamater his closest, most intimate friend.[4] DeLamater's leisure moments were spent at his Beacon Farm on Eatons Neck, on Long Island, New York state where he had 1,250 acres (5.1 km2) of choice land on the North Shore of the western end of Long Island, and the "finest blooded stock in America" as described by the famed daily newspaper The New York Times.The children and grandchildren of DeLamater also built mansions over time in Eaton's Neck and Asharoken that still stand today, namely "The Point", "The Nest", "The Crest", and "The Hill".The DeLamaters also renovated two nearby smaller existing colonial structures for family estates, namely "Cherry Lawn" and "Oak Leaf".