Wrought iron is infinitely more durable than wood, and once American foundries became sophisticated enough to handle such work, dozens of iron-bridge companies sprang into existence. The proud speciality of the Berlin Iron Bridge Company was its patented Parabolic Truss. Increasing use of steel in bridges had already rendered the truss obsolete when the patent was granted in 1878, but vigorous salesmen kept flogging it with considerable success well into the nineties. The arresting form can be seen below in an 1893 bridge at Norfolk, New York, and opposite in the splendid five-span vehicular bridge of 1885 that is still in use over the Merrimack River at Lowell, Massachusetts.