Built to cross one of the steepest valleys along the Douro River, the Ponte Maria Pia was the first major work to emerge from the French firm of Gustav Eiffel and Company, establishing Eiffel as an important bridge designer and civil engineer of his day. Resting on a parabolic arch spanning 160 meters, the Ponte Maria Pia was the longest iron arch bridge in the world at the time of its construction. The bridge's latticework construction reflects the later design of the well-known Eiffel Tower, erected in Paris to commemorate the International Exposition of 1900.
In the 1850s, the Lexington and Danville Railroad began building a suspension bridge over the Kentucky River. The bridge was designed by John A Roebling. Due to unforeseen increases in train loads, the Roebling bridge was never completed. The High Bridge would then be built 20 years later on the existing foundations.
Edison's simple and unprecedented instrument allowed for the first time the permanent recording and reproduction of sound, especially the human voice. On December 6, 1877, Edison put tinfoil around the cylinder, turned the handle of the shaft and, shouting into one of the diaphragms, recorded a verse of Mary Had a Little Lamb "almost perfectly." From this machine evolved the phonographs and record industries of the world.
Designed by Sam Diescher, son-in-law of the Monongahela's designer John Endres, the Duquesne Incline opened May 20, 1877, as the second of seventeen built and operated in the Pittsburgh area. It has operated with only minor interruptions for the last one hundred years. A preservation group from Duquesne Heights and Mount Washington interceded in 1962 to refurbish this incline to working order. Like the Monongahela, the Duquesne was steam powered and then converted to electric and updated with modern safety devices.