EVANS

EVANS 13.09. 1755 Newport DE/USA 21.04. 1819 New York NY/USA Oliver Evans was apprenticed as a wheelwright. He invented at age 22 a machine for manufacturing the carding teeth used in textile industry. While working in the flour business he invented the grain elevator, conveyor and the hopper boy, automating the milling process to the point that a mill could be run by only one person. Around 1800 Evans refined the steam engines of the day, developing the first steam engine based on the high-pressure principle. Although he had been working on plans for a steam-powered carriage, he adapted his high-pressure steam engine to further improve the milling process, which had been normally powered by water wheels. In 1803 the Philadelphia Board of Heat commissioned Evans to build a steam-powered dredger, the first to be used in the USA. It consisted of a small steam engine and the machinery to raise the mud from the Schuylkill River. It was powered to move on land over wheels and in the river by means of a paddle wheel. This amphibious vehicle was the first in the USA in which steam power was used to propel a land carriage. He urged that his idea be adapted to move vehicles on rails of wood or iron and, although he lobbied for a railroad to be built between Philadelphia and New York, the country’s first commercial railroad track was not laid until the early 1830s, years after Evans’s death. He refined the steam engine throughout his life and initiated innovative manufacturing techniques. While he failed to develop his Orukter Amphibolos into a true steam-carriage or a true paddle wheel boat, Evans long maintained that he could have well created these conveyances. He grieved that the credit had gone to other inventors. Evans published in 1797 a book on his early inventions relating to milling techniques, and in 1805 The young engineers guide. Both books were translated into French. He also founded in 1811 the Pittsburgh Steam Engine Company, which in addition to engines made other heavy machinery and castings. The location of the factory in the Mississippi watershed was important in the development of the high-pressure steam engine for the use of river boats. While in New York City in 1819, he was informed that his workshop had burned to the ground in Philadelphia. Evans suffered from a stroke, and died soon after. Anonymous (1887). Oliver Evans and the steam engine. Scientific American Suppl. 24(620): 9896. Evans, O. (1805). The young engineer’s guide. Philadelphia. https://www.madehow.com/inventorbios/26/Oliver-Evans.html https://en.wikipedia.org/wiki/File:Oliver_Evans_(Engraving_by_W.G.Jackman,_cropped).jpg P

EWALD 12.06. 1881 Fairchild WI/USA 17.07. 1953 Mount Lebanon PA/USA Robert Franklin Ewald was educated at University of Wisconsin, with a BS degree in 1905, and the CE degree in 1915. He accepted in 1906 a position as assistant engineer to Daniel W. Mead (1862-1948), becoming in 1907 engineer within the US Bureau of Reclamation USBR. He joined in 1912 as engineer the Aluminium Company of America, where he then stayed all through his career. Ewald was a member of the American Society of Civil Engineers ASCE, and the Engineers Society of Western Pennsylvania. Ewald had interest in hydraulic engineering practice all through his career, being involved for instance in the construction of Cheoah Dam in Tennessee, and later in the preliminary planning of Fontana Dam, erected later by the Tennessee Valley Authority TVA. The 1931 paper deals with energy dissipation, as from the years after World War I became important due to increased dam heights. These flows contain an enormous hydraulic energy which must be dissipated at the dam toe, to avoid large-scale erosion and scour of the tailwater. Depending on the fall height and the tailwater topography, stilling basins were normally employed involving a hydraulic jump basin in which the hydraulic excess energy is considerably reduced. The paper gives a short overview on these hydraulic structures and presents the results made by a laboratory study. The 1916 discussion adds to the first important study of hydraulic jumps in the USA conducted by Karl R. Kennison (1886-1977). After hydraulic jumps have first technically been described in the early 19th century in Italy, the Frenchman Jean-Baptiste Bélanger (1790-1874) correctly applied the momentum equation in 1838 and determined the so-called sequent depths of the classic hydraulic jump. Kennison was one who checked this result using hydraulic observations, and found agreement also for large so-called approach flow Froude numbers. Anonymous (1906). Robert F. Ewald. The 1906 Badger 20: 70. Univ. Wisconsin: Madison. P Anonymous (1948). Ewald, Robert F. Who’s who in engineering 6: 608. Lewis: New York. Anonymous (1953). Robert F. Ewald. Engineering News-Record 151(Aug.13): 67. Dunham, H.F., Ewald, R.F. (1916). Discussion of The hydraulic jump in open channel flow at high velocity. Trans. ASCE 80: 390-404. Ewald, R.F. (1912). Historical report of office engineer, 1910 to 1911. USBR: Denver. (P) Ewald, R.F. (1931). Preventing erosion below overfall dams. Civil Engineering 1(6): 527-531. Ewald, R.F. (1948). Discussion of Saint Anthony Falls stilling basin. Trans. ASCE 113: 550-551. https://www.waterhistory.org/histories/strawberry/