Read the excerpt from "Elevator Systems of the Eiffel Tower, 1889" by Robert M. Vogel.The first complete elevator machine in the United States, constructed in 1855, was a complex and inefficient contrivance built around an oscillating-cylinder steam engine. The advantages of an elevator system independent of the mill drive quickly became apparent, and by 1860 improved steam elevator machines were being produced in some quantity, but almost exclusively for freight service. It is not clear when the first elevator was installed explicitly for passenger service, but it was probably in 1857, when Otis placed one in a store on Broadway at Broome Street in New York.In the decade following the Civil War, tall buildings had just begun to emerge; and, although the skylines of the world’s great cities were still dominated by church spires, there was increasing activity in the development of elevator apparatus adapted to the transportation of people as well as of merchandise. Operators of hotels and stores gradually became aware of the commercial advantages to be gained by elevating their patrons even one or two floors above the ground, by machinery. The steam engine formed the foundation of the early elevator industry, but as building heights increased it was gradually replaced by hydraulic, and ultimately by electrical, systems.
Which phrase signals a cause-and-effect relationship?
According to The Evolution of Useful Things, what caused the popularity of Post-it notes?
Read the excerpt from The Evolution of Useful Things.Fry was committed to his brainchild, however, and he finally convinced an office-supply division of 3M to test-market the product, which "met an unperceived need." Early results were not at all promising, but in those cases where samples were distributed, customers became hooked.
Read this sentence from The Evolution of Useful Things.Making waterproof sandpaper would allow wet sanding, which in turn would cut down on dust, and thus be a great improvement.
Read the excerpt from The Evolution of Useful Things.The new two-tone style of painting automobiles was popular in 1925, but it presented considerable problems for auto manufacturers and body shops alike. In order to get a clean, sharp edge when applying a second paint color, the first had to be masked, of course, and this required that newspaper or butcher paper be fastened to the car body. If shop-brewed glue was used, it would sometimes stick so well that it had to be scraped off, more often than not pulling paint with it. Surgical adhesive tape was sometimes employed, but its cloth backing tended to absorb solvents from the newly sprayed paint and cause the masking materials to stick to the paint they were intended to protect. Clearly, existing means of masking had serious flaws.
Read the events that led to Art Fry's creation of temporarily permanent bookmarks described in The Evolution of Useful Things.Fry spent nearly a year and a half experimenting.Fry's idea was accepted as being commercially viable.Spencer Silver came upon a curious adhesive that he demonstrated to Fry.Fry reflected on the failure of bookmarks to do all that might be expected of them.
Read the excerpt from The Evolution of Useful Things.The laboratory in time made possible the research and development necessary to produce new and improved items in response to problems experienced by sandpaper users.
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