19th century in science Carnot captured some of the ideas of thermodynamics in his discussion of the efficiency of an idealized engine. Sadi Carnot's work provided a basis for the formulation of the first law of thermodynamics—a restatement of the law of conservation of energy—which was stated around 1850 by William Thomson, later known as Lord Kelvin, and Rudolf Clausius. Lord Kelvin, who had extended the concept of absolute zero from gases to all substances in 1848, drew upon the engineering theory of Lazare Carnot, Sadi Carnot, and Émile Clapeyron–as well as the experimentation of James Prescott Joule on the interchangeability of mechanical, chemical,
19th-century turnpikes in Massachusetts 19th-century turnpikes in Massachusetts In the late 18th century and early 19th century, turnpikes, as opposed to ordinary roads of the same time, were roads where gates barred travelers from continuing and at which payments were demanded for the use of the road. The word "turnpike" itself comes from the fact that these gates, called "pikes," were "turned" once the toll was paid. The privilege of building and operating turnpikes was conferred by the state legislature to "turnpike corporations". Turnpikes were constructed using private capital, were privately owned, and were operated for revenue from toll collection. The turnpike era in