Answer:
a machine used for imitation
Explanation:
To simulate is similar to imitate. In the passage, the machine allows the turtles to move their legs as if they were swimming. It copies the conditions turtles need to swim.
Simulators can be mechanical, as in the example, but there are also virtual simulators which are used in all kind of experiments, training, and leisure. Think of videogames or flight simulators.
John D. Rockefeller went into business when he was 20, and he picked up his first oil well as a sideline. He soon saw that that was the right horse to ride. Even before automobiles and airplanes laid their heavy claim on oil, it'd begun replacing coal in the power industries.
Andrew Carnegie makes the better hero. He, after all, was part and parcel of the emerging technologies that made our country. And his giving sprang from some deep-seated core of principle. Yet the Rockefeller clan assumed the mantle of public service. They've become political leaders and professional givers -- one died doing anthropological research in New Guinea.
