Used chiefly as a demonstration apparatus, the Wimshurst machine is an electrostatic device capable of generating high voltages. The device has two large glass or mica discs that rotate in opposite directions, and each disc is in contact with a thin metal wiper that produces a charge on the disc by induction. The machine was named for its inventor, British engineer James Wimshurst, who developed it in the early 1880s. What defect in earlier electrostatic generators did Wimshurst eliminate?
Arthur Conan Doyle
Back in the day
Thousands of dusky seaside sparrows once inhabited the natural salt marshes around Merritt Island and the area along the St. Johns River in southern Florida. The non-migratory birds lived exclusively in this small area, and this proved to be their undoing. From the 1940s onward, pesticides, pollution, and habitat loss caused the subspecies' population to decline precipitously. By 1979, just six males remained. Why were the remaining birds eventually relocated to Walt Disney World theme park?
Born on a day like today
Edward became king upon the death of his father, Henry III, in 1272 but was not crowned until he returned from a crusade two years later. His 35-year reign was characterized by constant warfare, including long and costly campaigns to conquer Wales and Scotland. It was a struggle to fund these endeavors, and he did so, in part, by exploiting the Jews under his rule. Finally, in 1290, he expelled them from England and seized their property. For how long did his Edict of Expulsion remain in effect?