Article: In 1886, Frank Julian Sprague invented the first practical DC motor, a non-sparking motor that maintained relatively constant speed under variable loads. Other Sprague electric inventions about this time greatly improved grid electric distribution (prior work done while employed by Thomas Edison), allowed power from electric motors to be returned to the electric grid, provided for electric distribution to trolleys via overhead wires and the trolley pole, and provided controls systems for electric operations. This allowed Sprague to use electric motors to invent the first electric trolley system in 188788 in Richmond VA, the electric elevator and control system in 1892, and the electric subway with independently powered centrally controlled cars, which were first installed in 1892 in Chicago by the South Side Elevated Railway where it became popularly known as the "L". Sprague's motor and related inventions led to an explosion of interest and use in electric motors for industry, while almost simultaneously another great inventor was developing its primary competitor, which would become much more widespread. The development of electric motors of acceptable efficiency was delayed for several decades by failure to recognize the extreme importance of a relatively small air gap between rotor and stator. Efficient designs have a comparatively small air gap. [a] The St. Louis motor, long used in classrooms to illustrate motor principles, is extremely inefficient for the same reason, as well as appearing nothing like a modern motor.

Question: What was the name of Chicago's first electric trolley system?
Ans: South Side Elevated Railway

Article: In 1845, Ireland was hit by a potato blight. In the next four years over a million Irish people died and another million emigrated in what became known as the Great Famine. In Ireland, Victoria was labelled "The Famine Queen". She personally donated 2,000 to famine relief, more than any other individual donor, and also supported the Maynooth Grant to a Roman Catholic seminary in Ireland, despite Protestant opposition. The story that she donated only 5 in aid to the Irish, and on the same day gave the same amount to Battersea Dogs Home, was a myth generated towards the end of the 19th century.

Question: How long did the Great Famine last?
Ans: four years

Article: While the French army under General MacMahon engaged the German 3rd Army at the Battle of Worth, the German 1st Army under Steinmetz finished their advance west from Saarbrucken. A patrol from the German 2nd Army under Prince Friedrich Karl of Prussia spotted decoy fires close and Frossard's army farther off on a distant plateau south of the town of Spicheren, and took this as a sign of Frossard's retreat. Ignoring Moltke's plan again, both German armies attacked Frossard's French 2nd Corps, fortified between Spicheren and Forbach.

Question: Who commanded the French army at the battle of Worth?
Ans: General MacMahon

Article: During the Miocene continents continued to drift toward their present positions. Of the modern geologic features, only the land bridge between South America and North America was absent, the subduction zone along the Pacific Ocean margin of South America caused the rise of the Andes and the southward extension of the Meso-American peninsula. India continued to collide with Asia. The Tethys Seaway continued to shrink and then disappeared as Africa collided with Eurasia in the Turkish-Arabian region between 19 and 12 Ma (ICS 2004). Subsequent uplift of mountains in the western Mediterranean region and a global fall in sea levels combined to cause a temporary drying up of the Mediterranean Sea resulting in the Messinian salinity crisis near the end of the Miocene.

Question: Which crisis occured towards the end of the Miocene period?
Ans:
Messinian salinity crisis