100-inch telescope

In no science is the advance of instrumentation as important and as dramatic as in astronomy. In 1917 a new reflecting telescope was put into action on Mount Wilson, near Pasadena, California. Its mirror was 100 inches across, which made it the largest telescope in the world at that time, and it was to remain the largest for three decades.
 United States 1917 100-inch telescope

In no science is the advance of instrumentation as important and as dramatic as in astronomy. In 1917 a new reflecting telescope was put into action on Mount Wilson, near Pasadena, California. Its mirror was 100 inches across, which made it the largest telescope in the world at that time, and it was to remain the largest for three decades.