Page:St. Nicholas, vol. 40.1 (1912-1913).djvu/663

length of the day of Venus is not much different from that of our own day. One thing is certain, it has a dense atmosphere, like the earth. Its year is 225 of our days.

The great nebula in Andromeda
Photographed through a forty-inch refractor telescope. Exposure four hours.

The great nebula in Andromeda

This object, which is visible to the naked eye as a dim spot of light, was known long before the invention of the telescope. Not very much was revealed even when great telescopes were turned upon it. It simply became an elongated mass of light having a small, central nucleus, with some suggestions of the rifts that are now shown, by photography, to be spaces between a magnificent system of rings that surround the central body.

Its nature was long a baffling subject, even after the spectroscope was applied to its study, because of the extreme difficulty of the observations. But the spectroscope finally prevailed, and we now look upon it as a magnificent system of stars, a universe possibly on the plan of our own stellar system, and at an enormous distance from us. Much has yet to be learned concerning its nature before we can decide definitely on its make-up and real magnitude. It seems definitely proved, however, that it is not a great mass of gas like the great nebula of Orion.

Edward Emerson Barnard,
Astronomer of the Yerkes Observatory,
University of Chicago.

A water-valve nine feet in diameter

This nine-foot valve is one of five built for the Ontario Power Company of Niagara Falls, Canada. They are used to control hydraulic turbines generating 12,000 horse-power each. The valves are operated by a fifteen-horse-power electric motor, arranged to be controlled from a distant station. The diameter of the waterway is nine feet. In each of these giant valves there are 4000 pounds of bronze, 18,000 pounds of steel plug, and 110,000 pounds of cast-iron. The motor