V. Rev.—Very Reverend.
yd.—yard.
yr.—year.
Acetylene Gas.—Acetylene gas is used largely for the search-lamps on automobiles. It is composed of carbon and hydrogen.
Adventists.—A religious sect whose members believe that the second coming of Christ is near at hand. There are over 100,000 communicants and ministers.
Æolian Harp.—This instrument was invented in the 17th century and was named after Æolus, the god of the winds. It is of the simplest construction, and its music is produced by the vibration of the strings automatically moved by the winds. In construction it is a rectangular box of thin boards of a few inches in depth and width and of sufficient length to extend across a window so that the breeze may pass through it. The strings are stretched lengthwise across the top of the box, and may be tuned by increasing or decreasing their tension.
Age.—About 50 per cent. of the persons living in the United States are under 20 years of age, 45 per cent. from 20 to 60 years, and 5 per cent. over 60 years, the average age being about 25 years. This average seems low, and is due largely to infant mortality. If the percentage was taken excluding those under 15 years of age it would be very much higher.
Agricultural Implement Industry.—Capital invested, about $260,000,000, and an annual output of about $150,000,000. About 60,000 people are employed.
Alaska.—Alaska is the only territory of the United States, the Hawaiian Islands, Porto Rico, and the Philippines being known as Possessions. It has an area of over 590,000 square miles, and a population of about 65,000. Its climate is semipolar.