Telescope

Assan Dina, Hindu millionaire, and his wife, formerly Miss Mary Wallace-Shillito, of Cincinnati, Ohio, will give to France the largest observatory in the world with a telescope more powerful than that on Mount Wilson, Calif.

The observatory will be erected on Mt. Saleve, on French territory, a few miles from Geneva. The total cost is estimated at $6,000,000. The diameter of the lens will be 105 inches; at Mt. Wilson it is 101 inches.

Meanwhile a photographic-telescopic excursion is to be made into the Southern Hemisphere, with an instrument 36 feet long, the largest ever to cross the Equator. It will be accompanied by observers chosen from the astronomers of Yale University. They are concerned chiefly with two problems: the determination of the stars and the directions of motions across the sky. The importance of this trip is due to the fact that one-third of the stars cannot be observed from north of the Equator, and many problems require observation from all parts of the sky for solution.

Said Dr. Schlesinger, director of the Yale University Observatory:

"The new Yale telescope, intended especially for photography, is nothing more than a camera 36 feet long. The principal lenses are 26 inches in diameter and average two inches in thickness. To secure good photographs, it is necessary that the telescope should exactly follow the stars. For this purpose, telescopes are provided with a mechanism for counteracting the effect of the rotation of the earth. Since the telescope must be rotated toward the west at the rate of one turn in 24 hours and this with great delicacy, the ball bearings on which the telescope moves must be of the highest type, and all parts of the telescope must be made with great precision. In addition the astronomer must provide his telescope with a special correcting device so that any irregularities in the mechanism can be at once compensated for by hand.

"For this purpose a ten-inch visual telescope is mounted on the same tube with the 26-inch camera lens. Through this the astronomer watches a faint star and counteracts every apparent displacement of the star from a fixed point by operating delicate motions up and down and right and left. In this way it is possible to secure star images on the photographic plate that are only about one-thousandth of an inch in size."