ASTRONOMY. 229 



It is still dropped in Washington near noon, and has long furnished the 

 standard time for the city and the departments of the Government. 



In !N^ew York City a time-ball was established in 1877, dropped by an 

 electric signal sent from the Naval Observatory at Washington. It 

 was erected on the plans of Prof. E. S. Holden, and is maintained by 

 the Western Union Telegraph Company, and is dropped from a staff on 

 the tower of their building on Broadway. 



At 11.55 the ball is hoisted half way up the staff on the tower. At 

 11.58 it is hoisted to its highest point, when it is about 250 feet above 

 the street, and can be seen by the shipping at the New York and Brook- 

 lyn docks, and vessels in the bay, and from suitable positions is visible 

 to a large portion of the citizens of New York, Brooklyn, Hoboken and 

 Jersey City. 



A time-ball at Boston, Mass., is dropped at noon of the latitude of 

 that city by means of the noon signal from the standard clock of the 

 Harvard College Observatory. It is placed in the large building of the 

 Equitable Life Assurance Company, and was put up and maintained 

 by that company at a cost of some $1,200. The ball itself in this case 

 is of copper and 'weighs 250 pounds. 



A time-ball has lately been established from the plans of Dr. L. Waldo 

 at "Hartford, Conn., dropped by the Winchester Observatory of Yale 

 College. 



At St. Louis, Mo., another has been recently established. 



At Kansas City another is dropped as a part of the time service of 

 the Morrison Observatory under the direction of Professor Pritchett, at 

 the expense of the city, and is highly commended. When raised the 

 ball is lifted about 140 feet above the street, and is generally visible to 

 the citizens of all parts of the city. 



The ball itself is about three feet in diameter, made of a wire skeleton 

 frame, covered with canvas, and painted black. To give it weight so as 

 to drop with the needed celerity it is loaded inside with lead. It has a 

 drop of about twenty five feet and falls on a set of steel springs. 



The manner of dropping these balls is extremely simple, and consists 

 of withdrawing a steel pin by means of a magnet touched at the exact 

 moment desired by the operator, whereupon the ball falls instantly. 



ASTRONOMICAL BIBLIOGRAPHY. 



The admirable Catalogue g6n6rale of Messrs. Houzeau and Lancaster is 

 being issued in parts, and it is certain to prove of great use. 



The second part of the Catalogus Lihrorum of the Pulkova Observa- 

 tory has been received in America (printed in 1880). It is edited by 

 Lindemann. This volume is on the same excellent plan as its prede- 

 cessor, and its arrangement renders it priceless to the student of the 

 history of astronomy. Tlie growth of this unrivalled library may be 

 exhibited by the following figures: 



In 1845 there were 4,150 volumes, CO maps, 3,109 dissertations. 



