290 HISTORY OF ASTRONOMY. 



Similar arrangements might be adopted in every large 

 commercial city. If, for example, there was a public ob- 

 servatory in the neighborhood of New York, a clock at 

 the observatory might be made every day, by means of 

 an electric current, to drop a time-ball on the Merchants 7 

 Exchange or the City Hall, another on Brooklyn Heights, 

 another on Staten Island, and another at Sandy Hook ; 

 as well as at any other point where public convenience 

 might require. It might also maintain in motion a 

 sympathetic galvanic clock at the City Hall, at the 

 Custom-house, at the Exchange, and at every railway 

 station in the city a clock which should never differ by 

 an appreciable quantity from perfectly accurate time. 

 Such a system would contribute not a little to the security 

 of commerce and the punctuality of business.* 



II. A second advantage to be derived from an astro- 

 nomical observatory is that, by extending our knowledge 

 of the heavenly bodies, it . directly contributes to the se- 

 curity of commerce. The prosperity of commerce depends 

 entirely upon the safety with which the ocean can t>e 

 navigated, and this depends upon the accuracy with 

 which a ship's place can be determined from day to day. 

 Had it not been for the labors of modern astronomers in 

 their observatories, vessels would still, as in ancient 

 times, creep timidly along the coast, afraid to venture out 

 of sight of land ; or if they were compelled to venture 



* Since the preceding was written, the officers of the Dudley observ- 

 atory at Albany have offered to furnish time for the city of New York, 

 substantially in the manner above suggested. 



