

/. Locke on the Electro-Chronograph. 241 



16. Lieutenant Maury's Letter announcing officially Dr. 

 Lockers invention to the Hon. John Y. Mason, Secretary of 

 the Navy. (From the National Intelligencer of June 8th, 

 1849, and dated, National Observatory, Washington, Janu- 

 ary 5, 1849.) 



I have the honor of making known to you a most important 

 discovery for astronomy which has been made by Dr. Locke, of 

 Ohio, and of asking authority from you to avail myself of it for 

 the use and purposes of this Observatory. 



The discovery consists in the invention of a magnetic clock, 

 by means of which seconds of time may be divided into hun- 

 dredths with as much accuracy and precision as the machinist 

 with rule and compass can subdivide an inch of space. 



Nor do its powers end here. They are such that the astron- 

 omer in New Orleans, St. Louis, Boston, and any other place 

 to which the magnetic telegraph reaches, may make his observa- 

 tions, and, at the same moment, cause this clock, here in Wash- 

 ington, to record the instant with wonderful precision. 



Thus the astronomer in Boston observes the transit of a star as 

 it flits through the field of his instrument, and crosses the meridian 

 of that place. Instead of looking at a clock before him, and 

 noting the time in the usual way, he touches a key, and the clock 

 here subdivides his seconds to the minutest fraction, and records 

 the time with unerring accuracy. 



The astronomer in Washington waits for the same star to 

 cross his meridian, and, as it does, Dr. Locke's magnetic clock 

 is again touched ;* it divides the seconds and records the time 

 for him with equal precision. The difference between these 

 two times is the longitude of Boston from the meridian of 

 Washington. 



The astronomer in New Orleans and St. Louis and every other 

 place within the reach of the magnetic wires, may wait for the 

 same star, and as it comes to their meridian, they have but to 

 touch the key, and straightway this central magnetic clock tells 



their longitude. 



And thus this problem, which has vexed astronomers and navi- 

 gators, and perplexed the world for ages, is reduced at once, by 

 American ingenuity, to a form and method the most simple and 

 accurate. While the process is so much simplified, the results 

 are greatly refined. In one night the longitude may now be 

 determined with far more accuracy by means of a magnetic tel- 

 egraph and clock, than it can by years of observation according 

 to any other method that has ever been tried. 



* The clock itself need not be touched, for it may be a thousand mile* away from 

 e observer. The b» ik-cimrit key n.u-t b* touched, as in Lt. Maury 9 nest para- 



the 

 graph. 



• 



Second Series, Vol. VIII, No. 23.— Sept., 1549. 31 



