8 LATITUDE AND LONGITUDE. 



15 degrees an hour, 6 degrees, 51 minutes, 45 seconds. 

 It is in this way, by knowing the difference of time 

 between two places, we can determine their distance 

 east or west of each other. 



From this, it is evident that all the methods which 

 have been proposed for determining the longitude, 

 depend upon one general principle, viz. " The com- 

 parison of the relative times under two different mer- 

 idians ;" so that if the time under a given meridian 

 was known, and also the time under any other mer- 

 idian, the difference of those times turned into degrees 

 and minutes, at the ratio of 15 degrees to an hour, 

 would give the longitude ; and if the time observed 

 was greater than the known time we should have 

 east longitude, if less, west longitude. 



METHODS EMPLOYED. We can now readily un- 

 derstand, the two general methods employed for 

 finding the longitude : 



1st. By having a chronometer (or nautical watch,) 

 so beautifully constructed, that it shall go uniformly, 

 without stopping, during a long voyage, notwith- 

 standing the agitation of a ship and changes of 

 temperature. By help of such a machine, we could 

 at any instant determine our longitude : for having 

 it well regulated at the time of departure, we could 

 always ascertain the real time under that meridian, 

 and therefore, when the time under any other mer- 

 idian was found and compared with that shewn by 

 the time-keeper, the longitude might be imme- 

 diately ascertained. 



To effect this purpose, Chronometers, by the ex- 

 ertions of many ingenious artists, have been brought 

 to an astonishing degree of, perfection, and have 

 become most valuable acquisitions to Navigators. 



To be continued. 



