THE LATITUDES AND LONGITUDES, 



ively of giving results which, in the circumstances of the case, have the gieat- 

 est attainable accuracy. 



TO FIND THE LATITUDE. 



Let us suppose the globe of the earth to be represented at O, and let N be its 

 north pole, and E its equator ; let P be a place upon it, whose latitude, that is, 

 whose distance from the equator is to be determined. Let n Z e. represent the 

 firmament surrounding the globe at an indefinite distance. The point n, imme- 

 diately over the north pole, and which is in fact, the continuation of the line 

 N will be the place of the north pole in the heavens, very near to which is a 

 star, called the Polar star. The point e, in the continuation of the line O E, 

 will be that which is directly over the equator and will be that point in the 

 heavens, representing the position of the equator and the point Z, in v'ie 

 continuation of the line O P, the point of the heavens which is directly 

 over the observer at the place P, will be that which is called his zenith. This 

 point is that to which a plumb line would direct itself. 



Now the points n, Z, and e, are the points in the firmament which correspond 

 with the points N, P, and E, upon the earth, and it is evident that whatever 

 arcs of the terrestrial meridian N P E are included between these points, 

 similar arcs of the celestial meridian must be included between the points n 

 Z e. If, then, P E were 40, Z e must also be 40, just as n e is 90, while 

 N E is also 9(P. 



In short, the zenith of any place in the heavens is the point in the firmament 

 which corresponds with the position of the place on the g.obe, and the distance of 



