290 FERGUSON'S LECTURES. 



LECT. meridians, are laid down upon the globe in the manner 

 Vm.&.lX. already (] escr i5 e d. The ecliptic is divided into 12 

 signs, and each sign into 30 degrees, which are gene- 

 rally subdivided into halves, and into quarters if the 

 globe is large. Each tropic is 23i degrees, from the 

 equator, and each polar circle 23i degrees from its re- 

 spective pole. Circles are drawn parallel to the equa- 

 tor, at every ten degrees distance from it on each side 

 of the poles : these circles are called parallels of latitude. 

 On large globes there are circles drawn perpendicularly 

 through every tenth degree of the equator, intersecting 

 each other at the poles : but on globes of or under a 

 foot diameter, they are only drawn through every fif- 

 teenth degree of the equator ; these circles are generally 

 called meridians, sometimes circles of longitude, and at 

 other times hour-circles. 



The globe is hung in a brass ring, called the brazen 

 meridian; arid turns upon a wire in each pole sunk half 

 its thickness into one side of the meridian ring ; by 

 which means, that side of the ring divides the globe into 

 two equal parts, called the eastern and western hemispheres; 

 as the equator divides it into two equal parts, called the 

 northern arid southern hemispheres. This ring is divided 

 into 360 equal parts or degrees, on the side wherein the 

 axis of the globe turns. One half of these degrees are 

 numbered, and reckoned, from the equator to the poles, 

 where they end at 90 : their use is to shew the latitudes 

 of places. The degrees on the other half of the meri- 

 dian ring, are numbered from the poles to the equator, 

 where they end at 90 : their use is to shew how to 

 elevate either the north or south pole above the horizon, 

 according to the latitude of any given place, as it is 

 north or south of the equator. 



The brazen meridian is let into two notches made in 

 a broad flat ring, called the wooden horizon, the upper 

 surface of which divides the globe into two equal parts, 

 called the upper and lower hemispheres. One notch is 



