16 



GEOGRAPHICAL DEFINITIONS. 



mon centre, and which revolve about him, or 

 rather about the centre of gravity of the system. 



Solstice is that point of time in which the sun 

 is at his greatest distance from the equator, or 

 when he is in those points of the ecliptic which 

 touch the tropic of Cancer and Capricorn. 

 There are, therefore, two solstices in the year, 

 the one when the day is the longest, and the 

 other when it is the shortest. 



Sound is a small sea so shallow that it may be 

 sounded. 



South is one of the cardinal points of tiic 

 compass, and that which is opposed to north. 



Sphere, in geography, generally implies the 

 lelative positions of the equator and the horizon 

 at any point on the earth's surface. Or, as the 

 horizon varies with the position of the observer, 

 it implies the relation of his situation with re- 

 spect to the equator. As there can only be 

 three distinct positions of these two circles, so 

 tiicre are said to be three kinds of spheres. 

 When the equator and horizon intersect each 

 olner, at right angles, the position of the sphere 

 is called a right sphere, which can be the case 

 with those who live at the equator only. When 

 the equator coincides with the horizon, and the 

 parallels of latitude are parallel to it, the posi- 

 tion is denominated a parallel sphere. This can 

 only take place at the poles. In all other cases, 

 the equator and horizon intersect each other 

 obliquely, and then the position is called an ob- 

 lique sphere. 



Steppes are plains of great extent, and wholly 

 destitute of the larger species of vegetables. 

 This term is generally employed to denote 



plains of this kind in Europe and Asia, while 

 the words savanna and pampas signify the same 

 thing in America. 



Ttvilight is the faint light between perfect 

 day and complete night. It is occasioned by 

 the atmosphere refracting the rays of the sun 

 after he has descended below the horizon. Its 

 duration, therefore, varies not only with the lat- 

 itude of the place, but also with the time of the 

 year. 



Vale signifies an extent of low country lying 

 between ranges of higher ground. Vale and 

 valley have distinct and appropriate meanings ; 

 the word valley is the diminutive of vale. 



Volcano is a mountain which emits fire, 

 smoke, or ignited matter. The number of ac- 

 tive volcanoes on the globe is estimated at 

 about 200. 



fVind is a current of the atmosphere. There 

 are three kinds of winds, permanent, periodical, 

 and variable. The former blow between the 

 tropics, and are called trade winds. Periodical 

 winds, called monsoons, blow with great force 

 in one direction nearly half the year, and 

 towards the opposite point during the remainder. 

 Variable winds blow from every point of the 

 compass in the temperate regions of the globe. 



Year is that portion of time which the sun 

 occupies in passing through the 12 signs of the 

 zodiac, or rather, which the earth requires to 

 complete one revolution about the sun. 



Zone is a division of the earth's surface made 

 by two parallel circles. There are five of these 

 zones, the torrid zone, the two frigid zones, and 

 the two temperate zones. 



