The Midnight Sun. 97 



wire through, its flattened poles, carry it steadily round a candle 

 or lamp placed in the centre of a table, taking care to slant 

 the wire about a fourth of the distance from the table to the 

 celling, and always keeping the point in the same direction. 

 At one part of the revolution the orange should be lifted a little 

 above the level of the flame, and at the opposite point a little 

 depressed. At the two opposite intermediate points only 

 should the orange and flame be in the same plane. If we now 

 examine the effects of the light upon the orange in its revolu- 

 tion, we shall get an exact representation of the sun's effect upon 

 the earth, and to show this accurately, let us notice particularly 

 four different positions in detail. First, if the orange be in one 

 of the positions level with the flame, it will correspond with 

 the earth in the northern spring, when the sun is exactly at the 

 same distance from both poles, and affects each hemisphere 

 alike — this being about the 21st of March; by the 23rd of June 

 the earth (or orange) will have moved to the point in its orbit 

 most depressed below the level of the sun (or flame), and the 

 north pole is then nearer to the sun than the south, and the 

 northern hemisphere receives a greater amount of heat than 

 is received by the southern — constituting the northern summer. 

 If we note carefully the rays of light falling on the orange, it 

 will be seen that in this position they extend over and beyond 

 the north pole, while the south pole remains altogether unen- 

 lightened, so that, notwithstanding the rotation of the earth 

 on its axis, the day will be continuous at and near the 

 north pole, while it will be constant night in the opposite 

 regions of the south. 



Proceeding with the illustration we arrive at another of the 

 equinoctial positions, corresponding to the northern autumn, 

 on the 21st of September, when the hemispheres are again 

 equally lighted, and the day and night again equal. Lastly, 

 from the 21st of September to the 21st of December, the 

 earth progresses to her position above the plane of the sun, and 

 the orange will then be above the level of the flame. Here 

 the north pole is turned away from the sun, while the south 

 pole inclines towards it ; hence the northern polo and hemi- 

 sphere receive a much smaller portion of light and heat than 

 the southern, and it is therefore to us winter, while the south 

 is enjoying its summer. It is a singular circumstance, that in 

 consequence of the eccentricity of the earth's orbit, we are 

 really nearer to the sun in our northern winter than in the 

 summer, by about three millions of miles ; but this is so small 

 a space in proportion to the whole distance of the earth from 

 the sun, and its consequences are so far outweighed by the 

 more important results of long days and short nights, with 

 greater verticality of rays, that its effect is immaterial. 



