THE FARMER AT HOME. 493 



haps never before disturbed ; occasionally having to cut off roots and 

 move large stones, it is apparent that it should be strongly made ; the 

 materials of which it is composed to be of the best kind, whether 

 wood or iron. It is always to be drawn by four, and sometimes by 

 six oxen. Of course, unless firmly constructed, it is liable to be 

 broken. In our first attempt at subsoiling, the implement a new 

 one broke, and was completely disabled before the end of the first 

 hour. We now use one of the Worcester manufacture, by Ruggles, 

 Nourse & Mason ; if this breaks, we shall be much mistaken. The 

 oak used in its construction, seems to be wholly unyielding, whatever 

 force be applied to it. 



SUCCESSION OF DAY AND NIGHT. By the daily motion 

 of the earth on its axis, the same phenomena appear as if all the 

 celestial bodies turned round it ; so that in its rotation from west to 

 east, when the sun or a star just appears above the horizon, it is said 

 to be rising, and as the earth continues its revolution, it seems 

 gradually to ascend till it has reached its meridian ; here the object 

 has its greatest elevation, and begins to decline till it sets, or becomes 

 invisible on the western side. In the same manner the sun appears 

 to rise and run its course to the western horizon, where it disappears, 

 and night ensues, till it again illuminates the same part of the earth 

 in another diurnal revolution. 



One half of the earth's surface is constantly illuminated, and by 

 its regular diurnal motion, every place is successively brought into 

 light and immersed in darkness. If the axis of the earth were always 

 perpendicular to the plane of the ecliptic, the days would every where 

 be of the same length, and just as long as the nights. For an in- 

 habitant at the equator, and one on the same meridian towards the 

 poles, would come into the light at the same time, and on the other 

 side would immerge into darkness at the same time. And since the 

 motion of the earth is uniform, they would remain in the dark hemis- 

 phere just as long as in the light; that is, their day and night would 

 be equal the plane of -the ecliptic coinciding with the plane of the 

 equator. 



But as the ecliptic and equator make an angle with each other of 

 twenty-three and a half degrees, or in other words, as the axis of the 

 earth has such an inclination to the plane of its orbit, it is manifest 

 that, except the earth be in that part of its orbit where the ecliptic 

 cuts the equator, an inhabitant at the equator, and one on the same 

 meridian towards the poles, will not come into the light at the same 

 time, nor, on the other side, immerge into darkness, at the same time. 

 And since the axis of the earth always preserves the same inclination, 

 they will, except at the points where the two great circles intersect 

 each other, remain in the dark and light hemispheres at different 

 times ; that is, their day and night will be unequal. The points 

 where the equator cuts the ecliptic are the beginning of the signs 



