THE FARMER AT HOME. 34 j 



which proceeds from the sun can be greatly increased. Indeed, the 

 intensity of temperature produced in this way is equal to that of the 

 hottest furnace. This is done, either by reflecting the sun's rays from 

 a concave polished mirror, or by concentrating or collecting them by 

 the refractive power of convex lenses, and directing the rays thus con- 

 centrated on the combustible body. 



If the rays of light, after passing through a medium, enter another 

 of a different density, perpendicular to its surface, they proceed through 

 this medium in their original direction. But if they enter obliquely 

 to the surface of a medium, either denser or rarer than v r hat they 

 moved in before, they are made to change their direction in passing 

 through that medium. If the medium they enter be denser, they 

 move through it in a direction nearer to the perpendicular drawn to 

 its surface. On the contrary, when light passes out of a denser into 

 a rarer medium, it moves in a direction farther from the perpendicu- 

 lar. To prove this, take an upright empty vessel into a darkened 

 room, which admits but a single beam of light obliquely through a 

 hole in a window shutter. Let the empty vessel stand on the floor, a 

 few feet in advance of the window which admits the light, and let it 

 be so arranged, that as the beam of light descends towards the floor, 

 it first passes over the top of the side of the vessel next the window, 

 and strikes the bottom on the side farthest from the window. Let the 

 spot where it falls be marked. Now, on filling the vessel with water, 

 the ray, instead of striking the original spot, will fall considerably 

 nearer the side towards the window. 



REAPING MACHINE. The tedious process of reaping or 

 cutting the different kinds of grain by a sickle is well remembered. 

 The labor required being generally at a season of the year when the 

 heat of the sun is the most oppressive, the toil is proportionally more 

 severe. The introduction of the cradle as a substitute of the sickle 

 was indeed a great attainment to the extensive grain culturer ; but to 

 such as have from twenty to two or three hundred acres to be cradled, 

 the toil was enormous. Nor was this the only evil to be alleviated. 

 As soon as grain becomes ripe it should all be cut and harvested 

 without delay. If it becomes overripe, or if wet by showers after 

 being cut, the damage may become great to the crop. To cut these 

 large fields by hand, and to harvest them without being damaged from 

 wet or over-ripeness, is not ordinarily to be accomplished. Laborers 

 enough to do it is among the impossibilities of the case. The inven- 

 tion, therefore, of reaping machines, to relieve laborers from such 

 severity of toil, and to save grain from loss and damage, is one of the 

 most important acquisitions to agriculture that has been made. 



Several reaping machines have been presented to the public, of 

 varying shades of merit ; but, as good as they all may be, it seems 

 now to be an admitted fact, the machine of McCormick takes prece- 

 dence. So it may be inferred from the success attending its mission. 



