428 THE FARMER AT HOME. 



arid are hence called conductors ; others not possessing this power are 

 called non-conductors. Metals, ores, and fluids, in their natural state, 

 excepting air and oils, are conductors ; vitrified and resinous substances, 

 amher, sulphur, wax, silk, cotton, and feathers, are non-conductors. 



From the similarity between lightning and the electric fluid, it had 

 long been supposed that they were one and the same thing ; but it 

 was left for Dr. Franklin to prove the truth of this supposition. When 

 the clouds and the different terrestrial objects, over which they pass, 

 are charged, one positively and the other negatively, in the passage of 

 this fluid from the former to the latter, there is presented what we call 

 lightning. So likewise, where two clouds come in contact, differently 

 charged, the same result takes place. Thunder is the report which 

 accompanies the taking place of this electrical union. It is occasioned 

 by the rarefaction or displacing of the air, and its sudden return to its 

 original position. Thunder and lightning bear the same relation to 

 each other, as the flash and report of a cannon. 



THUNDER ROD. This is a rod of metal attached generally to 

 the side of a building, and extending from below the level of the 

 ground, to a point several feet above the highest part of the roof of 

 the building, in order to secure the edifice from the effects of thunder 

 and lightning. The upper end of the rod terminates in a point, some- 

 times in several points. It is to Dr. Franklin that the world is in- 

 debted for the idea of raising pointed rods in order to secure buildings 

 from the effects of atmospherical electricity ; and the recommendation 

 was immediately adopted. These rods should be thick enough to con- 

 vey the electric fluid to the ground without being melted by it ; and 

 they should reach so far into the ground, as to relieve the building 

 from danger of receiving the fluid from the lower extremity of them. 

 It is surprising that so few farmers avail themselves of a protection 

 against one of the most fearful calamities to which they are always 

 liable, when several times every year they are shocked with the reports 

 of persons killed and valuable property destroyed by it. 



TILLAGE. This term, applied to arable land, signifies the stir- 

 ring and preparing the soil, so as to render it fit for the vegetation of 

 seeds ; and its object is to destroy the weeds as well as to make the 

 soil mellow. The whole art of cultivation consists in tillage and 

 manuring, and the profits of the husbandman depend on the perfection 

 of this process, and the economy 01 labor in producing his crops. A 

 defect in tillage, bad ploughing, or any other want of due preparation 

 of the soil, will cause a deficiency of his crops ; and, if such defect 

 be perpetuated for a course of years, most land will become incapable 

 of yielding enough to remunerate for the labor bestowed upon it. To 

 ensure remunerating crops, the soil should be in such a state that the 

 rains and dews may readily be diffused through it, without giving it a 

 wet appearance, or evaporating too rapidly. The effect of deep tillage 

 is most remarkable. This may be seen in the use of the spade upon 



