FARMERS' IN^STITUTES. 237 



peddlers by this rule? It may be that a tender solicitude for your worldly pros- 

 perity is the main motive that influences the patent-right agent to offer you a 

 splendid chance to make your pile by buying his patent. It may be a sudden 

 sympathy for your overburdened wife that leads the sewing-machine man to 

 offer you a machine for $100 that actually cost only $15. It may be that an 

 overwhelming fear lest "your beautiful wife and dear blessed children should 

 suddenly be destroyed by liglitning'" that leads him to offer you "the neatest, 

 safest, and most scientific lightning-rod the world ever saw for only $75," which 

 actually cost — you don't know how little. It may be that in entertaining these 

 smoothed-tongued gentry we are ''entertaining angels unawares," but in a busi- 

 ness point of view it will not be financially sound to proceed on this " angels' - 

 visit" basis. Their motives are too transparently benevolent, for we have no 

 authentic account of angels having an inordinate appetite for greenbacks. 



Xow do not understand me to say that patent rights are all a humbug, that 

 sewing machines arc useless, or that lightning rods are of no worth, I simply 

 call your attention to the motive which leads these men to so persistently urge 

 their wares upon your notice. I will not charge the lightning-rod peddlers 

 with uro-insf the sale of their wares with an amount of cheek that has become 

 proverbial, — that they study every device to come it over you, appealing to your 

 vanity, your fear, your affection for your family, and even making your relig- 

 ious devotions a stepping-stone to their succesf?, — but will leave you to say 

 whether such things ever occur. Now, why tliis sudden and alarming interest 

 in your welfare? Does it not spring from enormous profits secured? Why 

 may you not put up your own rods and. save this profit for yourselves? 



I do not propose to discuss the cpiestion whether you should put lightning- 

 rods on your buildings, but if you have for any reason determined to put up 

 a rod, I will endeavor to tell you what kind of a rod to put up, and how to do it 

 with the least expense to yourself and the greatest security to your buildings. 



LIGHTNING-ROD. 



A lightning-rod is a metallic bar by which unusual and dangerous amount of 

 atmospheric electricity in the vicinity of your building may be safely conducted 

 to the earth and dissipated in it, without injury to the building or its contents. 

 Metals are used for this purpose, because metals as a class are good conductors 

 of electricity; that is, a metallic rod of sufficient size will safely transmit 

 through its substance a large quantity of electricity without being disrupted, 

 melted, or dangerously heated, while a bar of wood in the same circumstances 

 might be torn to fragments, or even set on fire. AYe find, therefore, that there 

 are two classes of substances : one will silently and safely conduct largo quanti- 

 ties of electricity ; the other will not, but when a very heavy shock of electricity 

 passes through it a kind of explosion takes place, and if the substance is a solid it 

 may be shattered by the shock. 



One of the best illustrations of non-conductors is cold, dry air ; but warm, 

 moist air is a much better conductor than dry, cold air, and this explains why 

 chimneys with a fire, and barns full of recently cut hay and grain, from 

 which ascend long columns of moist, warm aii', are so liable to bo struck by 

 lightning. These columns of warm vapor, extending hundreds of feet towards 

 the clouds, afford a readier passage of electricity to the earth, and serve to draw 

 down the lightning uj)on such buildings. 



While the metals are all classed as conductors, they differ greatly in their 

 conducting power. Silver is the best conductor, but it is too costly a metal to 



