194 



STATE BOARD OF AGRICULTURE. 



Results of analyses of commercial fertilizers for 





3 



c 



o 



1531 

 1542 

 1532 

 1543 



Manufacturer and Trade Name. 



The Buffalo Fertilizek co. 



General Crop 



General Crop 



Ohio and Michigan Special. 

 Ohio and Michigan Special. . 



Buffalo, N. Y. : 



Nitrogen. 



Found. 



0.88 

 0.88 



Guar- 

 anteed. 



0.82 

 0.82 



THE PROTECTION OF BUILDINGS FROM LIGHTNING. 



A. R. SAWYER^ PROF. OF PHYSICS AND ELECTRICAL ENGINEERING. 



Bulletin No. 249. 



All the modern ideas on protecting buildings from lightnings are based 

 on the reports of the Research Committee appointed in Great Britain 

 a few years ago, which go to show that iron is preferred electrically 

 to copper, as a lightning rod. One objection to iron being that it is 

 liable to rust, therefore it is desirable to put the lightning rod up in 

 one piece. Secondly, it should be well grounded and it should protect 

 the highest part of the building. In regard to the first recommenda- 

 tion we find the following words: 



"Now, however, it is perceived that it is not so much quantity of 

 electricity that has to be attended to as electrical energy; that this 

 electrical energy is stored between clouds and earth in dangerous 

 amount, and that our object should be to dissipate it not as quickly 

 but as quietly as possible. A sudden dissipation of energy is always 

 violent. No one in his senses wi??hes to stop a fly wheel or a railway 

 train suddenly; sudden or hasty dissipation is not what is wanted. 

 Gun cotton possesses a store of potential energy locked up in it to a 

 dangerous extent; if it be dissipated suddenly, as by percussion, a 

 violent explosion results ; but if, it be dissipated gradually, as by a 

 flame, the energy is got rid of without much damage, beyond the liability 

 to fire. An armor plate maj' be able to stop a cannonball quickly, 

 but a heap of sand or loose earth does it more safely, because more 

 gradually. 



So it is exactly with the store of energy beneath an electrified cloud 

 or between one cloud and another. A lightning conductor of perfect 

 conductivity, if struck, would deal with the energy in too rapid and 

 sudden a manner, and the result would be equivalent to an explosion. 

 A conductor of moderately high resistance, such as an iron wire, would 

 get rid of it in a slower and therefore much safer and quieter manner, 

 though with too thin a wire there may be risk of fire. 



