BiRKS AND Webb. — Resistance of Earth Connections. 



473 



tant pipe was salted and tested, then the next nearer salted and tested,, 

 and so on, to avoid any interference-effect due to salted soil between. The 

 curve of retests after two or three days, when the soil between was more 

 or less impregnated with salt, is also shown. The introduction of the salt 

 has substantially reduced the resistance of the pipe earth, and has at the 

 same time very considerably flattened the curve of potential drop. 



8 16 . 24 32 



Distance betrreen p/pas in feet 



Fig. 3= 



Fig. 3a. 



Messrs. Liversidge and Creighton both record that salting had the effect 

 of reducing the resistance to about 50 per cent, of the original value. 

 Apparently the tests on which this statement is based were of earths of 

 fairly low initial resistance — i.e., below 150 ohms. 



On the majority of the pipe earths tested during the course of our inves- 

 tigations, with initial resistances ranging from 400 to 4,000 ohms, we found 

 much larger percentage reduction of the initial resistance as the result of 



