204 STATE BOARD OF AGRICULTURE. 



permanently damp earth which is generally reached 8 or 10 feet below 

 the surface. 



Lightning meets with high resistance when discharged into dry ground. 

 This fact is curiously illustrated when a heavy discharge strikes the 

 sand dunes common to the shores of the great lakes. The tremendous 

 resistance met by the lightning as it bores its way downward, fuses the 

 sand into a vitrefied tube, which is sometimes called by the name 

 Thunderbolt. 



There is a stratum of clay under the college farm which is 

 from 6 to 9 feet below the surface. Holes for the "grounds" were 

 bored from one to two feet into the clay, depending upon the 

 depth of the stratum, thus providing a good place for moisture to 

 collect at the lower end of the "ground." The holes were bored by 

 the use of an old 1" wood auger welded to a long y^" square iron 

 rod. The auger was sunk into the earth by means of a handle 24 

 inches long made from a piece of V square iron. A %" square hole 

 was punched in the center of this handle through which the rod could 

 slide. The handle could be fastened any place along the rod by means 

 of a rough thumb screw made by flattening the head of a short %'' ma- 

 chine bolt. When such an arrangement is not accessible, the hole for the 

 "ground" can be easily made by driving a common 1 inch wrought- 

 iron pipe into the earth and drawing it out again by means of a short 

 chain and any piece of timber acting as a lever. The lower end of the 

 pipe should be hammered to a chisel-like point. This will make it 

 easy to drive the rod and to force aside any small stones. A crowbar 

 is often useful in starting the upper part of the hole. In filling in 

 about the cable, only fine sand was used, a pailful of water being 

 first poured in about the cable to help the sand pack together. The 

 best "ground" is secured when that part of the cable under the surface 

 of the earth is in close contact with the soil throughout its whole 

 length. With two exceptions, the barns protected from lightning have 

 three "grounds" each; one going to ground at the center of the barn. 

 The horse barn has two grounds, and the pure herd barn has four. 

 It may be said here that one good "ground" is better than two poor 

 ones. 



The method of connecting the center "ground" to the horizontal cable 

 running along the ridge board is illustrated by No. 1 Figure 2, where 

 the cable coming up the roof from the center "ground" is fastened in the 

 y^" galvanized tee by a %" setscrew % of an inch long, setscrews not 

 shown in figure. The tee is drilled (5-16 inch drill) and tapped for 

 two %'' setscrews, one to hold the horizontal cable and one to fasten 

 the cable running down the roof to the ground. 



METHOD OF SPLICING CABLE. 



If for any reason, the cable must be spliced, it can be quickly accom- 

 plished as shown in No. 3 of Figure 2, which simply represents a piece 

 of V2' galvanized iron pipe, G inches long, drilled and tapped for four 

 %'' setscrews, one set being drilled "on the quarter" with the other 

 set. The ends of the cables are inserted in the pipe until they touch 

 at the center and each end is then securely fastened by two setscrews. 



