Efficient Points 



333 



The points for attracting the discharge 

 should be made very carefully, and with a view 

 to accommodating the brush discharge par- 

 ticularly. As a rule, the more 

 points in the bunch at the head 

 of the rod the better will the 

 brush discharge be attracted ; 

 and for the same reason these 

 points should be sharp and 

 bright. These facts have been 

 determined by experiment, from 

 which it has been learned that 

 the discharge is quieter and at 

 a lower pressure from sharp, 

 bright terminals than from others. 

 Aluminum wire fulfils the re- 

 quirements for the points better 

 than any other metal of reason- 

 able cost. Unfortunately this 

 metal is difficult to solder, but 

 if the directions here given are 

 carefully followed there will be 

 no difficulty in producing a good Fig. i.jg. ' Efficient pn„us 



bunch. ^^'" ^ lightning rod. 



The sketch (Fig. 136) shows the general con- 

 struction. In the end of a block of copper of 

 the dimensions shown, drill a hole % of an inch 

 in diameter and 1 inch deep. Cut off a number 

 of pieces of aluminum wire, of about 1-16 of an 



