Wisconsin State Agricultural Society. 103 
does often fall upon rods explosively. This takes place when by 
wind the charged cloud is suddenly brought within striking dis¬ 
tance of the rod before there is time for the electricity to be con¬ 
ducted off silently. 
That lightning-rods may be so constructed as to protect any 
building, and all within, from the fearful thunder-bolt, does not ad¬ 
mit of reasonable doubt. On this point it is sufficient to quote the 
language of Prof. Henry, the highest living authority on this sub¬ 
ject. He says; u In a house properly provided with lightning-rods, 
however many discharges may fall upon it, we are well assured from 
full experience and established principles, no damage can ensue to 
the occupants within. There is perhaps no edifice in the country 
more exposed to explosive discharges of lightning than the Smith¬ 
sonian building. It is situated on a plain at considerable distance 
from any other building, at present without trees near it, except 
of a few years growth, and surmounted with nine towers of hights 
varying from 60 to 150 feet. Five of these are provided with light¬ 
ning-rods, and although we should have advised the furnishing of a 
rod to each tower, yet thus far the building has escaped unscathed, 
although several explosive discharges have passed down the rods.” 
It is not enough to have a fine looking rod upon a building. It 
must conform to the principles we have endeavored to set forth, 
otherwise it may actually invite the thunder-bolt. We believe that 
rods as commonly put up by traveling agents, are, to say the least, for 
the most part, worthless. 
We shall close this long paper by some 
/ 
PRACTICAL DIRECTIONS IN REGARD TO THE CONSTRUCTION AND PUT¬ 
TING UP OF LIGHTNING-RODS. 
1. The rod should be of good conducting material. Though copper 
is a better conductor, an iron rod having sufficient conducting sur¬ 
face, answers every purpose, and is much cheaper. 
2. The best form is the cylindrical, because in a rod of this form 
every part of the surface is equally conductive, and its capacity is as 
its surface or diameter. If the rod be of iron, the diameter should 
not be less than an inch; it need not be solid. 
3. The rod should be continuous. There should be as few parts as 
possible, and these should have perfect metallic connection. The 
joints should be carefully protected from moisture to prevent rust. 
