AONE ad ge 
On Lightning-Rods. 336 
Lighining-Rods for Churches, 
For a tower, the stem of the rod should rise 15 or 25 feet, 
according to the area: the domes and steeples of churches 
being usually much bigher than surrounding objects, do not 
require so high a conductor as buildings with extensive flat 
roofs. For the former, therefore, their : stems. rising six feet 
above the cross, or weathercock, will be sufficient ; and being 
light, may be easily fixed to them, without here | their ap- 
pearance, or interfering with the motions of the v 
Lightning-Rods for Powder-Magazines. 
These require to be constructed with the greatest care. 
They should not be placed on the buildings, but on poles, at 
six or ten feet distance. The stems should be about seven 
feet long, and the poles of such a height. that the stem ma 
rise fifteen or twenty feet above the building. It is also 2% 
viseable to have several lightaing-rods about each magazi 
If the magazine be in a tower, or other very lofty building, it 
may be sufficient to defend it by a double copper conductor, 
without any stem. This is done on the European continent. 
s the influence of this conductor will not extend beyond the 
building, it cannot attract the lightning from a distance, and 
will yet protect the magazine should it be struck. 
Lightning-Rods for Ships. 
The stem of a lightning-rod for a ship consists merely of a 
copper point, screwed into a round iron rod, entering the ex- 
tremity of the top-gallant mast. An iro n bar, connected with 
the foot of the round rod, descends ies 1e pole, and is 
terminated by a crook, or ring, to which the conductor of the 
ligittelagaed is attached, which in this case is formed of a 
metallic rope, connected at its lower extremity with a bar or 
plate of metal, and which latter is connected to the copper 
sheathing on the bottom of the vessel. Small vessels require 
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