292 Hints on the use of Conducting Rods for Lightning. [Sept. 
It is easy to calculate the force of this machine, which will raise at every stroke of 
the lever a volume of water determined by the arc described by the flap D, its radius 
and the length of the cylinder A. The force required to move it will be as its 
velocity, and the weight of a column of water whose base is equal to the flap D, 
and its height that of the rising pipe. — Means should be taken to prevent any 
substances in foul water from clogging the valves. 
VIII. Hints on the use of Conducting Rods for Lightning. 
The violence of thunder storms, and the numerous accidents that occur in 
Bengal, render it an object of great importance to endeavour to prevent as much 
as possible the occurrence of fatal consequences from lightning. At this season 
few days pass without bringing us accounts of its fearful ravages. 
In this neighbourhood, within the last month, I have heard of six houses having 
been struck by lightning, which killed one man, and knocked down four others ; 
besides doing considerable damages to the premises. For these reasons I am « « 
suppose, that a few hints on the best method of averting this evil may not be unin ■ 
esting to your numerous readers, and may direct the attention of ot ieis 
important, and too much neglected subject. t 
This may be accounted for, by some people being incredulous as to their e ca j» 
and others, from ignorance, neglecting to erect them. So that we find many ^ 
houses both public 1 and private without them. In some instances, 1 un(ierS 
the rods have been removed, from the erroneous supposition that they ' uU 
gerous appendages, and likely to attract the lightning to the building:, 
would in all probability otherwise escape. Nor is the idea without some apj 
ance of truth, not from the inefficacy of the preventive means, but from the care^ 
manner in which the conducting rods are constructed and allowed to get in J ur j 
when they may convey the lightning in an improper direction. The inuti ^ ^ 
rods, when not well erected or allowed to get out of repair, was strongly ^ 
on my mind a few days since, when examining a house which had been stiuc ' ^ 
electric fluid a short time before, although there was a conductoi about 
from the part which had been struck. In this case a high semicircular v ^ 
close to the river attracted the electricity. It demolished part of the cornice, ^ 
itself and descended along two of the pillars : in one of them near the centre, ^ 
was found, to where it came to the level of an iron rail near the bottom- ^ 
it divided by the attraction of the iron on each side, and the pillar fell ro ^ 
point. It then passed through other pillars on the same level, leaving a sn, ° ^ j t0 
pearance, and a square hole, about a quarter of an inch each way ; descer 
the ground floor, burst open and shattered several doors, and knocked do«^ ^ 
servants. Such an example may be supposed to militate against the use 
ductors ; but on examining the situation and state of the rod, it imme ia 
plained its inutility. The pointed extremity was broken off, and the P ar ^ ^ 
should have been above the house was completely bent over the para ^ 
rod was fastened to the building by strong pieces of iron, and its inferior^ 
ty fixed in a large stone. This proves the necessity of attending to 
. ft 
1 The large dome of Government House in Calcutta may be instance ^ , 
markable example. Elevated above the buildings in the neighbourhoo ^ g r jtan n i* 
powerful conductor of electricity, on the top of which is placed a figuie ^tio* 
studded with iron prongs, as if to defy her Father’s thunder. Can sue 
he considered safe ? 
