7 5 
construction of gas apparatus, would, however, be attended 
with great inconvenience and expense, and moreover, would 
not avert other dangers incident to the disruptive discharge 
from the conductor to the gas and water pipes within a 
building. I have therefore recommended that in all cases 
where lightning conductors are attached to buildings, fitted 
up with gas and water pipes, the lower extremity of the 
lightning conductor should be bound in good metallic con- 
tact with one or other of such pipes outside the building. 
By attending to this precaution the disruptive discharge 
between the lightning conductor and the gas and water 
pipes is prevented, and the fusible metal pipes in the 
interior of the building are placed out of the influence of 
the lightning discharge. 
Objections have been raised by some corporations to the 
establishment of metallic connexion between lightning con- 
ductors and gas mains, on the ground that damage might 
arise from ignition and explosion. These objections are most 
irrational, as gas will not ignite and explode unless mixed 
with atmospheric air, and the passage of lightning along 
continuous metallic conductors, will not ignite gas even 
when mixed with air. Moreover, in every case of the ignition 
of gas by lightning, the discharge is actually transmitted 
along the mains, such objections notwithstanding. A grave 
responsibility therefore rests upon those, who, after intro- 
ducing a source of danger into a building, raise obstacles 
to the adoption of measures for averting this danger. 
Dr. Joule remarked that, at 20 minute past 4, when the 
hail storm was at its height, the atmosphere was illuminated 
