156 Proceedings of Societies. 
also, filled her house with the brimstone odour, and so firmly im- 
pressed her with the belief that the Monument had been struck, 
that she sent out her servant “to see if the time-ball was still at 
the top of the building ;” believing that if mischief had occurred 
anywhere from lightning, it would be near the summit of the 
structure. The answer, however, brought back was, that the time- 
ball was quite safe, but that sparks were coming out of the roof of 
the low west room. ‘The policeman of the hill was likewise on 
the ground almost immediately after the flash, and testified both 
to the then sudden appearance of sparks issuing from the roof of the 
uninhabited room, and its accompaniment,by the traditional sul- 
phurous smell in the air of strong lightning, or ‘ ozone.” 
The door of the Monument was then speedily opened, access to 
the roof obtained, and the new-lit fire, caused by the burning of gas 
and wooden rafters, speedily extinguished. In this manner the gas, 
no doubt, after it was set on fire, did much mischief to both leaden 
roof and wooden rafters, especially at the place on the sketch 
marked B, which contains big and rather confused holes; but if 
any one still asks what first set the gas on fire, I think there is 
equally little doubt that we may answer “it was that particular 
slanting flash of local and ozone-producing lightning which excited 
the residents on the hill so much at the time.” 
We may probably also assume that the lightning struck at the 
point A. I had already been directed to that point from the 
similarity of the hole there, to a lightning hole inisand, but could 
uot imagine why the fluid should have pierced a hole through 
a good conductor, viz., a sheet of lead. On mentioning this diffi- 
culty to Professor Tait, he remarked, ‘ that if the hole was due to 
the immediate action of the spark, I might be quite sure that there 
was a conductor below, which the lightning was trying to get at 
and pass off by,” and after that opinion had “been 80 expressed, the 
lead was lifted at the place (it had previously only been raised at 
B), and the gas-pipe was found precisely there at its closest point 
of approach anywhere to the roof, as may be seen clearly repre- 
sented in the assistant architect’s subsequent and independent 
drawing.* 
However anomalous, therefore, the case may appear at first, some 
theoretical principles are remarkably borne out by it; and that the 
foot of the building should have been struck, and not the top, seems 
to follow from the low, level and almost horizontal direction in 
which the lightning was sensibly observed to come, and with the 
wind and rain,—causing thereby the windward foot of the tall 
building to become for that occasion the shortest passage for the 
fluid to reach the ground by. 
* Professor Tait has also remarked, and it seems well worthy to be noted 
as a memorandum for any future occasion, that it would have been advisable 
to have preserved the boarding at “A,” as well as the lead; for the manner 
of action and of piercing through wood by lightning is very different to the 
burning action of flame; and thick wooden planking was everywhere inter- 
posed between the gas-pipe and the leaden roof. 
