Existing comment:
"Indeed, in the construction of an instrument [lightning rod] so new, and of which we could have so little experience, it is rather lucky that we should at first be so near the truth as we seem to be, and commit so few errors."
-- Benjamin Franklin, Autobiography
Ungrounded vs. Grounded:
Franklin's experiments demonstrated the importance of grounding a lightning rod. Grounded rods were, in Franklin's words, "protective" devices. Ungrounded rods, on the other hand, were used for studying the characteristics of thunderstorm electricity, in all of its brute and fiery power.
Thunder House:
Late 18th century
Thunder houses vividly demonstrated the protective effects of grounded rods and were used by Ebenezer Kinnersley in his sensational but educational lectures. A model building was filled with gunpowder and equipped with a lightning rod that could be grounded or ungrounded. Applying a spark to the grounded rod, the charge would pass through the house without harm. But a spark applied to the ungrounded rod would ignite the gunpowder, blow the roof off the house, and flatted the four walls in a fiery explosion. |