Those we found inconvenient in these respects: they admitted
no air below; the smoke, therefore, did not readily go out above,
but circulated in the globe, lodg'd on its inside, and soon
obstructed the light they were intended to afford; giving, besides,
the daily trouble of wiping them clean; and an accidental stroke
on one of them would demolish it, and render it totally useless.
I therefore suggested the composing them of four flat panes,
with a long funnel above to draw up the smoke, and crevices
admitting air below, to facilitate the ascent of the smoke; by this
means they were kept clean, and did not grow dark in a few hours,
as the London lamps do, but continu'd bright till morning,
and an accidental stroke would generally break but a single pane,
easily repair'd.
<12> See votes.
I have sometimes wonder'd that the Londoners did not, from the
effect holes in the bottom of the globe lamps us'd at Vauxhall
have in keeping them clean, learn to have such holes in their
street lamps. But, these holes being made for another purpose,
viz., to communicate flame more suddenly to the wick by a little
flax hanging down thro' them, the other use, of letting in air,
seems not to have been thought of; and therefore, after the lamps have
been lit a few hours, the streets of London are very poorly illuminated.
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