The Complete Works in Philosophy, Politics and Morals of the late Dr. Benjamin Franklin, Vol. 2 [of 3]

By Benjamin Franklin

Page 216

in them. The surrounding atmosphere is
frequently changing its temperature; but stacks of funnels, covered
from winds and sun by the house that contains them, retain a more
equal temperature. If, after a warm season, the outward air suddenly
grows cold, the empty warm funnels begin to draw strongly upward;
that is, they rarefy the air contained in them, which of course
rises, cooler air enters below to supply its place, is rarefied in
its turn and rises; and this operation continues till the funnel
grows cooler, or the outward air warmer, or both, when the motion
ceases. On the other hand, if after a cold season, the outward air
suddenly grows warm and of course lighter, the air contained in
the cool funnels, being heavier, descends into the room; and the
warmer air which enters their tops being cooled in its turn, and
made heavier, continues to descend; and this operation goes on, till
the funnels are warmed by the passing of warm air through them, or
the air itself grows cooler. When the temperature of the air and of
the funnels is nearly equal, the difference of warmth in the air
between day and night is sufficient to produce these currents, the
air will begin to ascend the funnels as the cool of the evening comes
on, and this current will continue till perhaps nine or ten o'clock
the next morning, when it begins to hesitate; and as the heat of the
day approaches, it sets downwards, and continues so till towards
evening, when it again hesitates for some time, and then goes upwards
constantly during the night, as before mentioned. Now when smoke
issuing from the tops of neighbouring funnels passes over the tops of
funnels which are at the time drawing downwards, as they often are
in the middle part of the day, such smoke is of necessity drawn into
these funnels, and descends with the air into the chamber.

The _remedy_ is to have a sliding plate, hereafter described[55],
that will shut perfectly the offending funnel.

9. Chimneys which generally draw well, do nevertheless sometimes give
smoke into the rooms, _it being driven down by strong winds passing
over the tops of their funnels_, though not descending from any
commanding eminence. This case is most frequent where the funnel is
short, and the opening turned from the wind. It is the more grievous,
when it happens to be a cold wind that produces the effect, because
when you most want your fire, you are sometimes obliged to extinguish
it. To understand this, it may be considered that the rising light
air, to obtain

Last Page Next Page

Text Comparison with The Complete Works in Philosophy, Politics and Morals of the late Dr. Benjamin Franklin, Vol. 1 [of 3]

Page 11
Page 19
This deserves, perhaps, the name of negligence.
Page 33
In this state I continued till the assembly dispersed, when one of the congregation had the goodness to wake me.
Page 48
Hamilton, who it was supposed would by this time be in Europe.
Page 71
The wealthy inhabitants, prejudiced against every sort of paper currency, from the fear of its depreciation, of which there had been an instance in the province of New England, to the injury of its holders, strongly opposed the measure.
Page 72
_, trade, buildings and population, having in the interval continually increased: but I am now convinced that there are limits beyond which paper money would be prejudicial.
Page 83
Collinson, it is said, were refused a place in the Transactions of the Royal Society of London.
Page 89
since called the Charitable School) was opened; and amidst all the difficulties with which the trustees have struggled in respect to their funds, has still been continued full for the space of forty years; so that allowing three years education for each boy and girl admitted into it, which is the general rule, at least twelve hundred children have received in it the chief part of their education, who might otherwise, in a great measure, have been left without the means of instruction.
Page 96
After several days' discussion, it.
Page 114
Edward Duffield, of Bonfield, in Philadelphia county, to be the executors of this my last will and testament, and I hereby nominate and appoint them for that purpose.
Page 124
Give him the electrised bottle in his hand.
Page 145
Page 155
Now if you would draw off this atmosphere with any blunt smooth body, and approach the middle of the side A, B, you must come very near, before the force of your attracter exceeds the force or power with which that side holds its atmosphere.
Page 174
--This colour given by the flash from two jars only, will wipe off, but four jars fix it, and frequently melt the needles.
Page 207
Page 210
Sulphureous smell.
Page 238
But you have shown me my mistake.
Page 279
If you have read my experiments made in continuation of those of Mr.
Page 293
To the upper end of the tin tube, which was not so high as a stack of chimnies on the same house, I fastened three needles with some wire; and to the lower end was soldered a tin cover to keep the rain from the glass tube, which was set upright in a block of wood.
Page 321
_Hints_ to those that would be rich, iii.