10. How is the fire-pot designed to increase the
efficiency of its radiating surface and how is it
strengthened against the expansive force of the
fire?
11. Is there a long enough passage for fire-travel,
so that no waste of heat is lost up the chimney?
12. Is the radiator flexible enough to permit of
the connection of the smoke-pipe from the most
advantageous point?
Most certainly this is an array of matters to be considered in the
selection of a furnace which no one, except an expert, would think of,
but they are all drawn from the advertisements, and this process of
study is open to any one who is interested in learning the technical
difficulties involved in the selection of this particular mechanical
device. Perhaps not all of the knowledge gained is scientific, but
at least there are stimulating bits of information that should be
investigated.
Let us take one more example of this amusing game of comparing
advertisements as applied to roofing materials. Here we will find many
conflicting statements, but out of the whole battle of words we can
glean some interesting truths.
Turn to advertisement (_A_) and we read the following: “Nearly every
objection to wood shingles as a roof-covering is applicable to slates,
which have still other adverse features. Slates are not fireproof.
Ask the underwriter how the insurance companies regard them, and
especially how, in comparison with clay tiles, they are not permanent,
though more so than wood shingles.... Slates attract lightning, and
while the sun warps shingles and the wind rips them off, slates are
easily broken, and if there is even a slight settlement or vibration,
repairs are necessary. Moisture gets under them, and during the winter
months especially causes them to lift up and break off. When the ice
thaws, the broken pieces slide out, leaving a defective place in the
roof. This will happen every winter with a slate roof, and to keep such
a roof in perfect condition it must be gone over each spring and the
broken slates replaced with new ones.”
Turning to advertisement (_B_) for asbestos shingles we read a
different point of view: “Unfortunately, however, slate, particularly
that which is obtainable on the market at present, does not last much
longer than _clay tile_ or tin shingles.”
But reading from advertisement (_C_) we are amused at the following:
“Slate being solid rock, they simply cannot wear out. They cannot
rust, decay, crack, tear, warp, shrink, disintegrate, melt, burn, or
smoulder. They will not contract or expand under the influence of heat
or cold. They never need painting. They will not attract lightning—nor
will they permit the growth of moss or decaying vegetable matter....
One of the most important advantages is from the insurance standpoint.
Many roofs (not alone wooden shingles) are highly inflammable; but
a slate roof will not ignite from sparks from fire in an adjacent
building, from passing locomotives, or from any other cause. This fact
is so well recognized that insurance companies allow a very substantial
reduction in rates on slate-roofed buildings.”
The contradictory statements here are very amusing, but the truth can
be seen between the lines, that the makers of clay tile really believe
that slate is their real rival, and have searched very hard to pick
flaws in it as a material for roofing. And when the advertisement of
the asbestos shingle manufacturer is read, we learn that slate does
not last much longer than clay tile. But both are insistent upon the
opinion of the fire underwriters, and for this reason we naturally turn
to see what they have to say, and we find that both slate and tile are
under Class A roofing materials, with little difference made between
them. As for the point of attracting lightning, why is slate used for
switchboards if it is as good a conductor of electricity as a statement
of the above type would imply? It is quite evident that one’s opinion
of slate after all this controversy will be about on a par with one’s
opinion of clay tile, and that one will realize that poor grades of
either slate or tile, or poor workmanship, are rather more the causes
of failure than the material itself.
Many more examples might be given of this interesting method of
learning the truth from advertisements, but the principle in all cases
remains the same, so that further quotations would only amuse rather
than instruct.