The Brattleboro daily reformer. (Brattleboro, Vt.) 1913-1955, 1914-12-09
BURNING CLASSES.
Powerful Lenses With a Few of
Their Fiery FeatS.
PENN'S MARVELLOUS MACHINE.

Garnets, Flint, Steel and Iron and
Did Other Wonderful Things.
1t is written that when the Roman
ships besieged Syracuse Archimedes
burned them to ashes by means of mir
rors, and Proclus is also said to have
destroyed the navy of Vitalian when
those galleys besieged Byzantium, by |
means of burning glasses. And there |
is the wonderful story of Ptolemy's |
mirror, which, placed on the tower of
the Pharos at Alexandria. represented |
accurately everything that transpired !
in all Egypt, on both land and water,
with which an enemy's feet could be
seen 100 leagues away.
Descartes branded. the story of Archi- |
medes' mirrors as fabulous. But Kir-
cher believed it to be true and made
many experiments to prove his con-
tention. He tried the effect of q num-
Der Of plane mirrors and with five of
the same size, placed in a frame, con-
trived to throw the rays reflected from
them to the same spot at a distance of
more than 100 feet, and the degree of
heat obtained led him to conclude that
by increasing the number of mirrors he
could increase the heat to any desired
degree. He made a voyage to SYRIA
cuse to inform himself exactly of local
conditions. From his observations he
was convinced that the Roman galleys
could not have been more than thirty
PAGES, or less than 100 feet, from the
place where Archimedes mounted his
unique engine of destruction
sisting of a number of mirrors, and
In his first experiment, using twenty
four mirrors, he set fire to pitch and
tow at a distance of seventy feet.
Then, with a kind Of polyhedron, con-
sisting of 16S pieces of plain looking
glass, each piece six inches square,
boards of beechwood We're set on fire
at a distance Of 100 feet Next there
were employed $50 plain mirrors, each
eight inches long and six broad, and
with all the mirrors in use wood
could be ignited at distance of 225
feet. The last machine of this nature
constructed by Button contained 400
mirrors, each six inches square, and
with the rays from this he could melt
lead and tin at Il distance of $50 feet.
The most powerful burning mirror of
modern times was constructed by one
Penn, an English artisan. He succeeded
in producing a burning lens no less
than three feet in diameter, and this
cost the man who was financing the
experiment upward of So, 500. Its pow
er was astonishing, and the hardest
and most solid substances, such as
iron, flint and steel, melted like wax
when exposed to its immense focus,
only a few seconds being required. A
diamond weighing ten grains was ex-
posed to the rays for thirty minutes
and was reduced to six grains by the
process. During the operation the
stone opened and foliated like the
leaves of a flower and emitted whitish
fumes; but when it had closed again
it still bore a polish and was Identical
in shape, though four grains lighter
and proportionately smaller. Ten cut
garnets melted and ran together il
a few seconds. In fact, nothing was
found that could resist the terrible
heat generated. This remarkable ma
chine was afterward taken to Chin;
by an officer connected with the Brit
ish embassy and finally lost sight Of.
With these modern experiments t.
consider, the tale Of the burning o
Marcellus' ships seems more probable
La Brocquiere, traveller of the ff
teenth century, says that at Damascu
they made mirrors of steel that mag
nified objects like burning glasses.
The telescope was not invented til
early in the seventeenth century.
This would seem corroborative ev.
dence concerning Ptolemy Euergetes
mirror, which La Brocquiere does no
mention and of which he perhaps neH
er heard. Abulfeda, in his descriptio
of Egypt, says that the wonderful mil
ror was made of Chinese iron and tha
soon after Mohammedanism prevaile
the Christians destroyed it by strati
gem.
In a work published at Marseilles
1853 Father Abbat argues ingeniousl
in favor of the probable existence {
the mirror, but contends that it's pow
er was far less than recorded in ii
legend.
''If this mirror existed he says, "
is probable that it was the only one {
its kind and that no other means ha
then been found of viewing distal
objects distinctly. 1t must therefor
have been considered as great wo
der i'm those times and must have file
with astonishment all who saw its c
fects. Even though its effects had II
been greater than those of small t
escope it is natural to thin
that those effects We're exaggerated b
yond all probability and even possibi
", as commonly happens to rare al
admirable machines and inventions"
Emmett Campbell Hall in Clevelal
Leader.
A Disclosure.
Little Willie was instructed by