This effect not unknown in 18th century? (Royal Circus, Bath.)
But not enough glass involved to do damage.

According to the 2nd century author Lucian, ships were destroyed during the Siege of Syracuse using a technique created by Archimedes of using polished shields to focus light onto attacking ships to set them on fire.

(The tv show Mythbusters tested this story using parabolic bronze mirrors, and concluded it was probably not true due to the difficulty of focusing enough light for a long enough time onto the sails of a moving ship. It would also have been a highly unreliable weapon since clouds would render it useless.)

That hotel is like the iPhone4 of the hospitality industry.

> concluded it was probably not true

Except Archimedes was a true genius.

hhp