Site is down. This should be the same PDF I think: http://wexler.free.fr/library/files/necker%20(1832)%20observations%20on%20some%20remarkable%20optical%20pheno

Site is down. This should be the same PDF I think: http://wexler.free.fr/library/files/necker%20(1832)%20observations%20on%20some%20remarkable%20optical%20phenomena%20see%20in%20switzerland;%20and%20on%20an%20optical%20phenomenon%20which%20occurs%20on%20viewing%20a%20figure%20of%20a%20crystal%20or%20geometric%20solid.pdf http://wexler.free.fr/library/files/necker%20(1832)%20observ...