Augustin Jean Fresnel, Letter to Arago on biaxial birefringence
“ From the beginning of 1820, Fresnel had caused M. Soleil Sr. to manufacture a prototype large polygonal lens intended to form one of the panels of a rotating dioptric drum. To illuminate these effectively, however, it was necessary to maintain a sufficiently voluminous and intense flame at their common focus — a problem that the inventor had managed to solve, in collaboration with Arago, by means of a nozzle with concentric wicks fed with oil by a clockwork mechanism ”
