A spell to increase light

This exceedingly useful spell (name unknown), especially convenient on dreary days, is employed by Mr Norrell to brighten rooms at Hurtfew Abbey when Mr Segundus and Mr Honeyfoot visit him. Mr Segundus is said to have noticed the effect, which made him uncomfortable, as "the light within the room did not seem to accord with the three tall twelve-paned windows", and he kept looking around to see if there were more candles burning to account for the light [1].