The first police officers had to carry a candle-lit lantern, instead of a torch. The wide ‘bulls eye lens’ helped to make the light wider a brighter. This lamp would have been really useful to police officers who were trying to catch criminals in the days before street lighting.
The most interesting thing about this lantern, is a clever bit of Victorian technology. The little stacked chimneys on the top of the lamp can be turned to let more or less air get in to the candle. This means that if the officer did not want to be seen when he was sneaking up on a criminal, he could almost totally stop the air flow. This means that the light would be hidden, but the candle did not go out.