Kerosene Lanterns were the original flashlights. The red lens on this is particularly useful because red light does not cause the pupil of the eye to contract as much as higher energy colors (i.e. yellow, green blue) so the night vision of the person carrying it is not as impaired.
Railroad workers had lanterns such as these and legend has it that when they visited the local bordellos they left them outside, leading to the term "red light district."