75 years ago, Americans were preparing for the possibilities of blackouts in case of enemy air raid. In this day’s issue of Life magazine, June 15, 1942, Eveready carried this ad explaining the importance of keeping a flashlight, and how to use it during a blackout.

The ad first admonished that every home should have one or more flashlights, but that before buying new ones, old ones should be inspected to see if they could be repaired. In many cases, only a new bulb or lens, or a fresh set of batteries was required. The flashlight should be kept in a convenient accessible spot, and always put back.

During a blackout, it was important to never point the light toward an unshielded window, skylight, or open door. Outside, the flashlight should be shielded. This could be accomplished by covering the lens with two layers of newspaper.

If unshielded, the flashlight should be used outside only when absolutely necessary, taking care to never point it even slightly upward, and never toward reflective objects.

And, of course, the flashlight should have Eveready batteries, with an extra set of spares.