Indiana once protected itself with a network of fire towers. The state began constructing them in 1930 with the goal of having no visibility gap, and by 1952 it had 33 towers, most in the southern half of the state. Fire towers were generally equipped with radio and telephone communication equipment, a psychrometer to measure humidity and determine fire danger, and an alidade, sometimes called an Osborne Fire Finder, to determine the exact location of a fire. The alidade used an oriented topographic map on a circular disk with moveable sighting apertures; a lookout lined the apertures on a plume of smoke to determine the line on which the fire was located, while another lookout did the same, and the fire was located where the two lines crossed. Many Indiana lookouts were local farmers recruited when fire danger was high, and sometimes a wife or other family member served as lookout. Their duties included watching for smoke, locating and reporting suspicious smoke plumes, taking weather readings, communicating with fire crews during a fire, recording fires, keeping the area around the tower mowed, and keeping the outhouse clean. Lookouts had to pass a vision test and be able to climb the tower several times. During WWII, many of Indiana’s lookouts were women. By the 1970s, planes replaced fire towers as the means of locating fires, and today fires are reported by local residents.