1941 Kosok noticed lines in the desert that converged at the point of the winter solstice in the Southern Hemisphere. Together he and Reiche began to map and assess the lines for their relation to astronomical events. Later Reiche found lines converging at the summer solstice and developed the theory that the lines formed a large-scale celestial calendar. Around 1946, Reiche began to map the figures represented by the Nazca Lines and determined there were 18 different kinds of animals and birds. After Kosok left in 1948, after his second study period in Peru, Reiche continued the work and mapped the area. She used her background as a mathematician to analyze how the Nazca may have created such huge-scale figures. She found these to have a mathematical precision that was highly sophisticated. Reiche theorized that the builders of the lines used them as a sun calendar and an observatory for astronomical cycles. Because the lines can be best seen from above, she persuaded the Peruvian Air Force to help her make aerial photographic surveys. She worked alone from her home in Nazca. Reiche published her theories in the book The Mystery on the Desert (1949, reprint 1968). She believed that the large drawing of a giant monkey represented the constellation now called Ursa Major (Great Bear). Her book had a mixed response from scholars. Eventually scholars concluded that the lines were not chiefly for astronomical purposes, but Reiche's and Kosok's work had brought scholarly attention to the great resource. Some researchers believe that the lines were made as part of worship and religious ceremonies related to the "calling of water from the gods." Reiche used the profits from the book to campaign for preservation of the Nazca desert and to hire guards for the property and assistants for her work. Wanting to preserve the Nazca Lines from encroaching traffic after one figure was cut through by the Pan American Highway government development, Reiche spent considerable money in the effort to lobby and educate officials and the public about the lines. After paying for private security, she convinced the government to restrict public access to the area. She sponsored construction of a tower near the highway so that visitors could have an overview of the lines to appreciate them without damaging them. Reiche contributed to the lines becoming a World Heritage site in 1994. In 1977, Reiche became a founding member