In 1937, Luis Enrique Erro, the founder of the National Astrophysical Observatory of Tonantzintla, went to France. Mexican President Lázaro Cárdenas gave him money to go the doctor and try to cure his deafness in that country. But, instead of going to the doctor, Erro used the money to buy a telescope. Later, he put a plaque in the telescope in memory of Cárdenas. Nowadays, all the visitors to Tonantzintla can see the plaque.