but then john frank stevens was appointed chief engineer. in 1905. and he was chief engineer for two years until 1907. and he created the basic infrastructure and the bureaucracy for the really, the work to start. but this was very slow because he was much more interested at the beginning in creating the infrastructure. and also, dealing with the disease. both malaria and yellow fever. so he worked very closely with a doctor. a public works program was started. garbage was collected on a regular basis. sewage, running water. and other measures to eradicate mosquitoes like spraying oil on standing water. so that the mosquito larvae would not be able to breed. and also he started building housing for the workers. so the first two years was basically public works and health. and i have to say that basically yellow fever and malaria were eradicated. and it made those efforts made panama city the healthiest city in latin america, you could say. the largest group of workers came from the west indies. about perhaps 25,000-35,000. the second largest group wa