In the following May, he asked to be transferred to a convalescent hospital inland, where he had more opportunity for research.
Dubois arrived in Padang in Sumatra in the second week of December, and for the first few months he was busy working in the local hospital. In the following May, he asked to be transferred to a convalescent hospital inland, where he had more opportunity for research. It was here that Dubois wrote the article5 that was intended to convince the Dutch East Indies Government to allow him to focus on paleontological research. His campaign of persuasion was ultimately successful, and in March 1889 he was officially transferred to the Directorate of Education, Religion, and Industry (ERI), and given permission to carry out paleontological research in Sumatra and Java. Dubois' initial research in Sumatra had only turned up the porcupine-gnawed teeth of extant mammals, and the discovery of Holocene modern human crania at Wadjak (now Wajak) in East Java led him to shift the focus of his pursuit of human ancestors, and in April 1890, Dubois was given permission to begin work in Java. Two corporals from the corps of engineers—Gerhadus Kriele and Anthonie de Winter—were assigned to assist him. He was also allocated 50 laborers to undertake any excavations, but the Dutch were harsh colonizers, and it needs to be acknowledged that the labor was forced, not voluntary. In November 1890, Dubois and his team found a more ancient-looking—but frustratingly fragmentary—mandibular fragment at Kedoeng Broebos (now Kedung Brubus) in the Kendeng Hills, but he decided to switch his attention to sediments along the Solo River, so in August 1891 the team began excavating along the banks of the Solo River, near the village of Trinil (Figure 2).