Some of the earliest experiments in tapping planted rubber trees were begun by Trimen at Henaratgoda in 1888. One of the largest of the original trees was tapped a few times in alternate years. Tapping consisted in making gashes in the bark with a hammer and chisel, in imitation of the methods employed in the Amazon country. The recorded yields were as follows:
Despite the fact that his first estimate of the probable yield of a rubber plantation was a very low one according to modern ideas, and although it was not considered safe in those days to tap the trees at an earlier age than 10 or 12 years, Trimen foresaw that a very handsome profit could be obtained from rubber planting, and strongly advocated the cultivation of this product in Ceylon in his report for 1888. In 1890 the Ceylon Forest Department opened an experimental plantation which was increased to some extent in subsequent years, but on estates little planting took place during the decade immediately following.