Ali as a general servant and cook, and spent the early 1856 wet season in a small Dyak house at the foot of Mount Santubong, overlooking a branch outlet of the Sarawak River. He read about species distribution, and wrote his "Sarawak Paper". In March he moved to the Simunjon coal-works, operated by Ludvig Verner Helms, and supplemented collecting by paying workers a cent for each insect. A specimen of the previously unknown gliding tree frog Rhacophorus nigropalmatus (now called Wallace's flying frog) came from a Chinese workman who told Wallace that it glided down. Local people also assisted with shooting orangutans. They spent time with Sir James, then in February 1856 Allen chose to stay on with the missionaries at Kuching. On reaching Singapore in May 1856, Wallace hired a bird-skinner. With Ali as cook, they collected for two days on Bali, then from 17 June to 30 August on Lombok. In December 1856, Darwin had written to contacts worldwide to get specimens for his continuing research into variation under domestication. At Lombok's port city, Ampanam, Wallace wrote telling his agent, Stevens, about specimens shipped, including a domestic duck variety "for Mr. Darwin & he would perhaps also like the jungle cock, which is often domesticated here & is doubtless one of the originals of the domestic breed of poultry." In the same letter, Wallace said birds from Bali and Lombok, divided by a narrow strait, "belong to two quite distinct zoological provinces, of which they form the extreme limits", Java, Borneo, Sumatra and Malacca, and Australia and the Moluccas. Stevens arranged publication of relevant paragraphs in the January 1857 issue of The Zoologist. After further investigation, the zoogeographical boundary eventually became known as the Wallace Line. Ali became Wallace's most trusted assistant, a skilled collector and researcher. Wallace collected and preserved the delicate insect specimens, while most of the birds were collected and prepared by his assistants; of those, Ali collected and prepared around 5000. While exploring the archipelago, Wallace refined his thoughts about evolution, and had his famous insight on natural selection. In 1858 he sent an article outlining his theory to Darwin; it was published, along with a description of Darwin's theory, that same year. Accounts of Wallace's studies and adventures were eventually published in 1869 as The Malay Archipelago. This became one of the most popular books of scientific exploration of the 19th century, and