Bauer had made 350 plant sketches and 100 of animals, and had "indeed been indefatigable and . . . bestowed infinite pains on the dissections of the parts of fructification of the plants.” Bauer, intent on capturing accurately the tone and shading of his specimens, but unable to carry with him the range of colours needed, covered his preliminary sketches with colour numbers. Banks was intrigued by Bauer's precision, and in January 1806 wrote that they "were prepared in such a manner by reference to a table of colours as to enable him to finish them at his leisure with perfect accuracy". A 2017 book contains reproductions of collections in Europe, the United Kingdom and Australia that have never before been published and reveals Bauer's innovative colour-coding technique for the first time. In June 1803, while Flinders returned to England in order to obtain a replacement for the Investigator, Bauer remained in Australia. He went to Norfolk Island for eight months and also undertook excursions to Newcastle, the Blue Mountains and the south coast of New South Wales. Bauer returned to England on the Investigator, accompanied by 11 cases of drawings containing 1,542 Australian plants, 180 Norfolk Island plants, and over 300 animals. Return to Europe After Bauer's return to England on 13 October 1805, the Admiralty continued to employ Bauer to allow him to publish an account of his travels. Bauer worked on the Illustrationes Florae Novae Hollandiae for five years, doing all the engraving himself. He also contributed ten plates to Flinders' Voyage to Terra Australis. From 1806 to 1813, 50 sets of Bauer's Illustrationes were published in three parts. Unfortunately, the publishing venture was a failure, and in August 1814 Bauer returned to Vienna, but continued to do much work for English publications including Lambert's Pinus and Lindley's Digitalis. He acquired a small house in Hietzing near the Schönbrunn Botanical Garden and spent his time painting and making excursions into the Austrian Alps until shortly before his death from dropsy on 17 March 1826. The bulk of Bauer's finished paintings was acquired by the British Admiralty. In 1843 they were transferred to the British Museum together with additional paintings that Robert Brown had bought from Franz Bauer. Most of the sketches, as well as the herbarium and a collection of skins, were acquired by the Austrian Imperial Museum and are now housed in the Natural History Museum