In the later years he moved into the development of analytic methods, and participated in the Standardization Committee of the Institute of Petroleum in London.

[3] In his last three years from 1952 to 1955 he managed the scientific publication department, and wrote about the history of the Royal Dutch Shell.

After his retirement from Shell in 1958 he was secretary of the Koninklijke Hollandsche Maatschappij der Wetenschappen in Haarlem as successor of the late Johannes Abraham Bierens de Haan.

In 1962 Forbes was awarded the first Leonardo da Vinci Medal by the Society for the History of Technology (SHOT).

Subsequently he had studied metals and mining from 1935 to 1950, and in between also ancient irrigation and water resource management in the years 1938 to 1941.

Under guidance of the Dutch archaeologist and orientalist Henri Frankfort, Forbes went to Iraq to collect samples of ancient mastic, which he analyzed in the Shell laboratory.

During this period, the inhabitants of Sumeria made use of asphalt to fix pictures and designs on walls and floors, while in Mesopotamia people used bitumen to help construct water canals.

They also used it as sealant in the joints of wooden boats to enable hitch free water transportation...[10]According to Hassan (2013) Forbes had also pointed out, that "by 347 AD the Chinese local oil and gas industry had developed considerably, because oil wells up to 800 feet were being drilled using bits connected to bamboo poles.

With Deterding Shell supported the Allard Pierson Stichting, which initiated the chair for the history of applied science and technology at the University of Amsterdam in 1946 for Forbes.

[29] [30][31][32][33] [34][35][36][37] After the Second World War Forbes published multiple specialized and more general books on the history of technology and engineering, which received several reviews, such as: With E. J. Dijksterhuis in 1963 Forbes published a History of Science and Technology with Penguin Books in two volumes.