which means practical learning, encouraged the use of science and industry, and Jeong incorporated fortress designs from Korea and China along with contemporary science into his plans. The use of brick as a building material for the fortress and employment of efficient pulleys and cranes were also due to the influence of Silhak. Construction of the fortress was also a response to the collapse of the Korean front line during the Imjin war. At the time, the dominant model for building fortresses in Korea was to make a simple wall for the city or town and a separate mountain fortress to which the people could evacuate in times of war. However, this fortress was built to include elements of a wall, defensive fortress, and town centre, the four main gates being used as the gates for the town. The arrow-launching platforms built along ramparts with crenellated parapets and battlements were defensive elements of the fortress while the wall also included secret gates for offensive actions. The fortress took 700,000 man-hours to build and cost the national treasury 870,000 nyang, the currency at the time, and 1500 sacks of rice to pay the workers. In the past, government work had been carried out by corvée labour, but in this case workers were paid by the government, another sign of Silhak influence. Records of Hwaseong Fortress Construction A white paper, Hwaseong Seongyeok Uigwe (Records of Hwaseong Fortress Construction), was published in 1801, shortly after the death of King Jeongjo. It has ten volumes and proved invaluable for the reconstruction effort in 1970 after the fortress had been severely damaged during the Korean War. The volumes were divided by subject, with the first covering the plans for building, including blueprints and a list of supervisors. The next six volumes detail the actual implementation of the construction, such as the royal orders and records of the wages of the workers. The final three volumes are supplements and detail the construction of the adjoining palace, Haenggung. Manpower was allocated by speciality, dividing workers by trade, categorising them as foremen, stonemasons, labourers, and so on. The records also detail the amounts of different materials used. An abridged French translation was published in 1898 by Henry Chevalier, who was consul of France in Korea, while a full German translation with commentary is provided in a thesis by Doo Won Cho of the University of Bamberg. Overview of