Shortly afterwards, in 1905, Viceroy Yuan Shih-kai transferred him to the north for the construction of the Peking-Kalgan Railway. At first he was resident engineer of the railway and afterward a district. engineer. He was in charge of the difficult portion of the line which passes through the famous Nankow Pass. Four tunnels, the longest of which was over 3,000 feet, and passed for a length of over 100 feet under the Great Wall at Pataling, were built under his direction. In 1906 after passing the Imperial Examinations for Returned Students, he was awarded by Edict the degree of Doctor of Engineering. In the spring of 1909, he was sent to inspect railways in Kiangsi and Anhwei, after the inspection of which he proceeded to Ichang as assistant chief engineer of the Szechuen railway. The work on that railway was stopped by the First Revolution in 1911. In the spring of 1912, Dr. Yen was appointed director of the Railway Department in the Provisional government at Nanking. When the Ministry of Communications was regularly organized in Peking in May 1912, he became Councillor of the Ministry. From July 1912 to January 1922 he held the post of managing director of the Canton-Hankow Railway, Hupei-Hunan Section. From 1919 to 1922 he was also in charge of the Han-I and I-Kuei sections of the Szechuan-Hankow Railway. From April to July 1919, he was detailed by the government to be Chinese representative on the Innter-Allied Technical Board. During his connection with that Board he made a tour of inspection from Harbin westward to Perm, beyond the Ural Mountains, in Russia. He was giver the Second Class Tashou Chiaho in April 1920 and the Second Class Wenfu in October 1920. In November 1920 he was made a member of the Railway Finance Commission. In January 1921 Dr. Yen left China on an official trip touring America and Europe to study the latest improvements in railway construction and operation with the object of adopting them in China. In September 1921 he was appointed Special Technical Expert of the Chinese Delegation to the Washington Conference. In January 1922 he was appointed Associate Director-General of the Harkow-Canton-Szechuan Railway. In February 1922 he was given the Second Class Paokuang Chiaho. In March 1922 he was made a member of the Commission on Communication interests in connection with the Shantung negotiation. In June 1922 he was awarded the Second Class Tashou Paokuang Chiaho and also app-inted Acting Councillor of the Ministry of Communications. In the same month he was detailed to be chairman of the Second Committee of the Sino-Japanese Joint Conference on Shantung Affairs. In July 1922 he received another concurrent position as member of the National Finance Discussion Commission and later was promoted to be the technical director of the Ministry of Communications. In September 1922 he was ordered to be concurrently the Superintendent of the Bureau of the compilation of China's Communication History. In January 1923 he was given the First Class Tashou Chiaho. Dr. Yen is a charter member of the Chinese Institute of Engineers of which he was vice-president, 1915; director, 1916-1920; vice-president, president, 1923-1924. He was dircetor of the Association of Chinese and American Engineers, 1920-1921; president, 1921-1923.
