Heinrich Franz Vosseler, generally known as Henry or Harry, was born on 18 October 1885 in Wellington, the son of German parents George Vosseler, a baker, and his second wife, Anna Marie Therese Wulff, a schoolteacher. George Vosseler's first wife had been the governess-companion of the German consul's children in Wellington, and Henry had an older half-brother and a half-sister. He attended Te Aro School in Wellington and then a small school at Newman, near Eketahuna, when the family moved there in the 1890s.
In 1900, at the age of 14, Henry took up an engineering apprenticeship with W. Crabtree and Sons in Wellington, where he lived with his half-brother, Frederick. After completing his apprenticeship he worked for a short time in engineering workshops in Wellington and Stratford, at one time splitting sleepers for the North Island main trunk railway line, then under construction. In 1910 Vosseler went to sea for five years as a marine engineer with the Eastern Extension Australasia and China Telegraph Company. He served on the cable-ships Patrol and Recorder, laying submarine cables around the Australian, East Indian (Indonesian), Singaporean and Chinese coasts. He learnt to speak fluent Cantonese and obtained his first-class marine engineer's certificate. Also during this time, Vosseler and another engineer bought a tin mine in Malaya, in which he was to retain an interest until the mid 1950s.
Returning to New Zealand, Vosseler started an engineering business in Eltham in 1915. On 19 January 1916, at Makara, he married Jessie Letitia Hawkins. There were six children of the marriage: four sons, two of whom died in infancy, and two daughters. Vosseler's 'alien parentage' prevented him from serving during the First World War. In 1922, with his brother-in-law Bert Harkness and Bill Young, Vosseler formed a sister company, Union Foundries, in Stratford. As well as general engineering work, Union Foundries manufactured multi-tubular boilers for dairy factories, locomotives for sawmills, roading machinery, and farm equipment. The firm was so successful, as were Vosseler's trainee-tutoring methods, that several of his apprentices (as well as his two surviving sons) followed in his footsteps and became marine engineers.
In 1930–31, with his associates William (Dick) Fossey and Stewart Huston, Vosseler constructed an oil refinery near Ngamotu Road, Moturoa, overlooking New Plymouth's port. It was the peak of his career. He bought a 40-horsepower steam boiler, which had previously been used at the Waitara freezing works, and Union Foundries produced the refinery's holding tanks and piping. This successful venture, in which Vosseler was a partner for 16 years, resulted in the production of locally refined motor fuel (later marketed as Peak Petrol), diesel and fuel oil. During the Second World War, when the search for oil was crucial to the war effort in the Pacific, American exploration companies in Taranaki relied on Union Foundries for the maintenance of their plants.
Of stocky build with dark curly hair and brown eyes, Henry Vosseler was a kind-hearted man who took an active role in his local community. He had joined the Stratford Masonic lodge at the age of 21, and served in the Home Guard during the Second World War, becoming an excellent rifle shot and winning several trophies. A foundation member of the Rotary Club of Stratford, he also belonged to the local chamber of commerce and the Taranaki apprenticeship committee. He loved Banjo Paterson's poetry, and his family remember him enthusiastically reciting verse while driving to picnics at the beach.
Vosseler sold his share in the refinery in 1947 and in 1957 its operations were transferred to a new, larger complex nearby. As his eyesight began to fail he retired as managing director of Union Foundries in the mid 1960s, and was succeeded by his son Bruce. He died at Stratford Public Hospital on 15 December 1975, at the age of 90, and was cremated following a service in the Holy Trinity Anglican Church, Stratford. He was survived by four children and his wife, Jessie, who died in 1981. A well-known figure in Taranaki, Henry Vosseler achieved prominence as an engineer, as a successful businessman and, in particular, as a pioneer of the region's prosperous oil industry.