Seager took over the position from George Richardson who recommended his appointment. Seager had been a junior clerk in the Education Department where Richardson worked for 27 years, finishing as Secretary.

Seager was married to Rose Seager. They had 8 children. The family lived on the site at the New Town Charitable Institution which was also the office for the Charitable Grants and Neglected Children's Departments. People who were destitute might turn up at any time of day or night so that the whole family was involved in the work. Seager's eldest son, Charles became a clerk in the charitable departments in 1900. His father had argued for his appointment ahead of two other applicants because he was 'peculiarly adapted for the service required', probably because of his upbringing.

Seager firmly believed in the importance of his work. In the Annual Report of 1907 he wrote that children's welfare which was 'for centuries … regarded with but little concern by public men, has in recent years, through the force of public opinion, been given its rightful place as the most important department of philanthropic endeavour'. He brought a personal touch to the work, occasionally visiting foster homes, making decisions about children's placements, and corresponding with those apprenticed in the country. Foster mothers brought disobedient children into his office to be reprimanded.

Seager was an advocate of the boarding-out system. He believed that training and industrial schools fell 'far short of the requirements of childhood 'and that the 'motherly interest' of foster mothers made training more effective. He argued that there was little difference between neglected and delinquent boys because all were 'more to be pitied than blamed'. He placed a few offenders in the boarding-out system as was done in Ontario because he thought that this was better than the 'barracks'.

In 1911, all the charitable departments were brought under the control of the Under-Secretary, HE Packer, and moved into his offices in the centre of Hobart. Seager remained Superintendent of the New Town Charitable Institution and the Boys Training School. Already suffering from ill health, he died on 4 May 1913.