He also served as high constable of the barony of Lower Toome from 1887 to 1899 and was secretary of a local investment company.

He gave evening classes on science and agriculture as a young man in Cullybackey, Portglenone, and Ballymena.

[1][2][3] Knowles dedicated all his spare time to archaeology, and was one of the first people to excavate in the sandhills of the Ulster coast.

He pioneered the study of neolithic flint implements in Ulster, resulting in a large personal collection of artefacts.

He served as secretary to the committee established by the British Association for the Advancement of Science in 1878 to excavate sandhill sites, and which later published a report on their activity.