In his younger days Hume had studied some geology from the likes of Gideon Mantell and appreciated the synthesis of ideas from other fields into ornithology. Hume included in 1872, a detailed article on the osteology of birds in relation to their classification written by Richard Lydekker who was then in the Geological Survey of India. The early meteorological work in India was done within the department headed by Hume and he saw the value of meteorology in the study of bird distributions. In a work comparing the rainfall zones, he notes how the high rainfall zones indicated affinities to the Malayan fauna.