The writing of A Comparative Grammar of the Modern Aryan Languages of India started in 1866 and vol. I on Phonetics was finished in 1871.
John Beames saw a copy of Caldwell's Grammar of the Dravidian Languages in 1865 and it immediately struck to him that a similar book was much needed for the Aryan group. The work commenced in 1866 and was planned in 3 vols. Vol I on the Phonetics of the group was finished in 1871. The remaining two volumes: vol. II on Noun and Pronoun, and vol. III on Verb and Particles followed.