Alexander Mair , son of William Mair and his wife Catherine, born Garland, was a sworn land surveyor in Natal.
In 1869 he compiled a "General plan of Vaal Kop and Dadel Fontein", which included several farms with the names of their owners. By 1870 he was city surveyor of Pietermaritzburg.
In 1875 he compiled the first topo-cadastral map of Natal, which was one of the best maps of that territory to appear before the turn of the century. It was based on property maps in the surveyor-general's office. This Map of the Colony of Natal, on a scale of 4 miles to the inch (1:253 440), was printed in London on four sheets. It had relief sketched in, but contained no contours. All the farms in the colony were shown, with their names. It would appear that Mair was acting surveyor-general of Natal at the time, in the absence of P.C. Sutherland*.
Though Mair was listed as absent from Natal in 1880, he later returned and in September 1885 took over the secondary triangulation of the territory from H.D. Laffan*, who returned to the geodetic survey of the Cape Colony.
Mair carried a triangulation into Zululand across the Tugela River as far as Melmoth. His triangulation stations near that town served as basis for the boundary survey carried out by Major McKean at the end of 1886. During 1887-1888 Mair worked mainly in the Umvoti region and the next year wrote a progress report on the survey of Zululand. He was still listed as a land surveyor in Natal in 1890.
He was married to Eliza Adelaide, born Varty (or Varlip), with whom he had a son and a daughter.