1911 Encyclopædia Britannica (1911)
“ William Blackwood died on the 16th of September 1834, and was succeeded by his two sons, Alexander and Robert, who added a London branch to the firm. In 1845 Alexander Blackwood died, and shortly afterwards Robert. A younger brother, John Blackwood (1818–1879) , succeeded to the business; four years later he was joined by Major William Blackwood, who continued in the firm until his death in 1861. In 1862 the major’s elder son, William Blackwood (b. 1836) , was taken into partnership. John Blackwood was a man of strong personality and great business discernment ”
