There are 2 titles associated with this firm.

Hemans, Felicia. Songs of the Affections, with Other Poems. By Felicia Hemans. Second edition. Edinburgh: William Blackwood [Princes Street], Thomas Cadell Jun., 1835.
Moir, David and Felicia Hemans. Poetical Remains of the Late Mrs. Hemans. London: William Blackwood and Sons, Thomas Cadell [London], 1836.