Name
- A'Court, William Henry Ashe, 2nd Baron Heytesbury, formerly A'Court-Holmes; politician, 1809-18911
- A. Asher & Co., booksellers and publishers, Berlin, The Hague, 1830-1
- A. and W. Galignani, booksellers, Paris, 1821-18731
- Abbott, Francis, Secretary of the Scottish General Post Office, Edinburgh, b 18021
- Abel, Niels Henrik, Norwegian mathematician, 1802-18291
- Abney, William de Wiveleslie, Knight, civil servant and photographic scientist, 1843-19201
- Académie Royale des Sciences, Paris, 1666-1
- Ackermann and Co, publishers, London, 1829-18551
- Adam, Alexander Forsyth, Honorary Secretary of the Photographic Society of Scotland, 1822-18811
- Adamson, John, MD, photographic pioneer, 1809-18701
- Addams, Robert, Professor of Experimental Philosophy at The London Institution and The Royal Institution, 1789-18751
- Adolphus Richter & Co., bookseller, fl 1833-18371
- Airy, George Biddell, Knight, Astronomer Royal, 1801-18922
- Alexander Garden, chemist, fl 1839-18621
- Alexander, Harry Head, printer and Secretary of the Chippenham Literary and Scientific Institution, 1811-18421
- Alexander, Richard, watchmaker and bookseller, of Chippenham, fl 18321
- Allen, Stephen, clergyman and tutor, 1813-18891
- Amici, Giovanni Battista, Italian astronomer, botanist and optician, 1786-18631
- Andrew Ross, optical, mathematical and philosophical instrument makers, 1830-18591
- Anglo-American Mining Association, fl 18261