A gold medal was awarded for a harvester and self-binder (McCormick's).
In 1921 he was awarded the gold medal of the Society of Arts, London.
In recognition of this work the medal of the Royal Astronomical Society was awarded him in 1833.
For his work on etherification Williamson in 1862 received a Royal medal from the Royal Society, of which he became a fellow in 1855, and which he served as foreign secretary from 1873 to 1889.
In 1882, at Reading, a gold medal was given for a cream separator for horse power, whilst a prize of roo guineas offered for the most efficient and most economical method of drying hay or corn crops artificially, either before or after being stacked, was not awarded.