Wiktionary
smitham
n. (context UK obsolete English) Small lumps of ore which free miners scavenged because small quantities were exempt from payment of taxes. The practice ended in 1760 when the Duke of Devonshire challenged the tax exemption.
Wikipedia
Smitham
Smitham is the small lumps of ore which free miners scavenged because they were exempt from payment of lot and cope duties. This practice was brought to an end in 1760 when the Duke of Devonshire challenged the practice in chancery on the basis that mine owners were breaking larger lumps down to avoid taxation.
Usage examples of "smitham".
She drove through the gateway, and once past Godstone Corner set her horses at a brisk trot up the long, straight road ascending the pass to Smitham Bottom.