Convict Trials 1848

[Leanne]

I was wondering if someone can tell me where to find Convict trials, Benjamin THOMPSON was tried at Wells on the 4 Jan 1848, aged 16 yrs for stealing and was sent to Van Dieman"s Land on the ship Maria Somes (2), it left Isle of Wight on April 30, 1850 and travelled to Van Dieman:s Land with 30 Parkhurst Boys on Board.
She arrived in Hobart on August 9 1850, Benjamin was listed on Tasmanian
Convict Department Assignment Lists 1849-51 but not specified as a
Parkhurst Boy on Home Office Records [11/16].
So any ideas on how to find his Trial record would be grateful, I do have his Convict Record.
Regards
Leanne