His journal, recording his career as Dunedin's first full-time gaoler, forms an historical document on social conditions in New Zealand in the 1850s.

[3] During Monson's first three years in Dunedin his struggle to survive as a builder and carpenter became increasingly difficult, and was brought to a head by the burning down of his own painfully built house.

Monson's administration was informed by his Christian principles, which led him to lead prayer meetings, teach some of his prisoners reading and writing, and (most unusually at the time) to abstain from the use of flogging.

[1] He set out his philosophy in an official report: The punishment of vengeance or anything else which is calculated to embitter the life of a Prisoner, beyond that of Barrs and Fence, I most strenuously condemn…A Criminal of any "Class" cannot be improved by any mode of severity; he may, and generally will be, by an enlightened spirit of humanity.

[4]This liberal policy, which was continuously opposed by his immediate superiors in the Provincial government, was found by a delegation of Visiting Judges in 1855 to produce encouraging results: Mr. Monson the Gaoler appears to have stood nearly alone in all efforts hitherto to improve the moral status of the prisoners…It is but just a tribute of praise to say that he has evinced great zeal, and that his system of "moral suasion" coupled with firmness appears to have succeeded where, perhaps, under the circumstances, no other would.