BBC Four HD

Programmes start at 7.00pm.

Professor Ben Garrod reveals how skin protects vertebrates from extremes of temperature, the harmful effect of UV and a host of living organisms that want to get in.

Gareth and Maureen enlist in tank school and gear up for a drive like no other. In the Brecon Beacons, they discover if they've finally cracked the art of narrowboating.

Documentary that explores Emperor Augustus's Alpine campaign, revealing for the first time the route, weapons and tactics used by the Romans to successfully annex the unconquered Alps.

Architect Sand Helsel applauds Trellick Tower, a brutalist tower block in west London, designed by Erno Goldfinger and completed in 1972.

Brian Cox explores a planet that dwarfs all the others: Jupiter.

Marlow is getting better, and the different strands of his fiction and reality begin to occupy the same time and place. Contains some strong language and some scenes of a sexual nature.

Marlow still dreams about the homecoming and the frightening figure of the scarecrow. Deals with adult themes.