Alongside the Taunton and Bridgwater Canal between Creech St Michael and Charlton (Cogload Junction). I assume you took notice of the 'scale model' of the solar system alongside the tow path?
Spot on. It was originally used to pump water from the river to the canal ( its Watt beam engine is now in a museum in Taunton) but was in later years used to pump water to the railway.
I did the entire "Somerset Space Walk", Taunton to Bridgwater yesterday.
As PhilWakely pointed out, it is a "to scale" sculpture walk of the solar system using the entire length of the canal with The Sun at the mid point at Maunsell locks with the planets placed at their correct sizes and distances in both directions from the centre.
I've posted a couple of pictures below to illustrate.
It's quite an interesting canal anyway, I'll post a couple of parts which I found surprising later on.
As I said previously, it was railway enabled as I took the outward train to Taunton and the return to Bristol was from Bridgwater.
My feet feel a little sore today.