Aqueducts are needed to get the canal over a lower level obstruction, frequently a stream or road, they can be such small simple things that you could easily miss them on your cruise, or simply spectacular.

Mention aqueducts and the first thing any one says, or at least tries to say is Pontcysyllte, which at over 1,000 feet long and at it's best 120 feet above the River Dee is surely 'the big one' of  the canal network. Built to a design of Telford's it uses a cast iron trough featuring dovetail joints, supported  on a row of stone columns. At the time this was a completely new concept, and you have to marvel at the sway Telford must have had with the investors to let him try such a venture. The channel is only just wide enough for one boat, and there's no hope of steering it's entire length without rattling down the sides, so check there's nothing else coming in the other direction, set your speed slow and marvel at the views. It is possible to step off on to the towpath, which has a safety rail, and it's impossible to resist the temptation to step off, run a few yards ahead and take a picture of 'your boat' coming towards you over this engineering masterpiece. Beware however of the non towpath side, there is nothing at all to stop you falling over the edge. Another point worth mentioning is that although to top looks several inches wide it is in fact a lip, so the thickness of the trough is nothing like it would appear to be, I don't know how thick it is, and I'm not sure I want to know.

In a class of it's own is Barton Swing Aqueduct which crosses the river Irwell, but in order to allow large river craft to pass, it, and all the water in it pivots out of the way. It is in effect a very large lock, there are two sets of gates at each end, one to seal the canal, the other to seal the bridge. It then pivots around an island in the Irwell, at 234 feet long and calculated to be in excess of 1,500 tons it too can only be described as impressive.

Bridges on the other hand allow other traffic to pass over the canal and whilst in towns now this invariably means road bridges which are normally drab concrete affairs, in the country they are often attractively simple. Most were built for, and are still used by farmers to get to fields that were cut off when the canal was constructed and are referred to as 'accommodation' bridges. Look out on the towpath side for a metal strip with grooves worn in it, this was put there to stop the tow ropes from horse drawn boats biting into the masonry, and judging by the depth of some of the grooves it's just as well they are there.

Also of note at bridges are the grooves set into the side of the canal, often accompanied by a long, low shed on the bank, or a cupboard built into the bridge wall. The grooves accept the planks, which are stored at the bridges to allow for a temporary dam to be put in place at short notice in the event of a serious leak.

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