Pluto

I have glasses and have just had a cataract operation on one eye, and using that eye, now returned to normal vision, it is stationary. However, there is perceived movement if I use my other eye with glasses. If you don't know about cataract replacement, they fit a new lense to the eye which returns your eyesight virtually to normal.

Perhaps they should have held the event at the last Boatmen's Mission still in use as a place of worship, St Andrew's at New Lane, Burscough. This photo was taken on the Mission's 100th birthday in 2005.

I would suspect that wide boats have longer bow decks so the jet of water would be much less likely to reach the hold. You just had to remember to keep the scuttle closed so that water did not pour into the bow cabin.

Ifyou can get there, the Libron crossing will certainly intrigue you. It is less than a mile from the town/village of Vias, on the way to Arles. The structure, including a floating river channel, allowed the canal to remain undamaged even when the River Libron was in flood and likely to overflow into the canal. The river is divided into two channels which normally pass through the canal. During floods, the boat is moved into place over one of the channels and the flood waters allowed to pass over the canal through the channel on the boat. Andreossy's drawing published in 1804 is below.

I am only going off the description in Maillard's book on canal building where he gives the two variations, depending on whether the chamber is drained or continues to have navigable water depth when emptied - what's the French for a tape measure, then you can buy one and get more exact details. The variation in freeboard you mention does suggest that there may have been some alterations when the aqueduct was built. There also seem to have been problems with leakage on the southern end of the canal in the late 18th century, so water levels could have been altered. They did not have a suitable source for clay for puddle and seem to have used a particular type of earth mixed with small stones, which was not that effective. The development of puddle is something I keep meaning to do a bit of research on. Hopefully they will have some information in the Canal du Midi Archive in Toulouse.

The riser locks on the Canal du Midi were designed to be operated by draining the chambers completely when descending. When the rise was three chambers or more, the centre chambers were built shallower than the top and bottom chambers by the navigable depth of the canal. This has the possible advantage of ensuring that no rubbish collects in the central chambers which can damage the cill or mitre when the gates close fully under water pressure. In England, riser locks were designed such that the chambers always kept a navigable depth when empty, with the fall of each chamber being the same. This does mean that rubbish can be retained within the chamber and this can cause damage to the gates if caught on the cill.

You would probably find who is responsible for navigation in the Preston Docks Closure Act of 1981, as I would expect the port, and thus Preston Council, to have been the responsible agency from the opening of the docks up until then. They certainly undertook much river improvement work to create a deep navigable channel.

Selkirk's suggestion of locks was dismissed in a subsequent PhD thesis by Anderson in 1991. There is a suggestion that pound locks could have been used on the Tiber on a site close to Rome's airport, though as far as I know nothing definitive has been found or published. In ancient times, boats using inland waters tended to be small, usually carrying only a ton or two, though much larger boats could be found on large rivers, such as the Rhine. These latter were usually flat-bottomed. From my research, the true pound lock was first used on the Canal de Bereguardo, near Milan, in the 1450s. There had been earlier developments in both China and the Low Countries, but these seem to have been improvements on the flash lock, with two such locks placed close to each other. The locks on the Canal de Bereguardo had mitre gates, with paddles in the gates. Ground paddles were first used on the Brussels Canal around 1590 on the deep lock giving access to the tidal River Rupel. One of the main difficulties in researching old technical structures is that those writing about them usually had no technical education, so their descriptions can be misleading.

Early inland waterways feature in the research done by https://www.db-thueringen.de/receive/dbt_mods_00035239#, who have databases for early inland ships and Roman inland ports. I have been discussing rates of work achieved by canal navvies with them, as well as providing information about the Russian voloks, which were simple inclines or muddy roads between the head waters of Russian navigable rivers. Some were in use into the 20th century, and the basic design was improved in Holland to create overtooms. One of the main difficulties in establishing were navigation has taken place is that land levels have changed, and that will definitely be the case in the fenland area, the changes being the result of land drainage.

If it was as simple as supply and demand, then we have lots of people applying for management jobs, so salaries and bonuses should fall, while we have a shortage of care workers, so their wages should rise. Despite their having been a shortage of care workers, even with immigration wages have remained much the same, though shortages have increased. However, can you really see the oversupply of managers reducing their salaries?

My partner's younger son was involved for a short period as he works for the company which makes the remote controlled underwater cameras. The photos he showed me of the various wrecks they found were amazing, especially considering their age.

Surely the real problem is our reliance on excessive use of transport, in particular for commuting and for moving goods around. Why can't we eat local products at specific times of the year, rather than import food from around the globe? Support local manufacturing as well, rather than move half-built items expensively, in terms of pollution, around the continent of world. Unfortunately, that would require a major change in our economic model - I can't see much evidence of a policy - which ensures that a small minority accrue vast fortunes at the expense of the majority, not just financially, but also in terms of declining health resulting from pollution of all types. The problem can also be seen in the Brexit negotiations with regard to the Irish border. Those with money want to maintain an open border for trade, whist I suspect the majority of those voting for Brexit wanted a closed border to control immigration. Once again, those accumulating the most money are making others pay for their greed.

Bridges on the L&LC seem to have been numbered in the 1960s, as the old canal company papers always used names. I suspect it was done during the national re-evaluation and identification of BW property. Bridges on the L&L Canal which are CRT's responsibility have a simple number, while those which are the responsibility of others end with a letter. The re-numbering could also have been done during the 'Bridgeguard' project of around the same time, where all BW's bridges had their condition recorded so that maintenance and reconstruction could be better organised.

Most contemporary sources I have found show single top gates on narrow canal locks, as seen in this French plate, which dates from c1820. The American Strickland published a book on English public works in 1826 in which he shows a Birmingham & Liverpool Canal lock, ie the SUC, with single gates at either end. One suggestion for the conversion to mitre gates is that it speeded traffic when railway competition began from the 1830s and 1840s.

As a suggestion, could I recommend the Rouge Canal, built circa 1390 just to the west of Nanjing. Unlike most Chinese canals, it was built purely for transport, and not for land drainage or irrigation. Only a few miles in length, it is called the Rouge Canal because it was cut through sandstone.