This thread was originally written and published in May 2019.

Rooting about on old maps on the topic of drydocks, I can across a location in Leith for “Mr Morton’s Patent Slip” Who was Mr Morton? What was his Patent Slip? This was all too intriguing not to look into further, and so look I did. And I’m glad I did because the answer to those two questions is quite fascinating.

The Patent Slip – or marine railway was basically 3 rails on an inclined plane, up which a ship could be winched out of the water on a special wheeled cradle. Ships had been hauled up onto the shore before, but Morton’s trick was the cradle and rails, which extended into the water and meant the ship could be sailed onto them and then easily hauled out. The patent slip could just be laid out on the sloping ground and did not need costly excavations, masonry, lock gates and pumps. It therefore cost about 1/10 of the equivalent for a dry dock to construct, and was both simpler and more efficient to operate. Importantly for shipowners, it was much cheaper too; an 1832 hearing to renew the patent noted that hauling a ship out on the Patent Slip cost £3, whereas drydocking the same vessel would cost £170. The same hearing described that “Mr Morton’s invention of the Patent Slip in question is one of the most ingenious and valuable description – of the highest advantage to the shipping interests of this maritime country“.

The below painting of the Burnham Patent Slip, by Fitz Henry Lane, is from 1857 and shows two ships hauled up out of the water for maintenance.

The patentee, Mr. Morton, was Thomas Morton (1781 – 1832) a native of Leith and a shipbuilder. He had trained in his craft at home, before moving to London to train in naval architecture and widen his experience. Returning to Leith in 1804, he invented his slip in 1818 and patented it in 1819. The Caledonian Mercury reported in December of that year that the brigantine Hope, built by Mortons in Leith in 1810, had been repaired on the New Patent Slip at Leith, including re-coppering her bottom. (No giggling at the back, coppering the bottom was to discourage marine growth and protect the timbers of the hull).

In 1821 Morton built a further slip in the harbour of Bo’Ness, up the Firth of Forth. In November that year, the Greenland whaler Juno of 353 register tons was the first ship to be hauled out at Bo’ness, the winches being worked by hand by 28 men. The map below shows the location of where the Leith slip was, to the west of the North Leith burial ground, south of Couper Street, an area now known as the Coalie Park. In October 1828, Morton erected a slipway for the Montrose Patent Slip Company in that town. January 1842, the Scotsman carried an advert for the sale of a shipbuilding yard possessed by G. & W. Napier at the Sheriff Brae in South Leith, complete with “one of Morton’s Patent Slips“.

Such was the success of his patented device, Morton’s representatives were in court as early as 1824 to contest an infringement of it, and won. Morton’s petition to extend his 10 year patent on the Slip was declined by a parliamentary committee in May 1832, but they did note and request that some other way should be found to recompense Morton for the advantages his slip had brought to the country at his own expense. He never lived to receive any such gratuity however, as he had died at home, 1 Pilrig Place, on December 24th 1832, aged 51. The business was continued by his brother Samuel (and Samuel’s son Hugh, “who has been bred as an engineer“):

Thomas was buried in the Morton family plot at South Leith Kirk; I managed to find it after 45 minutes methodical searching in beautiful weather. Thomas is just legible on the panel on the left.

I have coloured in the revlevant letters to help you to visualise it:

In 1846, the Edinburgh, Leith & Granton Railway arrived in North Leith, hugging the north bank of the water of Leith, passing underneath the Junction Bridge and then turning north through a tunnel to the terminus at North Leith station. In May 1846, the Caledonian Mercury reported that the ship Galway Lass was exporting a Patent Slip from Leith to St. Thomas; I suspect this was the removal of the slip from Morton’s yard. Thus cleared of the slip, the yard now became a railway coal yard (hence, Coalie Park). On the map below of 1849 we can still see the straight edge of where the slip came out of the water, just above the “OF” of Water of Leith. The Scotsman on June 13th of that year reported that a further “one of Morton’s Patent Slips” complete with a 10hp steam winch was being sold from the Hawthorn’s Leith Engine Works yard across the river in South Leith. We can see on our map below that it is no longer present on site in 1849.

Samuel and Hugh, as S. & H. Morton & Co., continued to run the business at Leith and Bo’ness after Thomas’ death. Having to make way for the railway in 1846, they relocated the yard first to Granton and, after 1852, to newly reclaimed ground to the west of the Leith dry docks. This plot would later be occupied by Henry Robbs, Leith’s last shipyard. An 1880 advert indicates that by this time the company had moved from shipbuilding to specialising in supplying shipyards with components, but were also still producing Patent Slips. The company was bought out by Hawthorn & Co. in the 1890s and it was Henry Robb that would buy them out in 1924..

A mile or so along the coast at the Granton yard, the patent slip was altogether grander than that at Leith. By the time the below map was published in 1876 it was then the yard of David Allan & Co.

The Granton patent slip was not only much bigger, but was also powered by its own engine house (rather than muscle-driven winch at Bo’ness or the North Leith yard). Notice that West Harbour Road crosses over the slip on a swing bridge! As shipbuilding in Granton waned due to competition from Leith and concentrated on building smaller craft (particularly trawlers and drifters), the patent slip appears to have been replaced by a more conventional and much smaller launching slip. It disappears from maps after 1912.

Patent Slips are still in use, and still called that even though the patent ran out nearly 200 years ago! Here’s a modern incarnation in Arbroath .

The Clyde, unsurprisingly, also got patent slips, here are those of Henderson’s (L) and Inglis (R) at the mouth of the Kelvin.

An advert for Bristol shipbuilders Ross & Sage mentions some of the virtues of the patent slip:

THE PATENT SLIP offers the most expeditious method of taking Vessels out of the water for inspection and repairs. Among the advantages are:- The free circulation of Air under Vessels’ Bottoms, longer time for working during winter days, a saving of time in not having to carry materials down into a Dock, and others which must be obvious on inspection. Vessels can be taken up and launched again in a few years.

Advert for Ross & Sage, Bristol.

I assume the “longer time for working during winter days“ is a reference to the dependence on daylight for working, which would have been in short supply at the bottom of a dry dock. Patent slips were also exported around the world, as seen in the below painting of one in Australia.

And for your viewing enjoyment, below is a video of Caledonian Macbrayne’s ferry Loch Striven being slowly let back down the patent slip and into the Clyde.

Other interpretations of the Patent Slip idea were made to solve particular problems. The Monkland Canal from Lanarkshire to Glasgow used an inclined plane railway at Blackhill, but the vessel being moved was kept in a caisson of water instead of on a dry frame. This was not a cost-saving measure, but a water saving one. The inclined plane was also found to be much quicker to transit, although speed was never particularly pressing on slow-moving canals whose primary business was moving non time-sensitive cargoes like coal. There’s a great model of this inclined plane lock at the National Museum of Scotland on Chambers Street, but I can’t find a picture of it so you can all just go visit it if you want to see!

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