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Endeavour’s Lightning Strike

 

Lightning is one of Nature’s less predictable phenomena. On land it can strike without warning causing death and destruction. At sea the situation is worse, as any ship is a veritable “sitting duck” for passing storm clouds. Naval literature is full of stories detailing the lightning damage suffered by ships both large and small, from the shivering of yard arms, to the shattering of main masts. The experience of the revenue cutter Chichester is a good example of the damage that results from a lightning strike to a small ship.

Greenock. — Her Majesty's Revenue Cruizer Chichester, Captain Stuart, arrived here on the 7th instant, from the west Coast of Ireland, having had her mast and part of the deck and bulwarks damaged by lightning, during a severe hurricane, on the 7th of last month on the Coast of Galway. The escape of the vessel and of the officers and crew is truly miraculous. A ball of fire, it is said, descended from the mast, and broke through the deck: it knocked down several of the crew, leaving a sensation as if a solid piece of timber had fallen upon them. The commander of the vessel (Captain Stuart) was sitting at dinner in the cabin with his two daughters when the accident occurred. The ball of fire passed over the table, shivering in pieces the whole of the dishes and glasses, without injuring any one. The skylights were thrown up, the whole deck in the centre of the vessel was raised off the beams, and the patent lights were all thrown out. The electric fluid passed through the bottom of the vessel, in many places along the copper bolts, and tore off the copper sheathing opposite to them and under water. The magnetic attraction of all the compasses was destroyed, and those who had watches found that they had stopped. The vessel was filled with smoke for some time after being struck, and serious fears were entertained of her being on fire.1

 

As if the physical damage to the ship was not bad enough, the compass could be re-magnetised, resulting in the captain sailing in completely the wrong direction!

 

In 1752, Benjamin Franklin had demonstrated the electrical nature of lightening with his famous kite-in-a-storm experiment.2 By 1762, Dr William Watson, one of Britain’s early electrical scientists, had devised a lightning conductor to be used on ships to prevent them being destroyed.3 It consisted of two foot lengths of thin copper rods, with an eye at each end, linked together to form a chain. The metal rods were supported by a rope that was used to haul the conductor up to the top of a mast in advance of any approaching storm. The lower end of the chain was placed over the side of the vessel and into the sea. When not in use, the conductor was packed away in a wooden box. These boxes are said to have been supplied to every ship in the Navy, including Endeavour.

 

These conductors certainly did protect ships, and in doing so saved the Admiralty thousands of pounds from not having to repair lightning damage. However the conductors did have their limitations. The copper rods and eyes were not robust, and any strain during handling might cause a break in the chain, thus rendering it ineffective.


Section of a lightning chain, showing the lengths of copper supported by rope

 

Furthermore, the conductor did not always protect the whole ship. It has been known for a conductor to be run up the main mast, only for lightning to strike the fore mast. Finally, the ferocity of a lightning strike has been known to melt parts of the conductor, thereby breaking the chain and removing any protection from a subsequent strike. Hence in any lengthy storm, the ship may only be protected from the first lightning strike.

 

There is no record of such a conductor being taken aboard Endeavour, but there is evidence to show that she carried one. Surprisingly this evidence for the initial use of the conductor is not found in the ship’s log, nor is it found in the journal of Captain Cook. Shortly after leaving Rio de Janeiro, on 13 December 1768, Joseph Banks wrote in his journal, “at night a squall with thunder and lightning which made us hoist the Lightning chain.”

 

Endeavour encountered numerous storms on her voyage around the world, and the lightning conductor appears to have worked well as the ship never received a direct hit. The closest she came to being struck was whilst she was anchored in Batavia Road in October 1770. Tropical storms had brought thunder and lightning nearly every day for a week. On 12 October, Cook recorded the following event in his journal.

About 9 oClock in the Evening we had much Rain with some very heavy Claps of Thunder, one of which carried away a Dutch Indiaman’s Main Mast by the Deck and split it, the Mn Topmt & Topgt mast all to shivers, she had an Iron spindle at the main Topgallant Mast head which had first Attracted the Lightning. This ship lay about two cables lengths from us and we were struck with the Thunder at the same time and in all probability we should have shared the same fate as the Dutchman, had it not been for the Electrical Chain which we had but just before got up, this carred the Lightning or Electrical matter over the side Clear of the Ship,

 

the Shock was so great as to shake the whole ship very sencibly. This instance alone is sufficient to recommend these Chains to all ships whatever, and that of the Dutchman ought to caution people from having Iron spindles at their Mast heads.

 

The length of two cables is approximately 1,200 feet or 366 metres.

 

This cautionary tale reminds us that not all of the dangers that Cook encountered were in the waters around his ships. It was well into the 19th century before permanent lightning conductors were incorporated into the masts of wooden ships.

 

 

Cliff Thornton

 

References

  1. The Nautical Magazine and Naval Chronicle for 1840. London. 1840.

  2. Franklin, Benjamin. The Life and Writings of Benjamin Franklin. Philadelphia. 1834.

  3. Priestley, Joseph. The History and Present State of Electricity with Original Experiments. London. 1767.


Originally published in Cook's Log, page 8, volume 36, number 2 (2013).

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