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In part 3, I talked about deck, cabin, and hold illumination. But there's also a need for lighting by which the ship sees what lies around it, and is seen in turn. Lighting may also be used for communication, ship-to-ship and ship-to-shore.
Stern Lanterns. When ships were traveling in formation at night, there needed to be a way for the helmsman on one ship to see the ship in front of him (rear-end collisions and meandering off both being frowned upon). Hence, sailing ships carried stern lanterns (Laughton 159). This practice was not limited to warships as, in the seventeenth century, European trading ships often sailed with escorts.
In Edward III's navy, the number of stern lanterns indicated the status of the commander; three or more for the King, two for the admiral, and one for the vice-admiral (Traill 186). On sixteenth-century Venetian galleys, those commanded by a squadron commander had a single stern lantern, and the flagship of the Capitano Generale da Mar or the Provveditore Generale da Mar had three. Indeed, the flagship was sometimes referred to as a lanterna (Motture).
The 68-gun warship La Couronne (1626) had three lanterns above the taffrail; the center one was 12 feet high and 24 feet in circumference illuminated by twelve pounds of candles. (Sephton). On the Sovereign of the Seas (1637) there were five lanterns on the stern (Sephton 57, 61) , two apiece on the port and starboard quarter galleries, and the fifth and largest on the aft end of the poop above the taffrail. It was six or seven feet high, and four to four and a half feet wide. In 1661, Samuel Pepys, then clerk of the Naval Board, gave a tour of the Sovereign to his patron's wife, Lady Sandwich, the Lady Jemimah, and their seven companions and servants, and persuaded this tour group to join him in squeezing inside the stern lantern (Dill 12)—plainly the seventeenth-century equivalent of squeezing into a phone booth.
While a single stern lantern reveals the position of the ship, it says nothing about its heading. But if you were looking at the stern of Sovereign, you would see three lights in circumflex (^) arrangement, whereas broadside you would see a rotated "L". Nonetheless, this does not seem to have initiated a general trend toward use of multiple lights to show orientation.
In the early eighteenth century, all British first-, second-, and third-rates carried three lights, and this privilege was extended to fourth-rates in 1722. In 1804 it was decided that only a flagship would carry two lights, and all others just one (Willis 56). However, I believe that the second light in question was a top-lantern (see next section).
At least some early lanterns had panes of green-tinted mica, but these were displaced by glass, which rendered the light easier to see. Hexagonal and octagonal designs were the most common, but the lantern on the Merhonour (1622) was seven-sided (Howard 114). It cost over eleven pounds, not even counting the glass plate, but almost half of that was attributable to gilding (Laughton 142).
Top-Lantern. When William, Duke of Normandy, sailed across the English Channel, he "had a lantern placed at the top of his ship's mast, so that the other ships could see it and hold their course behind him" (Musset, 196). On the 1564 Legazpi Pacific expedition, a ship in need of assistance at night would place a lantern in the main mast and fire a shot, and if it were an emergency, it also hung a lantern in the foremast and fired two more shots (Licuanan 64). In 1595, Drake ordered his fleet that if they had to unexpectedly make sail on a night that it had previously shortened sail, it would show "a single lantern with a light at the bow, and another at the fore-top" (Maynarde 64).
Later, it became customary that a British navy flagship leading a squadron would display a lantern at the aft edge of a masthead: the main top (full admiral), fore top (vice admiral), or mizzen top (rear admiral) (Lavery 255). It was supported on each side by iron braces (Falconer 294).
In 1762, Admiral Howe ordered that a ship tacking at night was to hoist a light and keep it visible until the maneuver was completed (Willis 56).
Lightships of course also displayed lanterns on high, but early lightships suspended small lanterns from a yardarm or dedicated crossarm. Robert Stevenson proposed a lantern that surrounded the mast of the vessel, and could be lowered to the deck to be trimmed and then raised back. (Stevenson 39). Presumably, the vertical traversal of that lantern would be limited by the yardarm above. It is conceivable that the lantern had a dedicated mast; i.e., one that did not ever carry sail.
In 1838, the US Congress enacted legislation providing that between sunset and sunrise every steamboat must carry one or more signal lights that can be seen by other boats navigating the same water. A three-light system was privately adopted by the Liverpool steam packets. In 1847, a different system—red on the port bow, green on the starboard bow, and a bright white light on the foremast head—was adopted for the mail steamers on the west coast of England. Finally, in 1848, a similar system was applied to all British steam vessels between sunset and sunrise. (Grosvenor).
By the 1870s, it was proposed that the masthead light be electric (Trowbridge 723). This was met with numerous objections—the ships met would be blinded by the light, the carrying ship's side lights would be rendered inconspicuous by comparison, the ship would be mistaken for a lightship, etc. (Thomson 190).
The Titanic carried a single electric masthead light on her foremast, 145 feet above the water. It was 32 candlepower, and its Fresnel lens concentrated the light into a horizontal arc with a vertical amplification factor of 25. It thus would have been as bright as a first magnitude star at a distance of 17 miles(Halperin).
There is an obvious downside to the use of any lights on shipboard, let alone lights intended to reveal one's presence to other vessels.. Drake ordered, "you shall keep no light in any of the ships, but only the light in the binnacle, and this with the greatest care that it be not seen, excepting the admiral's ship . . . ." (Maynarde 64). And even today, there are waters where small boat captains don't switch on their mast lights (Liss 62).
On the other hand, in 1800, Thomas Cochrane in the brig sloop Speedy was able to evade a frigate at night by placing a lantern on a barrel and letting it float away (Wikipedia).
Lighting the Waters: Star Shells
Sometimes it is desirable to illuminate the surrounding waters at night, in order to spot navigational hazards or enemy craft.
The star shell ("light ball") is fired by a mortar (high trajectory gun) and contains a small explosive charge and a time fuse. The charge in turn ignites the illuminating composition. Early compositions included mixtures of sulfur, saltpeter (potassium nitrate), and realgar (arsenic tetrasulfide), orpiment (arsenic trisulfide), or antimony (Griffiths 91)
Appier's La Pyrotechnie (1630) gives a formula for "fire balls . . . so white that one can scarcely look at them without being dazzled," that comprises saltpeter, orpiment, gum arabic, and, strangely enough, ground glass and brandy (Skylighter).
In its original form it was not very useful at sea as the "stars" would fall into the water, and be extinguished within a few seconds. And even in land warfare, the enemy could be expected to throw water or sand over it.
Edward Boxer (1819-1898) proposed modifying this shell to be composed of two hemispheres, one containing the illuminant ("stars") and the other a calico parachute connected to the first by ropes or chains. The explosion of the charge not only ignites the illuminant, it separates the hemispheres, but only insofar as the connector permits. The parachute slows the descent of the illuminant (Ibid.). Boxer was probably unaware that there had been experimentation during the time of Louis XIV with rockets equipped with parachute flares (Faber 181). For that matter, Congreve had a rocket light ball with a parachute (Sterling 401).
I have documented use of magnesium flares in photography of the Comstock Lode mine (1868) and the Great Pyramid (1865). I wasn't able to determine when magnesium, aluminum, or magnalium ribbons were first used in star shells, but the first reference I found was from just before World War I (US Army, 2-11). The parachutes were also minimized, so that six or eight parachute-illuminant combinations could be fit inside a single shell.
Lighting the Waters: Searchlights
Searchlights are essentially a military development of the spotlight—that is, they combine a highly luminous source, a light concentration system, and a pivotable and tiltable mount.