Page:All the Year Round - Series 2 - Volume 1.djvu/209

 their roughness, and to lessen in some degree the splash of water into the open boat not actually to level the rolling billows, but to allay their wild tossing and breaking into spray. Whether oil was taken on board the boat for that purpose we are not told; we only know that it was thus used, two or more times, during that eventful 25th of November.

This subject of oil upon the waves is a curious one. It is by no means of modern date, either in its knowledge or its application; and yet there is only an indistinct appreciation of it amongst us generally. We do not place it among our every-day truths.

In ages long past, the effect of oil in stilling the waves was known to many grades of seafaring men. Pliny stated that the divers in the Mediterranean and the Archipelago were wont to take in their mouths a bit of sponge dipped in oil, and that they were by this means enabled to remain longer under water than other divers who were not so provided. As the diver wants to retain all the breath he can, and as long as he can, it is difficult at first to see how the attainment of the desired object could be facilitated by this agency; but an explanation soon offers itself. The object of taking oil into the mouth was to calm those small waves on the surface of the sea, which prevent the light from being so steadily transmitted to the bottom as is necessary to enable the diver to find the small objects they search for without delay. By ejecting a little oil from the mouth, it rises to the surface, and, spreading out upon it, calms the waves sufficiently to admit a good daylight to penetrate through the water. The habit followed by many fishermen and boatmen gives probability to this explanation. Dr. Halley mentioned that he saw some of the Florida Indian divers remain under water two minutes at a time; and he proceeded to notice the effects of a thin film of oil in facilitating the divers' work. A century and a half ago the fishermen of some of the Hebrides were accustomed, when the sea was getting rough, to tie to the end of a cable a mass made chiefly of the fat of sea-fowl, and allow it to dip into the sea behind the rudder; the oil from the fat exerted a smoothing agency upon the waves. The Lisbon fishermen sometimes allay the waves on the bar across the Tagus, when they wish to cross, by means of a little oil. During the siege of Gibraltar in the last century, the British officers often observed the Spanish fishermen pour a little oil upon the sea, to enable them to see oysters at the bottom. Herring-fishers on the coast of Scotland can see from a long distance when and where a shoal is approaching; the water acquires a peculiar smoothness of appearance from the oil of the fish. Seal-catchers in the Arctic regions have often observed that, when the seals eat oily fish (which they often do), the surface of the sea above them becomes much smoother than at other parts. The ocean is often observed to have a peculiar quietness in the wake of a laden whale ship. This is due to the small quantity of oil which, somehow or other, manages to exude from the vessel, perhaps pumped up with the bilge-water from the hold. Off some coasts, where fish are speared instead of netted, a little oil is poured on the water, to enable the fishers to see their prey below.

Dr. Franklin, who had an indefatigable habit of searching out a scientific explanation for everything that could be explained by science, resolved to experiment upon this subject of oil on water. He had read and heard and seen that oil is thus used, either to make voyaging more safe and pleasant or to enable the rays of light to penetrate the water, and he wished to know the reason why. He first tried a pond upon a common. Selecting the windward side, he poured a little oil on the water. Quickly it spread further and further over to leeward, until a considerable area of the pond had a very thin film, which calmed the water in a singular way. We rather suspect that some error has crept into the original account of this experiment; for it is difficult to believe that a tea-spoonful of oil would render half an acre of watery surface as smooth as a looking-glass, which is the substance of Franklin's statement. On another occasion he made a deep harbour the scene of his experiments. He anchored a boat at a certain distance from the shore, and another boat made several short trips out to windward and home again. In this second boat a man had a bottle of oil, which he poured out in a very small but continuous stream through a hole in the cork. Franklin, seated in the first boat, watched the effect of the oil, while others watched on shore. Leeward of the anchored boat, little or no change was visible; but out windward the oily track spread far and wide, preventing the waves from breaking into ripple, foam, and surf.

The poor Hibernia was not by any means the first ship, the crew of which had cause to welcome the effect of oil upon the waves. About a century ago a Dutch East Indiaman made a voyage to the East, and fared pretty well until nearing the islands of Paul and Amsterdam. A storm then arose, and the captain poured out a few ounces of olive oil into the sea, to prevent the waves from breaking against and over the ship; the plan succeeded, and the ship went on her way. One of the passengers, in a letter to the Dutch ambassador at the court of St. James's, stated that the parsons to whom he afterwards narrated this incident were so incredulous, that the officers and himself signed a certificate declaratory of its truthfulness, so hard did it seem to believe the effect of a very little oil upon a very great sea. Numerous examples of a similar character are to be found scattered here and there among the records of voyages. One of the many trading ships which ply between Manilla and Singapore had a singular oil adventure a few years ago. While on the voyage she encountered a very rough and unpleasant sea. Suddenly there appeared a peculiar smoothness of the sea, although the wind was still blowing, and the ship advanced favourably for three days over a