ICEBERGS AND NAVIGATION.

Daily Southern Cross, Volume XIV, Issue 1020, 7 April 1857, Page 4

ICEBERGS AND NAVIGATION.

J. T. Towsen, Esq , delivering the inaugural lecture at the Devonport Mechanics' Institute on "Glaciers and Icebergs," detailed some of the extraordinary passages recently made to and from Australia by some of the Liverpool clipper ships, in which they averaged only a trifle under ten nautical .tuiles per hour for the eutire voyage, a result attained by the adoption of the composite route. This system, it had been said, by leading the ships in high latitudes, cause them to be endangered by iee — a statement which was incorrect, inasmuch as the quantity of ice met with did nut depend upon the height or lowuess of the latitude, all other things being equal. As the inventor of that system, he had received a substmtial mark of their aense of its usefulness from the Liverpool merchants, and he felt himself bound, in the first place, to keep the ships out of unnecessary danger ; and in the second, if the danger ■was not unnecessary, to seek into its cause and nature, with a view of arriving at a certain knowledge of it. He had been partially urged in this course by a letter written to Lloyd's by a Mr. Christopher, residing at Heavitree, which charg ed him with having endangered, amongst others, the "Ked Jacket," and the "Golden Era," and of having probably been the cause of the loss of the "Aladagasear." From these various causes, therefore, he had been led to enquire into the laws which governed those floating bodies of ice, which did, no doubt, exist to a great extentiri the tracks of the ships to and from Australia. Observations had been made, at his request, by upwards of 100 captains of Vessels who bad sailed from the port of Liverpool, and drawings of the icebergs met with had been executed, chiefly by the passengers, who had never once rofu&ed to do so when reque^d by the captain. The results thus attained were communicated to him, and from them be constructed charts, which were furnished to the various vessels proceeding to Australia The lecturer then proceeded to give an account of the different forms in which ice existed on the ocean. What was called the field ice was the result of one winter's freezing of the surface of the sea in the frigid zones. It varied from three to thirty feet thick, and had no doubt been the cause of the loss of many vessels in the Polar regions. As it came into lower latitudes, however, it be came broken np"^ and with one or two exceptions, $he only danger that would arise from it would be the destruction of the copper at the water's edge. One case, however, had occurred, in which the ship had, thiongh the neglect of the captain Had taken her where no man in his sober senses would have gone — been surrounded, and liad been for some time in great danger from broken fee. That arose from the captain being in a continual state of intoxication, for which lie was put on bis trial when he came home, and received eight month's imprisonmont. With that ex-

ception, there bad been no considerable amount of dan *er The other form of ice— icebergs— wasm.ich more formidable. They were frequently 300 thigh and when tneyo midered only that one tenth part of them was above the water, an idea co-iid he formed -t tiioir enormous magnitude. They were produ.-oH by the immense glaciers tilling the valleys ..f the I'oUr regions, which, a 'tot accumulating fur a long : eriod, were no longer able to adhere, and accordingly broke off, forming icebergs. Icebergs were chiefly produced in the Northern Ocean, on the coast of Greenland ; in and the Antarctic Sta they were for the m-stpart formed at Graham's Land, although there were other regions from «hich they emanited They were of different shapes and sizes and weie easily recognised if seen before ; in fact, rhe captain of the "Royal Charter" had told bin* that he had seen the 'same iceberg on different voyages. Iceberg* did n.-t take the track of the surface current, and accordingly there was some difficulty in estimating their course They were met with in various parts of the course, both out and home. Mr.Townsen then pointed outonachart (the original one on which he had.laid down the various icebergs as they were reported to him) the d'ffereut tracks he recommended ships to take during the Austral winter and summer months on their voyage to Australia, it being possible in the latter to take higher latitudes than in the former. With reference to the greater probability of meeting with icebergs in high or low latitudes, the lecturer referred to the voyage of the "Great Britain," when that ship was surrounded, whilst in a low latitude, by no less than 360 jcebercs: at the same time the "Golden Era," in the'high latitude of 64, was clear from icebergs Having stated that the tracks out and 'home to Australia were not the same, because of the great prevalence of westerly winds, which made it advisable for the ships to sail to the east, Mr Towsen stated that it was necessary to take a high latitude to clear the Horn j and with reference to the confidence placed in his charts on this subject, said that one lar_e firm in Liverpool had 'declared that, if one of their captaius took a ship through a portion of the ocean prescribed by him (the lecturer,) he .should never take another. An immense mass of ice (having the shape of a fish hook, rounded at the corners,) 80 miles one way, 40 on each of the others, and from 4 to 7 miles broad, had beeu fallen in with in a low latitude, where a small iceberg would have raeUed,two or three years since by the "Cambiidge" and other ships, which entered at the long line, coasted it, aud got out at the other side of the opening. This took place in March, and in tho Apiil fullowiug the "Salem" likewise met with it. As this immense mass of ice was lying in the track of the vessels, he thought it likely that the "Guiding Star," of which nothing had been heard since leaving Liverpool for Australia on her outward voyage, had fallen in with it, and, le«s fortunate than the "Cambridge" and the "Salem/" been lost. Since May, 1855, nothing had been heard of this enormous body of ice, asithailg.ineout of the track to the southward. He had had some conversation with Dr. Scoresby about it= origin, and it was their belief that it had been produced by centuries of frost acting upon a number of icebergs closely packed together. It was a remarkable faoUhat no icebergs had ever been seen while the Horn was in sight, which he attributed to numerous currents ; therefore he recommended captains of vessels to sight the Horn, and keep along the Falkland Islauds, which would keep them dear of the icebergs and out of the greatest danger They need not fear being thrown upon the land by so doing, as no current would ever take a ship upon the rocks. Mr. Towsen then gave some interesting particulars with reference to the breaking off and toppling over of icebergs, and stated that their neighbourhood couldbe detected by the thermometer, as they formed a cold atmosphere around them. They moved quickest in the high latitudes, and slowest in the low— their greatest rate of progress being ten miles in the twenty four hours, and the slowest about one. The lecturer stated that the result of his investigation showed that the ships were not thrown in greater danger from ice through taking the track laid down by him, and that^ in many cases a higher latitude was freer from icebergs than a lower one— DevonportTelbqraph.3