June 15, 1882] 



NATURE 



151 



which bear?, with seamen, the ugly name of " Dead Man's 

 Bay," from an embayed vessel caught in a south-west gale 

 seldom escaping shipwreck. More than half a century back, 

 Fleet was inundated from a breach in the beach, and the church 

 washed down, and many houses in Chesilton destroyed. 



It is said locally, that the material is so finely graduated, that 

 a native boatman or fisherman can tell in the darkest night the 

 exact locality his boat may come ashore or be beached on, by 

 picking up a handful of the gravel. In a south-west gale it is 

 next to impossible to stand on the eastern crest, from the rain of 

 pebbles projected over its summit by the breaking waves. 



The Chesil is shown with great accuracy in early manuscript 

 maps, especially in a remarkable series of drawings collected 

 by the great Cecil, well known at the British Museum as "Lord 

 Burleigh's Book ;" also in drawings by Collins and Lilly. From 

 these it would appear, that two or three centuries back the 

 "Fleet " was wider, leading to the inference that the beach had 

 retreated landward ; but a close inspection of the bank does not 

 support this conclusion, but appears to show that the surplus 

 material is driven in heavy weather right over the crest sloping 

 towards the " Fleet," the area of which has been narrowed and 

 reduced by this continued process. 



The gradation of material here again shows the ultimate lee- 

 ward movement from west to east, due to preponderance of 

 winds from the first quarter; the altitude from three to four 

 times that of the normal elevation of ordinary English beaches 

 above high water ; also the upper plateau above the usual neap 

 and spring " fulls" are striking features, showing its abnormal 

 character. 



The largest shingle travelling to leeward and to the sum- 

 mit, is illustrative of the accumulative energy of the heavier 

 projectiles, and their being less acted on by the recoil than 

 the smaller materials. 



It may be well to notice here the soundings taken in H.M. S. 

 Beagle, between Santa Cruz and the Falkland Islands, referred 

 to by the late Mr. Darwin in his work "Geological Observa- 

 tions," published in 1876, and which he truly describes as pre- 

 senting the usual phenomena in such ca*es. The material 

 quickly and regularly decreasing in size with increased depth and 

 distance from shore, under two miles out large and small pebbles 

 were found intermixed. 



Miles. 

 At 2 to 4 



Depth, 

 fathoms. 

 II to 12 



Pebbles size of walnuts and 

 smaller. 



4*o 7 ... 17 to 19 ... Do. size of hazel nuts. 

 10 to II ... 23 to 25 ... T y to T y m«. diameter. 



12 ... 30 to 40 ... T V' diameter. 



22 to 150 ... 45 to 65 ... ,V' do. to fine sand. 

 This is confirmatory of, or supported by, observations around 

 our own coasts. J. B. Redman 



6, Queen Anne's Gate, Westminster, S.W., June 10 



Meteor 



On Wednesday, June 7, 945 p.m. G.M.T., at a station 396 

 yards north-west by we-t of the transit-circle of the ob-ervatory, 

 Mr. W. H. Robinson's attention was attracted by the sudden 

 appearance of a fine meteor about 3° below Mars, which parsed 

 through a point 5 below Regulus, and, continuing its course 

 about 12° further, finally disappeared. Almost instantly after 

 being first seen, it shone very brightly, then assumed a train of 

 detached luminous beads, and towards the end of its path hurst, 

 presenting an appearance similar to the bursting of a rocket. Its 

 greatest brilliancy was equal to Venus. The length of the whole 

 track was about 25°, and the time of visibility of the train was 

 about five seconds. E. J. Stone 



Radcliffe Observatory, Oxford, June 8 



Earthquakes in Naples 

 The seismographs of the Vesuvian Observatory and of the 

 Naples University have shown increased activity the last two 

 days. This culminated this morning at 6.47 a.m. in a distinct 

 shock seven seconds duration, direction north to south, chiefly 

 undulatory, but elevatory towards the end. From these facts 

 Prof. Palmieri considered it to come from a distance, and not of 

 local origin. This was proved by telegrams from Isurnia and 

 Vinchiaturo in the Apennines. All to-day the amount of vapour 

 frjni \\ mius is much more abundant, and this evening it is 



brilliant ; the quantity of lava flowing is increased. This is a 



good example on a small scale of seismic activity having its 



focus in a mountain chain affecting the neighbouring volcanoes. 



Naples, June 6 H. J. Johnston-Lavis 



THE "POLYPHEMUS" 



T_T ER MAJESTY'S ship Polyphemus, which has been 

 five years under construction, is now being prepared 

 for her final trials. She contains so many peculiarities of 

 design and novelties of various kinds in her machinery 

 and fittings that much scientific interest attaches to her 

 performances. Her form is different from that of any other 

 ship ever built. The part above water has been described 

 as resembling a cylinder floating on its side and deeply 

 immersed, which is tapered at the ends to form a bow 

 and stern. An idea of her appearance above water may 

 be obtained by imagining such a cylinder to be flattened 

 over a large portion of its area to form a deck, and to float 

 at a height of 4 feet 6 inches out of water. The whole of 

 the exposed part of this surface, which has great curva- 

 ture near the water line, and enters the water at an angle 

 of about 45 degrees, is plated over with steel armour, 

 which is carried some distance below water. The curva- 

 ture of the sides is continued to a depth of several feet 

 below the water line, and from this point they turn sharply 

 in and converge towards each other at the keel almost in 

 straight lines. A cross section of the vessel is similar to 

 a pegtop. which is floating in water at a depth below its 

 greatest breadth, and the emersed part of which presents a 

 convex surface only. Upon this form of hull an iron 

 superstructure is mounted, which carries a hurricane deck 

 from which the ship is worked, and to which the openings 

 into the main body of the ship are carried up. Two pro- 

 tected coverings are fitted on this deck, one at each end, 

 which are connected with the structure of the hull, and 

 give means of communication with the interior. There 

 are three revolving turrets on each side, which are eich 

 armed with one of the heaviest Nordenfelt guns. This 

 superstructure may all be shot away without injuring the 

 vessel or impairing her powers, except as regards the use 

 of the Nordenfelt guns. 



The lines of the ship are very fine, and have been deter- 

 mined chiefly with a view to great speed. The armour 

 plating is very light; no heavy guns are carried ; many 

 devices have been adopted to reduce the weight of the 

 machinery ; and some of the main fighting qualities of 

 most other men-of-war have been sacrificed, in order that 

 a high speed may be realised. The speed she was de- 

 signed for is 17 knots ; although with the great amount 

 of horse-power ; for her size, she is intended to indicate, 

 a higher speed might be expected if it is efficiently 

 utilised. The offensive weapons of the Polyphemus con- 

 sist of the ram and torpedo. She will carry no guns 

 except six Nordenfelt machine-guns, which will each be 

 carried in a projecting turret at the height of the flying 

 deck. These will serve to repel boat attack ; but for 

 offensive operations against powerful vessels, she will only 

 be able to employ the ram and torpedoes. The succes-ful 

 use of these weapons will depend primarily upon speed. 

 High speed is essential, to prevent failure in ramming ; 

 and in using torpedoes under heavy gun-fire, it is very 

 important to be able to approach an enemy quickly, and 

 to get away again with all possible celerity, as the contin- 

 gencies of this mode of fighting may require. The effi- 

 ciency of the Polyphemus thus being a question of speed, 

 it will be understood why so many sacrifices have been 

 made in order to enhance this quality. The vessel has 

 been constructed as light as possible throughout, and 

 saving of weight has been carried to a great extent. 



The hull is built of mild steel ; the frames being of 

 Bessemer, and the bottom plating of Landore-Siemens 

 steel. There is a double bottom, and the hold of the 

 ship is largely divided into separate watertight compart 



