372 



SCIENCE. 



[Vol. V., No. 117. 



general presentation of theory and fact than any- 

 work we have seen. The value of the winds as 

 the chief motive force, and the inefficacy of gravity 

 Drought into play by changes of temperature, are 

 clearly made out, so far as surface-currents are con- 

 cerned. The part played by the deflective forces 

 coming from the earth's rotation is also well stated. 

 So long as the surface-waters are brushed along by 

 the wind in any given direction, the tendency to 

 depart from this direction is practically overcome by 

 the wind itself; but, whenever the waters set in 

 motion by the wind enter a region of calm, they at 

 once begin to describe the 'inertia curve,' — a line 

 whose radius of curvature decreases with the sine 

 of the latitude. Already in latitude 5°, this radius of 

 curvature for a velocity of one metre a second is only 

 forty-two and a half nautical miles: hence, when the 

 South-Atlantic current runs into the region of calms 

 just north of the equator, its waters will quickly turn 

 to the right, easily falling into the power of the 

 south-west monsoon of that region, and so forming 

 the Guinea current, and, during the northern summer, 

 the equatorial counter-current as well. The author 

 therefore concludes, that, after the winds and the 

 configuration of the coasts, the diurnal rotation of 

 the earth must be recognized as the most important 

 factor in determining the existing system of ocean- 

 currents. 



— Messrs. Sampson Low & Co. of London an- 

 nounce ' Under the rays of the aurora borealis, in the 

 land of the Lapps and Kvaens,' — an original work 

 by Dr. Sophus Tromholt, edited by Mr. Carl Siewers. 

 The book contains an account of the work of the 

 recent circumpolar scientific expeditions, and an ex- 

 position of our present knowledge of the aurora 

 borealis, to the study of which the author has de- 

 voted the greater part of his life. 



— The second session of the summer course of bot- 

 any at McGill college, Montreal, will be opened to 

 ladies on Tuesday, May 5. The course, which will be 

 in charge of Professor Penhallow, will continue for 

 seven weeks. It is designed to give practical instruc- 

 tion in general morphology, including the analysis 

 and study of Canadian plants as found in the vicinity 

 of Montreal. Instruction will also be given in his- 

 tology with the microscope. 



— In the annual report for 1884, of Prof. G. H. 

 Cook, state geologist of New Jersey, there is a de- 

 scription of some remarkable recent changes in the 

 condition of the land near South Amboy. A forest 

 of common timber, such as oak and chestnut, stand- 

 ing on land ten or twelve feet above high-water mark, 

 was cut down, and the underlying sands to a depth 

 of twelve feet were stripped off preparatory to taking 

 out the stoneware clays below; but, before reaching 

 the latter, a swamp deposit a few feet thick, with 

 white-cedar trees embedded in it, was passed through; 

 and at the bottom of this, standing in the clay, were 

 several oak stumps, at a level two feet below the 

 adjacent salt-marsh, which is overflowed by high 

 tides; and near the stumps there was a log about a 

 foot in diameter, eight or ten feet long, that had been 

 cut with an axe. There is no tradition telling of the 



burial of this forest, but it must have been less than 

 two hundred and eighty years ago. The successive 

 deposits are well shown in the excavation. The clay 

 at the bottom; the old oak forest in the soil on this 

 clay; then the black swamp-earth, and its small cedars 

 embedded therein; finally the overlying plain of sand 

 and gravel, with its late growth of upland timber, — 

 with this, there is good evidence that the ground, 

 which was formerly high enough above the level of 

 the sea to sustain a growth of upland timber, is now 

 so low that every tide could cover it with salt water. 

 Some valuable figures are given in illustration of 

 the superposition of glacial drift on unconsolidated 

 tertiary clays, and of the columnar trap-rocks and 

 water-bearing sands. The Green-Pond Mountain 

 rocks, which were thought triassic by Rogers, and 

 which were regarded as Potsdam in the earlier reports 

 of the present survey, are now placed in the middle 

 Devonian. The crystalline rocks of the Highlands, 

 which have been called Laurentian on the strength 

 of their lithological' characters, are here prudently 

 called simply archaean, in the absence of sufficient 

 evidence to correlate and identify them. 



— Major.-Gen. Sir F. J. Goldsmid has an article 

 in the April number of the Contemporary review on 

 Russia and the Afghan frontier. The gist of the 

 article is, that the apathy with which the English 

 government and people have hitherto watched the 

 Russian advance from the Caspian towards India is 

 due to a lamentable ignorance, on their part, of the 

 geography and topography of central Asia. This is 

 undoubtedly true; but how far the remedy proposed 

 by the gallant general would be a remedy, is an alto- 

 gether different matter. 



— The Royal medals of the Royal geographical 

 society, says Nature, this year were awarded to Mr. 

 Joseph Thomson and Mr. H. E. O'Neill; to the 

 former for his well-known work in Africa, and to 

 the latter for his thirteen journeys of exploration 

 along the coast and in the interior of Mozambique. 

 The Murchison grant for 1885 was awarded to the 

 Pandit Kreshna for his four explorations made while 

 attached to the survey of India, and especially for 

 his extensive and important journey in the interior of 

 Tibet. The Back grant went to Mr. W. O. Hodkinson 

 for his Australian explorations, and the Cuthbert 

 Peek grant to Mr. J. T. Last for his surveys and 

 ethnological researches in the southern Masai, Nguru, 

 and other neighboring countries. The following 

 were made honorary corresponding members: Chief- 

 Justice Daly, president of the geographical society of 

 New York ; Mr. Elise'e Reclus, the eminent geogra- 

 pher ; and Herr Moritz von D3chy, the distinguished 

 Austrian explorer of the Sikkim Himalayas, the Cau- 

 casus, and other regions. 



— On the night of the 5th of April, the steamship 

 Nurnberg, in latitude 49° north, longitude 18° 30' 

 west, during a very heavy storm from west-north- 

 west, had mast-heads and yard-arms lighted with St. 

 Elmo's lights. It was raining and hailing at the time, 

 and the barometer showed 29.19. A ball of fire ex- 

 ploded during the storm, with a loud noise, similar to 

 the explosion of a gun. 



