NATURE 



{May 2, 1878 



West Mediterranean, which represent the chief commer- 

 cial areas of home navigation, are near the points where 

 the first weather indications present themselves. It is 

 not surprising, therefore, that notwithstanding the 

 vigilance of coast-observers, and the prompt distribution 

 of warnings from London and Paris, that many vessels 

 are overtaken and fairly surprised by storms within sight 

 of the British and French coasts. The New York 

 Herald warnings have been forwarded to lessen this 

 danger to navigation in European waters, as well as to 

 give notice of bad weather in the Atlantic to vessels 

 bound for our coasts. 



I shall first deal with the field of observation from the 

 West Pacific Ocean to the Ural Mountains. 



I will limit my remarks on the general and local 

 phenomena of storms, to which the New York Herald 

 system of cable weather predictions relates, to the field of 

 observation that extends from the western part of the 

 Pacific Ocean in a great but irregular zone, eastward to 

 the line of the Ural Mountains. 



The irregularity in the width of this field which lies 

 generally between the loth and 70th parallels of northern 

 latitude is caused by our want of information regarding the 

 meteorology of the far northern sections of this continent 

 and of the region in North Africa between the equatorial 

 zone and the northern Umit of the great desert of Sahara, 



While the prevailing conditions in these regions may be 

 correctly inferred from their relations to contiguous terri- 

 tories, it will be unsafe for the present to base any 

 assumptions thereon, especially when such are not abso- 

 lutely necessary for my purpose in this article. I will 

 therefore refer only to the Pacific Ocean, between the 

 loth parallel and the Aleutian Islands, the North 

 American continent between the same parallel, and the 

 regions of Manitoba and north of the great lakes 

 and Canada ; the Atlantic between a line drawn from 

 the intersection of the 40th meridian and the loth 

 parallel, to the African coast at Cape Blanco ; and the 

 line drawn from Cape Farewell, in Greenland, and the 

 North Cape, in Norway; and Europe between the 30th 

 and 70th parallels. 



This immense area contains two great oceans familiar to 

 navigators, and the two continents that represent in the 

 majority of their peoples, the commercial enterprise, the 

 power, and the intelligence of the world. It also repre- 

 sents a considerable portion of the earth's surface sub- 

 jected to a diurnal and equal share of solar influence 

 according to latitude. Whatever may be the real effect 

 of the sun's heat and magnetism in producing atmo- 

 spheric perturbations, the field selected is that which 

 they must almost uniformly influence, and on which the 

 extent of that influence is most likely to be accurately 

 determined by scientific observation and study. 



It will be observed that the oceanic and continental 

 areas are each divided into two sub-areas by well-marked 

 lines ; the oceans by equatorial currents having a 

 general direction from south-west to north-east, and the 

 continents by distinct regions of mountain and plain. 

 The distinction in the latter case is most marked on the 

 N-brth American continent, but is also very clearly 

 defined in Europe. We have therefore eight sub-areas 

 of the field of observation, each exercising its peculiar 



influence on the movement of the atmosphere over the 

 whole field. The Kt{ro Siwo or Japan current of the 

 Pacific Ocean, which corresponds so closely with the 

 Gulf Stream in the Atlantic, moves north-eastward with a 

 smaller resistance from the north polar waters than the 

 Gulf Stream. The narrow Behriitg Strait, through which 

 the Arctic current must pass southward is even narrower 

 than Smith Sound, consequently the northern waters of 

 the North Pacific maintain a higher general temperature 

 than those of the North Atlantic, but owing to the 

 spreading out of the Kuro Siwo over a greater area 

 than the Gulf Stream covers in corresponding latitudes, 

 the waters of the latter are relatively warmer and probably 

 deeper between latitudes 30° and 60°. Hence a more 

 uniform tempet^tiire overspreads that part of our field of 

 observation represented by the North Pacific Ocean. It 

 is reasonable to suppose that the compensatory flow of 

 polar water toward the equator comes chiefly from the 

 Antarctic regions in the Pacific Ocean and in nearly 

 equal proportions from both poles in the Atlantic. The 

 effect therefore must be, as I suggest, that the surface of ' 

 the North Pacific has a very uniform temperature, 

 making due allowance for latitude. The atmospheric 

 conditions are consequently affected so far as to pro- 

 mote the development of large areas of low pres- 

 sure without many important centres of very violent 

 disturbance. I cannot say if the infrequency of storm 

 centres, as we are accustomed to regard them, on the 

 Pacific, suggested the name, but it cannot be considered 

 an inappropriate one. Violent storms cross the northern 

 parts of this ocean, but they come from the Asiatic con- 

 tinent, and are probably identical with those which had 

 already passed over Northern Europe in their east- 

 ward courses. We have no satisfactory evidence that 

 such storms again pass over Europe, but they un- 

 doubtedly traverse the circumpolar seas, carrying to 

 those regions the great winds and snows that are ex- 

 perienced by whalers and explorers in the far north. 



Over such an immense area of warmVater surface as 

 the Pacific presents the atmosphere absorbs an extra- 

 ordinary evaporation, and in its general eastward move- 

 ment brings the humid air to the western coast of the 

 American continent, where, by condensation against the 

 mountain chains that extend from Lower California to 

 the Arctic Ocean, it becomes deposited in heavy rains. 

 The liberation of latent heat consequent to this process 

 causes a barometric fall near the coast line, and the 

 development of storm centres which move inland over 

 the Continent, and have been traced from Oregon to 

 Armenia. Cyclones that are developed in the equatorial 

 zone of the Pacific cross the ocean and are experienced 

 on the American coast from latitude 20° to 55°, according 

 to their point of origin, and high or low trajectories. 

 The movements of these storms will be referred to under 

 another head. 



On the North American Continent the mountain sub- 

 area extends eastward from the Pacific Coast to the line 

 of the Rocky, Mountains. It is represented by a great 

 elevated plateau from four to eight thousand feet above 

 the sea-level, and from three to six thousand feet above 

 the general level of the sub-area of the plains which 

 extends eastward from it to the Atlantic. The peculiar 

 alignment of the axes of the mountain chains running 



