June 29, 1882] 



NATURE 



207 



prominent are the low pressures which occupy the centres 

 of comments in the summer months, and the northern 

 portions of the Atlantic and Pacific Oceans in the winter 

 months ; and on the other hand, the high pressures which fill 

 the centres of the continents in the winter months, and the 

 high pressures in the oceans immediately to the west 

 sides of the great continents, about lat. 36°, as shown by 

 the Admiralty's physical charts of the Atlantic, Pacific, 

 and Indian Oceans. 



To take, as an example, the great summer barometric 

 depression of Central Asia with the winds, flowing in upon 

 it on all sides vortically, carrying with them the moisture of 

 the ocean from which they come. Thus East Siberia is then 

 swept by south-east and east winds, which distribute to west- 

 ward as far as Irkutsk, in July, a monthly rainfall of 3 inches 

 andupwards. Now since the annual rainfall ofthisregion 

 is all but wholly determined by the rains of the summer 

 months, the extension of these rains inland wholly deter- 

 mines the position of the annual iso-hyetal lines. Again, 

 to westward of long, too in Siberia, the rains have their 

 origin in the Atlantic and Arctic seas, and since west 

 and north-west winds prevail from Archangel to Central 

 Asia, they bring with them comparatively so large a share 

 of moisture from the ocean, as to raise the annual rainfall 

 over the greater part of these northern regions to about 20 

 inches, or even more. On the other hand, on the east | 

 side of the Ural Mountains, which drain these winds of | 

 much of their moisture, the summer rainfall is much i 

 less. From north of the Caspian and Aral Seas, south- 

 ward to the Persian Gulf, and eastward to the Indus, 

 the summer winds are north-west, and since they thus 

 advance over regions rapidly rising in temperature, little 

 if any moisture is deposited in their train, thus rendering 

 this extensive region one of the largest arid tracts of the 

 globe. 



These, with other considerations, indicate that the 

 courses of several of the iso-hyetal lines, where observa- 

 tions are sparse, should be regulated to a greater extent 

 than has be?n done in the map before us, by the positions 

 of river-basin'! and mountain ranges in their relations to 

 those seasonal winds, which really determine the annual 

 amounts of the rainfall. 



One of the most important points to which attention is 

 drawn by Prof. Loomis, is that more rain falls on the 

 eastern than on the western sides of continents. This 

 remark holds good everywhere, until we reach the higher 

 latitudes of both hemispheres, where the predominating 

 winds become westerly. Thus the rainfall at San Fran- 

 cisco is only from a half to a third of the amount which 

 falls on the coast of Pennsylvania in the same latitude ; 

 and about the same proportions, or even proportions still 

 more striking, are seen on comparing Morocco with the 

 Chinese coast, and the west with the east coasts of South 

 Africa, Australia, and South America. The explanation 

 is to be found in the portions of the areas of low and high 

 pressures, with their accompanying winds, during the sea- 

 son whose rainfall determines the annual amounts. On the 

 east side of the continents the prevailing summer winds are 

 south-west, south, or south-east, which having traversed a 

 large extent of ocean, and constantly advancing into higher 

 and colder htitudes, spread a copious rainfall over the 

 regions they traverse. But on the other hand, since the 

 west side of continents in the same latitude lies between 

 the region of abnormally high pressure in the ocean 

 immediately to westward, and the low pressure of the 

 interior, north-west winds in the northern, and south-west 

 winds in the southern hemisphere prevail there ; and as they 

 advance into lower latitudes or overregions of aconstantly 

 increasing temperature, they deposit little or no rain in 

 their course. Hence, owing to the failure, more or less 

 complete, of the summer rains, it follows that the annual 

 rainfall of these portions of the continents is small. 



In preparing the second issue of the map, attention 

 should be directed, in addition to the regions already 



indicated, to the rectification of the lines of equal rainfall 

 over Iceland, the south-east of Norway, the Gulf of 

 Guinea, the temperate regions of South America, and 

 Northern, Central, and Western Australia, and we feel 

 assured meteorologists will heartily co-operate with Prof. 

 Loomis, and give him all possible assistance in com- 

 pleting the important work he has so successfully begun. 



NOTES 



The name of Prince Leopold (Duke of Albany) bas been 

 added to the General Committee of the Darwin Memorial Fund, 

 subscriptions to which, we may remind our readers, are still 

 being received at the Royal Society, Burlington House, by the 

 Hon. Secretaries, Prof. T. G. Bonney and Mr. P. Edward 

 Dove. 



The communication from Greenwich which appeared in our 

 last number, p. 175, showed that in the double magnetic storms 

 of April, the Greenwich times of commencement of disturb- 

 ance were, for Greenwich, April 16, nh. 32m., and April 19, 

 I5h. 35m. ; and for Toronto, Canada, April 16, lib. 34m., 

 and April 19, 15b. 34m. The communication in question was 

 followed by one from M. Dechevrens, reporting the magnetic 

 disturbance as commencing suddenly also at Zi-ka-wei, China, at 

 7h. 36m. on the morning of April 17, and as being as suddenly 

 renewed at llh. 40m. on the morning of April 20 ; equivalent to 

 April 16 — llh. 30m., and April 19, I5h. 34m. Greenwich time. 

 The outbursts thus occurred at the same absolute time at 

 Toronto, Greenwich, and Zi-ka-wei. 



The Trince and Princess of Wales opened the handsome new 

 Technical School at Bradford on Friday. The Prince, in the 

 various speeches he gave showed that he has a real appreciation 

 of the necessity for scientific training in this country, if we are 

 to keep on a level with the other great nations in our industry 

 and commerce. 



The Commission appointed by M. Ferry to report on the 

 con -traction of the rotating dome for the large refractor of the 

 Pari-; Observatory, has held numerous meetings at the Conserva- 

 toire des Arts et Metiers, Col. Laussedat, director of the esta- 

 blishment, being in t'ae chair. Only two projects have been 

 reserved for final choice. M. Eiffel proposes to use a saline 

 solution in a horizontal circular channel placed on the wall to 

 diminish the weight of the rotary roof. 



We are glad to learn that owing to the exertions of Admiral 

 Mouchez, magnetical observations will soon be resumed at 

 the Paris Observatory, in subterranean chambers which have 

 been excavated in the newly annexed grounds. These observa- 

 tions will be self-registering by photography, in conformity with 

 the instruments established by M. Mascart at the College de 

 France. Direct observations will also be conducted with the old 

 instruments which were used by Arago, which were famous 

 for his prognostications of Aurora;, at a period when, the elec- 

 tric telegraph not having been invented, many days must elapse 

 before the arrival in Paris of news from the northern parts of 

 Europe. 



In the course of a few weeks all the International circum- 

 polar observatory parties will have arrived at their different 

 destinations, or be on their way thereto, and on August I the 

 observations will commence simultaneously on the common plan 

 framed by the different conferences held in Hamburg in 1879, 

 in Bern in 18S0, and in St. Petersbarg in 1881. By the present 

 arrangement Russia has three stations, the United States and 

 Germany two each, whilst England, Austria, Sweden, Norway, 

 Denmark, France, Holland, Italy, and Finland maintain one 

 each, of which three— the French, the Italian, and one German 

 —will be established in the Antarctic regions. The total number 



