April 1, 1887.] 



♦ KNOWLEDGE ♦ 



121 



^ ILLUSTRATED MAGAZINE ^ ' 

 ENCEHTERATURE,& ARf 



LONDON: APRIL 1, 1887. 



THE COMPLEXITY OF THINGS. 



By Grant Allex. 



«y» y| gyjf»]|XE of the feelings wbich most grows upon tlie 

 trff^rr-^'j^ scientific observer, as his knowledge of the 

 vroild in which his life is cast gradually 

 increases, is a profound and abiding sense of 

 the infinite interaction of cause and eflect, 

 the immense and immeasurable complexity 

 of things in this universe. Glib ignorance 

 is always ready with an easy explanation or a hasty pro- 

 phecy ; mature experience distrusts more and more from day 

 to day its own power of prognostication, or even of analysis. 

 Look, for example, at the readiness with which the local 

 weather prophet will confidently assert that we are going to 

 have a hard winter or a late spring. Upon what endless 

 interrelations of causes and events, all the world over, does 

 the weather of an English season depend 1 What know- 

 ledge of the ice packs in the Arctic regions, of the bergs 

 that float and melt in the Atlantic currents, of the depth of 

 snow on the Siberian plains, of the strength and direction of 

 the Gulf Stream and its divergent branches, of the pre- 

 valent conditions in Sahara, Spain, and the Mediterranean, 

 is necessary in order adequately to forecast the British 

 weather for the next twenty-four hours ! An east wind, 

 blowing over the frozen plains of Central Europe, brings us 

 frost and ice and sunshine today ; a westerly breeze, fresh 

 from the warmer currents of the Gulf, brings us cloud and 

 rain and thaw to-morrow. Our fruit-trees have their 

 blossoms nipped in the flowering season, beaiuse great 

 blocks of glacier have disengaged themselves prematurely 

 from the melting cliffs of the Greenland ice-sheet ; our 

 strawberries ripen in good time because a change in the 

 distribution of atmospheric pressure causes a downward 

 current of heated air to set in towards Britain from the 

 African desert. Why is the west wind so unwontedly 

 bitter to day 1 Because there are ice-floes off the coast of 

 Labrador. Why does the fog hang heavy over London this 

 morning? Because a certain motionless state of air prevails 

 over Western Europe, from Hammerfest to Lisbon. Why 

 did our pears fail to set their fruit 1 Because of the early 

 spring in Xorth-Eastern America. Why did our roses get 

 nipped by the frost? Because of the clear weather over the 

 Hindu Koosh and the valley of the Lena. Mr. Robert 

 Scott, enthroned in the Meteorologi&il Office in London, 

 with constant telegrams informing him from moment to 

 moment of every fluctuation in barometric i-eadings at 

 Valentia or Bayonne, every rise of temperature in the 

 Bay of Biscay or the North of Scotland, every shower 

 of rain off the Norwegian Islands, every passing thunder- 

 storm in Auvergne or Dalecarlia, can scarcely prognosticate 

 the coming weather for twenty-four hours in advance with 

 any approach to probability. Yet the local weather prophet. 



unabashed by his utter ignorance of the conditions of the 

 entire problem, will predict the weather of a whole season 

 as confidently as though he held all the threads in his 

 own hands, and directed the winds and waves irresponsibly 

 from an easy-chau- in his own drawing-room. 



What would be the effect upon the climate of Western 

 Europe if we wei'e to turn Sahara into an inland sea ? 

 What would be the result upon the world's weather if 

 we were to cut a large outlet for the heated waters of 

 the Caribbean Sea through the Isthmus of Panama 1 Most 

 people are prepared at a moment's notice to dogmatise 

 freely as to what would happen in ■either of these extreme 

 and improbable eases. They will say offhand that the 

 flooding of Sahara would improve the climate of Xorth 

 Africa generally, and that the diversion of the Gulf Stream 

 would reduce Scandinavia and Britain to the respective 

 conditions of Greenland and Manitoba. But how infinitely 

 complex is each such problem ! Who shall say what changes 

 might be induced, when Sahai-a was flooded, by the altera- 

 tion in the hot, dry winds which now blow oft' the wide 

 expanse of desert ] What melting- effects do they ultimately 

 produce upon the ice and snow of the Spanish Sierras, the 

 Pyrenees, the Alps, and the Carpathians? What extra 

 growth of glaciers would descend, in their absence, upon 

 the plains and valleys of Castile, of Languedoc, of Switzer- 

 land, and of Lombardy ? What varieties would these, 

 again, induce in the Fiihn, in the Bora, in the Mistral, 

 in the Tramoutana ? Every variation in the amount of 

 moisture due to evaporation will give rise to changes in 

 rainfall, in snow, in ice, in glaciers; wUl produce new 

 phenomena of denudation, of river forming, of earth 

 sculpture, of local climate ; and will therefore react at 

 last ujion vegetation, upon fauna, upon agriculture, and 

 upon human life and industry in general. More seas 

 in Africa might mean more rain and snow and ice on 

 Atlas ; more cooling of the air in Southern Europe as 

 a whole ; more accumulation of glaciers over all the 

 mountain ranges of our peninsular area; Ln short, a 

 complete upsetting of the climatic balance in this 

 quarter of the world as we actually know it. But I 

 do not say it would neces.sarily do so. I do not wish to 

 dogmatise. On the contrary, I believe the complexity of 

 these problems surpasses existing human powers of com- 

 bination. It is impossible to keep all the factors of so vast 

 a sum always before one's mind in the act of computation. 

 AVhen one reads speculations like Dr. Croll's or Mr. Alfred 

 Eussel Wallace's the mind is carried away for the moment 

 by their sustained reasoning: it seems all as clear as day; 

 the glacial epoch was doubtless due to the earth's eccen- 

 tricity, and if we could once melt off the Polar ice-cap, sub- 

 tropical vegetation might once more spread to the frozen 

 shores of Spitzbergen and Alaska. But when we come, on 

 the other hand, to read such a book as Professor Mohn's 

 " Meteorologie " we feel as though the problems of our ex- 

 isting climate even were far too complex for human solution. 



Let me give a single instance in illustration of the diffi- 

 culty of predicting the effect upon climate or earth-sculpture 

 of local changes. In a small town in the AVest of England 

 the cliffs were being rapidly washed away by the sea. 

 Groynes were erected along the beach, but where they ter- 

 minated the current formed a scour, and, e;iting away the 

 cliff worse than ever at the end, began to attack the town 

 by a flank movement. So an eminent engineer was called 

 in to advise the Corporation as to the erection of a break- 

 water. The eminent engineer, after duly inspecting the bay 

 and cliffs, reported that to erect a breakwater on ledges of 

 rock in the neighbourhood would be comparatively e;isy, but 

 when erected it might produce either of two effects with 

 equal probability. It might protect the menaced clifl's, or it 



