170 The Ottawa Naturalist, [December 



This evaporation, of course, varies constanth' v/ith the tempera- 

 ture, pressure, winds, etc. It has been computed that the area 

 of the United States, on an average, evaporates from its surface 

 0.4 (four tenths) inches every 24 hours. This vapour ascends 

 until its temperature is reduced to the " dew^ point" and thus 

 clouds are formed. Fogs and mists are clouds on the surface 

 of the earth, condensations to minute watery particles due to 

 reduction in temperature. Rain and snow result from further 

 condensation and the formation of larger particles. This 

 ascension and descension of the world's moisture is an essential, 

 fundamental factor in the maintenance of vegetable and animal 

 life on the earth. 



In the Industrial World. 



The flovv of our streams and the immense volumes of water 

 that pour over our numerous water-falls are dependant for their 

 supply upon the annual precipitation, i. e. upon rain and 

 snow. Possibly no country in the world has such wealth of 

 power in her water courses as Canada. It has onlv been partially 

 developed as yet, but from Niagara Falls alone and it is only 

 one of many, though the largest there is a total power chartered 

 for of 850,000 H.P. Of this, 299 H.P. are at present developed. 

 These figures include the product of the works on both sides of the 

 river. The three works generating electricity on the Canadian 

 side can to-day furnish 154,000 H.P., and their ultimate output 

 will be 425, 000 H.P. Datamight similarly be given for a score of 

 other water -falls being utilized to-day. This water-power 

 converted into electrical energy is employed for a thousand 

 useful purposes. It carries us through the streets of our cities, 

 and in many parts of Western Ontario from town to town. 

 It lights our houses, and in the realm of manufacture has already 

 largely replaced coal as a source of power. To tell of all its useful- 

 ness would be to give a catalogue of well nigh all our manufactures. 

 Carbide, itself a source of light, is made through the assistance 

 of electricity directly obtained through the power of the v/ater- 

 fall. Phosphorus, wood pulp, paper are similarly prepared, 

 a.nd so the list might be continued almost ad infinitum. It 

 would indeed be difficult to estimate the value from the com- 

 mercial standpoint of our precipitation and of our water-falls 

 they constitute one of Canada's most important natviral 

 assets. 



In the Agricultural World. 



It is, of course, to agriculture that the greatest benefit 

 comes from our rain and snow. Vegetable life requires large 



