26 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



mcnse tracts of land in Algiers, especially with Australian 

 trees, namely, the Acacia mollissima and Acacia lophantha. 

 Plantations of these trees, started a few years ago, have at- 

 tained a height of from nine to twelve feet, and in their rapid 

 growth and great extent have already changed the climate 

 very much twice as much rain and dew falling in the neigh- 

 borhood as before. Under the same auspices, sixteen square 

 miles of the swampy, unhealthy country along the coast of 

 the Bay of Biscay, in the department of the Landes, was 

 planted with millions of trees especially the cork, oak, and 

 swamp pine with surprisingly beneficial results, the trees 

 having drained the land so as to destroy the swamp fevers, 

 and to change it into a healthy country with pine forests. 

 Biscay law requires that for every tree cut down two shall 

 be planted, and it is said to be executed with rigorous sever- 

 ity. 17 A.March 1, 1871, 35. 



CYCLES OF TEMPERATURE. 



Professor Piazzi Smythe, the eminent Scottish astronomer, 

 endeavors to establish the existence, in addition to the an- 

 nual cycles of temperature, of three seasons, which he calls 

 supra-annual. One of these corresponds to Schwabe's sun- 

 spot period of a little over eleven years, although it is sug-, 

 gested that this is simply a coincidence, and that the actual 

 occasion of the waves of the terrestrial temperature is to be 

 found in the red prominences of the sun. Another of these 

 cycles is a little more than two years in duration, while the 

 third is about fifty-six years. It is to the effect of these cy- 

 cles that the so-called changes of climate are believed by 

 Professor Smythe to be due. According to him there is no 

 actual change, only that these cycles in their course bring 

 back the same temperature. Taking a series of observations 

 from 1837 to 1869, Professor Smythe finds that a hot time 

 occurs once in about every eleven years, followed at intervals 

 of a little more than two years by a very cold period ; and, 

 arguing from these data, he suggests that the temperature 

 for any season may be foretold a year in advance, and that 

 the past winter in England was the first of a cold cycle, of 

 which the next will probably be exceedingly severe. 2 , 

 June 11, 663. 



