NO. 4 TEMPERATURE VARIATIONS IN THE NORTH ATLANTIC 1 57 



highest at sun spot minimum and lowest at sun spot maximum, and 

 the ampHtude between the two he determined on the average for 

 winter to be 0.61 ° C, for summer 0.48° C, while for the year it 

 is only 0.25° C. 



Newcomb (1908) investigated by means of a special mathemati- 

 cal process temperature series for the years 1871 to 1904 in widely 

 separated regions covering the tropics and the lower latitudes of 

 the United States, Argentina, West Indies, Mauretius, India, Cey- 

 lon, Australia, and the Pacific Ocean, He found the temperature 

 maximum occurs 0.33 years before the sun spot minimum and the 

 temperature minimum 0.65 years after the sun spot maximum. The 

 amplitude between temperature maximum and minimum he deter- 

 mined as 0.26° C. The result is similar to that of Koppen only that 

 Newcomb's amplitude is considerably smaller. 



Newcomb concluded from this that the observed difference in 

 the temperature of the earth indicated a corresponding fluctuation in 

 the radiation of the sun of 0.2 per cent on both sides of the mean. 

 He found further a somewhat doubtful indication of another varia- 

 tion in the temperature of the earth with a period of about six years, 

 which could most probably be associated with variations of the radia- 

 tion of the sun. This was first noticeable after the year 1870 and 

 the average deviation from the mean temperature was less than 

 0.1° C. Finally he found, though without decisive proof, that 

 " there is a certain suspicion of a tendency in the terrestrial tem- 

 perature to fluctuate in a period corresponding to that of the sun's 

 synodic rotation. If the fluctuations are real they affect our tem- 

 peratures only by a small fraction of one-tenth of a degree." This 

 agrees to a certain measure with Bigelow's result (1894), except 

 that Newcomb's variations are much smaller. But he treated his 

 observational material in a wholly different way and, for example, 

 took no account of the consideration which Bigelow advances that 

 by the variations in the solar radiation (which Bigelow calls the 

 " polar magnetic solar radiation ") variations could be produced in 

 the temperature of the United States at certain times in the same 

 direction, at other times in the reverse. 



By means of bolometric measurements made in Washington, Lang- 

 ley (1904) found it probable that the solar radiation outside our 

 atmosphere ("the solar constant") from the end of March, 1903, 

 and for the rest of that year was about ten per cent diminished. By 

 collection of temperature observations at 89 stations in seven dif- 

 ferent regions of the North Temperate Zone in Asia, Europe, North 



