84 Generating Economic Cycles 



pressures are compared with Clough's in America, it 

 will be seen (1) that they are approximately synchro- 

 nous; (2) that the common interval between the maxima 

 is about eight years; (3) that they are approximately 

 synchronous with the maxima of the crop cycles in the 

 United States, in the United Kingdom, and in France; 

 (4) that they are approximately synchronous with the 

 cycles in Sauerbeck's index numbers from 1818 to 1914. 



The next evidence of meteorological cycles is found in 

 an official publication by the United States Weather 

 Bureau. In 1901 the United States took "the lead in 

 reducing its barometric observations to a standard 

 system." ^ The work was conducted by Professor F. H. 

 Bigelow and included "a reexamination of the various 

 elevations, the local and instrumental errors, the re- 

 duction of the station pressures to a homogeneous sys- 

 tem, and the preparation of noraial tables and charts of 

 pressure, temperature, and vapor pressure at sea level 

 and at the 3,500 foot and 10,000 foot planes." ^ This 

 monumental work bears the title Report on the Barom- 

 etry of the United States, Canada, and the West Indies, 

 and constitutes volume II of the Report of the Chief of 

 the United States Weather Bureau, 1900, 1901. 



After the completion of this Report with the reduced 

 and standardized material, it became possible for the 

 first time to combine the many thousands of observa- 

 tions that had been made in the United States since the 

 beginning, in about 1870, of the systematic work of 

 official weather observation. The tremendous impor- 



^ Prefatory note in vol. ii of Report of the Chief of the Weather 

 Bureau, 1900, 1901. 



2 Report of the Chief of the Weather Bureau, 1900-01, vol. i, p. 12. 



