66 
MIGRATION AND BUSINESS CYCLES 
TABLE 14,—CvycLEs OF PIG IRON PRODUCTION, BY CALENDAR YEARS: 
1860-1919» 
Percentage deviations from a seven-year moving average, expressed in multiples of their 
standard deviation (12.68 per cent) 
Vian Pia 1roN VAR Pig 1rRON Vian Pig 1roN 
PRODUCTION PRODUCTION PRODUCTION 
1860 +0.97 1880 40.82 1900 —0.32 
1861 —1.23 1881 40.80 1901 40.28 
1862 —0.99 1882 41.20 1902 | +0.41 
1863 —0.20 1883 40.29 | 1903 —0.25 
1864 +0.65 1884 —1.15 1904 —1.48 
1865 | —1.62 1885 —1.67 1905 +1.03 
1866 +0.09 1886 +0.17 | 1906 41.40 
1867 —0.02 1887 +0.25 1907 +1.03 
1868 +0.13 1888 —0.38 1908 —2.61 
1869 +0.28 1889 +0.06 1909 +0.32 
1870 —0.78 1890 +1.47 1910 +0.53 
1871 —1.17 1891 +0.50 1911 —0.50 
1872 41.74 1892 +0.91 1912 40.72 
1873 41.68 1893 1.16 1913 +0.48 
1874 40.84 1894 —1.65 1914 | 21.92 
1875 —0.80 1895 +0.47 1915 —0.74 
1876 —1.43 1896 —0.77 | 1916 +1.48 
1877 —1.27 1897 —0.64 1917 41.06 
1878 —1.20 1898 —0.03 1918 +1.42 
1879 —0.88 1899 +0.36 1919 —0.41 
sComputed from data given in Table 12-A for 1870-1919. 
INDEXES OF EMPLOYMENT BY MONTHS 
We have previously noted the desirability of a monthly index of 
employment conditions. For the quarter century preceding the 
Great War it has been possible to build up by the synthesis of 
somewhat fragmentary series, an index of factory employment. 
This index has been supplemented by an index of monthly changes 
in pig iron production. Charts of the cyclical movements in these 
two series are given in Chapter V. The methods of compilation 
are set forth in the subsequent pages of this chapter. 
The Census of Manufactures. 
The United States Census of Manufactures furnishes a virtually 
complete census of the number of wage earners employed in fac- 
tories, by months, for the years 1899, 1904, 1914, 1919, and 1921. 
In taking the census of manufactures in 1899 workers in the hand