SEASONAL FLUCTUATIONS 23 
seasonal fluctuation in this occupation, we have the indirect evi- 
dence afforded by the amounts expended each month from 1910 
to 1921 in the maintenance of way and structures, and also the 
number of track and roadway section laborers employed at the 
middle of the month, from July, 1921, to December, 1924, on Class 
[ steam roads in the United States. A seasonal index of these 
TABLE 56—INDICES OF SEASONAL VARIATION IN ACTIVITY IN SELECTED INDUSTRIES» 
Monthly average=100 
FACTORY EMPLOYMENT RArLwaAy COAL MINING 
MAINTENANCE 
- BrruMiNous : 
Monta SELECTED Unitep | Compo- EXPEND- EMPLOY- Snr SR 
STATES | StaTES SITE ITURES MENT Propbuc- | EmprLoy- DUCTION 
| TION MENT 
FADE EE ch cB a Fe Bu 
Jan... 99.5 99.8 f 99.6 i 84.8 81.0 104.2 104.2 96.1 
Feb... . 100.5 | 100.5 | 100.5 I 86.7 | 80.6 a 101.3 103.1 93.9 
Mar... | 100.7 | 101.3 | 101.0 | 89.4 | 84.7 | 101.9 | 100.3 96.0 
Apr.... 100.6 [| 100.7 | -100.6 i 103.6 | 97.0 81.8 94.2 99.2 
May... 99.6 | 100.4 | 100.0 I 108.7 106.4 | 89.1 94 0 [| 103.5 
June... 99.2 100.0 | 99.6 | 114.1 110.0 | 95.6 95.7 106.6 
July... 98.8 | 98.5 { 08.6 t 107.7 110.4 | 94.0 96.7 ! 99.4 
Jug... 100.3 { 98.4 | 90 4 BR 111.8 Isi1x5.4 102.1 97.3 100.9 
Sept... 101.2 | 99.6 | 100.4 1 2110.9 114.0 I 109.1 | 100.0 [ 97.5 
Oct... 101.1 "100.4 | 100.8 106.5 | 112.3 j—i15.3 | 102.8 a 107.7 
Nov.... 100.2 100.4 | 100.4 96.3 102.2 | 103.5 | 106.0 N-102.5 
Dec... . 08 ~ 100.5 Qo 4 79.5 86.0 © 102.2 105.2 96.7 
»—=Computed from data, briefly described below, in such a way as to eliminate so far as practicable the 
influence of trend, cyclical variations and, in the case of the production and expenditure series, the effect 
of the varying length of months. 
v SeFuDloyment in Massachusetts, New Jersey, and New York factories, 1904 to 1914. See Table 
, appendix. 
B=Employment in factories in the United States, as given in the U. S. Census of Manufactures for 
1904, 1909, 1914, 1919, and 1921; and in statistics of factory employment for 1915 to 1924, issued by the 
U. S. Bureau of Labor Statistics. 
C=An average of Series A and B. 
D=Expenditures for maintenance of way and structures, with adjustment for varying length of 
month, 1910 to 1921. Interstate Commerce Commission, Thirty-Fifth Annual Report on the Statistics of 
Railways in the United States. 
E=Track and roadway section laborers at middle of month, July, 1921, to December, 1924. Inter- 
state Commerce Commission, Wage Statistics Class I Steam Roads in the United States, monthly issues. 
F=Tonnage of bituminous coal produced, 1913 to 1922, adjusted for varying length of months. U. 
S. Geological Survey, Mineral Resources of the United States, 1921, Pt. 11, p. 464, and weekly reports of coal 
production in 1922, 
G=Employment in bituminous coal mines, as given in the Fourteenth Census of the United States, 
Mines and Quarries, for 1909 and 1919; and in the U. S. Bureau of Labor Statistics. Monthly Labor Review, 
for April, 1920, to March, 1922. 
H=Tonnage of anthracite coal produced, 1913 to 1921, adjusted for varying length of months, U. S. 
Geological Survey, Mineral Resources of the United States, 1921.Pt. 11, p.465. 
maintenance expenditures, with an adjustment for: the varying 
length of the months, is shown as Curve (e) in Chart 52, Fig. B; 
and an index constructed from the aforementioned employment 
data appears as Curve (d). Although this index of employment is 
based upon a very short period, it is sufficiently well supported by 
the collateral evidence of the index of expenditures to lead us to 
accept 1t as a reasonably accurate approximation. 
aE :