Source: Survey Of Current Business, March 1941: Lowell J. Chawner, "Capital Expenditures For Manufacturing Plant And Equipment, 1915-1940."
This NBER data series q10096 appears on the NBER website in Chapter 10 at http://www.nber.org/databases/macrohistory/contents/chapter10.html.
NBER Indicator: q10096
Release: NBER Macrohistory Database
National Bureau of Economic Research, New Manufacturing Capital Expenditures For Plant and Equipment, Current Prices for United States [Q10096USQ144NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/Q10096USQ144NNBR/, September 2, 2015.