Data For May-November 1926 Were Adjusted By The Economist To Nullify The Effects Of The Coal Strike. Figures Reflecting The Strike'S Effects (No Coal Exports) Are As Follows: May--962; June--104.4; July--116.0; August--122.8; September--131.3; October--182.7; November--196.7. Source: The Economist, February 26, 1938, P. 484, And Following Weekly Issues; Figures For May-November 1926 Are From The Source For These Months.
This NBER data series m03033a appears on the NBER website in Chapter 3 at http://www.nber.org/databases/macrohistory/contents/chapter03.html.
NBER Indicator: m03033a
Release: NBER Macrohistory Database
National Bureau of Economic Research, Index of Shipping Freight Rates, British Routes for Great Britain [M0333AGBM316NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M0333AGBM316NNBR/, October 7, 2015.