Bureau of Public Roads THOMAS H. MACDONALD, Chief.

  Weather Bureau CHARLES F. MARVIN, Chief.

U. S. GOVERNMENT PRINTING OFFICE:  1938

For sale by the Superintendent of Documents, Washington, D. C. Price 5 cents

[Transcriber’s Note:  Footnotes 10 & 11 renumbered to avoid the confusion generated by two footnote 9’s.]