Robert Creighton to Thomas Lincoln Casey, August 30, 1881

Robert Creighton to Thomas Lincoln Casey, September 2, 1881

Robert Creighton to Thomas Lincoln Casey, September 3, 1881

Robert F. Stevens to General A. A. Humphreys; A. A. Humphreys to Thomas Lincoln Casey, February 20, 1872

Robert F. Weir to Emma Weir Casey, January 22, 1895, telegram

Robert F. Weir to Thomas Lincoln Casey, April 10, 1894, telegram

Robert F. Weir to Thomas Lincoln Casey, April 11, 1894, telegram

Robert F. Weir to Thomas Lincoln Casey, October 12, 1893; Thomas Lincoln Casey to [Henry] M. Adams and H. M. A. to Thomas Lincoln Casey to Thomas Lincoln Casey, October 13, 1893

Robert H. Hunt to Thomas Lincoln Casey, February 25, 1886 (1)

Robert H. Hunt to Thomas Lincoln Casey, February 25, 1886 (2)

Robert H. Hunt to Thomas Lincoln Casey, February 26, 1886

Robert H. Hunt to Thomas Lincoln Casey, June 25, 1888

Robert H. Hunt to Thomas Lincoln Casey, November 9, 1895

Robert Herrick Hunt to Thomas Lincoln Casey, July 13, 1893

Robert J. Stevens to Alexander Ramsey, January 29, 1881

Robert J. Stevens to Alexander Ramsey, January 29, 1881.

Robert J. Stevens to Thomas Lincoln Casey, April 11, 1882

Robert J. Stevens to Thomas Lincoln Casey, December 24, 1873

Sidney S. Rider to Thomas Lincoln Casey, February 9, 1892

Sidney S. Rider to Thomas Lincoln Casey, January 6, 1892

Sidney S. Rider to Thomas Lincoln Casey, July 27, 1894

Sidney S. Rider to Thomas Lincoln Casey, June 21, 1881

Sidney S. Rider to Thomas Lincoln Casey, June 27, 1894

Sidney S. Rider to Thomas Lincoln Casey, May 13, 1893

Sidney S. Rider to Thomas Lincoln Casey, November 12, 1894

Sidney S. Rider to Thomas Lincoln Casey, November 30, 1878

Sidney S. Rider to Thomas Lincoln Casey, October 12, 1886

Silas Casey to Thomas Lincoln Casey, April 8, 1892

Silas Casey to Thomas Lincoln Casey, January 26, 1892

Silas Casey to Thomas Lincoln Casey, March 12, 1892

Simeon Draper to Thomas Lincoln Casey, September 2, 1856

Simeon Draper to Thomas Lincoln Casey, September 9, 1856

Simon Newcomb to Thomas Lincoln Casey, November 15, 1880

Society of River and Harbor Engineers - Circular, Constitution and By-Laws, October 5, 1882

Society of the Army of the Potomac to Thomas Lincoln Casey, May 15, 1893

Sophia G. Casey to Thomas Lincoln Casey, June 5, 1881

Sophia G. Casey to Thomas Lincoln Casey, May 28, 1872

Sophia G. Casey to Thomas Lincoln Casey, May 29, 1872

Sophie G. Casey to Thomas Lincoln Casey, May 3, 1872

Spaulding to Thomas Lincoln Casey, February 25, 1870

Specific Gravity of Marble, April 4, 1883

Specifications for bidders for Torpedoes, May 1889

Specifications of Electric Lighting, undated

Speech of Hon. Henry W. Slocum to Thomas Lincoln Casey, February 14, 1871

Spencer F. Baird to Thomas Lincoln Casey, March 31, 1882

Spirito Bernardi to Louisa Seymour, February 24, 1892

Spoffard to Thomas Lincoln Casey, November 15, 1895

St Paul & Duluth R. R. Co. to Thomas Lincoln Casey, June 25, 1889

St. John's Rectory to Thomas Lincoln Casey, January 5, 1892

Stability of the Foundations of the Washington Monument, undated