- Estimate of the Crops of Wisconsin
- Maps of Town 12, Range 16
- Letter from Lyman C. Draper to Increase Allen Lapham, December 21st
- Letter from Increase Allen Lapham to James Leffel & Co., December 21st
- Letter from William Stimpson to Increase Allen Lapham, December 21st
- Letter from Charles H. Hart to Increase Allen Lapham, December 7th
- Letter from John Wesley Hoyt to Increase Allen Lapham, Including Two Printed Circulars by Lucius Fairchild and John Wesley Hoyt, December 19th
- Expenses of Parit [sic] Exposition
- Resolution to Employ Increase Allen Lapham for the Purpose of Examining the Dam, November 28th
- Letter from Henry M. Wright to Increase Allen Lapham, November 14th
- Letter from Charles Whittlesey to Increase Allen Lapham, November 10th
- Letter from Asa Gray to Increase Allen Lapham, November 9th
- Receipt of Gift from George Templeman Kingston to Increase Allen Lapham, October 24th
- Letter from James Watson Robbins to Miss Lapham, October 13th
- Letter from Increase Allen Lapham to H. Richardson, October 12th
- Letter from H. Richardson to Increase Allen Lapham, October 9th
- Letter from Folix Foucou to Increase Allen Lapham, October 9th
- Letter from James Watson Robbins to Increase Allen Lapham, October 8th
- Letter from Benjamin Davis Gilbert to Increase Allen Lapham, October 1st
- Letter from Thomas C. Theaker to Increase Allen Lapham, September 25th
- Letter from James Hall to Increase Allen Lapham, September 24th
- Letter from James Watson Robbins to Increase Allen Lapham, September 21st
- Letter from Benjamin Davis Gilbert to Increase Allen Lapham, September 16th
- Letter from Increase Allen Lapham to William Franklin Raynolds, January 12th
- Letter from William Franklin Raynolds to Increase Allen Lapham, January 15th
- Letter from Increase Allen Lapham to Samuel Stone, January 17th
- Letter from Lyman C. Draper to Increase Allen Lapham, February 2nd
- Barometer and Thermometer during the Cold term Jan. 1866. From Observations Made at the Dudley Observatory
- Letter from George Washington Hough to Increase Allen Lapham, February 3rd
- Letter from George Washington Hough to Increase Allen Lapham, February 19th
- Letter to Increase Allen Lapham, February 24th
- Letter from James Craig Watson to Increase Allen Lapham, February 28th
- Letter from Charles Christopher Parry to Increase Allen Lapham, March 5th
- Letter from James M. Safford to Increase Allen Lapham, March 5th
- Letter from Samuel Stone to Increase Allen Lapham, March 6th
- Letter from Edward F. Hobart to Increase Allen Lapham, March 8th
- Letter from William Gooding to Increase Allen Lapham, March 14th
- Letter and Circular from J. Y. Bergen and T. S. Bradley of Peoria Pottery to Increase Allen Lapham, March 22nd
- Letter from J. Y. Bergen of Peoria Pottery to Increase Allen Lapham, March 28th
- Letter from L. Burstall to Increase Allen Lapham, April 11th
- Letter from William Stimpson to Increase Allen Lapham, April 30th
- Letter from Chester Dewey to Increase Allen Lapham, April 18th
- Letter and Bill from Increase Allen Lapham to the Common council of the City of Milwaukee, First Copy
- Letter and Bill from Increase Allen Lapham to the Common council of the City of Milwaukee, Second Copy
- Letter from Daniel Steele Durrie to Increase Allen Lapham, May 29th
- Letter from Increase Allen Lapham to Joseph Henry, may 31st
- Letter from Charles H. Hart and Alfred B. Taylor to Increase Allen Lapham, June 8th
- Letter from George Engelman to Increase Allen Lapham, June 19th
- Letter from Charles Fairchild on Behalf of Lucius Fairchild to Increase Allen Lapham, June 27th
- Receipt of Gift from Charles H. Hart to Increase Allen Lapham, June 30th
- Letter from Charles H. Hart to Increase Allen Lapham, June 30th
- The Death of General Cass
- Letter from Charles H. Hart to Increase Allen Lapham, July 21st
- Letter from Lyman C. Draper to Increase Allen Lapham, July 9th
- Letter from Ellen E. Phillips to Increase Allen Lapham, July 13th
- Letter from James Watson Robbins to Increase Allen Lapham, July 19th
- Letter from Increase Allen Lapham to M. D. Ogden, August 10th
- Letter from Increase Allen Lapham to William Franklin Raynolds, August 12th
- Letter from William Franklin Raynolds to Increase Allen Lapham, August 17th
- Letter from George Engelman to Increase Allen Lapham, August 29th