Question: When did this Washington & Jefferson College alumnus and politician serve in the House of Representatives for the state with the capital Des Moines ?

text: List of Washington & Jefferson College alumni
Law and government -- Members of Congress
Rush Clark Melissa Hart John Herron Hopkins S. Addison Oliver Tom Rooney Clement Vallandigham
Washington & Jefferson College is a private liberal arts college in Washington, Pennsylvania, which is located in the Pittsburgh metropolitan area. The college traces its origin to three log cabin colleges in Washington County, Pennsylvania established by three frontier clergymen in the 1780s: John McMillan, Thaddeus Dod, and Joseph Smith. These early schools eventually grew into two competing colleges, with Jefferson College in Canonsburg, Pennsylvania being chartered in 1802 and Washington College being chartered in 1806. These two schools merged in 1865 to form Washington & Jefferson College. As of 2009, Washington & Jefferson College had about 12,000 living alumni. Before the union of the two colleges, Washington College graduated 872 men and Jefferson College graduated 1,936 men. The alumni association recognizes as alumni all students who have completed at least one college year as full-time students. These alumni include James G. Blaine, who served in Congress as Speaker of the House, U.S. Senator from Maine, two-time United States Secretary of State and the Republican nominee for the 1884 presidential election. Other graduates have held high federal positions, including United States Secretary of the Treasury Benjamin Bristow and United States Attorney General Henry Stanbery, who successfully defended Andrew Johnson during his impeachment trial. As a U.S. Congressman, Clarence Long was a key figure in directing funds to Operation Cyclone, the CIA's effort to arm the mujahideen in the Soviet-Afghan War.
Alumni Class year Notability
Ernest F. Acheson 1875 U.S . Congressman from Pennsylvania ( 1895-1909 ) ; owner/editor of the Washington Weekly Observer
Carl G. Bachmann 1911† U.S . Congressman from West Virginia ( 1925-1933 ) , serving as Minority Whip ( 1931-1933 )
David Barclay Washington 1843† U.S . Congressman from Pennsylvania ( 1855-1857 )
Samuel Steel Blair Jefferson 1838 U.S . Congressman from Pennsylvania ( 1859-1863 )
Rush Clark Jefferson 1853 U.S . Congressman from Iowa ( 1877-1879 ) ; member of the Iowa House of Representatives , serving as Speaker of the House from 1863 to 1864
Sherrard Clemens Washington 1841 U.S . Congressman from Virginia ( 1852-1853 , 1857-1861 )
Samuel Alfred Craig Jefferson 1862† U.S . Congressman from Pennsylvania ( 1889-1891 )
John D. Cummins Jefferson 1834 U.S . Congressman from Ohio ( 1845-1849 )
John Littleton Dawson Washington 1833 U.S . Congressman from Pennsylvania ( 1851-1855 , 1863-1867 )
Philip Doddridge Canonsburg U.S . Congressman from Virginia ( now West Virginia )
Augustus Drum Jefferson 1832† U.S . Congressman Pennsylvania ( 1853-1855 )
John Hoge Ewing Washington 1814 U.S . Congressman from Pennsylvania ( 1845-1847 )
Daniel Duncan Jefferson 1825 † U.S . Congressman from Ohio ( 1847-1849 )
John Rankin Franklin Jefferson 1836 U.S . Congressman from Maryland ( 1853-1855 ) ; member of Maryland House of Delegates ( 1840-1843 ) , serving as Speaker of the House for the 1849 session
Alfred Gilmore Washington 1833 U.S . Congressman from Pennsylvania ( 1849-1853 )
Louis E. Graham 1901 U.S . Congressman from Pennsylvania ( 1939-1955 )
Moses Hampton Washington 1827 U.S . Congressman from Pennsylvania ( 1847-1851 ) ; founded Buchanan , Ingersoll & Rooney law firm
Melissa Hart 1984 U.S. Congresswoman from Pennsylvania ( 2001-2007 ) ; Pennsylvania State Senator ( 1991-2001 )
Stephen Ross Harris Washington 1842† U.S . Congressman from Ohio ( 1895-1897 )
Henry William Hoffman Jefferson 1846 U.S . Congressman from Maryland ( 1855-1857 ) ; Sergeant at Arms of the United States House of Representatives ( 1860-1861 )