Utah legislative rosters list Orson Pratt as the Speaker of the Utah House of Representatives in 1870.
“Territory of Utah, Legislative Assembly Rosters, 1851–1894,” Utah Division of Archives and Records Service, 34-35
Legislative Assembly of the Territory of Utah Nineteenth Session, 1870
. . . .
OFFICERS OF THE HOUSE
Orson Pratt, Sen., Speaker.
Robert L. Campbell, Chief Clerk.
John H. Smith, Assistant Clerk.
Franklin Merrill, Sergeant-at-Arms.
Robert S. Campbell, Messenger.
Arthur Pratt, Foreman.
Samuel H.B. Smith, Chaplain.