During the years when the House Chamber was at the north end of the Old Capitol and the Senate Chamber was in the east wing, the presiding officers could not see each other nor were they in telephonic communication. On those occasions when the houses adjourned sine die simultaneously, the House and Senate Sergeants would stand in the rotunda where they could be observed by the Senate President and House Speaker. The Sergeants would drop a handkerchief at the moment agreed upon for adjournment and the gavels would fall in each house to formally signal the end of the session.
Later, when the Senate occupied the south wing in 1947, the need for this ritual disappeared as the Speaker and President could see each other when the Chamber doors were swung open fully at the time of adjournment. This line-of-sight arrangement prevails in the New Capitol. Nevertheless, from time to time, the Sergeants will drop the handkerchief, primarily for the benefit of news photographers.
Also, there have been more occasions nowadays than in the past when the two houses adjourned at different times and no signal, by telephone, handkerchief or line-of-sight, was necessary.
Accompanying note: "The 1979 session of the legislature ends with House Sergeant-at-Arms Wayne Westmark (l) upstaging Senate Sergeant-at-Arms John Melton by bringing a tablecloth to the traditional dropping of the handkerchief 'sine die' ceremony in the rotunda."
"The dropping of the handkerchief began in the 1920s when the chambers were not in line of sight, so that the House and Senate could be gaveled 'sine die' simultaneously."