Final answer:
The text does not directly reference Senator Redfield Proctor's speech, but it highlights the context of anti-slavery sentiment in the U.S. Senate during that era through figures like William H. Seward and Charles Sumner.
Step-by-step explanation:
The purpose of Senator Redfield Proctor's speech to the U.S. Senate is not directly provided in the text snippets given, as they do not pertain to Senator Proctor. However, we can glean the broader context of this period in American history which is around the time of pro- and anti-slavery debates in the Senate, as well as the discussions around the compromises on slavery and the power structure of the Senate. William H. Seward's speech, for example, represents the northern opposition to slavery as incompatible with both natural law and the founding principles of the United States, a sentiment echoed by other anti-slavery advocates like Rufus King. Similarly, Charles Sumner's 'Crime against Kansas' speech exemplifies the height of tensions and the vehemence of the era's anti-slavery sentiment.