这句话中"but"是副词 = only
but a few of the disorderly manifestations是表语从句中has produced 的宾语
that too often attend upon such times是定语从句that too often attend upon such times是定语从句，从句中的主谓宾又是什么呢？that 是关系代词 代替先行词 引导定从 并作定从中的主语 too often 是定从中的状语 attend upon是定从中的谓语 such times是定从中的宾语attend upon英[əˈtend əˈpɔn]美[əˈtɛnd əˈpɑn]照顾;服侍;陪伴; （危险、风险等）伴随