He has refused for a long time,after such dissolution,to cause others to be elected,whereby the legislative powers,incapable of annihilation,have returned to the people at large for their exercise.
1.after such dissolution是插入语,与for a long time一起,作状语,修饰refuse；
2.whereby后面是从句,表示结果,修饰整个主句；incapable of annihilation是插入语,修饰powers.
整句翻译：
此次解散之后的很长时间,他拒绝让/使他人当选,如此一来,不能被废止的立法权又全部回到人民手中,由人民行使.