The last Illinois Republican contains a letter of A. Lincoln, one of the Representatives of Sangamon county, and some comments thereon, concerning a remark attributed to Mr. L. in reference to the internal improvement system. As we understand it, this controversy has grown out of a very remarkable night scene which occurred in the House of Representatives at its late session, at which some atouishing developments were made, but which, in charity to the parties, we then forbore to publish. A bill amending the law establishing a general system of internal improvements was pending before the House. Mr. Baker pronounced himself against the system. Mr. Lincoln replied tartly to his colleague, that he for himself and every other Representative of Sangamon county, present and future, should forever support the system of internal improvements because the Sangamon delegation had obtained the seat of Government at Springfield by an understanding with the friends of the system. Mr. L. said he considered the pledges then made as forever binding, not only on him but on Sangamon county itself.