The Southern Pacific Railroad.
--There are now 270 hands employed in grading the road west of Marshall, Texas, and it is expected that, by the 1st of January, there will be a force of 500 employed. Besides, a considerable number in addition to this force are engaged in getting out cross-ties, building bridges, &c. The sub-contractors have obligated themselves to complete 25 miles of road ready for the iron by the 1st of May.