  CL209/31-- WAR DEPARTMENT, UNITED STATES ENGINEER OFFICE, PHILADELPHIA, PA TO USC&GS, MARCH 21, 1931; IN ORDER TO AVOID A ROCK SHOAL, THE 35-FOOT CHANNEL AT THE END OF THE MARCUS HOOK RANGE HAS BEEN SWUNG APPROX. 200 FEET TO THE EASTWARD.  A 31.9-FOOT