DescriptionDigital image of Hudson & Manhattan R.R. postcard titled: The entrance to the twin tubes. 1908. Courtesy of Leon Yost. The tunnel location is not indicated. Two men, unidentified are at the right. Note the tunnel on the right has a standard guage track leading into it from the left and is joined by a narrow guage work track on the right. Postmarked 1911. From a series: The Hudson and Manhattan Railroad Company Tunnel (McAdoo system) under the Hudson River.