[Frederic Shonnard & W.W. Spooner (1900)] development was effected by the extension of the line from High Bridge to the terminus of the Elevated Railway at One Hundred and Fifty-fifth Street, and by the building of the branch from Van Cort-landt Station to Yonkers. In common with the New York and Har-lem, the Now York and Putnam is now incorporated in the New York Central and Hudson River system, with which also the New York, New Haven, and Hartford is closely affiliated; so that all the steam railways of Westchester County are substantially under one management. Aside from the building of the railways, there were not many events of local importance in Westchester County from tin-completion of the Croton Aqueduct until 1850. Two new townships were erected — Ossining (1845) and West Farms (1840), and the territorial dimensions of four others were somewhat changed by the annexation of a portion of North Salem to Lewisboro in 1844, ami of a portion of Seniors to New Castle in 1840. From 1810 until 1845 Mount Pleasant, embracing the village of Sing Sing, had been the most populous township of the county. The federal enumeration of 1840 gave it a population of 7,307. It was also one of the largest townships in area, and chiefly on this account its 576 HISTORY OF WESTCIJ ESTER COUNTY division was determined upon. By a legislative act passed May 2, 1845, the present Township of Ossining was erected from it. "The meaning of the term ' Ossining ' and its derivation," says Dr. Fisher, -wore given by Mr. Henry M.