The numbered series such as "Ausable No. 4" are from the USGS survey that was conducted in the early 1940's. This is the survey that set most of the benchmarks we now find on summits. (I guess because of WWII the commercial topo maps derived from that survey weren't available until 1953 or so)
The surveyors would establish a main station on summits such as Hurricane, Cascade, and Marcy. On most of these summits one can find a main disk and two reference marks with arrows pointing to the main disk. The surveyors then "turned angles" to both the reference marks and to the flags placed in drill holes at the numbered locations in order to establish the correct horizontal position for these features. While hikers are usually most concerned about elevation, a GPS unit wouldn't be worth anything without accurate horizontal positions.
As for Gore Mt., the term "gore" came from the textile trade and referred to a long narrow triangle of cloth that could not be used for anything else. When two survey lines differed, they often diverged at only a slightly different angle and thus created long thin triangles. After the Gore Mt. gore, perhaps the most significant gore is the "Gore around Lake Colden, which extended west through the Cold River area. Noah Rondeau's Hermitage was in this gore as it wasn't clear that the State had actually bought this gore when they bought the land to the north and south from the Santa Clara Lumber Company.