三角原點系列會著重於日治時期的二等與三等原點，這系列的寶難度都很簡單，也會提供Spoiler
柴梳山3-139是少數在新竹市仍然存活的平地三角點，可能距離科學園區稍遠加上身處地形崎嶇的丘陵地才讓這個標高僅67公尺的基石得以倖存。從標定的登山口右轉上山後可見到一土地廟，廟後即有指標往三角點。一開始草稍長而且路徑不太清楚，但朝著指標方向硬幹一兩分鐘後即可接上清晰且布條眾多的路徑。走約8-10分鐘可達基石，Cache在三角點旁邊。
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Mt.ZaiSu is only 69 meters height,the rugged hills and the distance from Hsinchu downtown protect this rare tri-benchmark from being destroyed.When you arrived the trailhead,turn right then you'll see a temple.There are some signs to the benchmark.Followed the signs,although the trail is not clear,but it will get cleaner after 1-2 minutes walk.The cache is near the benchmark,where you may walk 8-10 minutes to appear.