公尺副原器是公尺的標準，以確保長度單位得到正確的衡量。 公尺副原器做成x型的原因，是為了減少溫度變化導致的金屬膨脹收縮，以減低誤差。 公制的長度單位最初以地球當標準，由北極經過巴黎到赤道的經線的一千萬之一定義為一公尺，再以此為依據製作鉑銥合金的「公尺原器」。 「國際公尺原器」有許多的副原器，分送各國妥善保存，日本也取得一個。日本再複製多個公尺副原器，其中一個送到臺灣總督府。 這個公尺副原器在臺灣光復後由臺灣省度量衡檢定所接管，轉經濟部標準檢驗局管理，於2001年捐贈給本館典藏。

The “Meter Prototype” serves as the standard for the meter, ensuring accurate measurement of length units. The X-shaped design of the meter prototype is intended to minimize errors caused by metal expansion and contraction due to temperature variations. The metric length unit was initially based on the Earth, defined as one ten-millionth of the meridian from the North Pole, passing through Paris, to the equator. This measurement served as the basis for creating the platinum-iridium “meter prototype. The “International Prototype of the Meter” has many standard copies distributed to various countries for proper preservation, and Japan obtained one as well. Japan then produced multiple copies of the meter prototype, with one being sent to the Governor-General’s Office in Taiwan. After Taiwan’s restoration, this meter prototype was taken over by the Provincial Weights and Measures Testing Institute and subsequently managed by the Bureau of Standards, Metrology, and Inspection of the Ministry of Economic Affairs. It was donated to the museum for collection in 2001.