中山伝信録 巻一 - 翻刻

翻刻

　舊錄云以木柹從船頭投海中人疾趨至梢人柹同
　至謂之合更人行先於柹爲不及更人行後於柹爲
　過更今西洋舶用玻璃漏定更簡而易曉細口大腹
　玻璃瓶兩枚一枚盛沙滿之兩口上下對合通一線
　以過沙懸針盤上沙過盡爲一漏卽倒轉懸之計一
　晝一夜約二十四漏每更船六十里約二漏半有零
　人行先木柹爲不及更者風慢船行緩雖及漏刻尚
　無六十里爲不及更也人行後於柹爲過更者風疾
　船行速當及漏刻巳踰六十里爲過更也

【図】天使館圖

現代語訳

旧録に云う、木片を船頭から海中に投じ、人が疾走して船尾に至り、人と木片が同時に到着するのを「合更」と謂う。人の歩行が木片より先であれば「不及更」とし、人の歩行が木片より後であれば「過更」とする。今、西洋船は玻璃漏を用いて更を定める。簡単で理解しやすい。細口大腹の玻璃瓶二個、一個に砂を満たし、両口を上下に対合させて一線を通し、砂を通過させる。針盤上に懸け、砂が過ぎ尽くすと一漏となり、即ち倒転して懸ける。一昼一夜を計ると約二十四漏、毎更船六十里は約二漏半余りとなる。人の歩行が木片より先で「不及更」となるのは、風が穏やかで船の進行が緩慢であり、漏刻に及んでもまだ六十里に達しないので「不及更」となるのである。人の歩行が木片より後で「過更」となるのは、風が速く船の進行が早く、漏刻に及ぶ時には既に六十里を越えているので「過更」となるのである。

【図】天使館図

英語訳

The old records say: cast a wooden piece from the bow into the sea, a person runs swiftly to the stern, and when the person and wooden piece arrive simultaneously, this is called "matching the watch." If the person's movement is ahead of the wooden piece, it is "insufficient watch," and if the person's movement is behind the wooden piece, it is "excessive watch." Now, Western ships use glass hourglasses to determine watches, which is simple and easy to understand. Two glass bottles with narrow necks and large bellies - one is filled with sand, the two openings are placed top and bottom opposite each other with a line connecting them to allow the sand to pass through. Suspended above the compass, when the sand finishes passing through it becomes one "leak," then it is immediately inverted and suspended again. Calculating one day and night yields approximately twenty-four leaks, and each watch of sixty li by ship takes approximately two and a half leaks. When a person's movement is ahead of the wooden piece resulting in "insufficient watch," this means the wind is calm and the ship's progress is slow - even when the hourglass time is reached, sixty li has not yet been covered, hence "insufficient watch." When a person's movement is behind the wooden piece resulting in "excessive watch," this means the wind is strong and the ship's progress is fast - when the hourglass time is reached, it has already exceeded sixty li, hence "excessive watch."

[Diagram] Diagram of the Imperial Envoy's Residence