雙語暢銷書《艾倫圖靈傳》第8章:水銀延時線(2)
Alan Turing did not wait to take up the NPL post before thinking about the practical construction of his universal machine.
In particular he discussed with Don Bayley the problem which dominated its engineering—that of the storage mechanism, or 'tape'.
他和唐·貝利一起，討論過通用機的一個工程問題，即它的存儲設備，或者說"紙帶"。They discussed every form of discrete storage that they could think of. For instance, they considered magnetic recording.
他們討論了他們能想到的所有的離散存儲形式，比如說磁帶。
They had seen a captured German Army 'Magnetophon', the first successful tape recorder,
他們看過一臺從德軍手中繳獲的"瑪尼託芬機"，那是最早的成功應用的磁帶錄機。but rejected the idea essentially because magnetic tape was too much like the tape of the theoretical Universal Turing Machine—it would require so much physical moving to and fro.
但他們從根本上排除了個選項，因爲磁帶與理論的圖靈機模型太像了，它需要來回移動，這會造成很多麻煩注。Instead, they favoured another solution with which Alan was by now well acquainted—that of the 'acoustic delay line.'
圖靈現在比較喜歡的方案是"聲音延遲線"。The idea was based on the fact that the time taken for a sound wave to travel along a few feet of pipe was of the order of a thousandth of a second.
這個方案的原理是，聲波穿過一條几英尺的管道，大約需要千分之一秒的時間。The pipe could be regarded as storing the sound wave for that period.
在這段時間內，可以理解成，這條管道將聲波存儲在其中。The principle had already been applied in radar, using information stored in the delay line to cancel out all the radar echoes which had not changed since the last scanning.
該原理已經在雷達技術上得到了應用，利用存儲在延遲線中的信息，來抵消前一次掃描之後沒有發生改變的反射信號。In that way the radar screen could be made to show only new, or changing, objects.
這樣一來，雷達屏幕就只顯示那些新出現的，或者正在運動的物體。
