沈括 著

【原文】

《夢溪筆談·卷24雜志（一）18》

方家以磁石磨針鋒，則能指南，然常微偏東，不全南也。水浮多蕩搖，指爪及碗唇上皆可為之，運轉尤速，但堅滑易墜，不若縷懸為最善。其法取新纊（kuàng）中獨繭（jiǎn）縷，以芥子許蠟綴于針腰，無風處懸之，則針常指南。其中有磨而指北者。予家指南、? 北者皆有之。磁石之指南猶柏之指西，莫可原其理。

【今譯】

看風水的人用磁石去磨針尖，針尖就能指出南方，不過常常略為偏東，并不完全指向正南。把 磁針浮在水面上，?；问幉煌?。也可以把磁針放在指甲上和碗口上，磁針轉動更靈快些，但這上面又 硬又滑，磁針容易掉落，不如用絲線懸掛為最好。其方法是從新絲棉中抽取一根蠶絲，用芥菜籽大小的一點蠟粘連在磁針的腰部，懸掛在沒有風的地方，磁針就常常指向南方。磁針也有經磨后指向北的。我家的磁針，指南指北的都有。磁石的指南，如同柏樹的指西，不能推究出其中的道理。

【英譯】

Mengxi Bitan Chapter 24 Zazhi (Part I) 18

Diviners can make a needle point to? the south by rubbing it with magnetite. However the needle often inclines to? the southeast direction, not pointing to due south. If the needle is floating? on water, it often sways. The needle may be placed on a nail or the edge of a? bowl, which may make it rotate a bit more flexibly, but the hard and smooth? surface may make it easily fall off. The best way is to hang the needle with? a silk thread. If we take a newly-reeled raw silk and paste it to the middle of the needle with wax similar to a seed of leaf mustard, and hang up the? needle in a windless place, the needle will often point to the south. Some needles? may point to the north after being rubbed with magnetite, for instance, in my? house some needles point to the south while others point to the north. When the? needle rubbed with magnetite points to the south, just as the cypress tree? leans to the west. Nobody knows the reason why it is so.

Article by Tao Steven Zheng（鄭濤）