1、The method of scientific investigation is nothing but the expression of the necessary mode of working of the human mind; it is simply the mode by which all phenomena are reasoned about and given precise and exact explanations.

【分析】

并列复合句。分号连接两个分句。第一个分句的主干为 The method is nothing but the expression；of the necessary mode of working of the human mind 是 expression的后置定语，前置译。第二个分句的主干为 it is the mode，后跟which引导的定语从句修饰限制the mode，由于定语从句较短，前置译为“的”字结构。

【点拨】

1、nothing but “仅仅，只不过”。2、mode“方式，样式；模式；状态”。3、reason about“推理，思考”。

【译文】

科学研究的方法不过是人类思维活动的必要表达方式，也就是对一切现象进行思索并给予精确而严谨解释的表达方式。 

2、It is not that the scales in the one case, and the balance in the other, differ in the principles of their construction or manner of working; but that the latter is a much finer apparatus and of course much more accurate in its measurement than the former.

【分析】

复合句。整个句子的主干为It is not that...；but that…。两个that均引导表语从句。第一个从句的主干为 the scales…and the balance…differ；介词短语 in the one case和in the other作状语，分别指代前文提到的两个例子，翻译时需具体化，并译作前置定语；状语in the principles of their construction or manner of working 按照汉语习惯，可译于谓语动词differ之前。第二个从句的主干为 the latter is a much finer apparatus and … much more accurate …than the former; in its measurement 作状语，前置译；than the former可译于该分句句 首“与前者相比”。

【点拨】

finer因为修饰的是appraturus“设备、装置”，所以译为“精密的，高质量的”。

【译文】

这不是说面包师或卖肉者所用的秤与化学家所用的天平在构造原理或工作方式上存在区别，而是说与前者相比，后者是一种精密得多的装置，因而在计量上必然更准确。