图26：电导仪

图27: 维尔纳·冯西门子

注释及参考文献

[1] If then we wish to obtain standards which will be absolutely permanent, we must seek them not in the dimensions or the motion of our planet, but in the wavelength, the period of vibration and the absolute mass of these imperishable and unalterable of these imperishable and unalterable and perfectly similar molecules.

来源：返朴

编辑：Quanta shuang

来源：新华号 中科院物理所