Yet in mechanics, whatever the mechanicians might think, both energies acted as interchangeable force on man, and by action on man all known force may be measured. Indeed, few men of science measured force in any other way.

然而在力学中，无论机械师怎么想，这两种能量都作为作用于人的可互换的力，并且通过作用于人的所​​有已知力都可以测量。事实上，很少有科学家以任何其他方式测量力。