Note 46 — Chapter III
Fred Rothwell translation
Such as the one with the magnet which, if too great a weight is suspended to its armature, loses strength, and this it only regains by degrees when "fed" with successively stronger charges. A steel spring that has borne too great a weight loses strength, and may break if subjected anew to the same weight that "fatigued" it. Pieces of iron break after being "fatigued" by a weight they easily carried before. Professor Kennedy made very useful experiments regarding the "fatigue" of metals at the time when metallic bridges were continually breaking, thus causing great perplexity in the engineering world.