Easily cracked: scientific instruments in states of disrepair.

There has been much scholarly attention to definitions of the term "scientific instrument." Rather more mundane work by makers, curators, and users is devoted to instruments' maintenance and repair. A familiar argument holds that when a tool breaks, its character and recalcitrance become evident. Much can be gained from historical study of instruments' breakages, defects, and recuperation. Maintenance and repair technologies have been a vital aspect of relations between makers and other users. Their history illuminates systems of instruction, support, and abuse. These systems were, for example, evident in the development of astronomical instruments around 1800 within and beyond the European sphere. Episodes from that milieu are used to explore how instrument users sought autonomy, how instruments' mutable character was defined, and how judgments of instruments' failure or success were ever secured.