Many of the methods discussed in this book produce considerable quantities of data, or at least they could do so if a means to take measurements and record them were available. It is particularly important for some tests that a continuous record be obtained (e.g. XRD or DTA). To this end, the manufacturers have provided a recorder of some type, which, when coupled to the instrument, provides a continuous record for subsequent examination. The cost of such instrument-recorder packages may be high, but both are required. Other tests may require only one pertinent value (e.g. a peak stress in a direct shear box test), yet the duration of the experiment could be many hours.