must be made with relatively large groundbased telescopes (high angularresolution requires large antennas). The theoretical case is notyet as strong for small-scale measurements because such anisotropiesare presumed to have been smeared out when matter and radiation interactedfor the last time at the epoch of photon decoupling. However, variantsof the Big Bang theory, such as theories involving cosmic strings(discontinuities in the structure of space), predict that importantclues to the universe's history might be embedded in the CMBR atthese angular scales. A few experiments have been done from singlelarge telescopes and from arrays of radio telescopes, such as theVery Large Array. Though sensitivities are comparable to the COBEdetection level, only a small fraction of the sky has been scanned.Signals are detected, but they are thought to be due mostly to radioemission from galaxies, quasars, or other foreground radio sources.Because of the need for large instruments and the extreme care requiredfor these measurements, progress on small-scale anisotropy is likelyto be relatively slow. But it should be remembered that only a decadeago there was almost no interest in even medium-scale measurements.As understanding has grown, so also has the need for more diverseexperimental data. And surely, as more data are analyzed, the simplemodels of structure formation must break down at some point. Improvementsin small-scale measurements are one way to find such weaknesses inthe models.