AbstractThis is the third review of a small calculator to appear in theSurvey Reviewin four issues. The Hewlett Packard 35 (Cox 1972) was heralded as a tremendous breakthrough in calculating machines for surveyors and is now very popular. The Casiofx−1 (Dowman 1973) is a larger machine but still portable and with similar features to the HP 35. This new machine—the Sumlock Micro Scientist—is comparable in size to the Casio but offers a combination of the best features of the others, and more. Despite a temptation to review the Sumlock by comparing it with the other two machines this will be resisted in the interests of objectivity. However in order to facilitate comparison by the reader a similar format to the other reviews will be followed.