this report describes the development of a horizontal inclinometer with an inductive acceleration transducer sensing unit. the inclinometer is designed to operate in horizontal or sub-horizontal boreholes and measure vertical ground movement. laboratory trials showed that at the 95 per cent confidence level, the instrument is capable of measuring vertical ground movements at the end of a 10 m borehole to within plus or minus 2 mm from a double run, ie measuring in and out of the borehole. repeated measurements will improve these limits and eliminate any bias. the inclinometer was successfully used for measuring vertical ground movement around a shallow tunnel in chalk at chinnor, oxfordshire, where movements of up to 18 mm were recorded. the horizontal inclinometer costs 300 and its readout unit 600; the latter cost could be significantly reduced with a purpose built amplifier (1974 costs). (a)

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