The Micro-Erosion-Meter was developed about 1970 in order to obtain absolute measurements of rock lowering. The instrument is relatively cheap to construct and consists of an engineering micrometer dial gauge, with measurement probe, bolted onto a tripod framework. The legs rest on stainless steel studs which are permanently inserted into the rock surface. The legs are constructed to allow exact relocation of the meter so that initial and subsequent measurements can be compared after a period of months or years. The construction and method of use of the M.E.M. is described with particular reference to the measurement of the weathering of rock art. See also 16-840. -- AATA