Abstract: A method and apparatus for locating multiple bar codes in a field. The apparatus includes a microcomputer programmed to detect the existence of bar codes in location cells in the field and then apply a location score to each location cell. Based on the scores assigned to the location cells, a particular location cell is selected and the location cells surrounding the selected cell are analyzed to determine whether they might contain a bar code segment. A location cell that is determined to be sufficiently likely to contain a bar code segment will be appended to the first selected location cell. In this manner, a bar code in the field can be located. The determination of whether the located bar code is a primary or a secondary bar code is made by further analyzing the located bar code. The further analyses may be to determine the located bar code's length, whether it has a predetermined prefix, or whether it has a predetermined pattern of descenders from its constituent line segments.

Abstract: A tiltmeter which uses two fluids of different thermal density coefficients, each of which is contained in its own fluid system consisting of a long tube connecting two vertical reservoirs. The two systems are deployed in physical contact along their entire length so that they experience the same thermal conditions. Measurements with this instrument are made by taking separate, simultaneous readings of the difference in fluid heights and/or bottom fluid pressure between the terminal vertical reservoirs in each of the two fluid systems; these measurements, together with known density coefficients of the fluids, provide the data to correct for errors in meter readings caused by temperature/density fluctuations in the fluids and permit a precise determination of vertical displacement and tilt over the measurement path. The ruggedness and unique design of this tiltmeter allow it to make more accurate measurements of regional tilt than previous tiltmeters and with less expenditure of money and effort.