Magnetic gradiometer data were obtained over a site at  which old maps indicate as a carpenter shop. Data were acquired on a grid 7 m wide by  9 m long. The line spacing was 0.5 m and data spacing along the line was about $
m.The gradiometer data without processing are not shown but are quite similar to  the plot in the upper right hand panel.  A rough half circle  of high gradient is present. Additional details including  at least two dipole  anomalies are visible within the half circle. I processed the data to yield additional details as follows. I  displayed logarithm to the base 10 of the data in the upper left hand panel as  smoothed (low pass filtered) the data by convolving it which a five by five uniform panel. The results are shown in the panel on the upper right. I subtracted this from the original data, and have presented this difference  in the panel on the lower right. This process is thus a high pass filter,  and is intended to remove or attenuate larger features and reveal smaller  features.  I plotted the logarithm to the base 10 of these high pass filtered data in the lower left hand panel.