A small air shower array of diameter 120 m is described. This array is used to study extensive air showers of sizes ranging from 10(^4) to 10(^6) and also to supply information required for the hadron studies carried out using a flash-tube chamber placed in the Cosmic Ray laboratory of the University of Durham. The array was also used to trigger the Magnetic Automated Research Spectrograph which had its location in that laboratory. Eight liquid scintillation counters have been added to the initial fourteen plastic detectors. The array detecting elements are located in a triangular geometry around the Physics Department. In the data handling procedures, the initial array data were assembled, digitised and then transferred to an on-line I.B.M. 1130 computer disc where the data were primarily stored before being transferred to the larger I.B.M. 370/168 computer in order to be analysed. The array could be triggered in different ways depending upon the mode chosen and upon other experiments present. Results arc presented showing the effect of the inclusion of the liquid counters on the accuracy with which the analysis programme determines the location of the shower core and on the shower size value resulting from the data analysis. The depth of the liquid in the liquid counters was 20 cm which means that these liquid detectors responded to the photons and nuclear active particles of the extensive air showers. The lateral distributions of the electron-photon component of EAS as measured by one of the liquid counters and one of the plastic detectors (5 cm thick) are deduced and compared with the results of other experiments. The present results show good agreement with those of other workers when the effect of the thickness of the used detectors is taken into account, except for the results of Hasagawa (1962). A comparison is made between the distributions of the number of flash-tubes discharged in the red-side top measuring tray of the spectrograph and the theoretically predicted distributions
