[en] Two prototype lead glass calorimeters have been constructed and tested at the AGS at Brookhaven National Lab. The first is a 25-element prototype (P1) which was tested in the A2 beam line using electrons and pions ranging in energy from 0.5 to 5.0 GeV. Results were obtained on energy resolution, the effect on energy resolution of pre-radiators and non-normal incidence, and on e/π separation. The second prototype (P2) has 319 elements and was tested in the A3 beam line using 3.0 and 5.0 GeV electrons and 15.0 GeV negative pions. Results were obtained on position resolution and effective mass resolution. Data were collected requiring multi-photon signatures in the calorimeter. The design, construction, monitoring, readout electronics (including a custom-built fast-encoding ADC system) and testing of the prototypes are described. These calorimeters are prototypes for a 3053-element lead glass calorimeter being built for Brookhaven Experiment 852: A search for mesons with unusual quantum numbers. Quality control procedures are also discussed. (orig.)