Single-phase portable a.c. and d.c. wattmeter, model 310 form 2 serial no.5622, by the Weston Electrical Instrument Corp., N.J., U.S.A., calibration certificate dated 1926 Single-phase portable a.c. and d.c. wattmeter 1926
Dynamometer wattmeter no.L79139, by Cambridge Instrument Co. Ltd., reflecting pattern, with permanantely connected control box, mounted on a slate base carrying lamps and triple length scale Dynamometer wattmeter no.L79139
Sumpner's portable standard volt- and wattmeter (an iron-cored electrodynamometer), patent no.24605 of 1904, serial no.190W, calibration certificate dated 1911 Sumpner's portable standard volt- and wattmeter (an iron-cored electrodynamometer)
Precision electrostatic wattmeter, Rayner and Paterson, 1913 Precision electrostatic wattmeter, Rayner and Paterson, 1913 1913
Low-loss electrodynamometer wattmeter, with torsion control, reflecting type with built-in lamp and screen, made by Everett Edgcumbe, London, No.673 243 Low-loss electrodynamometer wattmeter
Wattmeter, GER, AC Wattmeter by Elliott Brothers, London No.2098. Dated 25-11-27. In wooden case with brass label: "Great Eastern Railway Electrical Engineers Dept. Liverpool St. Station". AC wattmeter by Elliot Brothers 1927
Electrodynamometer wattmeter no.1263438 by Evershed and Vignoles Ltd,for 50Hz a.c. at 0.2 power factor, voltage ranges 125, 250 and 500W (and 1000V with external resistor), and two separate 5A current Electrodynamometer wattmeter no.1263438 by Evershed and Vignoles Ltd 1950-1970
Irwin dynomometer wattmeter by the Cambridge Instrument Co. Ltd. No. L 24972, with accompanying documentary material Irwin dynomometer wattmeter by the Cambridge Instrument Co. Ltd. No. L 24972 1930