Filings coherer, glass tube formed into T-shape at one end and bent round into U-shape at other end with bulb, 1899 1899
Filings coherer, small glass tube with bulb at one end and cap of red sealing wax at other end, 1898 1898
Model of Robert Duncan's screw propeller, with stern frame and rudder, as fitted to the Egyptian government yacht 'Sareea 1886-1887