Schraven, Thomas, <br/><br/>
Folliott Gray's invention "The Duo Electric clock" / 
by Thomas Schraven ; Krefeld. 
 - 17 pages :  illustrations ;  28 cm 
<br/><br/> "Lecture given on the 5th anniversary of the Cologne Clock Society 31/5/1997." 
<br/><br/><label>Subjects--Personal Names: </label><br/>Gray, Folliott.
<br/><br/><label>Subjects--Topical Terms: </label><br/>Clocks and watches, Electric.
<br/><br/><label>Subjects--Index Terms: </label>Clock (general) UnitedKingdom Grey electric Schraven, Thomas ElectricalScience