For an explanation about the history of steam engine indicators, visit: http://www.archivingindustry.com/Indicator/contentback.htm [last viewed 20 May 2013]. For information about the Richards' Improved Patent Steam-Engine Indicator see John Walter's publication 'The Engine Indicator: a short history of the autographic patterns from 1800 to the present day' - available online via: http://www.archivingindustry.com/Indicator/chaptertwo.pdf Information on Casartelli, Manchester is also available online via: http://www.archivingindustry.com/Indicator/chapterfour.pdf Refer pp.21-22 [last viewed 20 May 2013]Brass steam-engine indicator 125mm tall - accompanied by four steel piston springs - and a wooden measuring ruleIndicator [a] Casartelli Manchester [b] 41 ; Ruler [a] 12 to the Inch [b] No.2 [c] Casartelli & Son Manchesterrichards improved patent steam engine indicator, casartelli manchester