Wynne's Innfallible actinometer. Watch form actinometer, plain glass and mask with standard tint over paper disc. Cailbrated in German. Wynne's Infallible actinometer
Wynee's Infallible Hunter meter. An actinometer - pocket watch form; opens to reveal sensitive paper holder in one half and calculator in the other, Scales: 64 seconds to 1/1000, f.3 1/2-156. Wynne's Infallible Hunter meter
Wynee's Infallible Hunter meter. Watchform actinometer. Sensitive paper visible through window in the face; two scale 1/128 - 64, F. 4-362. Wynne's Infallible Hunter meter
Wynne's Infallible Actinometer. Watch-form actinometer, clear glass and mask with standard tint over sensitive paper disc. Yellow filter disc cemented on rotating glass. Wynne's Infallible actinometer