Electric meter with light responsive limit indication

Claim 1

IN A METER DEVICE FOR MEASURING AN ELECTRICAL QUANTITY INCLUDING A POINTER ROTATABLE IN A GIVEN PLANE ABOUT A PIVOT AND ELECTRICAL CURRENT RESPONSIVE MEANS FOR DEFLECTING SAID POINTER ABOUT ITS PIVOT POINT TO AN EXTENT DEPENDENT UPON THE MAGNITUDE OF SAID ELECTRICAL QUANTITY, SAID POINTER HAVING A PREDETERMINED MAXIMUM ANGULAR DEFLECTION, MEANS FOR INDICATING WHEN SAID QUANTITY REACHES A GIVEN VALUE COMPRISING, AN INDEX MARKER MOVABLE IN A PLANE SUBSTANTIALLY PARALLEL TO SAID GIVEN PLANE ABOUT A PIVOT POINT COAXIAL WITH THE PIVOT POINT OF SAID POINTER, A PHOTOELECTRIC CELL CARRIED BY SAID INDEX MARKER AND MOVABLE THEREWITH ALONG A SUBSTANTIALLY ARCUATE PATH, A GENERALLY PLANAR ELEMENT OF LIGHT TRANSMITTING MATERIAL LYING GENERALLY IN THE PLANE OF THE ARCUATE PATH DESCRIBED BY SAID PHOTOELECTRIC CELL, SAID ELEMENT HAVING APPRECIABLE THICKNESS AND PRESENTING A CONCAVE ARCUATE LIGHT-EMITTING EDGE CONCENTRIC WITH SAID SPACED OUTWARDLY OF SAID PATH OVER ITS ENTIRE LENGTH, SAID LIGHT-EMITTING EDGE HAVING AN ARCUATE LENGTH GREATER THAN TWICE THE MAXIMUM ANGULAR DEFLECTION OF SAID POINTER, A LIGHT SOURCE COPLANAR WITH SAID PHOTOELECTRIC CELL PATH AND SAID LIGHT-EMITTING EDGE, AN INDENTED PORTION IN AN EDGE OF SAID ELEMENT OTHER THAN SAID ARCUATE EDGE FOR ACCOMMODATING SAID LIGHT SOURCE, AN OPAQUE COATING OVER ALL SURFACES OF SAID ELEMENT OTHER