Fluid indicator

Claim 1

IN A FLUID INDICATOR HAVING A FLOW PASSAGE BOUNDED AT ONE PORTION BY TRANSPARENT MEANS PERMITTING THE VIEWING OF THE INTERIOR THEREOF, AND MEANS IN SAID PASSAGE FOR INDICATING THE PRESENCE OF ANOTHER SUBSTANCE IN THE FLUID, INCLUDING A SHEETLIKE ARRANGEMENT OF MATERIAL HAVING AN APPEARANCE VARYING AS A FUNCTION OF THE PRESENCE OF SAID ANOTHER SUBSTANCE IN THE FLUID, AND SPRING MEANS BIASING SAID SHEETLIKE ARRANGEMENT OF MATERIAL OUTWARDLY TOWARD THE TRANSPARENT MEANS, SPACING MEANS COMPRISING A PLURALITY OF ELEMENTS BETWEEN SAID SHEETLIKE ARRANGEMENT OF MATERIAL AND THE TRANSPARENT MEANS AND SPACED TRANSVERSELY TO THE DIRECTION OF FLUID FLOW THROUGH THE PASSAGE TO FORM A PLURALITY OF FLOW PASSAGE PORTIONS ADJACENT THE TRANSPARENT MEANS, EACH OF SAID ELEMENTS EXTENDING FULLY ACROSS SAID SHEETLIKE ARRANGEMENT IN THE DIRECTION OF FLUID FLOW SO THAT THE OPPOSITE ENDS OF SAID PASSAGE PORTIONS ARE OPEN TO SAID FLUID FLOW PASSAGE WHEREBY A PORTION OF A FLUID FLOWING THROUGH SAID FLUID FLOW PASSAGE FLOWS THROUGH SAID PASSAGE PORTIONS, SAID SPACING MEANS BEING DEFINED BY A SHEET MEMBER HAVING A PLURALITY OF PARALLEL, SPACED RECTANGULAR OPENINGS, THE LANDS BETWEEN SAID OPENINGS DEFINING SAID ELEMENTS.