Explosion-proof pressure gauge

Claim 1

A GAUGE COMPRISING (A) A CASING HAVING INTERMEDIATE ITS ENDS AN INTEGRAL, TRANSVERSE WALL, AND HAVING FIRST AND SECOND CLOSED CHAMBERS FORMED ON OPPOSITE SIDES, RESPECTIVELY, OF SAID WALLS, (B) A CONDITION RESPONSIVE ELEMENT MOUNTED IN ONE OF SAID CHAMBERS FOR MOVEMENT IN RESPONSE TO A CHANGE EXISTING AT THE EXTERIOR OF SAID CASING (C) A FIRST MAGNET ROTATABLY MOUNTED IN SAID ONE CHAMBER, (D) A FIRST ARM MOUNTED AT ONE END TO ROTATE WITH SAID MAGNET IN SAID ONE CHAMBER AND EXTENDING RADIALLY OUTWARDLY FROM THE AXIS OF ROTATION OF SAID MAGNET, (E) A SECOND ARM CONNECTED ADJACENT ONE END THEREOF TO SAID ELEMENT TO MOVE THEREWITH ANGULARLY ABOUT SAID AXIS OF ROTATION UPON A CHANGE IN SAID CONDITION, AND HAVING A PORTION ADJACENT THE OPPOSITE END THEREOF ENGAGING SAID FIRST ARM INTERMEDIATE THE ENDS THEREOF TO TRANSMIT THE ANGULAR MOVEMENT OF SAID SECOND ARM TO SAID FIRST ARM, (F) A SECOND MAGNET ROTATABLY MOUNTED IN THE OTHER OF SAID CHAMBERS COAXIALLY OF SAID FIRST MAGNETL AND MAGNETICALLY COUPLED TO SAID FIRST MAGNET TO ROTATE THEREWITH, (G) A GRADUATED DIAL AND A POINTER MOUNTED IN SAID OTHER CHAMBER TO BE VIEWABLE FROM THE EXTERIOR OF SAID OTHER CHAMBER, AND (H) MEANS MOVABLE WITH SAID SECOND MAGNET UPON A CHANGE IN SAID CONDITION TO CAUSE A CORRESPONDING RELATIVE MOVEMENT BETWEEN SAID IAL AND POINTER, RESPECTIVELY, THEREBY TO PROVIDE A VISUAL INDICATION OF SAID CHANGE, (I) SAID WALL HAVING A CENTRAL OPENING THERETHROUGH, OPPOSITE SIDES OF SAID WALL CONFRONTING THE INTERIOR OF SAID IRST AND SECOND CHAMBERS, RESPECTIVELY, AND (J) A STATIONARY PIN EXTENDING THROUGH AND SEALING SAID CENTRAL OPENING IN SAID WALL, (K) SAID MAGNETS BEING ROTATABLY JOURNALED ON OPPOSITE ENDS, RESPECTIVELY, OF SAID PIN TO ROTATE IN UNISON IN SAID CHAMBERS.