Pressure gauge instrument

Claim 1

AN ABSOLUTE PRESSURE GAUGE COMPRISING: A HOLLOW HOUSING STRUCTURE HAVING A SINGLE OPENING THROUGH A WALL THEREOF THROUGH WHICH AMBIENT ATMOSPHERIC PRESSURES ARE EXERTED; A BELLOWS MOUNTED BETWEEN END PLATES MOUNTEND WITHIN THE HOLLOW OF SAID STRUCTURE ON THE WALL THEREOF HAVING SAID OPENING, SAID BELLOWS HAVING AN APERTURE THROUGH ONE OF SAID END PLATES AND BEING MOUNTED IN SUCH A MANNER THAT SAID APERTURE IS COEXTENSIVELY ALIGNED WITH SAID OPENING; A FLEXURE PIVOT RIGIDLY JOINED TO THE OTHER OF SAID END PLATES AT ONE END THEREOF, SAID BELLOWS BEING OPERABLE TO ROTATE AROUND SAID PIVOT FROM A NULL POSITION IN RESPONSE TO AMBIENT ATMOSPHERIC PRESSURES EXERTED INTERNALLY AGAINST IT; AND OPTICAL APPARATUS MOUNTED WITHIN SAID STRUCTURE AND ONE SAID BELLOWS FOR PROVIDING A MEASURE OF THE DISPLACEMENT OF SAID BELLOWS FROM ITS NULL POSITION, SAID APPARATUS INCLUDING AN OPTICAL DETECTOR FIXEDLY MOUNTED AT ONE POINT INSIDE SAID STRUCTURE AND MEANS FIXEDLY MOUNTED AT ANOTHER POINT INSIDE SAID STRUCTURE FOR PROJECTING A SPOT OF LIGHT ONTO SAID OPTICAL DETECTOR WHOSE POSITION ON SAID OPTICAL DETECTOR CORRESPONDS TO THE DISPLACEMENT OF SAID BELLOWS.