the edge 46 the tether eyelet assemblies 74 are affixed to the bottom panel 40 at this time referring next to fig5 and 3 the hour glass segment 50 is prepared the four dart edges 53a and 53b 54a and 54b 55a and 55b and 56a and 56b are overlapped and sealed along their lengths likewise the non symmetrical dart edges 65a and 65b and 66a and 66b are overlapped and sealed referring now to fig2 and 3 the upper panel 30 is positioned with its chordal edge 39 generally coincident with and slightly overlapping the three edges 51 57 and 58 of the hour glass panel 50 and sealed thereto likewise the lower panel 40 is positioned with its edge 49 coincident with and overlapping the edges 52 59 and 60 and sealed thereto next the generally spherical ends of the breather bag 10 are formed by overlapping and sealing the following pairs of edges 35 and 61 36 and 62 45 and 64 and 46 and 63 finally the full length seal along the convex outer periphery of the breather bag 10 comprised of the edges 32 and 42 is sealed by placing these edges in overlapping coincidence and applying sealing energy it will be appreciated that the breather bag manufactured according to the preceding description exhibits extended service life due to two features first the upper panel 30 the insert 31 the lower panel 40 and the hour glass panel 50 shaped and cut according.