1. AN ACCELERATION RESPONSIVE ACTUATING DEVICE COMPRISING A HOUSING, MASS MEANS DISPOSED WITHIN SAID HOUSING FOR LINEAR MOVEMENT WITH RESPECT THERETO BETWEEN PREDETERMINED POSITIONS IN RESPONSE TO VARIATIONS IN THE ACCELERATION OF SAID HOUSING, BIASING MEANS FOR URGING SAID MASS MEANS TOWARD ONE OF SAID PREDETERMINED POSITIONS, ACTUATING MEANS IN JUXTAPOSITION WITH SAID MASS MEANS AND OPERABLE IN RESPONSE TO MOVEMENT OF SAID MASS MEANS TO SAID OTHER PREDETERMINED POSITION AGAINST THE ACTION OF SAID BIASING MEANS, AND DAMPING MEANS FOR FORMING A PARTIAL VACUUM WITHIN A PORTION OF SAID HOUSING UPON MOVEMENT OF SAID MASS MEANS TOWARD SAID OTHER PREDETERMINED POSITION IN RESPONSE TO MOMENTARILY APPLIED ACCELERATION FORCES, BUT SAID DAMPING MEANS PERMITTING MOVEMENT OF SAID MASS MEANS TO SAID OTHER POSITION IN RESPONSE TO ACCELERATION FORCES OF SUSTAINED DURATION.