1. AN ELECTRICAL SWITCHING DEVICE ADAPTED TO BE ACTIVATED ONLY BY AN ACCELERATION FORCE OF A PREDETERMINED MINIMUM MAGNITUDE AND DURATION, COMPRISING: FIRST AND SECOND MOVABLE MEMBERS MUTUALLY ARRANGED FOR RELATIVE MOVEMENT IN RESPONSE TO SAID FORCE; MEANS ADJACENT TO BOTH OF SAID MOVABLE MEMBERS FOR HOLDING SAID SECOND MOVABLE MEMBER IN A SOLIDLY ENGAGED, FIXED POSITION UNDER THE INFLUENCE OF SAID FORCE UNTIL SAID FORCE HAS CAUSED SAID FIRST MEMBER TO BE DISPLACED A FIRST PREDETERMINED DISTANCE AT WHICH SAID SECOND MEMBER IS QUICKLY AND FULLY RELEASED BY SAID HOLDING MEANS TO BE FREE TO BE DISPLACED A SECOND PREDETERMINED DISTANCE WHEREIN DISPLACEMENT THEREOF IS EFFECTIVELY LIMITED INDEPENDENTLY OF THE DISPLACEMENT OF SAID FIRST MEMBER TO SAID FIRST PREDETERMINED DISTANCE; FORCE RESISTING MEANS IN CONTACT WITH SAID MOVABLE MEMBERS TO EXERT A COUNTERACTING FORCE