Low rotary speed detecting switch

A rotary switch including a closed rotary hollow housing angularly displaceable about a horizontal center axis, said housing defining an annular cavity therein at least generally centered relative to and extending about said axis, first outer peripheral wall means defining the outer periphery of said cavity, second inner peripheral wall means defining the inner periphery of said cavity extending about said axis in radial spaced relation thereto and opposite end wall means extending between said inner and outer peripheral wall means closing the opposite ends of said cavity, said inner and outer peripheral wall means being constructed of electrically conductive material, said end wall means being constructed of dielectric material whereby said inner and outer wall means are electrically insulated relative to each other, a quantity of electrically conductive liquid disposed in said cavity engaging said inner and outer wall peripheral means and to a level below which said inner peripheral wall means projects in at least one angular position of said housing about said axis when said housing is stationary, and first and second stationary electrical contact means disposed exteriorly of said housing and engaging said outer and inner wall means, respectively, in a manner enabling rotation of said housing about said axis and relative to said contact means while maintaining constant electrical connection between said contact means and outer and inner wall means, at least the outer peripheral portions of said cavity including liquid flow restricting means restricting the flow of liquid about the outer peripheral portion of said cavity, whereby rotation of said housing about said axis above a predetermined speed will cause a sufficient quantity of said liquid to be held by centrifugal force against said outer peripheral wall means to lower the standing level of liquid in said cavity to a level below the lowest portion of said inner peripheral wall means and thereby break electrical connection between said inner and outer peripheral wall means and said second and first electrical contact means.