Swimming pool alarm system

Claim 1

For use in a swimming pool, a device for providing a signal in response to a change in the water level at a particular location in said pool, at which said device is mounted, said device comprising a bracket mounted to a side of said pool, a housing member slidable mounted to said bracket for adjustable movement in a vertical direction, fastening means accessible only from within said housing for locking said housing in an adjusted position of said bracket, a magnetically operated normally closed switch mounted in a fixed position near the top of said housing a substantial distance above said fastening means, an axially polarized permanent bar magnet, a float disposed in said housing between an upper position overlying said fastening means and a lower position below said fastening means, means mounting said magnet at a fixed position in said float whereby said magnet maintains said switch open when said float is in said upper position and permits said switch to close when said float is in said lower position, a cover member secured to said housing member to prevent access to said float and said fastening means, whereby said housing may be positioned whereby said magnet maintains said switch open until the water level in said housing drops a predetermined amount and said switch closes.