the base 20 wood screws may be inserted through the holes 42 and 43 to fix the base 20 in place on the window sill 15 as shown in fig5 the bottom of the base 20 is angled slightly to accommodate the typical outward and downward pitch of a sill the adjustment screws 26 and 27 operable within the slots 25 allow the grill 11 to be located perpendicular to ground with some adjustment for individual sill slopes all within a range of approximately fifteen degrees as shown in fig5 the reed switch 35 is then located directly over a magnet 45 embedded in the sill 15 by the circuitry described below it will be understood that the reed switch will cause an alarm to sound when it is removed from the influenece of the magnet 45 the electrical circuitry of the invention is not critical and may be varied though one suitable circuit is shown in fig6 contacts 50 and 51 correspond to the trunnions 29 and 30 contact 51 is connected to a one half watt resistor 52 a ceramic capacitor 53 and a quad gate 54 a second quad gate 55 also is included as shown connected to ground by a resistor 56 and a capacitor 57 a resistor 58 is provided together with a tansistor 59 resistors 60 and 61 and a second transistor 62 a capacitor 63 is incorporated as shown along with a diode 64 the reset switch 33 of fig3 and 4 is shown in the circuit diagram of fig6 together with the.