Popular science monthly . th a small L-shaped bar, throughwhich the current runs to the largescrew. This part of the apparatus isan automatic switch. When it is desired to set the switch,the disk on which the bottle shouldstand is pulled up, and the lower endof the wire loop bears against the smallrod which breaks the circuit. Theswitch is turned on in the house. Whenthe bottle is set upon the disk thecontact is broken at the large screw,and the small rod is forced into itsoriginal position by making a contactwith the L-shaped bar. If the bottle is removed before thehouse switch is opened, the
Popular science monthly . th a small L-shaped bar, throughwhich the current runs to the largescrew. This part of the apparatus isan automatic switch. When it is desired to set the switch,the disk on which the bottle shouldstand is pulled up, and the lower endof the wire loop bears against the smallrod which breaks the circuit. Theswitch is turned on in the house. Whenthe bottle is set upon the disk thecontact is broken at the large screw,and the small rod is forced into itsoriginal position by making a contactwith the L-shaped bar. If the bottle is removed before thehouse switch is opened, the spring riseswith the disk and makes a contact, butowing to the play in the loop, does notbreak the circuit through the rod. Thecircuit can only be broken by pullingthe disk up farther than the spring canforce it. With this arrangement, it is absolutelyimpossible for any one to steal thebottle without your knowledge. Ofcourse, the milkman must be instructedto be sure to set the bottle upon thedisk each day.—Ed. /nsulated Tif/ ^OocH Spring Mechanism of the Automatic Switch forCatching the Milk Thief 448 Popular Science Monthly A New Variable Condenser MOST experimenters find difficultyin constructing \ariiible condenserssuch as sold on the market, in whichthe effectiw area of the plates the condenser here described, thedistance between the plates is varied. The instrument is mounted on acircular base 5K ins. in diameter; A andB are brass disks 2}4 ins. in diameter;B is soldered to screw E and fastened tothe base as in the drawing. A wire fromE connects B with a binding-post; Cand C are rubber pillars upon which thebrass rod D is mounted. The rod isthreaded so that A will remain parallelto B. Between the two disks, insert asheet of mica F, about .005 of an in. inthickness. The capacity is varied byturning the knob G. The maximumcapacity will be .00176 mfds. with thebest grade of mica.—Matt Jarosz. r-\.
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectscience, bookyear1872
