Adapted to be removably attached to the upper edge of the receptacle 14 is a sleeve 18, preferably of aluminum or some similar suitable material, the attachment being removable, and being made by means of pin 20 operating in bayonet slots or the like formed in the lower portion of the sleeve 18. The wind-proof plumb bob itself of this invention consists of a casing or receptacle 14 which forms the bottom of the device and which is kept about three-fourths filled with oil, glycerine, or some other preferably viscous liquid as illustrated at 16.
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