The device is used by placing the object whose thickness is to be measured on the base under the bolt, and screwing the bolt down until its end just touches the object, then removing the object, and screwing the bolt down until its end just touches the base, carefully noting while doing so the distance that the end of the wire moves over the scale.  The part of a rotation of the bolt, or the number of rotations with any additional parts of a rotation added, divided by the number of threads to the inch, will be the thickness of the object.  Quite accurate measurements may be made with this instrument, says the Scientific American, and in the absence of the expensive micrometer, it serves a very useful purpose.

** Another Electric Lamp Experiment [131]

Break a portion of the end off from a 16-cp. globe that has been thrown away as useless.  Shake the globe until all the filament is broken away, leaving only the ends of the platinum wire exposed.  Screw the globe into a socket that sets upright and fill it with salt water.  Make one connection to the socket from the positive wire of a 110 volt circuit and the other to a ground.  When the current is turned on small stars will be seen in the globe, which show up fine at night.  —­Contributed by Lindsay McMillan, Santa Maria, Oal.

** Removing Ink Stains [131]

Two or three applications of milk which are wiped up with a dry cloth will remove india ink spots on carpets.

** Feat of Balancing on Chairs [131]

[Illustration:  For Boys Balanacing]

Among the numerous physical exercises is the feat of balancing on the two rear legs of a chair while one foot rests on the front part of the seat and the other on the back of the chair.  This may appear to be a hard thing to do, yet with a little practice it may be accomplished.  This exercise is one of many practiced by the boys of a boys’ home for an annual display given by them.  A dozen of the boys will mount chairs at the same time and keep them in balance at the word of a commanding officer.

** How to Make a Merry-Go-Round Swing [131]

A 6 by 6-in. piece of wood 12 ft. long is used for the center pole.  Bore a 3/4-in. hole in each end to a depth of 6 in.  Place a 3/4-in. bolt in each hole, the bolt being long enough to protrude 2 in. beyond the end of the wood.  Short pieces of wood are nailed on the center pole about 2 ft. from the end that is to be used for the bottom.  This should form a hub on which to place the inner ends of the extending spokes that hold the platform.  The spokes are made from twelve pieces of 2 by 4-in. material 12 ft. long.

Usually a wheel can be found in a scrap pile suitable to place on the pin that is in the top end of the center pole.  The wheel should be open

[Illustration:  Side and Top View]