Popular Science Monthly 



633 



A Teeter Swing for Public or 

 Private Playground 



THE illustration shows a way to make a 

 permanent amusement device for chil- 

 dren's playgrounds. It is inexpensive to 

 build and if erected will prove as attractive 

 to children as many 

 other more elaborate de- 

 vices. 



Two planks A 16 ft. 

 long, 10 in. wide and 2 

 in. thick form the sup- 

 port for the teeter B, 

 which is made of two 

 pipes, each 1 Y% 

 in. in diameter 

 and 9 ft. long. 

 The seats C 

 consist of a 

 board strapped 

 on the pipe ar- 

 rangement D 

 which provides 

 an opening for 

 the legs, mak- 

 ing it almost 

 impossible for 

 a child to fall 

 out of the seat. 

 The support 

 for the main 

 pipes is shown at E, each end of which 

 passes through the planks with a coupling 

 on the ends to prevent the piece dropping 

 out of the holes bored in the planks. 



The plank ends are sunk into the ground 

 at one end and fastened together with a 

 bolt F. The 

 piece G is 

 made from 

 i3^-in. pipe 

 strapped to 

 the planks at 

 H. Window 

 cord is at- 

 tached at the 

 ends /. Two 

 children, even 

 of very un- 

 equal weight, 

 can have an 

 enjo ya b 1 e 

 time on this 

 swing, as the teeter is worked by pulling on 

 the cords rather than by balancing weight. 

 The riders can use their feet to help the 

 movement. If required, a brake can be 

 easily added to prevent the seats striking 

 the ground. — James E. Noble. 



An Interesting Experiment with 

 Sulphate of Soda 



A 



A playground teeter made 

 swinging part and planks set 



of pipe and fittings for the 

 in the ground for the supports 



Details of the parts for 

 making a teeter swing 



N experiment of an unusual character 

 may be made with a thoroughly 

 sterilized glass rod and a supersaturated 

 solution of sulphate of soda. The phenom- 

 enon is so extraordinary 

 that any one who may 

 make the trial will find 

 it difficult to clearly 

 explain the result. 

 To make it more 

 interesting four 

 glass tumblers 

 should be used. 

 Place them in a 

 saucepan of cold 

 water with their 

 bottoms resting on 

 cardboard, then 

 bring the water to 

 a boil. Meantime 

 dissolve some 

 sulphate of 

 soda in an- 

 other vessel, 

 by pouring 

 the soda sul- 

 phate into 

 boiling water 

 until the 

 water will take on no more. Now remove 

 the tumblers and place them upon a board. 

 Fill them with the saturated solution and 

 stand them aside to cool in a place free 

 from vibration. If this part of the work 

 is done at night the solution will be quite 

 cold in the morning and ready for the test. 

 Do not disturb the contents of the tumblers, 

 or crystallization will set in at once and 

 spoil the experiment. 



Take an ordinary round glass stirring- 

 rod that is about 1 ft. long and 5/16 in. 

 in diameter and clean it well; then in the 

 flame of an alcohol or other burner heat 

 about 3 in. on one end of the rod almost red 

 hot and place it to cool in such a position 

 that the heated end will not touch anything. 

 As soon as cold, take the rod and dip the 

 end that was heated into one of the tum- 

 blers containing the solution. No action 

 whatever will take place; but as soon as 

 the other end is inserted, the salt will im- 

 mediately start to crystallize and will 

 rapidly continue to do so until the solution 

 becomes a solid mass. 



If each tumbler is stirred at the start 

 with the sterilized end of the rod, the same 

 performance will take place. 



