Now heat the edge of the hole and the end of the short piece in the lamp flame, and make a joint (2, Fig. 76) exactly as described in Experiment 53. Be particular to heat and blow all around the joint at least three times to make the glass uniform, and on the last blowing leave the joint a little larger than the tube. Cut off the closed ends, make the arms equal in length, smooth the ends, and your tee is made (3, Fig. 76). Your first attempt may not be beautiful, but if you will repeat the heating and gentle blowing often enough, the joint will be strong, which is the main point. Repeat until you can make a tee easily. Make a tee with No. 2 tubing. Your flame is hardly large enough to make a tee with No. 6 tubing. Experiment 57. A three-armed siphon. Make a three-armed siphon as shown in Fig. 77. Put two arms in tumblers filled with water, suck air out of the third arm until the water runs, and then put it in an empty tumbler. Stand the three tumblers on the table. Does the water run until the levels are the same? Put one tumbler on a book. Does the water run into the other two tumblers until the levels are the same? Return the one tumbler to the table and put the other two on the book. Does the water run from both tumblers to the lower tumbler until the levels are again the same? Experiment 58. To make a repeating air gun. [Illustration: FIG. 81 BALANCING COLUMNS ] Take a full length of No. 4 tubing, put a branch about 3 inches long at a point about 2 inches from one end; leave the end of the branch closed (Fig. 78). Now load the branch with shot or coarse dry sand, and your repeating air gun is ready for use. Tilt the branch slightly above the horizontal and blow intermittently. Does your gun reload after each blow, until the ammunition is used up? Experiment 59. To make a four-way junction. Make a tee as in Experiment 56, but do not cut off the closed ends. Now attach a fourth arm, as in Fig. 79, and heat and blow gently as before to work the glass into uniform condition. Cut off the closed arms at equal lengths, smooth the ends, and your four-way junction is made. Experiment 60. A four-arm siphon. Make a four-arm siphon, repeat the experiments described in Experiment 57, and make others of your own. Experiment 61. To make a Y. Make a tee as in Experiment 56, then make a bend about ½ inch from the stem on each side (Fig. 80), and your Y is complete. Experiment 62. Balancing columns. Arrange the apparatus as in Fig. 81, put the arms together in a glass of water, suck a little air out of the top coupling and close it with a glass plug. Do you find that the water rises to the same level in each? Place the arms in separate tumblers filled with water to the same level and repeat. Does the water rise to the same level? [Illustration: FIG. 82 THE WATER LEVELS ARE THE SAME ]