Put a cork into one end of one of the tubes and hold the other end in the flame as well as one end of the other tube as shown at A in Fig. 91.

Let the ends of the tubes get hot enough to melt but not thicken; now press the melted ends together hard enough to make them stick together but not hard enough to make them form a thick ring.

Fig. 92A. A Regular Blow-Pipe

To make a good job you should now use a pointed flame and heat the juncture all around red hot and blow into the open end of the tube to spread the glass a trifle. While you are blowing keep turning the glass in the flame to make the joint nice and smooth.

To Join One Tube to the Side of Another One.

First make a hole in the side of the tube in the manner already described and then cork up both ends; heat the tube around the hole and one end of the other tube as shown at B, in Fig. 91. When they are soft press them together hard enough to make a good joint. It is a good scheme to wrap cotton around the joint while it is still hot to anneal the glass, which means to make it less brittle by letting it get cold slowly.