210 GREENHOUSE CONSTRUCTION AND HEATING. 
Elbow syphons (Fig. 146) are employed where the ends of 
{wo or more rows of piping are to be connected and taken 
Fig. 147. 
away at a right angle; a A are two forms of the ordinary 
elbow syphon, B a three-way, and c a four-way elbow 
Fig. 148. 
syphon. Another form of the same thing, but with 
straight outlets, is shown in Fig. 147; these are sometimes 
Fig. 149. 
termed branch syphons. ‘‘ Branch” pipes are shown in 
Fig. 148, where a is a two-way, and B is a three-way 
