HEATING BY HOT WATER. 211 
branch pipe or piece. ‘T-pieces are shown in Fig. 149; 
these are cast in several forms, with one, two, or three 
sockets apiece, and they are also made with one or more 
reducing sockets, to suit different positions, 
Cross-pieces (Fig. 150) are less frequently required, but 
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Fig. 150.: Fie, 161. 
may also be obtained in the usual sizes. The swan-neck 
(Fig 151) is very useful for taking pipes from one level to 
a higher one, or vice-versa, and answers much the same 
purpose as two cominon elbows cast or joined together. 
These are usually made with set-offs of 9in., 12in., and 18in. 
The }-piece is a useful contrivance for use where the 
current in two contiguous pipes (flow and return), is required 
to be occasionally stopped at a certain point, as at the end 
of one house, the pipes passing onward into the next (see 
Fig. 152). This fitting is frequently made with two throttle- 
valves, as shown, to prevent the current passing on any 
Pp 2 
