174 GREENHOUSE CONSTRUCTION AND HEATING. 
that it is quite fresh and “quick,” as it must invariably 
be for all work of this kind. Pack the yarn in tightly with 
a proper caulking-iron (see Fig. 113) and hammer, and 
then fill up with the cement, freshly mixed with water 
Fig. 113. 
to the consistence of mortar, working it in well all round 
with the blunt end of a bit of lath, or the like, and finally 
smooth it off neatly with the fingers, or a small pointing 
trowel. Good fresh cement will set quite hard in about 
an hour—less in hot weather—and will practically last 
for ever. We generally go over the joints a second time 
about ten minutes afterwards, making good any faults 
and finishing off 
well and neatly. 
Should any 
“weep” a little 
when the pipes 
are filled, throw 
a little fresh, dry 
cement on re- 
5 / : peatedly, and it 
SECTION El aap Ca will probably 
Fic. 114. cease as the 
water becomes 
hot. Should any leak badly, better draw off the water, 
cut out the cement, and re-make the joint. 
The ‘‘expansion-joint” pipes are cast with a small 
socket and narrow flange at one end, with two ‘‘lugs” 
