228 Commercial Gardening 



angle than is usual, and the temper should be as hard as possible to 

 stand without chipping. The wide angle helps in this matter. A mark is 

 made round the pipe where it is to be cut, and the pipe laid on the ground 

 so that it is touching immediately beneath the cut. The line is now 

 followed round with the chisel, giving light sharp taps to the tool with 

 a hammer. As soon as the line is chipped all round, go round again, 

 hitting a little harder, but still as sharply as possible. During the third 

 time round the pipe will probably crack all along the mark and break 

 off clean; if not, the process must be repeated till it does crack. The 

 flow pipes in the house should stand 6 in. higher than the returns, 

 and an air pipe must be fitted at the highest point in each row. 



A tank for keeping the pipes supplied with water must be placed 

 somewhere where it can be filled easily. This tank should not be too 

 small, or when the water in the pipes gets hot the expansion will cause an 

 overflow and a consequent shortage when the water cools again; 20 gal. 

 will do for a small house or two, but a 30- or 40-gal. tank will not be 

 a bit too big for say 1500 ft. of pipe. An expansion pipe must be fitted 

 to the boiler, and should be 1 in. diameter for anything but a very small 

 boiler; this pipe should rise to a height of 6 ft. above the highest point 

 in the pipes. When setting the boiler, a good rise should be given to it. 

 The makers will say what rise to give their special boiler, but any of the 

 forms of saddle boiler will want a rise of f in. to the foot. 



With regard to water supply, for forcing, it will be necessary to 

 have tanks in the houses, and for obtaining warm water one of the 

 pipes should be taken through the walls. To do this a sliding collar 

 with a joint formed with indiarubber rings must be put on to the pipes 

 where they will pass through the walls of the tank, and this must be 

 done before the pipes are joined together. These collars are built into 

 the walls of the tank, and the pipe inside is thus free to move a little 

 with the expansion and contraction due to the temperature. If this is 

 not done the movement will crack the walls of the tank. Tank walls 

 should be 6 in. thick, made of good concrete, and faced with sharp sand 

 and cement in the proportions of 1 part cement to 2 parts sand. When 

 the facing is set it should be brushed over with a wash made of neat 

 cement, or, better still, let the walls get quite dry and then paint over, 

 first with a solution of Castile soap, f Ib. to the gallon of water, allow- 

 ing twenty-four hours for drying, and then with a hot solution of 2 oz. 

 of alum to the gallon. This process can be repeated if necessary; but 

 it is said that four coats are impervious to a head of 45 ft. of water, so 

 that one coat should be sufficient for a greenhouse tank. When ground 

 clinker is used for making the concrete it may be economized by making 

 old bricks or the concrete to a batter, and as it is filled into the mould 

 any kind of hard rubbish can be bedded in it. Long tank walls should 

 have old lengths of gas pipe put in to strengthen them, and pieces of 

 small pipe or iron bar should be bent round and set in the corners. 

 Corner irons should be put in the greenhouse wall as well. 



