224 Commercial Gardening 



places, then where two planks meet their ends are made secure by screwing 

 a piece of wood over the join on to the planks above and below. The 

 joints in the top and bottom planks have to be made with a short piece 

 of board put lengthways. When the walls are finished they should be 

 left to harden while the woodwork is painted and prepared. All the wood 

 can be bought ready formed, and it only requires the joints to be made, 

 and the sash bars cut to the right length and angle, to be ready for use. 

 When ordering, make allowance for the joints and order a few sash bars 

 extra, for some are sure to be a little short or twisted; these are reserved 

 for filling in the ends. The bars where the ventilators come can be shorter 

 than the others, and are supported by the ventilator seat instead of the 

 ridge. This plan makes a better job of the ventilators and saves a little 

 wood into the bargain. 



All houses are the better for a purlin, even if the bars are short ones 

 and no purlin supports are used. Many houses 16 ft. wide have no purlin 

 supports, but the facilities these offer for the supporting of shelves soon 

 make up for the extra cost. Besides 

 this, a house built with purlins pro- 

 perly supported and tied to one another 



Fig. 169. Scarf Joint Fig. 170. Half-lap Joint 



across the house will be much stronger than the other form and will not 

 require the iron ties running from the plate to concrete blocks in the 

 border. These ties are nothing but a nuisance, and a poor substitute for 

 the purlin ties at the best. 



The best joint for the plate, purlin, and ridge is the scarf joint (fig. 169). 

 It takes a little more wood than the half -lap joint (fig. 170), but is stronger 

 and easier to make. The latter, however, is used at the corners. To get 

 the correct angle for the ends of the bars an experiment must be made. 

 A piece of plate is laid in position on either wall, and a small section of 

 drip nailed in position on either side; a little piece is also cut off a length 

 of ridge about 2 in. will do. Two bars are then taken and carefully 

 fitted until they will occupy their final position with the little piece of 

 ridge between the upper ends, and fit nicely down on the plate as well. 

 Care must be taken to keep the bars exactly the same length while fitting. 

 The cuts can be made almost exactly right the first time if a good large- 

 scale drawing is prepared first and the bevel gauge set to the angles so 

 obtained. 



W T hen once the correct angles are obtained the rest is easy. A trough 

 is made to take the finished bar and a saw-cut made through the sides 

 of the trough at each end of the bar as in a mitre block. The uncut bars 

 are now ] f ajc} in the trough, one after the other, and the saw, guided by 



