CUTTA G E. 



45 



Zinc Propagating-tarik. 



nected by iron pipes with the tank, one pipe leading to one side 

 of the partition and the other to the opposite side, as shown in 



the drawing. 

 If water is 

 placed in the 

 tank it will fill 

 the pipes and 

 form a contin- 

 uous c i r c u - 

 lating system 

 through t h e 

 pipes and up 

 one side of the 

 box past the 

 end of the 

 partition, and 

 down the 



other side. A fire in the stove causes the water to circulate 

 through the tank and impart to the bed a genial warmth. 



There are various tanks designed to rest upon the pipes in a 

 greenhouse. The principle of their construction is essentially 

 the same as of those described in previous pages bottom heat, 

 a tray of water, and a bed of soil. Earthenware tanks are 

 commonly employed, but a recent English device, Fig. 40, is 

 made of zinc. It is about seven inches deep, and holds an inch 

 or two of water in the bottom. A tray five inches deep sets into 

 the tank. The water is supplied through a funnel at the base. 

 Cuttings usually "strike" better when they touch the side of 

 the pot than when they are wholly surrounded by soil. This is 

 because the earthenware allows greater uniformity in moisture 

 than the earth, and supplies air and a mild bottom heat. Vari- 

 ous devices are employed for the purpose of securing these 

 advantages to the best effect. These are usually double pots, in 

 one of which water is placed. A good method is that repre- 

 sented in Fig. 41, which shows a pot, b, plugged with plaster of 

 Paris at the bottom, placed inside a larger one. The earth is 

 placed between the two, drainage material occupying the bot- 



