128 VEGETABLE GARDENING 



mercial houses is often much greater. As plants do not 

 do well next to the walls, it is desirable to have walks 

 there, and the house space can then be divided in such 

 a manner as may seem convenient for the care and har- 

 vesting of the crops to be grown. 



184. Steam versus hot water heating. Hot water is 

 unquestionably the best system for heating small houses, 

 and there are many arguments in its favor for large 

 ranges of houses. If pumps or a pressure system are used 

 to secure rapid circulation, the radiating surface need not 

 be much greater than in a steam system. The higher 

 cost of installation has always been one of the greatest 

 objections to hot water. With the pressure system in- 

 stead of the open tank, the water is heated to a higher 

 temperature and also made to circulate more rapidly. 



The advantages of hot water over steam may be stated 

 as follows: (i) As the hot water in the pipes retains 

 heat for a greater length of time, the boiler may be left for 

 a longer time without attention. This is a great advantage 

 in small greenhouses, where it would not pay to employ a 

 night fireman. (2) Less fuel is consumed. (3) Proper 

 conditions of moisture are maintained with less difficulty. 

 Other advantages are often stated, but the foregoing are 

 the most important. It is not so expensive, however, to 

 install a steam plant nor so troublesome to make repairs. 



185. Pipes and piping. Formerly, 4-inch cast iron pipe 

 was used extensively and rust joints were in common 

 use. Wrought iron pipe is now generally employed, and 

 it is always threaded an advantage that makes installa- 

 tion more rapid and provides joints which are not so 

 likely to leak. Most frequently iy 2 and 2-inch pipe is 

 used for the coils in hot water heating and i^-inch pipe 

 for steam heating, connecting with mains of proper size. 

 Whatever the system, the pipe should be placed with the 

 greatest care, observing the principles of the method of 

 heating to be used. 



