THE VACUUM Ul^AlM^K AINJJ 



353 



washing machines, ice cream freezers, grinding wheels, 

 sewing machines, vacuum cleaners, and ironing machines. 

 They are inexpensive for the amount of work they do, 

 and save the strength of the housekeeper for other impor- 

 tant duties. 



The vacuum cleaner and sweeper. The electric 

 vacuum cleaners are of two types. One produces a vacuum 

 by means of an air 

 pump of the piston 

 type, the other by 

 means of a fan. A 

 higher vacuum can 

 be produced with 

 the pump; and yet 

 a very high vacuum 

 is not needed: in 

 fact, it has several 

 disadvantages. A 

 strong vacuum is hard on the rugs and carpets, or any 

 cloth which is being cleaned. 



The principle of vacuum cleaning is easily demonstrated 

 by holding the end of a glass tube near a loose ball of 

 paper (C) and drawing up the piston (A). A vacuum is pro- 

 duced in the tube, and air rushing into the tube pushes the 

 paper along with it. By making the opening (0) smaller 

 by using a stopper with a small tube, sand may be 

 forced into the tube, and if a piece of muslin cloth (m) 

 is fastened over the inside of the stopper near the end of 

 the larger tube, this will hold the sand and dirt which 

 enters, but will allow the air to pass on. This illustrates 

 the use of the bag for holding the dirt in the pump cleaners. 

 In the fan cleaners, however, the dirt and air are blown 



H.-WHIT. CIV. SCI. IN THE HOME 23 



To show the principle of vacuum cleaning. 



