276 THE SCIENTIFIC PAPERS OF 



2. It must not be affected by the pressure of a high column 

 of water upon its working parts. 



3. It must allow the water to pass through without obstructing 

 or at intervals checking the same. 



4. Its working parts must be protected against the effects of 

 mechanical impurities or corrosive agencies in the water, so as to 

 insure its continuous working without frequent attention. 



5. It must be a cheap and compact instrument, adapting itself 

 conveniently and locally to ordinary circumstances. 



6. Its working and registering parts must be inaccessible to 

 the employer, in order to prevent fraud. 



The fulfilment of these conditions might at first sight appear 

 but an easy problem for a skilled mechanician, but the numerous 

 and fruitless attempts that have been made at its solution have 

 proved the real difficulty of the task. In order to combat these 

 difficulties successfully, it is necessary to discriminate between 

 those that are inseparably connected with certain principles of 

 action, and those of mere detail of arrangement, or choice of 

 material. All meters that have hitherto been proposed may be 

 classed under the four following heads, viz. : 



1. Cistern or Bucket Meters. 



2. Piston Meters. 



3. Meters by Area of Channel. 



4. Meters by Impact. 



The intermittent supply system which prevails in London and 

 elsewhere, is indeed a supply by cistern or bucket meter, in its 

 most primitive form. Each house or factory is provided with a 

 cistern capable of holding the necessary supply for a day, or other 

 convenient period of time. The turncock in making his regular 

 rounds fills the cistern?, which are provided each with a separate 

 ball-cock, to prevent their overflowing. 



This mode of supply has been found quite inadequate for large 

 and irregular consumers, but even for private houses it entails so 

 much inconvenience and expense (principally to the consumers) 

 that the legislature has thought fit to interfere, and now insists on 

 a continuous supply. With the continuous supply, the liability 

 to the water being wasted is very much increased, unless a self- 

 registering method is applied. 



Mr. Mead, of London, proposed a registering bucket meter, of 



