MECHANICS AND USEFUL ARTS. 69 



larger divisions of the valve could then be easily lifted. By this con- 

 trivance the mains could be opened and closed by one man. Another 

 object to be accomplished was to arrest the flow of water in case the 

 large pipes with such a pressure upon them should burst and flood the 

 neighborhood. This was successfully effected by introducing into the 

 main pipe a kind of flood-gate, which was opened at a certain angle 

 by the ordinary flow of the water, and at that inclination it held sus- 

 pended, by means of a lever, a heavy weight connected with a throttle- 

 valve. When the rush of water greatly exceeds the ordinary flow, a 

 catch that retains the lever is withdrawn, and the fall of the weight 

 closes the throttle-valve and stops the flow. This self-acting machinery 

 has more than once prevented serious damage that would have arisen 

 from the bursting of the pipes. Another contrivance deserves men- 

 tion. The water in the reservoirs is generally beautifully clear, but 

 during heavy rains it becomes turbid, and would be unfit for the con- 

 sumption of the inhabitants without being filtered. To avoid the 

 inconvenience and expense of filtration, Mr. Moore suggested a plan 

 for separating the turbid water from the clear. A weir was con- 

 structed, over the edge of which during dry weather the water in the 

 reservoir flows perpendicularly into a drain-pipe immediately below, 

 which conveys the clear water to the service reservoir ; but in heavy 

 rains, when the water is turbid, the extra flow shoots it over the first 

 drain into the second, to convey it to the reservoirs that supply water 

 power to the mills. By this simple arrangement the turbid and clear 

 waters are separated, and it is calculated that a saving of 100,OOOZ. has 

 thus been effected. In supplying Manchester with water, a new kind 

 of fire-plug has been adopted, consisting of a gutta-percha spherical 

 valve, which closes the apertures, and when the water is required to 

 escape, an instrument is introduced which forces down the valve. The 

 great water pressure in the pipes forces it so high that there is no 

 necessity for fire engines ; and the effectual manner in which fires are 

 extinguished by the torrent of water that can be thus applied has 

 greatly diminished the cost of insurance in that city. Mr. Bateman 

 stated, that in large establishments the diminished premiums on fire- 

 insurances, produced by the increased facility of extinguishing fires, 

 are sufficient to pay the water-rate. 



WATER METERS. 



Improvements in apparatus for measuring the flow of water and 

 other liquids, have been made by S. R. Wilmot, of New Haven, Conn. 

 The improvements relate to that description of fluid meters, consisting 

 of a piston made to move reciprocally within a cylinder of known 

 capacity, by the admission of the water on opposite sides alternately, and 

 by which the flow of liquid is measured by registering the number of 

 reciprocations of the piston. These kind of meters Avork with great 

 accuracy, and the only objection to their use, is the great amount of 

 friction the piston, when tightly packed, requiring a considerable 

 pressure of water to move it. The object of the new improvements is 



