We learn that Messrs. H. N. Hooper & Co., of Boston, Mass., are now manufacturing some of the above instruments for the Water Board of that city, with a view to their experimental employment for the purpose of determining the practicability of measuring the water delivered to each consumer. Last fall the Board made extended experiments with a ( large number of different meters, hut settled upon Niles' patent as the best of any presented. It is said to be very simple in construction, and very accurate in its results. One of its prominent features consists in the employment of a differential piston which operates the valves. We have long been of the opinion that the only way to ptit an end to the present wanton waste of water in our large cities is to charge each consumer a certain tariff for each gallon used. This cannot be done except by the introduction of some instrument like a gas meter, which shall indicate the exact quantity of water drawn off