Mechanic:, PhyJics, and Gh~rai~try. tested, been found to act very satisfactorily, and that, practically, they could be received as very good efficient machines, both for the water companies and the consumers. It was shown, that there had been at least eleven distinct classes of metres, and probably not less than ten varieties in each class, which could be taken as one hundred and ten distinct inventions. They might be divided into two great classes ;--high pressure metres, i. e., working under

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... the direct pressure of the mains, and delivering the water without any sensible diminution of the pressure ; and low-pressure metres, which receiving the water under pressure, merely delivered it into a cistern, or other receptacle, generally situated at the top of the building to be supplied. The latter class was asserted to be generally the best, especially m those eases where the consumption was large and irregular,--as that of brewers, dyers, bleachers, calico printers, &c. Of this class, Parkinson's was said to register accurately under all circumstances of change of head, and velocity or quantity delivered. The piston, diaphragm, puff-bag, ~nd screw-metres, were then successively described. In reference to Siemens' metre it was asserted, that it was in principle simply a turbine, or a Barker's mill, and that it partook of the errors of those machines, which no superiority of manufacture, or skill in invention, could entirely overcome. It could not register so small a quantity as would not give impulse to the machine. It had also been remarked that in some situations, it was liable to become corroded, which materially lessened the speed, and that, in some instances, the metres had actually been stopped. Explanations were given of the cases of objections to Siemens' metres, and the question was announced to be further treated on a future occasion. ./lstronomlcal Expedition to the Peak of Teneriff'e.*