80 Progress of Invention. 



to cease to circulate round an electro magnet; and that a 

 stretched membrane will vibrate in unison with a note produced 

 near it. But, since the same membrane will respond only to 

 certain notes, the range of sounds producible by a single appa- 

 ratus is more or less circumscribed. It is proposed to apply 



to practical purposes the enormous water power which will soon 

 be available in Paris, in consequence of the vast waterworks 

 now in progress there, and which, when complete, will raise about 

 400,000,000 litres a day to the level of the highest houses. The 

 large amount of pressure generated by this will be distributed 

 throughout the city, so as to be easily applicable by means of simple 



machinery at any given point. A steam and air engine has been 



recently patented. The cylinder used, like that of Watt's single 

 acting steam-engine, is open at one end. Round the part of it which 

 is near the open end are a great number of holes, which, when the 

 piston has passed them, forms a communication between the interior 

 and the atmosphere, and allows the mixture of steam and air after 

 it has done its work, to escape. At the return stroke of the piston 

 air enters in front of it through these apertures, and is driven into 

 a small chamber at the closed end of the cylinder, where, being 

 mixed with high pressure steam admitted by a valve opened at the 

 proper time by the piston itself, its temperature and therefore its 

 pressure are suddenly raised ; and along with the expanding steam 

 associated with it, it drives the piston to the open end of the cylinder. 

 The repetition of these movements causes a reciprocating motion, 

 which is changed into a rotatory, in the usual way. Independently 

 of other objections the heat and pressure acquired by the air are 

 detracted from those of the steam, and what is thus gained in one 



way, may be found to be so much lost in another. There is reason 



to believe that telegraph wires may be made to serve a useful 

 purpose, not hitherto contemplated : since it is supposed that they 

 will afford a very effective aid in foretelling changes of weather. It 

 has long been remarked that they are liable to considerable variation 

 in the transmission of the electric currents : but it has been recently 

 observed that when these variations are unusually great they are 

 always followed by bad weather, which is stormy in proportion to 



the greatness of the irregularities exhibited. The metal caesium has 



hitherto been obtained only in very small quantities. To get only 

 seven grains of its chloride Bunsen was obliged to evaporate forty 

 tons of water ; and only - 3 per cent, of it are contained in the Lepi- 

 dolite of Hebron in the United States. But it has recently been 

 found that the mineral Pollux, which is very abundant in the island 

 of Elba, contains thirty-four per cent, of this metal, which had been 



previously mistaken for potassium. Tellurium also, hitherto one of 



the rarest of substances, is found in considerable quantity asso- 

 ciated with bismuth, about 15,000 feet above the level of the sea, 



in one of the loftiest peaks of the Andes. The reduction of chloride 



of aluminium by means of zinc was patented in 1854, but the 

 principle was not successfully carried out until recently. The vapour 

 of zinc is found to reduce cobalt, nickel, and manganese with 

 great facility. Cotton seed oil may be obtained to the amount of 



