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FOREIGN AND MISCELLANEOUS INTELLIGENCE. 



I. MECHANICAL SCIENCE. 



1. RESISTANCE OPPOSED TO WATER MOVING IN PIPES. 



(U Aubuisson.) 



NOTWITHSTANDING the endeavours made to deduce formulae from ex- 

 periments on the passage of water through tubes, so as to assist and 

 guide the engineer in laying down pipes to supply manufactories 

 or towns, yet frequent mistakes have occurred: thus at Paris, at the 

 Fontaine des Innocens, only two-thirds of the water calculated upon 

 were obtained ; whilst, in the faubourg St. Victor, only the half of that 

 expected issued from the pipes. These differences appear to result 

 from experiments made on too small a scale, or with apertures dis- 

 proportionate to the areas of the tubes ; for the results of practice 

 come sufficiently near to the formulae of MM. Prony and Eytel- 

 wein, when the velocity of motion in a pipe was small in conse- 

 quence of a contracted aperture made in a plate of metal being used. 

 When the contracting plate was altogether removed, then the pro- 

 duct in water was a fourth or third less than that given by the 

 formulae, from which M. D'Aubuisson concludes that the resistance 

 increases with the velocity in a greater ratio than that given to it in 

 the calculations; where it is supposed to increase proportionably as 

 v 9 + m v, m being nearly equal to 0.055, and v representing the 

 mean velocity. 



In consequence of the arrangement and state of the water-pipes 

 at Toulouse, some large and accurate experiments have been made 

 there by MM. Castel and D'Aubuisson, in systems of pipes of 4.7 

 inches and 10.63 inches in diameter, and 1434 and 1986 feet in 

 length. In these experiments the quantity of water passed and the 

 pressure were varied; the results were noted, and also calculated 

 by the formulae, so as to deduce the loss of pressure due to the 

 resistance of the pipes: that by calculation came out 27., 25., 32.7, 

 and 31.7 per cent, below the result of experiment. As the two 

 latter were the principal experiments, it is concluded that, generally, 

 calculation gives the resistance nearly one-third less than what is 

 obtained by actual and careful practice *. 



2. ON THE RESISTANCE OF LEAD TO PRESSURE, AND ON THE 



INFLUENCE OF A SMALL QUANTITY OF OXIDE UPON ITS 

 HARDNESS. 



The recent experiments of Mr. Bevan on the compression of lead f, 

 and his proposal of applying balls of that metal to estimate the force 

 of presses, screws, &c., must be well known to English readers. 



* Annales de Chimie, xliii. p. 224. 

 f Quarterly Journal of Science, N. S., vol. vi.,p. 392. 



