THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



FEBRUARY 185Q. 



XI. Hydraulic Researches^. By G. MAGNUsf. 



[With Two Plates.] 



1. TT^EW subjects in physics have been so much experimented 



JL upon as the efflux of water from apertures made either in 

 the bottom or in the sides of vessels. A glance at these nume- 

 rous researches is sufficient to show that their object is for the 

 most part a practical one, — the determination of the coefficients 

 of efflux. Eevv have hitherto attempted to discover the physical 

 conditions which give rise to the remarkable forms of water-jets 

 issuing from differently formed apertures. This is the more 

 remarkable, seeing that the phsenomena in question are of daily 

 occurrence ; and we might have expected that the desire of un- 

 derstanding these phsenomena would have, before this, suggested 

 experiments calculated to explain them. Whilst the mysterious 

 phsenomena of electricity and the delicate phsenomena of optics 

 have been examined on every side and reduced to simple prin- 

 ciples, the phsenomena attendant upon the efflux of liquids 

 not only lack explanation, but have not been even accurately 

 observed. 



2. The remarkable forms of liquid jets have often been de- 

 scribed, particularly in the second half of the foregoing century 

 by Michelotti, who, howevei-, mentions them but briefly in his 

 Sperimenti idraulici. Eitelwein has added to the German trans- 

 lation of this work, by Prof. Zimmermann (Berlin, 1808), several 

 faithful drawings of these jets, without, however, entering upon 

 their cause. George Bidone has published the most complete 



* These investigations form a continuation of the Author's paper ' On 

 the Motion of Fhiids,' which appeared in the Phil. Mag. for January 1861. 

 t From PoggendorfF's Ann. der Ph. und Chem. 1855, vol. xcv. 



Phil. Mag. S. 4. Vol. 11. No. 70. Feb. 1856. H 



