T II E 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



JANUARY 1851. 



I. On the Motion of Fluids. By G. Magnus, Professor of Na- 

 tural Philosopky in the University of Berlin*. 

 [With a Plate.] 

 1. A LTHOUGH the empire of physics is daily expanded by 

 •'^ the experimental investigations conducted upon all sides, 

 still our knowledge regarding the motion of fluids is up to the 

 present time very imperfect, and there is almost a total want of 

 investigations calculated to enlighten us in this department of sci- 

 entific inquiry. The cause of this is certainly not a lack of interest 

 as regards the subject itself; but the difficulties which lie in the 

 way of such investigations are so considerable, as to leave little 

 hope of a favourable result. These difficulties are in part owing 

 to the magnitude of the necessary apparatus, and the unpleasant- 

 ness of operating with large masses of water ; but chiefly to the 

 total absence of proper methods of carrying out observations or 

 even measurements in connexion with this subject. These con- 

 siderations will perha])s obtain for the following experiments a 

 more favourable judgement. 



2. As far as I know, Veuturi was the first to assert that in 

 the motion of fluids a lateral communication of the motion takes 

 place ; at least he is to be regarded as the first who sought to 

 establish an experimental basis for this view, which has since 

 been favoured with manifold recognition. There are two expe- 

 riments cited at the commencement of his memoir, Recherches 

 cxperimentales sur le principe cle la Communication luttrale du 

 Mouvement dans les Fluides, which form the real supports of his 

 opinion. He there asserts, that if any very mobile body be caused 

 to approach a jet of water, the body will be carried forward by 

 the air to which a motion has been imparted by the jet. I have 



* Translated from the Transactions of the Royal Acudciuy of Sciences of 

 Berlin for 1H4H. 



PhU, Mar/, S, 4. Vol. 1, No. 1. Jan, 1851. B 



