72 



Lord Rayleigh on 



[May 15, 



elliptical figure, whose major axis is 22 lines long and minor axis 

 14 lines long. 



D is the section at 24 inches from the orifice. It also is an ellip- 

 tical figure, whose vertical axis is 45 lines long and horizontal axis 

 about 12 lines long. 



In fig. 2, the orifice (A) is an equilateral triangle, with sides 2 

 inches long. The head of water is 6 feet. The vein resolves itself 

 into three flat sheets disposed symmetrically round the axis, the planes 



Fig. 2. 



of the sheets being perpendicular to the sides of the orifice. These 

 sheets are very thin, and retain their transparence and continuity to a 

 distance of 42 inches, reckoned from the orifice. The sections repre- 

 sented by B, C, D, E are taken at distances from the orifice equal 

 respectively to 1 inch, 6 inches, 12 inches, and 24 inches. 



Similarly, a vein issuing from an orifice in the form of a regular 

 polygon, of any number of sides, resolves itself into an equal number 



