( 659 ) 



In order to tind the formula {11") for curved wii-es we can put, 

 approximately, for b its value at the point x =: y ^0. 

 So that we may put for 



Sn S 



By this the formula fll") gives 



S /d 



(lib) 



12iid\R^ 



S being equal to the weight hanging at each end. 

 If the angle between the tangents at the ends is 2o, we have 

 other formulae. The equation of the curve becomes 



2« -t^ 



cos — ,v =z e , 



d, 



and the velocity, if F is again the weight at each end 



2aCF 



(III") 



d^sinct 



By the hydrodynamical method the same velocity is found to be 



2aP . . 



(lie) 



P fd\' 

 l^sitia V.-K/ 



\2nndy 



Dr. J. H. Meerburg has made a series of experiments, of which 

 he will communicate the results at a later opportunity. The agree- 

 ment with the theory is not very satisfactory. It must be noticed 

 however that d is very small. The roughness of the surface of the 

 wire will therefore greatly increase the resistance to the motion of 

 the water, so that the result of the hydrodynamical method can no 

 longer be considered as correct. 



Zoology. — "On the Polyandry of Scalpellum Stearnsi" by P. P. 



C. HOEK. 



One of the largest forms of the genus Scalpellum which is so 

 rich in species is Scalpellum Stearnsi, Pilsbry from shallow water 

 near the coast of Japan. 



This species is represented by two varieties or sub-species in the 

 collection of Cirripedes made by the Siboga Expedition in the waters 

 of the Dutch East Indies and handed o\Qr to me for description. Both 

 forms agree in the main with Pilsbry's species — they differ, however, 



