161 



2. Notice of ExperimeiUal Researches into the Laws of cer- 

 tain Hydrodynaniical Phenomena that have not hitherto 

 been reduced into Conformity with known Laws. By 

 John Scott Russell, Esq. Lecturer on Natural Philoso- 



Tliis Paper contained the results of researches in hydrodyna- 

 mics extending over a period of two years, and whicli the author is 

 continuing to prosecute under the auspices of the British Associa- 

 tion in conjunction with Mr Robison, the Secretary of this So- 

 ciety. The present paper contained the development of two new 

 laws in hydrodynamics, which appeared of sufficient importance to 

 form a paper hy themselves. 



These two laws are, 



1. The Law of Emergence— as an Element of Resistance. 



2. The Law of the Wave — as an Element of Resistance. 

 The state of our knowledge in hydrodynamics is well known to 



be very imperfect in comparison with the other departments of Na- 

 tural Philosophy. Mr Challis, in his Report to the British Asso- 

 ciation on the present state of hydrodynamics, remarks, that his 

 review may serve to shew that this department of science is in an 

 extremely imperfect state, and that possibly it may on that account 

 be the more likely to receive improvement ; and he adds, that a sin- 

 gular fact relating to the resistance of bodies, partly immersed in 

 water, has been observed, riz. that a boat drawn on a canal with a 

 velocity of more than four or five miles an hour rises perceptibly 

 out of the water, making the resistance less than if no such eflFect 

 took place ; and he further observes, that though theory never pre- 

 dicted any thing of that kind, it may probably soon be able to ac- 

 count for it on known mechanical principles. Professor VVhewell 

 makes the same avowal, and the Institute of France have made it 

 the subject of their prize for three years without having obtained a 

 solution of the difficulties with which this part of Natural Philoso- 

 phy is beset. 



There is one law well established by the labours of Newton, 

 Bernoulli, Eider, D'Alembert, and tlieir followers, that the resist- 

 ance of a fluid to a body moving in it is proportioned to the squai'e 

 of the velocity. 



Tliis law holds in a-arreat variety of instances, for vessels or ob- 



O • 



jects wholly immersed in the fluid. 



