ON THE ACTION OF WAVES AND CURRENTS. 387 



Council of the Owens College for the facilities afforded for conducting the 

 experiments in the Whitworth Engineering Laboratory. 



Having considered the disposal of the apparatus, which has no 

 pecuniary value, the Committee resolved to recommend the Association 

 to place it at the disposal of the Owens College. 



At a second meeting held in the Committee room of Section G at 

 Cardiff the report submitted by Professor Reynolds was adopted. 



0?i Model Estuaries. 

 By Professor Osborne Reynolds, F.B.S., M.Inst.G.E. 



§ I. — Introduction to Report III. 



1. In accordance with the suggestions in the Second Report, read at 

 the Leeds meeting of the British Association, the inyestigation has been 

 continued with a view — 



(1) To obtain further information as to the final condition of 

 equilibrium with long tidal rivers entering the head of a V-shaped 

 estuary. 



(2) To obtain a more complete verification of the value of the criterion 

 of similarity. 



(3) To investigate the effect of tides in the generator diverging from 

 simple harmonic tides. 



(4) To determine the comparative effect of tides varying from spring 

 to neap. 



Opportunity has also been taken : — 



(5) To investigate the effect of prolonging the walls of the river into 

 the estuary through the bar which was below low water, with prolonga- 

 tions reaching up to low water, and others reaching up to half-tide — this 

 being done in both models, so that the similarity of the effects might be 

 seen ; and 



(6) To investigate the effect of rendering the estuaries unsym- 

 metrical by means of large groins, and so to test the laws of similarity 

 obtained in the symmetrical estuaries as applied to unsymmetrical estu- 

 aries. 



2. The two models have been continuously occupied in these investi- 

 gations, when not stopped for surveying or arranging fresh experiments. 

 In this way each of the models has run 600,000 tides, corresponding to 

 840 years. These tides have been distributed over six experiments in the 

 large tank E, and four in the small tank F, in number from 50,000 to 

 250,000. 



3. The experiments have all been conducted on the same system 

 as described in the previous reports. 



All the experiments but one have been made in tanks E and F, with- 

 out further modification ; and in all these land water to the extent of 

 0'5 per cent, of the tidal capacity per tide has been introduced at the top 

 of the river. 



Initially, the sand has been laid to the level of half-tide from Section 

 13 up the river to Section 26 down the estuary. The vertical sand gauges 

 distributed along the middle line of the estuary have been read and 

 recorded each day. Tide curves have been taken at frequent intervals. 

 Contour surveys have been made, generally after 16,000 tides, and again 



c c 2 



