REPORT ON HYDRAULICS. — PART 11. 441 



ferable to have united all the waters of the Great Rhine into the 

 ancient branch of the Issel, and thus have conducted them by 

 the shortest dii-ection to the sea, because by the union of the 

 waters their rapidity would have been increased, while the am- 

 plitude of the sections would have continued the same, and the 

 evils complained of would have been avoided : he supports his 

 opinion by several examples of the junction of the Mayne and 

 Moselle rivers with the Rhine, without any sensible increase of 

 section in the Rhine before or after the junction ; but, in order 

 to satisfy himself of this apparent anomaly, he caused an 

 artificial river to be constructed at Leyden, in the year 1755, 

 which was supplied with water by means of a vessel, five or six 

 feet in height, and connected by sluices with six other small 

 streams. 



" The bottom of the recipient and of the tributaries had a 

 slope of ysTj '} ^^^ ^^ observed all the variations that occurred 

 either in adding the tributaries or in retrenching their streams." 



The results of these experiments were, that when a stream, 

 equal to half the water in the recipient, was added, and after- 

 Avards another stream equal to another half, the quantities 

 of water in the recipient being successively as 1, 1|, and 2, 

 the height of the water in the recipient was apparently the 

 same, while the velocities and quantities of the fluid in- 

 creased in the same proportion, viz., 1, 1|, 2. Again, when 

 the augmentations to the quantity in the recipient were in the 

 ratios of 3, 4, 5, 6, and 7, the increase in the height of the water 

 in the recipient was only -^-q, J^, ■^■^, -^^f and ^, respectively. 

 By a contrary proceeding he let off the six tributary streams 

 successively, and found the diminution of the height of the wa- 

 ter in the recipient to prevail in the same proportion as the 

 augmentations. 



Having witnessed these apparent anomalies in the junction of 

 rivers, it occurred to me to repeat the experiments of Gennet^ ; 

 and having provided a suitable apparatus, consisting of a wooden 

 trough ten feet in length, and six inches in width and eight inches 

 in depth, together with troughs of similar dimensions let into 

 the sides of the inner trough at angles of 30 degrees, and fur- 

 nished with suitable openings and valves, I caused one and two 

 streams respectively of water to be let into the main stream 

 from equal apertures and under equal and constant pressures, 

 from a cistern of two feet internal dimensions every way, and the 

 following Table shows the results : 



