Proceedings, &c, for 1885. 173 



feet per second. He made a new culvert of 370 square feet water- 

 way, and put an end to further floods. 



The effect of a heavy rainfall on the catchment should be 

 noticed. The first effect is to soak the ground. The ultimate 

 absorption is greater in summer than in winter, but averages 

 about -08 inch per hour in the Bendigo Creek country, or say 

 l-10th inch per hour. Mr. Steane found that with a heavy down- 

 pour, after steady rain, took one hour and fifty minutes for rain 

 at the end of the catchment to reach the mouth, so that to get a 

 maximum flood we must have two hours' rainfall. If the rain 

 lasted two hours, we should get a maximum, and then flood would 

 fall ; but if it lasted three hours, we should get maximum, stay 

 there for one hour, and then fall. 



The dimensions of the culverts on the Cootamundra line do not 

 seem to have been fixed with regard to catchment areas at all. 

 There is one of 8 feet at Albury for a catchment of 1 square mile, 

 and in most cases the sizes are excessive. 



25th November, 1885. 



A paper was read by the Secretary on Mr. Claxton Eidler's 

 graphic method of computing the stresses on continuous girders. 



The method is merely a graphical expression of the equation of 

 three moments, and was not new to any of the members present. 

 At the conclusion of the paper there was a discussion on the use 

 of continuous girders. 



Mr. Behrendt pointed out that the English engineers are far 

 behind the Germans in many matters, and particularly in this 

 question of continuity. Twenty years ago a German engineer — ■ 

 Gerber — had solved the difficulty by using overhung girders 

 carrying a central girder between them. 



Professor Kernot remarked that, quite independently of Gerber, 

 Mr. T. W. Fowler had suggested an almost identical arrangement 

 at the meetings of section A. It was also remarked that the 

 American engineers now invariably avoid the use of continuous 

 girders. 



Mr. John Booth read a paper on " Systems of Electric 

 Lighting." 



A system consists of three essential parts — 



1. A dynamo. 



2. A lamp. 



3. Conducting wires. 



Considering, first, the simple incandescent lamp system. In 

 this case we have an electro-motive force, E in the dynamo falling 

 through a resistance R in the dynamo itself, r in the wires, and S 



