44 PROCEEDINGS AT BOARD MEETINGS. 



" 3. A second basin, like the first, and fixed at the same level, should be 

 constructed at the outlet of the siphon, that outlet being at the place thought 

 most suitable for the discharge of the water, whatever may be the distance to 

 be traversed ; this basin we will call the outlet basin. The outlet of the siphon 

 or main pipe should there be fixed, and immersed at the same level as its inlet 

 at the receiving basin. There will be in the upper part of this outlet basin an 

 opening some inches in depth of a size calculated and proportioned to the 

 quantity of water which it will have to discharge. 



" 4. At the highest part of the siphon or pipe there will be a branch of some 

 inches in length, fitted with a strong cock, to which there may be connected a 

 suction pump for making a vacuum in the pipes once for all. 



" 5. The end of the siphon fixed in the outlet basin, before making the 

 vacuum, should be tightly and hermetically closed, so as to prevent the air 

 getting in. The vacuum having been once obtained, the pump will begin to 

 draw water, and then the cock should be shut immediately, and the pump 

 carried away for good. 



" We must then go to the outlet basin, open the pipe, and the water will in- 

 stantly begin to flow. The flow of water will only cease when the land drains 

 shall cease to supply the receiving basin. The flow having ceased, the two 

 basins will remain filled with water at the same level, and the main pipe 

 forming the siphon will remain full of stagnant water by the effect of the 

 atmospheric pressure exercised equally upon the water of the two basins. The 

 water will not again begin to flow of itself except when, in consequence of rain, 

 the drains begin to supply water to the receiving basin, so as to raise the 

 level of the water in it. The two basins should be surrounded by walls, and 

 covered so as to prevent the walls freezing in the winter, and furnished with 

 a grating to protect it from all mishaps. The branch pipe at the summit 

 of the siphon should be equally secured from any unforeseen accident. I do 

 not think I need give more ample details. If you would like to try the 

 experiment, which can take place in any locality, I shall be very glad to 

 place myself at your orders, provided you give me two days' notice, so as to 

 prepare. The expense of that would not exceed five guineas. The experi- 

 ment would be made with cubes of lead arranged with boxes for basins." 



The Secretary stated that he had placed Mons. Borne's letter in the 

 hands of Professor Macquorn Rankine, who had transmitted the following 

 report : — 



" Remarks on Mons. Cretin Borne's proposed method of drainage by means 

 of a Siphon. 



« 



1. There can be no doubt that cases frequently occur in which the method 

 of drainage proposed by M. Cretin Borne, by means of a siphon pipe, would 

 be very useful. It is certain also that the method is quite practicable, and 

 that there would be no serious difficulties in carrying it into effect. 



" 2. It must be observed, however, that it is only when the siphon pipe is 

 very short that its summit can be raised to 28 or 30 feet above the level of 

 the water in the discharge or outlet basin, because of the necessity for 

 making an allowance for the friction in the pipe. The effect of that friction 

 can be calculated by rules to be found in any treatise on hydraulics. 



" 3. It must also be observed that the exhausting pump at the summit of 

 he siphon ought to be kept always ready for use when required, for all water 

 contains air in suspension, and that air disengages itself by degrees when the 

 water is exposed to a diminished pressure ; and there is thus a tendency to 

 the slow and gradual accumulation of air at the summit of a siphon. 



" 4. The method of drainage by means of siphon pipes has already been 

 put in practice in this country on a very large scale, and with perfect success. 

 Annexed is a very brief account of the work referred to, which was executed 

 in 1862. A detailed description by the engineer, John Hawkshaw, Esq., 



