Feb. 24, 1888.] 



SCIENTIFIC NEWS. 



173 



its pressure must be sufficiently reduced to produce a 

 sudden upward movement of tlie column of water, and 

 consequently the action of the syphon. 



In consequence of the presence of a certain volume of 



compressed air in the inner chamber a, the rate of efQux 

 of the syphon is very low, and it increases propor- 

 tionately with the external level of the liquid much less 

 rapidly than under ordinary circumstances. Hence, what- 

 ever the supply of water, the tube S will be entirely 

 submerged. This tube is in reality merely an auxiliary 



I'lG. 



syphon, the diameter of which is so small that its auto- 

 matic action is always certain ; it will then almost 

 instantly empty the reservoir R'. As this can only fill 

 again slowly, on account of the narrowness of the tube 

 /, there will be, to fill the vacuum thus caused, a sudden 

 indraught of the air occupying the chambers a and jS 

 through the tubes T T restoring the equilibrium. 



At this moment the jet of water issuing from the 

 auxiliary syphon into the central tube or the main 

 branch of the syphon causes a suction in the 

 chamber /3, and produces in a /3 a pressure 

 decidedly inferior to that of the atmosphere. From 

 this disturbance of equilibrium between the liquid 

 and gaseous layers inside the syphon, there results a 

 sort of small ram-stroke which causes the automatic 

 discharge. The moment the residual air is carried away 



Fig. 3. 



speed 



the syphon discharges a full stream with a 

 depending on the height of the water in the tank. 



This invention is said to be useful for expelling water 

 from sewers, for irrigating meadows, emptying and re- 

 filling fish-ponds and removing water from quarries, etc., 

 provided that there is a lower point of drainage. 



COLOURED WORDS. 



Under this strange name we wish to call attention to 

 certain facts which have only attracted attention very 

 recently, and which are far from being understood. The 

 phenomena in question are certainly not physical, but 

 seem to belong rather to the border-land between phy- 

 siology and psychology. Perhaps they are connected 

 with the mutual reactions of the senses (Scientific News, 

 p. 126), or perhaps they depend simply upon an associa- 

 tion of ideas. 



Put in the briefest form the facts are these : There are 

 persons, and not few, on whose minds sounds — especially 

 musical sounds — and words are so associated with 

 colours that the hearing of the sound suggests the colour, 

 whilst the sight of the colour calls up the sound. 



The words thus visualised are, we believe, chiefly 

 proper names, whether of persons, places, of days or of 

 months. For instance. Professor C. S. Minot (writing in 



