220 THE RAINBOW 



in a mixed shower of water and paraffin, or water and 

 turpentine, the smaller and more luminous circle of 

 the latter would be seen within the larger circle of 

 the former. The result was exactly in accordance 

 with this anticipation. Beginning with water and 

 producing its two bows, then allowing the turpentine 

 to shower down and mingle with the water within 

 the large and beautifully-coloured water-wheel the 

 more richly-coloured circle of the turpentine makes its 

 appearance. Or beginning with turpentine and form- 

 ing its concentrated iris ; on turning on the water- 

 spray, though to the eye the shower seems absolutely 

 homogeneous, its true character is instantly declared by 

 the flashing out of the larger concentric aqueous bow. 

 The water primary is accompanied by its secondary 

 close at hand. Associated, moreover, with all the bows, 

 primary and secondary, are the supernumeraries which 

 belong to them ; and a more superb experimental illus- 

 tration of optical principles it would be hardly possible 

 to witness. It is not the less impressive because ex- 

 tracted from the simple combination of a beam of light 

 and a shower of rain. 



In the * Philosophical Transactions' for 1835 the 

 late Colonel Sykes gave a vivid description of a circular 

 solar rainbow, observed by him in India during periods 

 when fogs and mists were prevalent in the chasms of 

 the Grhats of the Deccan. 



'It was during such periods that I had several 

 opportunities of witnessing that singular phenomenon, 

 the circular rainbow, which, from its rareness, is spoken 

 of as a possible occurrence only. The stratum of fog 

 from the Konkun on some occasions rose somewhat 

 above the level of the top of a precipice .forming the 

 north-west scarp of the hill-fort of H urreechundurghur, 

 from 2,000 to 3,000 feet perpendicular, without coming 



