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POPULAR SCIENCE MONTHLY. 



This base may be either a flat of an eroded 

 elevated reef or of a similar substructure of 

 volcanic rocks, the nature of that base de- 

 pending absolutely upon its character when 

 elevated in a former period to a greater 

 height than it now occupies. . . . The Fijis 

 are not situated, as was supposed, in an area 

 of subsidence, but on the contrary, they are 

 in an area of elevation, so that the theory 

 of Darwin and Dana is not applicable to the 

 islands and atolls of the Fiji group." As it 

 was a study of these and similar groups 

 which led Darwin and Dana to adopt their 

 theory of subsidence, Mr. Agassiz seems to 

 dispose of the theory as applied to any 

 islands, although he says in a later para- 

 graph, " The great variety of causes which 

 have been active in shaping the present 

 physiognomy of the reefs and atolls of Fiji 

 shows the impossibility of assigning any one 

 factor ... as the single cause for the forma- 

 tion of the many different kinds of atolls 

 and barrier-reef islands to be found in the 

 Fiji group." Mr. Agassiz promises a fully 

 illustrated report some time during the com- 

 ing summer. 



New Theories regarding the Rainbow. — 



The old theory of the rainbow, which is still 

 found in optical text-books, only imperfectly 

 accounts for the true bow and fails entirely 

 to explain the "spurious bows" which often 

 accompany the former. It is usually possi- 

 ble by close examination to distinguish cer- 

 tain colors on the inside edge of the primary 

 which are not consistent with the simple 

 series of spectrum colors, accounted for by 

 the Descartes theory. In a paper on The In- 

 tensity of Light in the Neighborhood of a 

 Caustic, Airy seems to have laid the founda- 

 tion for an adequate theory of the rainbow. 

 Au article in Nature on this subject says that 

 Mr. J. M. Pernter is working out the new 

 theory, and his general conclusions are given 

 as follows : " The greater the drops the more 

 spurious bows." A chief bow of intense 

 pink and green (hardly any blue) indicates 

 drops of diameters ranging from one to two 

 millimetres ; intense red always speaks for 

 big drops. Secondaries (spurious bows) of 

 green and violet (the blue is marked by con- 

 trast) without yellow, immediately forming the 

 chief bow, correspond to drops of 0.5 milli- 

 metre, while five and more secondaries with- 



out white and without breaks mark drops of 

 0.1 millimetre. A partly white bow is pro- 

 duced by drops of 0.06 millimetre, and 

 when the drops are still smaller, a real white 

 bow with orange-yellow and blue margins is 

 the result. The net result of these elabo- 

 rate investigations will be to add a new in- 

 terest to a natural phenomenon already en- 

 dowed with many associations of magic and 

 beauty." 



The Recent Total Eclipse of the Sun. — 



While there have been no complete reports 

 from any of the observation parties of the 

 total eclipse of the sun of Saturday, Janu- 

 ary 22, 1898, enough information has been 

 received to indicate that the majority of 

 them were successful and that much data of 

 extreme scientific value has been obtained. 

 The only district in which the weather was 

 not propitious seems to have been southern 

 Russia, only a few good photographs being 

 obtained. A telegram received from the 

 Rev. J. M. Bacon, in charge of the British 

 Astronomical Association at Buxar, an- 

 nounces perfect weather and " observations 

 satisfactory all round." This party is re- 

 ported to have taken a successful series of 

 cinematograph pictures. The party located 

 at Jeur, from the Lick Observatory, under 

 the direction of Prof. W. D. Campbell, re- 

 ports very successful observations. The 

 unusually favorable weather, the number of 

 trained observers on the ground, and the 

 delicate and powerful instruments at hand, 

 have evidently combined to make this one 

 of the most important scientific events in 

 the closing years of the century. In calling 

 attention to this fact Nature says : " With 

 such a list of successes we may safely say 

 that this eclipse, as befitting the last one of 

 the century, has surpassed all previous rec- 

 ords; but, unlike many eclipses at the be- 

 ginning of the century, it can not be truly 

 said that the event of Saturday was over at 

 the end of two minutes of totality. To many 

 the eclipse has yet to begin and will last for 

 many months, during which time each line 

 in the spectrum, each streamer of the coro- 

 na, each prominence on the sun, will be an- 

 alyzed little by little to discover if we have 

 similar streamers in other coronas or identi- 

 cal lines in our laboratories. It may be con- 

 fidently expected that the results obtained 



