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SCIENCE 



[N. S. Vol. XXVII. No. 691 



period is ill marked or wanting. These meth.- 

 ods are then applied to the determination of 

 the relation of changes in temperature to the 

 sun-spot period, the synodic period, and to 

 several others. 



Koppen, from a study of meteorological 

 observations in various regions of the globe, 

 made from 1767 to 1877, arrived at the con- 

 clusion that the temperature of the tropical 

 regions was lower by 0°.7 C. near the time of 

 maximum sun-spots than near the time of 

 minimum. Briickner has more recently shown 

 some evidence of a period of thirty-five years 

 in meteorological phenomena, including tem- 

 perature. 



Professor Newcomb arrives at the following 

 conclusions : " The reality of the 11-year 

 fluctuations seems to be placed beyond serious 

 doubt, the amplitude being several times its 

 probable error." But, " Its amount is too 

 small to produce any important direct effect 

 upon meteorological phenomena." The fluc- 

 tuation is about one half that found by Kop- 

 pen, or less than half a degree Fahrenheit. 

 The reality of the 35-year period was not 

 established. 



The above results were obtained by the use 

 of annual mean departures. From a study of 

 monthly mean departures the conclusion is 

 reached that " The evidence is rather weak in 

 favor of very minute fluctuations in the sun's 

 radiation for periods greater than one month 

 and less than several years. If they esist, 

 they are too small to produce any noticeable 

 meteorological effect." The most probable 

 period of these possible fluctuations is about 

 sis years. " Apart from this regular fluctua- 

 tion with the solar spots, and this possible 

 more, or less irregular fluctuation in a period 

 of a few years, the sun's radiation is subject 

 to no change sufficient to produce any meas- 

 urahle effect upon terrestrial temperatures." 

 Ten-day and five-day departures were also 

 studied. " There is a certain suspicion, but 

 no conclusive evidence, of a tendency in the 

 terrestrial temperature to fluctuate in a period 

 corresponding to that of the sun's synodic 

 rotation. If the fluctuations are real they 

 affect our temperatures only a small fraction 

 of one tenth of a degree." 



These results obtained by Newcomb are in 

 direct opposition to results obtained by Lang- 

 ley and published in the Astrophysical Jour- 

 nal for June, 1904. Langley's bolometer ob- 

 sei-vations appeared to show that early in 1903 

 a marked diminution in the solar radiation 

 took place, amounting perhaps to about ten 

 per cent. The bolometer results appeared to 

 be confirmed by synchronous temperature ob- 

 servations at widely different stations. If 

 Newcomb's results are accepted as conclusive, 

 it follows that the bolometer as well as the 

 temperature observations which Langley used 

 were influenced by terrestrial causes, though 

 this, in the case of the bolometer, was guarded 

 against with extreme care. This seems the 

 more probable since several of the meteorolog- 

 ical stations which were used by Langley in 

 verifying his results were in high latitudes, 

 rather than in low latitudes, where any 

 changes in the solar radiation would be most 

 felt. At such stations during that year only 

 small changes of temperature appear to have 

 taken place. 



THE RETURN OF HALLEY's COMET 



An event of extreme interest, not only to 

 astronomers, but to the world at large, will 

 soon take place. This is the return of the 

 periodic comet made famous by the genius of 

 Halley. 



Before Halley's time comets had been re- 

 garded as chance visitors to our solar system, 

 except when they were looked upon as special 

 messengers of divine wrath. Newton, how- 

 ever, showed that comets were subject to the 

 law of gravitation. By mapping the paths of 

 many comets, Halley found that three of them 

 apparently had the same orbit, that is, they 

 were different apparitions of the same object. 

 He observed this comet in 1682 and predicted 

 its return again after 76 years. He knew 

 that he could not live to witness the event, and 

 his words concerning it are rightly famous : 

 " If it should return according to our predic- 

 tions, about the year 1758, impartial posterity 

 will not refuse to acknowledge that this was 

 first discovered by an Englishman." It re- 

 turned in March, 1759, a few months later 

 than Halley expected, and only seventeen years 



