664 



SCIENCE 



[N. S. Vol. XXVII. N&. 



asphaltum varnisli screen it was found that 

 the quality of coronal and solar radiation 

 transmitted by glass differed little in relative 

 proportion of visible and infra-red rays. From 

 this and other observed facts it was inferred 

 that the coronal radiation may probably be 

 mostly reflected sun rays. The absence of 

 Fraunhofer lines in light of the inner corona 

 was attributed to the bright line spectrum of 

 hot gases in the corona superposed on the 

 spectrum of reflection. 



In the discussion that followed Mr. Abbot's 

 address, Professor Frank H. Bigelow reviewed 

 the difficulties of determining the solar con- 

 stant and Professor C. F. Marvin remarked 

 upon the great ingenuity and skill shown dur- 

 ing this investigation in devising instnunents 

 and making observations in a difficult field. 



Mr. J. F. Hayford expressed his ardent 

 admiration of the research presented in Mr. 

 Abbot's address and stated that as he had 

 heard of the research during its progress and 

 read the proof of the complete paper of which 

 his address is an abridgement his view-point 

 was intermediate between that of the expert- 

 Mr. Abbot — and that of the audience. 



According to Mr. Hayford the grand tactics 

 of this research are especially admirable. 

 They involve broad principles, skilfully ap- 

 plied, which are of general importance in any 

 line of scientific research. 



This has been a long investigation, extend- 

 ing over a series of years. The judgment of 

 the investigator has had time to become 

 mature. 



The investigator has been wise in extending 

 the effective period of his investigation back- 

 ward by utilizing the work of those who came 

 before him, by being careful to supplement 

 their work rather than to supersede it. Sim- 

 ilarly, he has greatly increased the forces 

 brought to bear upon the problem by supple- 

 menting, rather than by attempting to super- 

 sede or to repeat, the work of contemporaries. 



Mr. Abbot has evidently been keen and skil- 

 ful in his search for the lines of least resist- 

 ance, along which greatest progress may be 

 made for a given expenditure of energy. His 

 reward has been the unusual progress made. 



These are some of the reasons for confidence 



in this research, for confidence that its only 

 weak points are those pointed out by Mr. 

 Abbot by cautious wording in the formal 

 printed report. 



It may be well to emphasize certain ideas, 

 developed in this investigation, which help 

 one to see the earth in proper perspective. 



" The true radiating surface of the earth as 

 a planet is chiefly the water vapor of the at- 

 mosphere at an elevation of 4,000 meters or 

 more above the sea level." In other words, 

 the man in the moon, when he looks at the 

 earth, is, in general, blinded to the small con- 

 trasts in color on the surface of the earth by 

 the light which comes to him from the air 

 and its contents. He secures but fleeting 

 glimpses of the outlines of the continents. 



The layer of air 13,000 feet thick, with its 

 load of other material, including water, is a 

 great blanket of peculiar kind such that it 

 allows the sun's radiation to penetrate down- 

 ward through it more readily than it allows 

 the radiation to return upward in the some- 

 what changed form in which it then exists. 

 The result is that, while the radiating layer 

 has a temperature of about — 10° C. the sur- 

 face of the earth is maintained at about 14° 0. 



It seems to be conclusively proved that the 

 amount of the radiation sent to us from the 

 sun varies 5 per cent, in each direction from 

 its mean value. The variation is irregular, 

 not periodic, and the intervals of marked ex- 

 cess or defect are only a few days or a few 

 weeks, as a rule. 



It was hoped, at the beginning of this in- 

 vestigation, that it might lead to the discovery 

 of means of forecasting climatic conditions 

 for some time in advance. The investigation 

 shows that the 5 per cent, variation in the 

 radiation produces only about 1° C. change in 

 temperature at favorable inland stations and 

 a fraction of a degree only at island and coast 

 stations. This direct effect is, therefore, very- 

 small. J. S. DiLLER, 



Recording Secretary 



DISCUSSION a:n3 correspondence 



WILD JAMAICA COTTON 



To THE Editor op Science : I send you here- 

 with a letter from Dr. N. L. Britton, who is- 



