^IaY 2, I918] 



NATURE 



169 



More than one independent line of argument will 

 be found to point to the conclusion that in a 

 period of two thousand years there has been no 

 appreciable change of climate. Therefore the 

 balance of the heat exchanges between the earth's 

 income from the solar radiation and its expendi- 

 ture in terrestrial radiation into space may be re- 

 garded as only fluctuating between narrow limits. 

 Eighty per cent, of the solar radiation fails to 

 reach the earth's surface through its protecting 

 envelopes, and 90 per cent, of the terrestrial radia- 

 tion fails to escape. Such is the beneficent effect 

 of our atmosphere, for want of which the tem- 

 perature of the moon's surface, as proved by 

 actual observation, falls during the short period 

 of a lunar eclipse many times as far as does that 

 of any part of the earth between day and night. 

 In most places on the earth the surface air tem- 

 perature rarely varies as much as i per cent, 

 from day to day, but the variation between day 

 and night is affected by the character of the sur- 

 face, Timbuktu, in the Sahara desert, having 

 twice the daily and four times the annual change 

 of temperature at Port au Prince, Haiti, in approxi- 

 mately the same latitude. 



Prof. Abbot considers that a slow increase of 

 I per cent, in solar radiation should produce a 

 change of i per cent, in terrestrial radiation, and 

 on the assumption that this varies as the fourth 

 power of the absolute temperature, he finds this 

 to be equivalent to a change of 0*7° C. for each 

 unit per cent, of change of the solar radiation. 

 The annual change of mean temperature at Tim- 

 buktu on this account should be 24° C, but is 

 actually only 13-6° C. From this Prof. Abbot 

 concludes that the annual variation (due to the 

 sun's changing altitude) is not slow enough to 

 produce its full effect, and suggests that the 

 variation in the period of the sun-spot cycle may 

 be more effective. 



Dr. G. T. Walker finds in general a lower 

 temperature at sun-spot maximum, and this is 

 confirmed numerically. Koppen, for instance, 

 finds at sun-spot maximum an average decrease 

 of 07° C. for the period 1815-73, and of 

 05° C, for the period 1873-1910, when the 

 maxima were, on the average, less intense. This 

 apparent paradox is tentatively attributed to 

 increased cloudiness, possibly due to greater pene- 

 trative power of the solar ions. Prof. Abbot's 

 short-period fluctuations in the solar radiation 

 provide another line of approach to the elucida- 

 tion of the problem, and Dr. Clayton, of Argen- 

 tina, has applied the method of correlation, for 

 about *fifty well-distributed stations, between 

 Mount Wilson solar constant values and local 

 changes of temperature for the few following 

 days, obtaining in some cases significant co- 

 efficients. Thus an increase of solar radiation 

 was followed by an increase of temperature at 

 Pilar, Argentina, with its maximum one or two 

 days late, and by a decrease at San Diego, Cali- 

 fornia, with its maximum three or four days late. 

 In the temperate zones, roughly speaking, the 

 correlation is negative, and elsewhere positive, 

 NO. 2531, VOL. lOl] 



but the tropical belt of positive correlation is nar- 

 rower over the oceans. The amount of the change 

 found by Dr. Clayton is several times larger than 

 Prof. Abbot's reasoning led him to expect. He 

 therefore concludes that the results require con- 

 firmation, but that they indicate secondary pro- 

 cesses set going in the atmosphere by changes in 

 solar radiation, and that the effect on winds, 

 cloudiness, and precipitation may be revealed. He 

 infers that as the changes in the sun are followed 

 by changes of similar magnitude on the earth, with 

 a lag depending on latitude, these changes could 

 be predicted if we can secure daily observation of 

 the solar emission. For this purpose new observ- 

 ing stations in cloudless regions are required, and 

 considerations of expense will probably defer this 

 until after the war. Prof. Abbot hints finally that 

 a bequest of half a million dollars would enable 

 the Smithsonian Institution to handle the 

 problem adequately. W. W. B. 



ANTI-VIVISECTIONISTS AND PROTEC- 

 TIVE MEDICINE IN THE ARMY. 

 IT is wonderful to what follies anti-vivisection 

 will betray those who believe in it. The 

 American Red Cross has been involved in a law- 

 suit by some of the American anti-vivisectionists, 

 who are endeavouring to prevent it from doing 

 medical research on active service. This research 

 would be, almost all of it, bacteriological ; it would 

 be inoculations of small rodents in the direct 

 course of the work of the Red Cross for the Army ; 

 but the anti-vivisectionists seem to care more for 

 the rodents than for the Army. Dr. W. W. Keen, 

 of Philadelphia, one of the very foremost of 

 American surgeons, whose name is well known 

 among our own physicians and surgeons, 

 has written an admirable article in Science 

 of February 22 last on this attempt to inter- 

 fere with the work of the Red Cross. He 

 tells again some of the oft-told truths : the facts 

 of the protective treatment against typhoid, of the 

 protective treatment against tetanus, of the results 

 of Lister's work, and so forth. He points out 

 that the anti-vivisectionists in his country all these 

 many years have done nothing, absolutely nothing, 

 to lessen disease or to save life either in animals 

 or in man ; and he quotes the statement made by 

 forty-one American medical officers on active 

 service in France : " We feel that anyone enr 

 deavouring to stop the Red Cross from assisting 

 in its humanitarian and humane desire to prevent 

 American soldiers from being diseased, and pro- 

 tecting them by solving" the peculiar new problems 

 of disease with which the Army is confronted, is 

 in reality giving aid and comfort to the enemy." 



This article by Dr. Keen is well worth study- 

 ing ; but some anti-vivisectionists are blind and 

 cruel; and it is not possible to reason with them, 

 any more than Antonio could argue with Shylock. 

 The fact is that the anti-vivisectionists, since the 

 War, have been rather out of work ; and, as Dr. 

 Watts says, " Satan finds some mischief still for 

 idle hands to do." 



Over here they have done, since 1914, very 



