January 13, 192 1 J 



NATURE 



631 



disturbances visible on the surface of the sun, including 

 spots and facula: to be recorded on a diagram of the 

 sun's surface and transmitted to the Meteorological 

 Office for the purpose of comparing them with the 

 observations of solar radiation received frorn the 

 Smithsonian Solar Observatory at Calama, Chile. 



The observations at first consisted chiefly of a 

 record of sun-spots, and although the time is short 

 the relation seems so apparent as to be worthy of 

 record. The records have been arranged in three 

 series, two of which are practically independent of 

 each other and the third partly so. 



The first series was derived from seven groups of 

 sun-spots by taking the day of their first apoearance 

 on the east edge of the sun three days before and 

 five days after, and obtaining the average values ob- 

 •served of solar radiation on these days in calories per 

 square centimetre. 



The second series was derived from six groups of 

 sun-spots by takinir out the mean solar radiation on 

 the last dav of visibilitv and for five days preceding 

 and three days following. 



The third series was derived from seven series of 

 spots bv taking the mean solar values on the days the 

 spots crossed the solar meridian and for eight days 

 preceding and eight days following. 



The results are shown in the following table : 



\tean Radiation I'alues for Different Positions of 

 Sun-spots. 



East Fir*l 

 (1) Day* before- edKe. «en. t>ayf after. 



stoi«3456 

 Radiation 40 J4 45 55 S' 4« 37 47 39 



Ijisl West 

 Ij) Days before. teen. edge. Days after. 



654321011 

 Radiation 46 45 35 30 41 50 54 40 38 

 Meri- 

 ' I )ays before. dian Days after. 



876543J'«'»t45«7' 

 4> 3« 40 49 41 48 33 46 44 45 35 47 40 49 4« 40 38 



The mean solar radiation vplue is formed by adding 

 iqoo to the values given in the table. 



.\s the spots are rarely seen exactly on the edge of 

 the sun, the day on which they are first seen is 

 numbered I, and the day before is numbered o; also, 

 *hrn last seen the day is numbered i, and the day 

 after o. 



The mean solar values during the interval covered 

 by the observations is 1-943, "o 'hat on the day when 

 the spots were first seen the radiation averaged 0012 

 caloric above normal, and when last seen 0-007 

 calorie above, or in the mean about } per cent, of the 

 solar r.-idiation. 



There was one day common to the two series 

 when spots were visible on both edges of the sun at 

 the ends of n diameter passing through the sun'« 

 centre, or, in other words, on a >jreat circle .nbout 

 180" apart. On this day the solar radiation value 

 was I <>6o, or more than i per cent, above normal. 



The grouping around the central passage of the 

 spots does not bring out the relation so distinctly, 

 although higher values are found five days before and 

 five days after the passage across the meridian, the 

 lowest values being found two davs before and two 

 davs after the central position. If one takes the 

 mean of the five days about the centre, including two 

 dav<> b«-fore and two davs after the central passacre, 

 a value of i-04t i» obtained, which is slichtly below 

 the normal value, as if some absorDtion of heat 

 resulted from the central passage of the spots. 



These results have an interest in connection with 

 the fact that Dr. .^bbot found a decrease in the con- 

 trast of brightness between the edce and centre of 

 the sun coincitling with short. prrio<l increase of solar 

 radiation (Smithsonian Miscellaneous Collections, 

 vr>|. Ixvi., No. 5). Both these results ran, I think, be 



VO. 2672, VOL. T06I 



explained in the same way. It is well known that 

 solar faculae and solar eruptions surround regions 

 where spots are numerous. 



These eruptions when seen near the edge of the 

 sun tend to decrease solar contrast and to increase 

 the total solar radiation. On the other hand, when 

 they are near the centre of the sun they are seen 

 directly above the hotter gases from which radiation is 

 coming vertically through the sun's atmosphere, and 

 hence is not greatly absorbed. 



The cooler gases within the spots may even absorb 

 more of this radiation than is made up for by the 

 increased radiation of the faculae in the outer atmo- 

 sphere. 



The results, if confirmed by more extended ob- 

 servations, will also have an important meteorological 

 bearing. Numerous investigators like Loomis, Veeder, 

 .Vctowski, and Huntington have found evidences of 

 increased solar influences on the earth's atmosphere 

 when the solar spots were near the edge of the sun. 

 E. Huntington especially has made an extensive in- 

 vestigation of the position of the solar spots as related 

 to the storminess in the North .-Xtlantic, and has found 

 that the most marked effects are shown when the 

 spots .ire near the edjje of the sun, and hence 

 when there is probably increased solar radiation 

 (Monthlv Weather Review, U.S.A. Weather Bureau, 

 March-June, i<)i8). H. H. Clayton. 



Buenos .Mres, November 6. 



Odours Caused by Attrition. 



TiiK unpleasant odour which attends the attrition 

 of pebbles, etc., appears to have been noticed at a 

 much earlier date than any mentioned by previou.s 

 correspondents. Robert Boyle ("The Efficacy of 

 Languid Motion," Works, edited by Boulton, 1699, 

 vol. i., p. 234) remarks: ".And that it may further 

 appear, that a peculiar Modification of Motion, mav 

 contribute to the various Effects produced by it, 1 

 shall observe, That those Stones which Italian Glass- 

 men make use of [quartz?], afford Sparks of Fire by 

 Collision; but if moderately rubb'd together, they 

 emit foetid Exhalations ; from whence probablv pro- 

 ceed those offensive Steams, emitted by Glass; and 

 what is more remarkable, and to our purpose is, the' 

 Glass w-hen Red-hot emits no such Effluvia ; yet if 

 two pieces be dextrously rubb'd togetner, they will 

 send forth Steams copious enough and foetid." 



!t seems to me that there are at least two sugges- 

 tions not brought forward by previous corresponaents 

 in Natl'RE contained in Boyle's observations, both of 

 which might well be followed up experimentally. The 

 implicit explanation of the cause of smell is also of 

 some interest. J. R. Partington. 



Lostock Gralam, Cheshire. 



The Energy of Cyclones. 



I sHAi.i. be glad if vou will allow me to refer briefly 

 to the objection Mr. \\'. H. Dines raises to my theory 

 of cyclones (Naturk, December 23, p. 534). Mr. 

 Dines remarks that if " cyclones are caused by an 

 access of warmth in the stratiwphere . . . the tropo- 

 sphere ought to bulge upwaras over the cyclone, 

 whereas, in fact, it bulges downwards." My view is 

 that where the stratosphere is warmest it must be 

 thickest, and the troposphere must be thin. As the 

 warmest portions of the stratosphere are at cyclonic 

 centres, the lower boundary of the stratosphere must 

 bulge downwards over such areas and the troposphere 

 be correspondingly thin. I assume that the heat of 

 the stratosphere passes downwards so rapidly that 

 the slowly rising air cannot maintain the troposphere 

 at its normal thickness. R. M. Dkri fv. 



Tintagil, Krw Gardens Road, Kew, Surrey, 

 December 24. 



