Feb. 26, 1880] 



NATURE 



593 



above and yet have found nothing more about this new 

 species. Has not H. B. Brady's paper, " On some Fora- 

 minifera from the Loochoo Islands" [Proc. R.I.Ac., vol. 

 ii. n.s. p. 589) been overlooked by the recorder or the 

 Protozoa? Perhaps Ross,F. O., "Myology of the Cheetah" 

 (Fclis jiibata), in the same Proceedings, vol. iii. n.s., 

 part 3, August, 1S77, was also worthy of a reference. 

 Uther papers are quoted from these same Proceedings, 

 which it is true contain little that is zoological. Without 

 a wish to start a controversy as to the reproducing the 

 Greek k by the English c, we venture to think that 

 a little discretion might be allowed to authors in this 

 matter. 



In concluding this notice we thank*, in common with all 

 zoologists, the editor for the volume he has published, 

 and we wish a long and prosperous life to the association 

 of which he is the officer, an association which deserves 

 every possible assistance from those interested in the 

 subject of zoology. 



LETTERS TO THE EDITOR 



[The Editor decs not hold himself responsible for opinions expressed 

 by his correspond* nts. .Veil her eon he undertake to return, or 

 to correspond with the writers of, rejected manuscripts. No 

 notice is taken of anonymous communications. 



[The Editor urgently requests correspondents to hap their letters as 

 short as possible. The pressure on his space is so great that it 

 is impossible otherwise to ensure the appearance even of com- 

 munications containing interesting and novel facts. ~\ 



Sunshine Cycles 



Prof. Piazzi Smyth in his letter headed as above to Nature 

 (vol. xxi. p. 24S) has given us the latest information regarding 

 those variations of temperature indicated by the Edinburgh earth 

 thermometers, commonly termed "waves of heat and cold." 

 He has, however, cited but one case in which an extraordinary 

 amount of sunshine was actually observed to occur simultaneously 

 with the crest of a heat wave, viz., in 1S26. 



Having lately been engaged upon a comparison of the annual 

 and seasonal amounts of cloud in different parts of Europe, I 

 think I can bring forward some evidence to show that these 

 waves of heat and cold are indeed veritable cycles of sunshine 

 and gloom. 



h Before proceeding to give proofs of this statement, however, 

 it will lie necessary to consider for a few moments the effects 

 that mo>t probably attend a prevalence of cloud or tbe reverse 

 at different seasons of the year. It is, I imagine, pretty generally 

 allowed that presence of cloud in the summer is associated with 

 coolness and in the winter with warmth ; and in like manner 

 that clear skies which in the summer by promoting solar radia- 

 tion favour the development of great heat, in the winter by 

 giving free scope to terrestrial radiation (in the then compara- 

 tively reduced stage of solar radiation) tend to produce excessive 

 cold. 



A warm year need not therefore be a very cloudless year, 

 provided tbe majority of its cloud occurs during the cooler 

 months. In like manner a cold year need not be very cloudy, 

 provided its clear sunshiny days occur mostly in the winter, or 

 when the sol >r altitude is small. 



It must, however, be noted that the effects of the presence or 

 absence of cloud are not of equal magnitude at the summer and 

 winter solstices respectively. At and near the former epoch the 

 temperature of the extra-tropics is more dependent on the direct 

 solar rays, and anything which intercepts these produces a more 

 marked effect than at the latter epoch, when the prevailing 

 direction of the wind becomes the predominating factor. 



If, then, any general relation with respect to cloudiness be 

 visible in the mean annual results, at the epochs of greatest heat 

 and cold as given by Trof. Smyth, the results for tbe summer 

 seasons alone, should exhibit the same relation but in a more 

 marked degree. 



The following tables have been prepared from the limited 

 data at my disposal, with especial reference to the foregoing 

 considerations. 

 k They comprise the billowing observations : - 



I. The relative monthly and annual mean cloud proportions. 



at Greenwich from 1841 to 1876, and at Oxford from 1850 

 to 1875, as supplied to me by Mr. Whipple, of the Kcw Obser- 

 vatory. 



2. Do. at Munich from 1843 to 1866, as summarised by Dr. 

 J. Lainont in the " Monatliche und jahrliche Resultate der an 

 der koniglichen Sternwartc bci Miinchen von 1843 bis 1866 

 angestellten meteorologischcn Beobachtungen." 



3. Do. at Breslau, as given by Dr. J. Galle in a similar 

 work. 



4. The results of the tri daily observations at Leipzig from 

 1830 to 1S59, and for the summer months at Minister from 1858 

 to 1874 (" Ueher die Beziehungen der Sonnenfleckenperiode i\\ 

 meteorologischen Erscheinungen," von Dr. F. G. llahn. 

 Leipzig, 1877, pp. 123-126). 



5. The annual number of cloudy days (giorni nuvoli) at 

 Bologna from 1814 to 1S58 (" Notizie sul clima Bolognese, etc , 

 nel quaranta cinquennio 1814-1S58," by Prof. L. Respighi). 



6. The number of days on which Schwabe was unable to 

 observe the sun at Dessau in each year, from 1S26 to 1S59. 



7. The number of days on which neither Prof. Wolf nor his 

 assistant could observe the sun at Zurich from 1S59 to 1S77 

 (" Ueber die Beziehungen der Sonnenfleckenperiode zu den 

 met. und mag. Erscheinungen der Erde," von II. Fritz. 

 Haarlem, 187S, p. 212). 



The figures in every case denote the difference from the corre- 

 sponding mean, but those for Greenwich, Oxford, Munich, and 

 Breslau only, are intercomparable. 1 



Piazzi 

 Smyth's 

 dates for 



Table I. — Mean Annual Cloud. 



Bologna. 



Munich. 1'reslau. 



1826-5 1S26 — — 



JS345 1S34 - - 



1S464 1S46 +c-2 — 



18579 1857 -0 - I -0"2 



iS6S'S 1868 -o-6 -0-2 



-043 — -is 

 -003 -o'S - 5 

 — -01 — 



Means 



6-83 



of cold- 



1829-6 1829 — — — — + 8+45 



JS37-3 1S37 - — - - -17 - 37 



1845-2 1S4:; -c-i — +o-io — +10 + 9 



[848-0 1S4S +0'2 — -0-23 — + 16 



1855*8 1855 -0-3 +C2 +0-50 ±o-o +13 + 2 



1S603 i860 -c-6 +07 -070 +o-6 — — 



1S663 ±00 -o-io +o-i — — 



1870-3 1S70 -o-6 -0-5 — ±o-o — — 



1S79-1 — — — — — — — 



Means 



-rO'I 



-o'l 



-o-i 



+ o-i 



+ 21 



Table II. — J 



Years. Greenwich. Oxford. Munich. Breslau. I* 



f826 — — — — 



183a — — — — 



1846 -0-38 — -1*35 -o-S 



1857 -108 -075 -0-70 -05 



1868 -145 -°'95 — — 



16 



Means -0-97 



-085 



I 07 



-o-6 



IS 



1829 — — — 



1837 - - - 



1845 -0-25 — 



1848 +0-59 — rfcO'O 



1855 -0-28 +041 +0-15 



1S60 +I-45 +"'7' +06S 



- o - 49 + o-;,S 



1870 -0-31 -0-62 



+ 21 — 



— + 2! 



+ o-i 

 + c'9 



+ o\S — 



+ 0-4 



— +'4 



Means +C2S +C47 +0-29 +0-55 



+ 6 



. .led to the srjinary scale of o-io. 



