460 



REPORT — 1884. 



then, to inquire whether tho fi-equcncy of these cirri or cirro-stratus 

 ^changes with the annspots. Tho connection has, indeed, been fairly well 

 established ; and the greatest number of cirri are nearly always observed 

 when many anrora; arc observed — that is, generally, when there are many 

 spots on the sun. Now, the cirri are clouds in which the water is, in all 

 probability, in a frozen condition ; and we are thus brought directly from 

 the sunspots through the aurora to temperature effects. The meteorolo- 

 gical quantities hang, indeed, so closely together that, as soon as we admit 

 a connection between sunspots and aurorte, we admit their connection 

 with other meteorological phenomena. We ought not then to ask, ' Is 

 there a relationship between sunspots and the weather? ' but rather, ' Is 

 the relationship sufficiently large to be observable by means of our ordi- 

 nary instruments ? ' 



If cirri occur most frequently at times of frequent aurora), and if cirri 

 are due to clouds of ice needles, we ought to see most solar halos at times 

 of many aurorjc. This has been shown to be the case by Sophus Trom- 

 holdt. Between the years 1857 and 1873 the number of solar halos varied 

 exactly in the same manner as the number of auroraj ; they also showed 

 the maximum in each year at the time of the equinoxes. 



Investigations have also been made with regard to other clouds, and it 

 has generally been found that the greatest number of clear days in Central 

 Europe occurred at times of few spots on the sun. 



Thunderstorms. 



Professor von Bezold ' has recently published a most interesting 

 memoir on the distribution of lightning flashes which have done damage 

 to dwellings in the kingdom of liavaria. As the insurance is altogether 

 in the hands of the Government, the kingdom is peculiarly fitted for 

 such an investigation, there being a fairly complete set of statistical data 

 available for the last fifty years. 



The following table will show that the numbers of fires caused by 

 lightning is quite sufficient to base an inquiry on them. It will also 

 plainly show the very remarkable fact that the flashes of lightning which 

 have done damage have enormously increased in the last fifty years : — 



This astonishing fact, which seems to hold true not only for the 

 kingdom of Bavaria, had already previously been commented upon, and 

 formed the subject of a separate investigation by Holtz. It is by no 

 means due to the greater number of houses insured in recent times, for 

 in the last fifty years that number has increased only thirty-five per 

 cent., while the number of houses struck has increased over three hnn- 

 dred per cent. Professor von Bezold thinks that there is evidence to 

 show that during the second half of last century the number of honaes 

 damaged was also larger than in the first half of the present one. Bat, 







' Abh. der Kais. Altad. Miinchen, vol. xv. (1884 . 



