?68 



NA TURE 



[January 28, 1909 



Jan. Feb. Mar.Apr.May June Julj-Aug. Sep. Oct.Nov. Dec. 

 (a) II 14 IS 14 12 10 13 12 10 14 13 13=151 

 \h) II 8 S 10 8 12 7 12 13 10 12 14=125 



(a') 40 43 41 36 35 35 35 36 37 40 



((5') 27 26 26 30 27 31 32 35 35 36 



W):{b') +13 + 17 + IS +6 +8 +4 +3 +1 +2 +4 



The series (a') and (6') are expressed in curve-form in 

 tlie middle section of tfie diagram. Note that the 

 {a') curve culminates in the third month {i.e. with the 

 3-month group February-April), and just then the other 

 curve is at its lowest point. The difference here is 

 43 — 26=17 (about 65 per cent, of the lower value). 



Curves of total warm months in 3-month group: 



We might extend these curves on either side, consider- 

 ing in one case the temperatures in those years of highest 

 and lowest sun-spot numbers, and in the other those in 

 the second years after. 



In both extensions we find, again, the extreme contrast 

 at the third month, but in both, the curves cross each other 

 in part; and in the third section there is general "break- 

 down," with year-difference small. Thus we have, for 

 totals of warm months : — 



Diff. 

 Years of (22) highest and (22) lowest sun-spot 



numbers 142-123=19 



1st year after 151-125 = 26 



2nd „ 134-130= 4 



The sharp contrast above referred to in the early part 

 of the year (February-April) -seems to me remarkable, 

 and may be usefully considered in relation to the flowering 

 of plants and other phenological phenomena, the variations 

 in which, from year to year, seem to be connected with 

 the sun-spot cvcle (as I have before tried to show). 



Alex. B. MacDowall. 



RECENT EARTHQUAKES. 



THE Italian earthquake still keeps a prominent 

 place in the daily newspapers, and earthquakes 

 stiU continue in the stricken country, but this is no 

 more than must be expected. Every great earthquake 

 is followed by numerous after-shocks, more frequent 

 at first and gradually becoming- fewer and fewer; 949 

 shocks were registered at Monteleone in 1783, and 

 159 in 1784. A similar experience is being repeated 

 in Calabria at the present time; reports of more 

 earthquakes at Reggio and Messina are common in 

 the papers, but the record is too incomplete to be 

 worth repeating in detail. Among these after-shocks 

 sonfe have been of sufficient violence to bring down 

 shattered or weakened walls and buildings, and some 

 were of a severity which would have caused serious 



NO. 2048, VOL. 79] 



damage and destruction to buildings had they stood 

 by themselves. The first of these destructive after- 

 shocks seems to have occurred at 7.24 p.m. on 

 January 23, which brought down a good many houses 

 left standing by the earthquake of December 28 at 

 Reggio, and was described as of equal violence. This 

 statement must be accepted with reserve, for experi- 

 ence has shown that after a very great earthquake 

 and during the period when after-shocks are frequent, 

 all sense of proportion is lost, earthquake-fear is 

 developed, and every shock of more than average 

 severity ranks out of proportion to its real importance. 

 Though the shock was apparently a considerable one, 

 and mav well have compared in violence with its pre- 

 decessor at Reggio, yet the much smaller area over 

 which it had the power of inflicting damage, as also 

 the much smaller size of the area over which it was 

 felt, mark it as an altogether minor shock. 



Besides the local after-shocks, earthquakes have been 

 reported in the daily papers from other parts of the 

 world, and not unnaturally a connection has been 

 assumed which has probably no foundation in fact. 

 The most important of these were the North .■\merican 

 earthquake of January 11, and that in .Asia Minor on 

 January 19; the former of 'hese was felt at Victoria, 

 B.C., at 3.55 p.m., local time, and was described as 

 severe ; it was also felt at Vancouver and Nanaimo, 

 in British Columbia, and in the Washington State, 

 where some slight damage was done at Port Towns- 

 end. The earthquake in Asia Minor seems to have 

 been more severe if not more extensive; it took place 

 at 6.40 a.m. on January 19, and is said to have 

 destroyed 679 houses at Phocoea, two persons are 

 reported to have been killed at Menemen, and the 

 same number at Cassaba. Neither of these was, hovi-- 

 ever, of any importance, and would probably have 

 passed without notice but for the attention directed to 

 earthquakes at the present moment. 



Much the same may be said of the shock which 

 shook northern Italy on January 13, though possibly 

 this may have been of the nature of a sympathetic 

 after-shock, that is to say, brought about by a change 

 in the distribution of strains in the earth's crust, con- 

 sequent on the movements which have taken place in 

 Calabria. It belonged to that little understood class of 

 shocks which affect a large area without anywhere 

 reaching destructive violence, and nowhere did more 

 than trivial damage, though felt at Triest, Trient, 

 Milan, Genoa, Siena, and in all the country between. 



In spite of these earthquakes, there is no indication 

 of any real increase in seismic activity ; on the other 

 hand, it is a somewhat remarkable fact that the 

 Calabrian earthquake was a solitary one. World- 

 shaking earthquakes almost invariably occur in 

 groups, and are seldom unaccompanied by one or 

 more companions, originating in distant parts of the 

 globe, but within a few hours, or at most a few 

 days, of each other ; so frequent is this phenomenon 

 that it has almost been elevated into a law, and an 

 ingenious explanation, with experimental illustration, 

 has been published. In the present instance, the 

 records of Prof. Milne's instruments at Shide show 

 that no other world-shaking shock accompanied the 

 Calabrian one, and none was reported until the morning 

 of January 23, when an earthquake, which probably 

 originated somewhere in western Central Asia, was 

 registered by seismographs in Europe, India, and at 

 the Cape of Good Hope ; probably we shall hear more 

 of this earthquake, for its origin was in a region which 

 is not devoid of villages ancl towns, but the interval 

 which had elapsed prevents our regarding the two 

 earthquakes as companions. This isolation of the 

 Calabrian earthquake may find its explanation in 

 the fact that although a great, it was not a very 



