53^ 



NATURE 



[August 24, 191b 



A paper of exceptional value and interest, on the 

 morphology and biology of the green apple aphis {A. 

 posni), is contributed by A. C. Baker and W. F. 

 Turner to the Washington Journal of Agricultural 

 Research (vol. v., No. 21). This is the •'common 

 apple aphid" in North America, as well as in these 

 countries, and the whole life-cycle is passed on the 

 apple. Very full and careful descriptions of the struc- 

 ture of the various forms are given by the authors, 

 who, in the course of their season's work, examined 

 no fewer than 75,000 specimens. Stages in the 

 embryonic development are described, from which it 

 appears that the embryo, after five days' growth, has 

 a long resting period through the colder Season of the 

 year, lying in the centre of the winter egg. Of all 

 the results obtained, however, the tracing of the suc- 

 cession through the spring and summer of a number 

 of forms derived from a single stem-mother is the 

 most important. Among the daughters of the stem- 

 mother there may be one winged insect, and interest- 

 ing "intermediates" — virgin females with rudimentary 

 wings — appear together with the usual winged and 

 wingless aphids. Sexual individuals may appear in 

 the eleventh generation from the stem-mother, the 

 earlier ones appearing as brothers and sisters of par- 

 thenogenetic females. The authors believe that tem- 

 perature is by far the most important factor in deter- 

 mining the appearance of the sexual insects. 



A paper by J. R. Malloch, on Chironomidas and 

 other Diptera from Illinois (Bull. 111. State Lab. Nat. 

 Hist., vol. xi., 4), is noteworthy because the systematic 

 descriptions of the midges and flies are accompanied 

 by detailed, well-illustrated accounts of the larvae and 

 pupae of many genera of Mycetophilidse, Asilidae, Bom- 

 bilidae, Syrphidae, and other families. G. H. C. 



CHILIAN METEOROLOGY.^ 



ALTHOUGH Chile, in common with other South 

 American countries, has suffered greatly from 

 the conditions brought about by the European situa- 

 tion, the large budget of memoirs recently issued by 

 Dr. Knocke shows little, if any, restriction in the 

 work of the Central Meteorological and Geophysical 

 Institute during 1915. No. 13, part i., of the 

 Meteorological Year Book gives in cxtenso the tri- 

 daily observations carried on at thirty stations during 

 the year 1913, the data comprising barometric 

 pressure, air temperature humidity, wind direction 

 and force (the latter both in Beaufort and by anemo- 

 meter), cloud, rainfall, evaporation, and exposed 

 temperatures. 



In No. 15, part ii., of the Meteorological Year 

 Book the data are summarised in great detail from 

 records kept at fifty-two stations, daily, monthly, and 

 annual abstracts being given. As the stations cover 

 more than 35° of latitude, and range in altitude from 

 4 to more than 3500 metres, all varieties of climate 

 are to be found among the records. The warmest 

 station, apart from Easter Island in the Pacific, was 

 Arica, mean temperature 19-4° C. (66-9° F.), and the 

 coldest Punta Arenas, 6-3° C. (43-3° F.). The abso- 

 lute maximum was 383° C. (1009° F.) at San Felipe, 

 lat. 32° 40' S., height 63:; m., and the absolute mini- 

 mum -80° C. (176° F.) at Punta Arenas. The 

 effect of the cold Humboldt current in keeping down 

 the temperature is well shown in the data for Arica 

 (lat. 185° S.) and San Felipe, the mean daily maxi- 



1 Institute Central Meteoroloeiico y Geofisico de Chile, Santiago, Dr. W. 

 Knocke, Directr. No. i^, "Anuario Meteoroldgico de Chile, 1913." 

 Pp. 339. No. 14, " Medidas de asua caida en 1913." Pp. 71 + plates, 

 No. 15, "Anuario Meteoroldgico de Chile." Segunda parte. Pp. 134 + 

 plates. No. 16, " V.Tlores horarios de lo= elementos meteoroMgico.s en I-os 

 Andes, 191 1 y 1912." Pp. 8i+plates. No. 17, "Valores horarios de los 

 elementos meteorologicos en Santiago, 1914." Pp. 91 + plates. 



NO. 2443, VOL. 97] 



mum values at the latter station on the mean of the 

 year being 17° C. higher than at Arica, 14° nearer 

 the equator, and situated at sea-level. A comparison 

 of the temperature data from Ollagiie, at a height 

 of 3695 metres, with those from Iquique shows a fall 

 of 1° C. for each 323 m., both stations being close to 

 lat. 2oi° S. 



Great variations in the mean amount of cloud are 

 to be found, the mean annual values ranging from 

 09 at Calama in the north to 8-8 at Evangelistas, 

 near the Pacific entrance to Magellan Straits. .•Xt 

 the former station there were 327 clear days (cloud 

 amount less than 2) and not a single cloudy day 

 (cloud amount more than 8), while at Evangelistas 

 only 2 days were clear and 305 cloudy. It is of 

 interest to note that at the island of Juan Fernandez 

 the barometric indications are very frequently an 

 index of those taking place twenty-four hours later 

 on the Chilian coast in about the same latitude. 



No. 14 gives the daily rainfall recorded at 112 

 stations for the year 1913, arranged in parallel 

 columns, thus exhibiting the distribution of the rain 

 throughout the whole length of the country. The 

 wettest station was Caf>e Raper, lat. 46° 49' S., long. 

 75° 36' W., with 4607 mm. (181-38 in.), the value's 

 for December being interpolated. .\t Calama and 

 Copiap6 in the north no rain fell, and ten other 

 stations, all to the north of 30° S., had less than an 

 inch. Hourly rainfall values are given in extenso for 

 seven stations. From these records it is seen that 

 torrential rains are uncommon, there being onlv two 

 instances of more than an inch (25-4 mm.) falling in 

 an hour, the maximum hourly fall being 40 mm. at 

 Contulmo. 



We are glad to see that in No. 16 Dr. Knocke 

 continues to give hourly values of all the elements, 

 the station selected in this instance being Los Andes, 

 situated at the foot of Aconcagua, at a heipht of 

 820 metres, where the Chilian section of the Trans- 

 andine railway begins. Los Andes enjoys an admir- 

 able climate- — cool in summer and temperate in winter. 

 Although 300 metres higher than Santiago, the mean 

 temperature is slightly higher, while peaches and 

 walnuts flower a fortnight earlier than in the Chilian 

 capital. No. 17 of the memoirs contains the hourly 

 values for the year 1914 of the principal climatic 

 elements at Santiago, including earth temperature 

 and the electric conductibility of the air observed once 

 dailv bv means of a Wulff electroscope. 



R. C. M. 



THE MOVEMENTS OF THE EARTH'S 

 POLE.^ 



MORE than a century ago it was shown bv the 

 mathematician Euler that if the axis round 

 which the earth was rotating were not coincident 

 with the axis of figure, which latter in the case of a 

 spheroidally flattened earth is the shortest axis that 

 can be drawn, the axis of rotation will revolve about 

 the axis of figure in a period which, upon certain 

 assumptions, can be precisely predicted. The time 

 of one revolution of the pole of rotation around the 

 pole of figure depends only upon the shape and degree 

 of elasticity of the earth. In Euler 's days the sup- 

 position that the solid earth had any appreciable 

 elasticitv was so far outside the range of experience 

 that it was not considered by him. He calculated 

 the period of the polar rotation on the assumption 

 that the earth was perfectly rigid, and showed that 

 this period would be about 305 days. 



If we determine the latitude of a point on the 



1 ni-v-ours.; I'elivered at the Royal Institution on Frday, May 19, by Col. 

 E. H. Hills, C.M.G., F.R.S. 



