I90 



NATURE 



[April 6, 191 1 



and contain more evergreen specie*. Kxt«*nsive areas of 

 the so-called black cotton soil form a special feature that 

 is rare in tropical West Africa. Pseudocedrela Kolschyi 

 is the most important tree, both in quantity and quality ; 

 l.ophira alata, the West African oak, and Plerocarpus 

 erinaccus are fairly common, and could be increased by 

 judicious fire-protection and cultivation. Afselia africana 

 is more localised, and Khaya senegalctisis grows mainly 

 above the eighth parallel. 



A RKi'ORT on the eruption of Taal volcano (I-uzon) of 

 January 30 has been issued by the Rev. M. Saderra Mas6, 

 assistant director of the U.S. Weather Bureau in the 

 Philippine Islands. The volcano rises from Volcano Island 

 in Lake Bombon, lies about 30 miles south of Manila, 

 and is 996 feet in height. On the night of January 27-28 

 the volcano began to emit black smoke from its main 

 crater instead of the usua' clouds of white steam. This 

 was accompanied by rumblings and earthquakes. During 

 the noxt two days the explosion*; nn<\ earthquakes increased 

 in sinni^ili and frequency until about 2.20 a.m. on 

 January 30, when a tremendous «\i>losion occurred, which 

 is said to have been heard at a distance of 250 miles from 

 the volcano. A huge black cloud issued from the crater, 

 and there was a heavy fall of boiling mud, which destroyed 

 all the houses and vegetation in Volcano Island and along 

 the western and north-western shores of the lake to a 

 distance of 10 miles from the crater, and caused the loss 

 of more than 1250 lives. Along these shores the mud 

 formed a layer 2 or 3 feet in thickness. The opposite 

 shores escaped with little or no fall of mud, the wind 

 li;ivin<4 been from the south-east. The damage was in- 

 ( I! as. (1 by the waves produced in the lake, which reached 

 a height of 10 feet. The rush of air towards the volcano 

 was perceptible for many miles. At Batangos, 17 miles 

 distant, an abrupt fall of 2 mm. in the atmospheric 

 pressure was registered. Volcanic dust was carried so far 

 as Manila. Earthquake shocks, though never of destruc- 

 tive intensity, were extremely frequent, nearly a thousand 

 having been recorded at Manila from January 27 to 

 February 7, when the eruption ended and the ground 

 ceased to tremble. 



The summary of the weather in the several districts of 

 the United Kingdom for the first quarter of the current 

 year, as comprised by the thirteen weeks ended April 1, 

 has just been issued by the Meteorological Office. The 

 mean temperature for the period was nowhere very 

 different from the average, and the record of absolute 

 temperatures was not at all exceptional. The highest 

 temperature in any district during the three months was 

 63°, which occurred both in the east and south-west of 

 England. The lowest lini]>.raiure was 11° in the east 

 of Scotland and 13° in the south-west of England. The 

 aggregate rainfall for the period was less than the average 

 in all districts except in the east of England, where the 

 excess for the three months was 063 inch. The- greatest 

 deficiency was 3-19 inches in the south of Ireland, and in 

 the north of Ireland it was 274 inches. The greatest 

 deficiency in any of the English districts was i-88 inches, 

 in the south-west of England. The largest absolute 

 measurement for the period was 14-42 inches in the north 

 of Scotland, the smallest 399 inches in the north-east of 

 England. The number of rainy days was nowhere very 

 different from the normal ; the highest number was 58 

 days in the north of Scotland, the lowest 42 days in the 

 Midland counties. The hours of bright sunshine were in 

 good agreement with the normal; the longest duration 

 was 269 hours in the Channel Islands, the shortest 196 

 hours in the Midlands. At Greenwich the mean tempera- 

 N). 2162, VOL. 86] 



turn for the three months was in absolute agreement with 

 the average; the rainfall was <»-6i inch less than usual, 

 whilst the bright sunshine was 25 hours deficient. For 

 the six months October to March inclusive, which com 

 prises the whole winter, the mean temperature at Gre«-i.- 

 wich was 430°, which is 0-6" in excess of the averag- . 

 October and December were decidedly warm monihv, 

 whilst November was decidedly cold. The lowest shad'- 

 temperature at Greenwich during the winter is 22*", whiih 

 occurred both in November and February. Out of iteH 

 days there were 94 days with the temperature above tflB 

 average, and frost occurred on 37 nights. There wefl"^ 

 99 days with rain, yielding a total of 13-31 inches, which 

 is 1-49 inches more than the average ; November, 

 December, and March were wet. The total duration of 

 sunshine in the six months w a 

 hours fewer than the average. 



The meteorological charts of the .Atlantic and Pacific 

 Oceans for March and April published by the U.S. 

 Weather Bureau contain useful notices (i) on West India 

 hurricanes, which usually occur between July and Octob«T. 

 Particulars are given of some of the more destructiv- 

 storms, with remarks on the premonitory signs of th- 

 approach of tropical hurricanes generally. The tracks o! 

 those which occurred in 1900-9 are laid down on charts 1 

 for separate months. The storms are liable to appear in 

 any part of the region between lat. 7° and 31° N., and 

 east of the ninety-fifth meridian, and to recurve at any 

 point between far to the east of the Bahamas and the 

 west coast of the Gulf of Mexico. (2) Cyclones and anti- 

 cyclones. The first clue to the rotatory character of 

 storms is attributed to Benjamin Franklin, in 1747. As 

 he was unable to observe an eclipse of the moon at Phila- 

 delphia owing to stormy and cloudy weather, while his 

 brother at Boston experienced clear weather, he made 

 inquiries as to the behaviour of the storm in question, and 

 as a result of the investigation he came to important con- 

 clusions on the movements of storms in general. Some 

 useful explanations are given by the author of this notice 

 of the conditions at work in weather changes, and of the 

 origin of storms. 



The Verhandluiigcn dcr Deutschcn Physilca. ...... :. 



.Gesellschaft for February 28 contains an account of a 

 theoretical and experimental investigation of the best 

 practical method of winding the coil of a needle galvano- 

 meter, by Dr. W. Volkmann. Maxwell showed long ago 

 that the wire should increase in diameter as the windings 

 get farther from the centre, and Volkmann finds that the 

 nearest practical approach to this is to make the diameter 

 of the wire used for successive portions of the coil increase 

 in geometrical progression. The loss of eflSciency due to 

 this step by step change is proportional to the ratio of the 

 step. The winding should be stopped when the loss due 

 to stopping it is equal to that due to the ratio of the step. 

 By finding experimentally the deflection due to single turns 

 of various diameters, and in different positions, and 

 dividing the deflections by the lengths of the turns, he 

 finds that the best shapes of the parts of the coil are not 

 quite t»-ose given by .Maxwell, the deviations being greatest 

 for tht parts near the needle. With the new winding a 

 coil of only 37 cubic centimetres produced the same deflec- 

 tion as a coil of 47 cubic centimetres wound on the old 

 lines. Each coil consisted of four parts, and had a resist- 

 ance of 5-5 ohms. 



The Scientific American for March iS is devoted to 

 cement and its uses. An interesting article by M. L. 

 Davey gives particulars of methods of saving trees which 

 have partly rotted by means of cement fillings. Once 



