1 



WATERSPOUT. 



WATERSPOUT. 



751 



.pouts hare occasionally been witnessed in this country. In 1718 one 

 ..i them bunt in Lancashire, when, at the place where it fell, the ground 

 as torn up to the extent of about half a mile in length, and to the 

 depth of term feet, *o a* to lay bare the ratface of the rock under- 

 neath. (' Phil. Tran*.,' No. 363.) 



The formation of waterspout* has been ascribed to a whirling 

 motion produced in the air by current* coming in opposite direction*; 

 it hat been rappoaed that the particle* of vapour in the upper region* 

 thu* acquire, by the centrifugal force, a tendency to move toward* the 

 exterior parti of the column, leaving the interior void or in a rarefied 

 state. The pressure of the atmosphere being thus removed from the 

 surface of the *ea or ground immediately below, that which takes 

 effect on the surrounding water (when the spout i* formed at sea) must 

 impel the latter toward* that part, and cause it to rise into the space 

 where the partial vacuum exists. There i* great probability that the 

 elevation of the eea under the cloud i* in part caused by the rarefaction 

 of the air ; but a the pressure of the atmosphere could only raise the 

 water in a perfect vacuum to the height of about 30 feet, and as the 

 height of a waterspout i* known to be sometimes about half a mile, 

 some other explanation of thin part of the phenomenon must be 

 sought for. 



Some valuable observations on waterspouts formed over land have 

 been recently made by Major Walter S. Sherwill, an officer to whom 

 we are indebted for various contributions to science, respecting the 

 physical geography and meteorology of India. Among other instances, 

 he ha* described in a very instructive manner a waterspout of 

 colossal dimensions which was seen to form and burst at Dum l)um, 

 eight miles north-east of Calcutta, on the 7th of October, 1859. The 

 circumstances preceding and attending the phenomenon were as fol- 

 lows: 



The south-west monsoon [MONSOON] during the week had received 

 its first check by the north-east monsoon endeavouring to cross the 

 Himalaya mountains, and to drive back the heavy masses of clouds 

 " and moisture " (probably clouds becoming floating small rain, having 

 the aspect of mist) that had been banked up along their flanks during 

 the whole of the rainy season, or during the prevalence of the south- 

 west monsoon. At Dum Dum, the visible heavens were wholly 

 occupied by a dense mass of very grandly shaped and massively grouped 

 strata of cumuli [CLOUD] at various elevations ; the lowest stratum, 

 from actual measurement by Major Sherwill, was 2UOO feet above the 

 earth, the highest probably reaching the altitude of 25,000 feet, the 

 entire mass being about five miles in vertical thickness. The aspect 

 of the heaveng during the past few days had been most remarkable, 

 presenting a scene of great disturbance ; the clouds, evidently impelled 

 from the south by the south-west monsoon, but, checked by the 

 north-east, the whole mass, extending for as many miles as the eye 

 could reach from north to south and from east to west, acquired a 

 rotary and at the same time an undulatory motion ; huge tracts of 

 clouds revolving rapidly around a centre which appeared, from the 

 observer's position, distant about 1 1 mile from Dum Dum, to be about 

 5 miles to the south-east. This rotary motion, performed in n very 

 large circle, gave the clouds the appearance of moving in two dintmct 

 directions, those nearest to the observer appearing to be going north, 

 and those furthest removed to be going south. In the early portion of 

 the day, the wind had been from the south, bringing with it from the 

 sea a large body of clouds ; at noon it changed to the south-west, at 

 2 P.M. to the west, and at 4 P.M. to the north : there had been but 

 little rain during the day. 



The greatest disturbance in the clouds took place between the hours 

 of three and four, the whole mass revolving and heaving violently ; 

 extensive masses of clouds were crushed and driven into others, but no 

 lightning was observed. It now rained heavily to the north and east. 

 " During this time," Major Sherwill says, " more than one waterspout 

 endeavoured to form, but unsuccessfully. It was whilst observing the 

 highly-agitated masses of clouds that were revolving and oscillating in 

 a most peculiar manner, that I witnessed the commencement and ter- 

 mination of the remarkable waterspout now under consideration. At 

 three P.M. it became suddenly quite calm, and during the calm a pale 

 watery -looking, but very watery, cumulus, the base of which was a right 

 line, and parallel to the horizon, was seen to bulge out downwards or 

 toward* the earth in a long well-defined and light blue coloured out- 

 line ; from the centre of this hanging curve a broad column of a pale 

 watery vapour rapidly sank toward* the earth, closely resembling a 

 very attenuated cone, dark at the edges and pale blue in the centre, 

 plainly showing it to be a solid cylinder; a* it neared the earth the 

 lower half of this elegant column commenced to gyrate rapidly, the 

 lower end oscillating violently to the right and to the left ; this latter 

 movement I imagine to be u more optical illusion, caused by the lower 

 end of the column revolving in a circle of large diameter; as the 

 ' -iilniun neared the earth it expanded and contracted in an agitated and 

 rapid manner about the centre into cloud-like protuberance*, which 

 partook at the same time of the motion of the revolving column. 

 Upon arriving nearer the earth the end of the column parted into two 

 lender column* about ISO (' or 200,' a* stated in another place) feet 

 each in length, and in thin condition reached the p-mmd. The shape 

 uf the column was now completely and iniitantaneously altered ; for 

 the whole cumulus burst, and was seen pouring down to the earth, not 

 as a chower of rain, but a* a heavy mam of water, resembling a waterfall 



more than a shower of rain, that completely exhausted and brought 

 the whole cloud to the ground in a few seconds of time." 



The estimated length of the cumulus, the lower portion of which 

 bad become a heavy nimbus, from which the waterspout depended, 

 bad been 3000 feet, and it* height, from base to summit, 5000 feet 

 By trigonometrical mean*. Major Sherwill ascertained that the perpen- 

 dicular height or length of the column or waterspout itself, from the 

 point of it* protrusion from the cloud* to its lowest extreme point, at 

 the moment of bursting, was 1500 feet. Its period of duration, from 

 it* first formation to its bursting, was about 25 second*. It burst 

 upon the artillery practice-ground, a large grassy plain, of which it 

 covered half a square mile with water to the depth of about half a foot, 

 nhu-h took fourteen day* to drain off by the usual drainage course* of 

 the country. The cattle fled in all directions as it descended, but no 

 noise was heard at the observer's position. 



Major Sherwill's observations are illustrated by excellent lithographic 

 representation* of the waterspouts he observed. Some of these are 

 somewhat roughly copied in the subjoined diagram, in which Jig. 3 

 represents the waterspout now described. Half an hour after this had 

 disappeared, he relates, " another formed to the east of the position : 

 it was a very attenuated column, about 900 or 1000 feet in length, but 

 the cloud from which it descended being upward* of 2000 feet above 

 the earth, no contact was completed ; the column, which lasted for 

 half-an-hour, gradually faded away, being absorbed upwards into the 

 cloud from whence it had descended. The cloud and column were 

 moving rather rapidly towards the south, which probably accounts 

 for the column never reaching the ground. The column gyrated 

 and oscillated violently, lengthening and contracting as shown in the 

 diagram (Jig. 4), where eleven different positions of the column are 

 given, sketched at intervals of from two to five minutes. Towards 

 sunset, the clouds began to yield to the north wind, and were gradu- 

 ally driven out to sea, leaving a clear cloudless sky; and at nine 

 o'clock at night not a cloud was to be seen. The northeast monsoon 

 had fairly set in. 



The following are the particulars of the other four waterspouts 

 figured. 1'lij. 1. Seen from Sooksagur, 35 miles north of Calcutta, on 

 the 27th September, 1855, at 8 30 P.M. Estimated length, 1000 feet. 

 Moving south. Dependent from a heavy nimbus at an angle of 46" 

 with the horizon. Upper portion gyrated rapidly. Lasted ten minute*. 

 Did not burst, but was absorbed upwards. Fig. 2, A, B, c. Seen from 

 Howrali (Calcutta) 24th September, 1856, P.M. Estimated length, 200 

 feet. Moving north. Depended from a very heavy and stormy 

 looking nimbus, accompanied by vivid lightning. It was greatly 

 agitated, throwing its lower end horizontally to the south, then to the 

 north, at an angle of 45 ; lasted about five minutes, and burst into 

 heavy deluging rain. 



/'<;. 5. Seen from Dum Dum, and from Calcutta, on the llth of 

 August, 1860, at 5 P.M. Estimated length, 1000 feet Moving south. 

 Very perfect and grand. Depended from a heavy nimbus, unaccom- 

 panied by lightning. Gyrated rapidly at the top, dark at the edge* 

 and pale blue in the middle. " Divided at the lower end into two 

 smaller columns of 50 or 80 feet in length." Lasted about ten 

 minutes, and burst into heavy rain. 



Fig. 6. Seen from Sulked, (Calcutta) on the same day, and at the 

 same hour a* the last; crossed the river Hoogbly at that 

 agitating the water beneath it Estimated length 800 or 900 feet 

 Moving north-west Depended from a heavy nimbus. " Had hanging 

 fringe-clouds, dropping rain, on the south side of the upper part of 

 the column." Gyrated rapidly at the summit of the o>lumn. Was 

 bent by a south wind into an elegant double cone resembling the letter 

 8. Lasted about ten minute*. Superior portion absorbed upwards, 

 lower part burst into heavy rain. The figures in the diagram, it must 

 be stated, have a more defined outline, and a greater appearance of 

 solidity, than in the original UthagnpbB. 



Major Slii-rwill, in con bri. !ly dr.-uTibed and also figured 



two other waU'rnpouts, l*>th ntum<l<il by or exhibiting rcmarkab; 



v, phenomena. One of these was seen by him from I >:u joeling, 

 in the Himalaya, on the 21th of May, 1852, at noon. This was a w;u m 



