753 



WATERSPOUT. 



WATER SUPPLY. 



754 



dry summer day, highly favourable to evaporation ; and the invisible 

 vapour with which the air had become charged was suddenly con- 

 densed, by a chilled stream of air descending from the snowy range of 

 the Himalaya, distant 35 miles, into a huge cumulus cloud, at an 

 elevation of 11,000 feet. The first effect of the cold blast was the 

 formation of a small cloud " the size of the hand," which rapidly 

 increased until it extended to the length of 15 miles and the vertical 

 thickness of 5000 feet, or nearly one mile. This body of cloud was 

 driven with great celerity to the south; and as it approached the 

 mountain Ponglo (distant 114 miles from Darjeeling, and slightly 

 exceeding 10,000 feet above the sea) the lower portion, hitherto nearly 

 horizontal, began throwing down about twenty waterspouts, each 1000 

 feet in length, which gyrated at a rapid pace, increasing in length at 

 the same time, until the whole cloud burst into heavy rain. " The 

 summit of the mountain," it is observed, " was evidently a point of 

 attraction for the electricity contained in the cloud, as the waterspouts 

 one mile north and south of the central group descended towards the 

 mountain at an angle of 45 with the horizon, and all seemed striving 

 to reach the very summit of the mountain ; and upon reaching it they 

 all burst into h.'avy rain. Time of duration, fifteen minutes." The 

 other, and the last waterspout of Major Sherwill's list, was observed 

 and sketched by the Rev. R. A. H. Norman, at Dum Duia, on the 28th 

 of October. 1 8o'0. It was a group, depending from a heavy nimbus, 

 and consisting of one central and large spout or column, 1500 feet in 

 length, flanked to the eastward by many smaller ones, some of them 

 500 feet long, hich were absorbed into the main column as fast as 

 they were formed. Between the nimbus and the mass of light haze 

 that covered the horizon, a long slip of blue sky was visible, and the 

 waterspout, where it crossed this, was invisible, appearing as if the 

 whole was divided into two portions. The entire group lasted twenty 

 minutes, and eventually burst into heavy rain. (' Proceedings of the 

 Asiatic Society of Bengal,' Sept. 5, 1861, Journal, new series, vol. xxix., 

 pp. 366-375, 418, 41 iO 



The manner in which several of the waterspouts described by Major 

 Sherwill burst into rain on coming into contact with the earth, is 

 strongly indicative of electrical agency, to which, indeed, these pheno- 

 mena, with more or less of vague conjecture or more or less of science, 

 have long been attributed, and which may be both cause and con- 

 sequence of the mechanical actions to which, in the former part of this 

 article, they have in part been referred. The circumstance just 

 mentioned points to an extension of the cloud towards the earth 

 caused by electrical attraction, between two surfaces (those of the 

 cloud and the earth), one of which has been charged by the other by 

 induction, until, by the contact, a discharge of the electricity takes 

 place, and the particles of water previously charged are at once pre- 

 cipitated upon the earth. Under other circumstances, the attractive 

 force of the earth ceasing, or being insufficient, the spouts are absorbed 

 into the cloud again by the force which holds the cloud together. 

 But the column or spout itself, being colourless and transparent, when 

 viewed by transmitted light, would appear to consist, not of cloud, but 

 of water, nearly in the state of rain, and bristling into it on the 

 discharge taking place. The entire system of cloud and water, and 

 the flooded earth also, being one of excellent conductors of electricity, 

 the discharge is comparatively or altogether silent. 



Strong corroboration of these inferences as to the electrical produc- 

 tion of waterspouts, may be found in their observed production in the 

 sequence of the phenomena which attended the submarine volcanic 

 eruption by which the temporary island, Sabrina, was elevated from 

 the bed of the ocean, near St. Michael's, in the Azores, from the 9th to 

 the 12th of June, 1S11 ; the important bearing of which on this subject 

 seems, hitherto, to have escaped attention. Captain Pillard,R.N., who 

 witnessed the eruption, describes (under the name of smoke, like all 

 other observers of volcanic eruptions until Mr. Poulett Scrope had 

 shown it to be condensing steam), the immense steam-cloud issuing 

 from the sea, which constituted a part of the eruption, together with, 

 and through which the columns of stones, cinders, and ashes the com- 

 minuted lavas were projected in rapid succession. " During these 

 bursts, the most vivid flashes of lightning continually issued from the 

 densest part of the volcano ; and the cloud of smoke [steam] now 

 ascending to an altitude much above the highest point to which the 

 ashes were projected, rolled off in large masses of fleecy clouds gradu- 

 ally expanding themselves before the wind in a direction nearly 

 horizontal, and drawing up to them [and being drawn down into] a 

 quantity of waterspouts, which formed a most beautiful and striking 

 addition to the general appearance of the scene." These, according to 

 the particulars stated (' Phil. Trans.,' 1812) must have been from three 

 or four hundred to eight or nine hundred feet in height or length. 



We have here, palpably, all the elements for the electrical causation 

 of waterspouts the immense evolution of electricity [VOLCANOES, col. 

 660], the charged surface of cloud, the dielectric atmosphere, the sur- 

 face of sea below and the actual production accordingly, of the phe- 

 nomena sought to be accounted for. Much more might be said on tins 

 branch of the subject, which indeed is one of great extent and 

 complication, the explanation now suggested being of a general nature 

 only. 



Much valuable information respecting waterspouts was introduced 



by the late Mr. Piddington, into part 5 of his ' Sailor's Horn-Book for 



i w of Storms,' including a view of the contents of M. Peltier's 



ARTS AND SCI. DIV. VOL. VIII. 



work entitled ' Observations et recherches experimentales sur les 

 causes qui concourent a la formation des Trombes,' under which 



| appellation whirlwinds and waterspouts are identified by the author ; 

 being applied, indeed, to them indifferently and convertibly, by French 



f writers in general. 



To a portion of this part of the subject we shall return when con- 



I sidering cyclones and whirlwinds in the article WIXD. 



WATER SUPPLY. The improvements which have lately been 

 effected in the practical details of civilised life, have given rise to so 

 great a demand for a copious domestic supply of water, that the 

 branch of hydraulic engineering connected with that portion of modern 

 social organisation has assumed a degree of importance, in excess even 

 of the importance attached to it by the most civilised nations of anti- 

 quity. Yet from the earliest periods in the history of man, the 

 attention of the governors of populous cities has been always directed 

 to providing for them copious supplies of the fluid so indispensable for 

 comfort, cleanliness, and safety ; and no surer test can be found for 

 the character of a national organisation, so far as its influence upon the 

 physical happiness of its subjects is concerned, than the one to be 

 discovered in the state of the water supply of its towns. Some of the 

 lessons to be derived from an examination of the various systems 

 hitherto adopted will be alluded to in the course of the following 

 review of their history. 



There are few indications left of the existence of a complete system 

 of water-works in the ruins of the Assyrian, or of the Babylonian 

 towns, although the numerous traces of canals upon the banks of the 

 Tigris and Euphrates show that great attention was there paid to the 

 irrigation of the laud, and to seeming a copious supply of water. In 

 Egypt, the same conditions appear to have prevailed, and numerous 

 canals were formed for the purpose of leading the waters of the Kile 

 to tanks, and wells, situated at distances from the shores of the 

 stream ; but the water was not habitually raised to any height, unless 

 in gardens, and then only in small quantities, and by very rude machi- 

 nery. It is interesting, however, to observe that the hieroglyphical 

 paintings of the Egyptians represent the use of the shadouf, or of the 

 balance' pole and bucket, still retained in that country, and by the 

 market gardeners of the neighbourhood of London. The iiuria was 

 not known to, or used by the ancient Egyptians, although so univer- 

 sally employed in that country at the present day ; but Diodorus 

 mentions that the machine known by the name of the Archimedean 

 screw was invented by them. In Phoenicia, and in Jud?ea, traces of 

 aqueducts, of tanks, and of wells, are frequently to be met with ; and 

 in those countries the first indications of works designed for the 

 purpose of conducting the waters which outburst at a high level at 

 some distance from the proposed place of consumption, may be observed. 

 There were no pipes used in any of these water-works, or conduits ; 

 and the first instance on record of their application is to be found in 

 the ruins of the aqueduct of Patara, in Lycia ; upon which line there 

 is a singular wall, or embankment of rough stone, across a valley 250 

 feet deep, and 200 feet across, bearing upon its curved top a line of 

 marble blocks cramped together and perforated, so as to form, in fact, 

 a reversed syphon. It would seem that the defective state of the metal- 

 lurgic arts, alone retarded the application of the principles of hydro- 

 statics known to the more ancient nations of the East ; for the hiero- 

 glyphical paintings of Egypt certainly show that the syphon and the 

 ordinary forms of pipes were occasionally employed by them ; "and the 

 aqueduct of Patara equally proves that the Greeks were aware of the 

 law by which water rose to equal heights in the two legs of a reversed 

 syphon. 



It was, however, under the dominion of the Romans that the ancient 

 world undertook the most gigantic works for the supply of their towns 

 with water; and, fortunately, the writings of Vitruvius, Frontinus, 

 and Palladio have transmitted to our days much curious information 

 with respect to the detailed methods of execution adopted by the 

 Roman engineers. According to Frontinus, the inhabitants of the 

 Eternal City for a long time contented themselves with a supply of 

 water obtained from the Tiber, from land-springs, and from wells ; but 

 about the year 312 B.C., the censor Appius Claudius completed the first 

 aqueduct, subsequently known as the A qua Appia, which conducted to 

 Rome the waters of a spring rising " in the field of Lucullus, between 

 the 7th and Sth milliaria of the Prencstine road." Subsequently, the 

 aqueducts of the Anio Vetus, Aqua Marcia, Aqua Tepula, Aqua Julia, 

 Aqua Crabra, Aqua Virgo, Aqua Alsietina, Aqua Augusta, Aqua 

 Claudia, Anio Novus, and the A. Alexandrina were added to the means 

 of supply ; and in the later days of the empire the daily distribution 

 of water amounted to the enormous quantity of 332,307,624 gallons. 

 As the population of Rome does not appear to have attained 1,000,000 

 under Aurelian, according to the calculations of M. Letarouilly, the 

 average supply must have been about 332 gallons per head per day ; 

 but as the registers of the distributions show that only one-fifth of the 

 totil quantity was tiken by private consumers, it must be evident that 

 the bulk of the water was devoted to the public fountains, baths, gardens, 

 and amphitheatres, &c. The text of Frontiuus contains many curious 

 details with respect to the manner in which the house services were 

 connected with the reservoirs, or distributory cisterns; the regula- 

 tion of the plumbers' works ; and the precautions observed to insure 

 the coolness and purity of the water; and there are few books illus- 

 trative of the manners and customs of the Romans which give so 



3o 



