Page:The American Cyclopædia (1879) Volume I.djvu/647

 AQUEDUCT Cii It is situated at the northern end of the palace, and is one story high, with a reservoir beneath the main saloon containing 80,000 gallons of sea water, and the tanks above 20,000 gallons in all, 100,000 gallons, weigh- ing 1,000,000 Ibs. Eighteen tanks with plate- glass fronts range along the left of the grand saloon, separated from the wall by a narrow passage, and a row of 21 shallow tanks, the inmates of which are held as a reserve force. To the right are two small rooms with 9 shal- low tanks each, in which the view is from above only ; here the* light is better suited to the growth of the sensitive rhodosperms (red algae). The 18 large tanks range in capacity from 4,000 gallons in the centre to 400 on the ends of the line. The water is elevated from the main reservoir through double sets of vul- canized rubber pipes, and discharged into the two central tanks at an average rate of 6,000 gallons an hour, the stream diverging north and south and passing through the main line into the reserve and side tanks, and thence returning to the reservoir. Independently, however, of the simple fall of water from one tank to another in steps of from 3 to 6 inches in height in the series 1 to 18, other streams of water, mixed with great quantities of air in minute bubbles, are driven from the main pipe into all the tanks with force, through jets ; so that myriads of such bubbles, controlled by stopcocks, are forced in a state of fine division (resembling falling sand, or steam) nearly or quite down to the bottom of each tank, and thus the fluid is charged with as much atmos- pheric air as it will take up in open vessels. The quantity of seaweed necessary to decom- pose the poisonous carbonic acid gas evolved from the animals, which could not be effected by mechanical agitation, is grown upon the rocks of the aquarium by the action of light on the spores of algae existing invisibly in the water. These tanks contain at present 95 distinct forms of marine life. A description of this work appeared in "Nature," vol. iv., p. 469. There are extensive aquaria in the principal continental cities of Europe, those of Naples, Brussels, and Berlin being the largest. For in- structions as to the management of the aqua- rium, Gosse's " Handbook of the Marine Aqua- rium " (London, 1854), and Hibberd's "Book of the Aquarium " (London, 1856), are safe and serviceable guides. See also Rossmass- ler's Das Susswasseraquarium (Leipsic, 1851). AQUEDUCT (Lat. aqua, of water, and ductw, a channel ; formerly spelled aquceduct), a chan- nel for the conveyance of water, or, in the more general acceptation of the word, a structure raised above the surface, upon which water conduits are laid. Methods of supplying water which do not include such structures are com- monly called water works. The use of these conveyances for water to supply cities may be traced back to a very remote period in Persia and in Judea. The "pools of Solomon," near Bethlehem, were three large reservoirs con- nected with each other, from which water was conveyed to Jerusalem, 6 m. distant. One of these pools was 582 ft. long, and, at an aver- age, about 180 wide. Jerusalem is still sup- plied with water from them through a 10-inch earthen pipe. In Egypt and Babylonia simi- lar works were constructed in very early ages. Enough remains of the ancient aqueduct of Carthage to show that it was one of the most remarkable of these great works ; upon it the waters from the mountains of Zeugis were con- veyed through an arched conduit 6 ft. wide Ruins of the Aqueduct of Carthage.