A T W A T mass, as determined by weighing in air of 30-inch pressure and 62 F. of temperature, is equal to 10 lb avoirdupois. The kilo gramme in like manner is the mass of 1 cubic decimetre of water, measured at the temperature corresponding to its maximum density (4 C. ). The two fixed points of the thermometer correspond the lower (0 C., or 32 F. ) to the temperature at which ice melts, the upper (100 C. or 212 F. ) to that at which the maximum tension of steam, as it rises from boiling water, is equal to 760 mm. or 30- inch mercury pressure. 30 inches being a little more than 760mm., 212 F. is, strictly speaking, a higher temperature than 100 C., but the difference is very trifling. Specific heats are customarily measured by that of water, which is taken as = 1. All other specific heats of liquids or solids (with one solitary exception, formed by a certain strength of aqueous methyl alcohol) are less than 1. The temperate character of insular climates is greatly owing to this property of water. Another physiographically important peculi arity of water is that it expands on freezing (into ice), while most other liquids do the reverse. 11 volumes of ice fuse into only 10 volumes of water at C. ; and the ice-water produced, when brought up gradually to higher and higher temperatures, again exhibits the very exceptional property that it contracts between and 4 C. (by about n^^ of its volume) and then expands again by more and more per degree of increase of temperature, so that the volume at 100 C. is 1 - 043 times that at 4 C. Imagine two lakes, one containing ordinary water and another containing a liquid which differs from water only in this that it has no maxi mum density. Imagine both to be, say, at 5 C., and cold winter weather to set in. Both lakes become colder, being cooled down by convection until they are at 4 C. The imaginary lake then continues losing heat in the same way ; in the real lake the colder water floats on the surface and the underlying mass of water can lose heat only by the slow process of conduction. The real lake retains its heat more tenaciously, but for the reason stated will draw a sheet of ice, while the imaginary lake is still on its way to C. The latter, indeed, if the winter is short, may fail to freeze altogether, while the former does freeze superficially. In either the freezing is a slow process, because for every pound of ice pro duced 80 pound-centigrade units of heat are set free. Let us now assume that, after even the imaginary lake had drawn a sheet of ice, warm weather sets in. In either case a layer of liquid water of C. is formed on the ice, and through it the heat from the air travels, in the imaginary case by slow conduction, in the real case by quick convection. The real ice is the first to disappear, and the upper strata of relatively cold water will soon come up to 4 C. by the prompt effect of convection, while in the case of the imagin ary lake it takes a far longer time before all the mass has come up to 4 C. by conduction. From 4 C. upwards, heat is taken in at the same rate on both sides. In former times water was viewed as an "element," and the notion remained in force after this term (about the time of Boyle) had assumed its present meaning, although cases of decomposition of water were familiar to chemists. In Boyle s time it was already well known that iron, tin, and zinc dissolve in aqueous muriatic acid or vitriol with evolution of a stinking inflammable gas. Even Boyle, however, took this gas to be ordinary air contaminated with inflammable stinking oils. This view was held by all chemists until Cavendish, before 1784, showed that the gas referred to, properly purified, is free of smell and constant in its properties, which are widely different from those of air, the most important point of difference being that the gas when kindled in air burns with evolution of much heat and formation of water. Cavendish, however, did not satisfy himself with merely proving this fact qualitatively; he determined the quantitative relations, and found that it takes very nearly 1000 volumes of air to burn 423 volumes of "hydrogen" gas ; but 1000 volumes of air, again, according to Cavendish, contain 210 volumes of oxygen; hence, very nearly, 2 volumes of hydrogen take up 1 volume of oxygen to become water. This important discovery was only confirmed by the sub sequent experiments of Humboldt and Gay-Lussac, which were no more competent than Cavendish s to prove that the surplus of 3 units (423 volumes instead of 420) of hydrogen was an observa tional error. (W. D.) WATERBURY, a city in Newhaven county, Con necticut, United States, is situated on the Naugatuck river, 77 miles north-east of New York, at the junction of three railroads connecting it with Bridgeport, Hartford, and Meri- den. It was settled by colonists from Hartford in 1G77, and bore at first the Indian name of Mattatuck. The land, rocky and hilly, was poor for farming, and the inhabitants began to turn to manufacturing pursuits, in a humble way, before 1800. But the growth in population and business was very slow, till the civil war created such a demand for brass and manufactured articles of that metal that the small factories rapidly grew in number and size, and Water- bury has now become the centre of the brass industry in the United States. Its factories represent an outlay of 10 million dollars, and turn out a great quantity of sheet brass and copper, wire, and tubing, with a multitude of small articles clocks, watches, lamps, pins, silver-plated ware, &c. The population, which is largely German and Irish, was 17,80G in 1880, and is now (1888) believed to approach 27,000. The city is well lighted by electric lights, and supplied with pure water from a spring-fed reservoir 6 miles distant. A free loan and reference library, founded in 1868, contains 42,000 volumes. Waterbury was incorporated as a city in 1853. WATERFORD, a maritime county of Ireland, in the province of Munster, is bounded E. by Waterford Harbour, separating it from Wexford, N. by Kilkenny and by Tipperary, W. by Cork, and S. by the Atlantic. Its greatest length from east to west is 52 miles, and its greatest breadth from north to south is 28 miles. The total area is 461,552 acres, or about 721 square miles. The coast-line is in some parts bold and rocky, and is in dented by numerous bays and inlets, the principal being Waterford Harbour ; Tramore Bay, with picturesque cliffs and some extensive caves, and noted for its shipwrecks, on account of the rocky character of its bed ; Dungarvan Harbour, much frequented for refuge in stormy weather ; and Youghal Harbour, partly separating county Waterford from county Cork. The surface of the county is to a large extent mountainous, especially towards the west and north west, consisting chiefly of metamorphosed Lower Silurian rocks, the valleys being occupied by Carboniferous Lime stone. There is also evidence on an extensive scale of former glacial action. The Knockmealdown Mountains, which attain a height of 2609 feet, form the northern boundary with Tipperary. A wide extent of country between Clonmel and Dungarvan is occupied by the two ranges of the Commeragh and Monavallagh Mountains, reaching in Knockanarian a height of 2478 feet. To the south of Dungarvan there is a lower but very rugged range, called the Drum Hills. The south-eastern division of the county is for the most part level, consisting chiefly of clay slate interrupted by patches of primitive limestone, and also by conglomerate and basalt, forming in some parts of the coast lofty columnar cliffs. Coal and iron were formerly wrought, but the only mineral product now of importance is copper, the mines at Knockmahon ranking next in Ireland to those at Berehaven. Lead mining, for merly prosecuted with some success, has now practically ceased. Lime is abundant, and coralline sea-sand is ob tained. Slate is quarried in considerable quantities at Lismore, and there are also quarries of valuable sandstone and of marble. Ochres and clays for the manufacture of earthenware are also obtained. Though Waterford has benefited in its communications by the important rivers in its vicinity, the only large river it can properly claim as belonging to it is the Blackwater. This enters the county to the east of Fermoy, and flows eastward along a trough of Carboniferous Limestone to Cappoquin, where it turns abruptly southwards, to fall into the sea at Youghal Har bour. At its junction with the Bride below Cappoquin it is navigable for vessels of 100 tons burden. Waterford Harbour may be called the estuary of three important rivers, the Suir, the Nore, and the Barrow, but neither of the last two touches the county. The Suir reaches it at its union with the Nier about 8 miles from Clonmel, and thence forms its northern boundary with Tipperary and Kilkenny. It is navigable for vessels of 800 tons burden to Waterford, for barques and large lighters to Carrick-on-Suir, and for boats of 50 tons to Clonmel. Agriculture. The land is generally better adapted for pasturage
than for tillage, although there are considerable tracts of rich soil in