BROKEN HILL (Willyama), a famous mining city in Yancowinna county in the central west of New South Wales, 35 m. from the South Australian border. It lies at an elevation of 5,000 ft. on the east flank of the Barrier range, some 200 m. from Spencer's gulf and 55o from the east sea-board. The region is sub-arid, hot in summer, cool (with frosts) in winter; mean annual temperatures: 78°-51° F; absolute extremes: 115.9°– 28.5° F ; average annual rainfall c. so in., but erratic-3.6-17.6; average annual evaporation : c. 7 ft. 6 in. Heavy dust-storms are frequent. The mulga, bluebush and salt-bush hills and plains, richly grassed after rains, form rather poor pastoral country where not bared by the mining settlements. The highly compressed and tilted sedimentary (pre-Cambrian) rocks (with igneous intrusions and quartz reefs) of the Barrier range had a "replacement" lode which outcropped as two connected arcs over a distance of c. 3 m. with a width varying from 200 to 3 ft. The outcrop originally appeared as a manganiferous ironstone (gossan) ridge and was first mined (1883-84) for tin, though silver and lead mines of some value had previously been worked in the area, notably at Silverton. Secondary enrichment, due partly to the arid climate, had led to ores (native silver, chlorides, etc., and further down, lead car bonates) of extraordinary richness in the upper parts. Below these the ores became lead-zinc-silver sulphides of lower but more uniform value. By 1924 workings had reached a depth of 1,800 ft.; some 35,000,000 tons of ore had been removed (19a 5) and a further 53,000,000 tons, with uncalculated reserves beyond, were available. The value of the total output (to end of 19z 5) was £127,500,000 and £28,000,000 had been paid in dividends. The maximum output was in 1913-1,750,000 tons; thereafter the average has been c. 1,250,000 tons, though 1919 and 1920 were years of strikes, low prices and very low production. Ore-treat ment methods have changed along with the type of ore and the growth of technical .knowledge. To-day the zinc-lead-silver sul phides are uniformly dealt with by the "flotation" (eucalyptus oil) process. Smelting and concentrating, formerly conducted on the field, were progressively transferred to Port Pirie (South Aus tralia) on Spencer's gulf (a S4 m. by rail) where fuel, fluxes and transport are more readily available. The zinc residues were for long used as filling or accumulated as enormous dumps. In 1913 c. 500,000 tons of zinc concentrates yielding some 200,000 tons of zinc or -A- of the world's supply, were shipped abroad from Broken Hill, only 5-7,000 tons zinc were produced at Port Pirie. In 1918, after experimental work, zinc production was started on a large scale (Ioo tons per diem) at Risdon (Hobart, Tasmania), where water-power is available for the electrolytic process. Con siderable quantities of zinc concentrates (1925: 226,500 tons) are still exported (United Kingdom, Europe and japan) but Risdon takes increasing quantities and amongst its by-products produces sulphuric acid valuable in the manufacture of superphosphates. The lead ores are now smelted almost entirely at Port Pirie. Broken Hill is the third city of New South Wales. Its population shows the fluctuations natural to a mining centre (1914: c. 35,000; 1926: c. 24,000). It is substantially built and well equipped. The difficulty of water supply has been met by the construction of two large dams, 1 o and 19 miles distant respectively, and the con struction of two additional reservoirs was under consideration in 5928. Broken Hill is 335 m. by rail from Adelaide and its main economic and business relations are with South Australia. Recently the line to Sydney (703 m.) has been completed and forms a pos sible alternative route from Adelaide to Sydney.