DEVONSHIRE, a maritime county, in the s.w. peninsula of England, between the Bristol and English channels. Greatest length, 71 m.; greatest breadth, 68; average, 46; area, 2,590 sq.m., three fourths being in pasture or arable. The n. coast, 60 m. long, is mostly steep and rocky; the chief indentation being Bideford bay, 18 m. broad and 8 deep. The s. coast, 100 m. long, is also lined with cliffs, and has Tor bay, 3 by 31- m., and Plymouth sound, 3 by 3 miles. The general surface is hilly, and the tablelands of Dartmoor in the, s. of D., Exinoor in the n.e. of Devon and n.w. of Somer set, and Blackdowu in the e. of D. are high, heathy, and rocky. The lower hills aro grassy. The loftiest eminence is Yes Tor, in Dartmoor forest, 2,050 feet. The chief rocks are granite in Dartmoor, and Devonian, carboniferous, and Permian strata, with some Silurian strata. magnesian limestone, greensand, chalk, and trap. Copper, tin, iron, and other metals occur, with potters' and pipe clays, Bovey coal, marble, gypsum, fluor-spar, and loadstone. The rivers are very numerous, the chief being the Exe, 54 in. long.; Dart, 36; Tamar, 59; Torridge, 53; and Taw. These rivers have tidal estua ries, 5 to 11 in. long. There is an intermitting spring at Brixham, The climate is humid and equable—cool in summer, and mild in winter. The great mildness of the s. coast in winter has made it much resorted to by invalids, especially those in consump tion. Here myrtles flourish in the open air, and, with a little care, the orange and lemon. From its humidity, D. is more grassy than Cornwall, and there are fine mead ows along the rivers. In the s., especially in Exeter Vale, the soil very productive.
The chief crops arc grass and clovers, alternating with corn and potatoes. The fertile red loam of Exeter Vale produces wheat, barley, beans, pease, and flax. D. has much oak-wood and extensive orchards. It is famed for clotted cream and cider. The apple trees grow on the hill-slopes and in the hedges. The chief manufactures are serges, linen, gloves, and lace; the chief exports are butter, cheese, cattle, and sheep. The red Devon breed of cattle is highly valued. Dartmoor mutton and Exmoor ponies arc famous. D. has important pilchard, mackerel, dory, and salmon fisheries. The elec tric torpedo occurs in the estuaries. D. is divided into 33 hundreds, 470 parishes, and 17 poor-law unions. The chief towns are Exeter (the county town), Plymouth, Devon port, Tavistock, Tiverton, and Barnstaple. D. sends 17 members to parliament-6 for the county, and 11 for the above towns. Pop. in '61, 584,531; in '71, 601,374. Prior to the reform act of 1867, D. had 22 members, but by that act, and the Scottish reform act of 1868, the county gained 2 members, while the boroughs lost 7. D. has many British and Roman remains, as stone circles, dolmens, barrows, and camps. The Sax ons failed to conquer D. till the 9th century. It was ravaged by the Danes in the 9th
and 10th centuries, and by the Irish iri the 11th century. At the reformation, 1549, there were great disturbances in Devonshire. In 1688, the prince of Orange landed at Tor bay.
DEW. For any assigned temperature of the atmosphere, there is a certain quantity of aqueous vapor which it is capable of holding in suspension at a given pressure. Conversely, for any assigned quantity of aqueous vapor held in suspension in the atmos phere, there is a minimum temperature at which it can remain so suspended. This minimum temperature is called the dew-point. During the daytime, especially if there has been sunshine, a good deal of aqueous vapor is taken into suspension in the atmos phere. If the temperature in the evening now falls below the dew-point, which after a hot and calm day generally takes place about sunset, the vapor which can be uo longer held in suspension is deposited on the surface of the earth, sometimes to be seen visibly falling in a tine mist. This is one form of the phenomenon of dew, but there is another. The surface of the earth, and all things on it, and especially the smooth surfaces of vege table productions, are constantly parting with their beat by radiation. If the sky is covered with clouds, the radiation sent back from the clouds nearly supplies an equiva lent for the heat thus parted with; but if the sky be clear, no equivalent is supplied, and the surface of the earth and things growing on it become colder than the atmosphere. If the night also be calm, the small portion of air contiguous to any of these surfaces will become cooled below the dew-point, and its moisture deposited on the surface in the form of dew. If this chilled temperature be below F., the dew becomes frozen, and is called hoar frost. The above two phenomena, though both expressed in our lan guage by the word dew, which perhaps helps to give rise to a confusion of ideas on the subject, are not necessarily expressed by the same word. For instance, in French, the first phenomenon—the falling evening-dew—is expressed by the word serein; while the latter—the dew seen in the morning gathered in drops by the leaves of plants, or other cool surfaces—is expressed by the word rosee.
The merit of the discovery of the "Theory of Dew" has been commonlv ascribed to Dr. Win. Charles Wells, who published in 1814 his Essay on Dew, which obtained great popularity. The merit should, however, be divided between him and several others. M. Le Rol of Montpellier, 11I. Pictet of Geneva, and especially prof. Alex. Wilson of Glasgow, largely contributed by experiment and induction to its formation. Its history is very the curious reader will be well repaid by a perusal of an article on the subject by Mr. Tomlinson of King's college school, London, in the Edinburgh :Yew Philosophical Journal (new series), vol. xiii. No. 1. Jan., 1861.