574 LOG LOGAN he attracted the attention of Sir Henry de la Beche, who procured him an appoi-ntment on the Turco-Persian boundary commission, and from 1849 to 1852 he was a resident of Tur- key in Asia, and explored the sites of the an- cient cities on the Tigris and Euphrates. In 1853 he revisited the same ground under the auspices of the Assyrian society, and published in 1857 "Travels and Researches in Chaldsea and Susiana," &c., with engravings. Subse- quently he received an appointment on the staff of the geological survey of India, the operations of which were interrupted by the mutiny of 1857-'8. The specimens of ancient sculpture which he sent to the British mu- seum are hardly inferior in interest to those excavated by Layard, and he was the reputed discoverer of the city or cemetery of Warka, supposed to be the Biblical Erech. LOG, and Log Line, an apparatus used in con- nection with the half-minute glass for obtain- ing the approximate rate of movement of a vessel through the water. The log is a trian- gular or quadrangular piece of board, one side of which has a circular edge, and is weighted with lead, so as to cause the piece ta sit up- right when thrown into the water. It is at- tached by cords from its corners to the log line, which is a stout cord about 150 fathoms long, divided by knots or slips of leather into spaces called knots, and wound on a reel which revolves with freedom. Its use is called "heav- ing the log," and consists in dropping the wood over the stern of the vessel, with a quantity of the line sufficient to reach from the vessel to the log, at the instant the half-minute glass is turned up. The reel is held up so that the line may run off freely as the vessel moves away from the log ; and as the last sands run through the glass, the reel is instantly stopped. The number of knots run off in the half minute indicates the rate of motion of the vessel. This method of measurement is very inac- curate, a heavy sea sometimes throwing the log after the ship, while a head sea may carry it in the opposite direction. The glass also measures the half minute differently in damp and dry weather, and the line is liable to change its length. Various empirical allow- ances are made, which add but little to the correctness of the apparatus. It is not known when or by whom this contrivance was in- vented. Humboldt says that in all writings on the subject, including the " Encyclopedia Britannica," he found the erroneous opinion expressed that the log was not introduced before the end of the 16th or the beginning of the 17th century, while it is certain that Pigafetta, the companion of Magalhaens, early in the 16th century, speaks of the log {la catena a popa) as of a well known means of measuring the course passed over. Purchas makes mention of it in 1607; but the length of a degree of the meridian not being then determined, its divisions were necessarily in- accurate. They were corrected in 1635 by Norwood. The length of a sea mile is now estimated at about 6,086 ft. ; and as the length of the knot is intended to bear the same pro- portion to this that half a minute bears to an hour, the measurement of the knot is prop- erly 51 ft. Each one is divided into 10 parts called fathoms. For glasses which run out in 28 seconds, the length of the knot should be 47'6 ft. Numerous substitutes for the log have been contrived. The best of these is that of Massey. A box shaped like a wedge is pro- vided with a spindle to which four wings are fixed spirally. With this are connected regis- tering wheels somewhat on the plan of those of the gas meter, their object being to record the number of revolutions of the spindle. This is carried round by the motion against the water as the box is towed astern by a stout line 60 fathoms long. The box is hauled in, and the record noted whenever the course is changed; but while the ship runs full three knots the register is not reset except once every 24 hours. At a less rate its indications are uncertain from not towing horizontally. LOGAN, the name of five counties in the United States. I. A S. W. county of West Virginia, bordering on Kentucky, and drained by the Guyandotte and the Tug fork of Sandy river; area, 750 sq. m. ; pop. in 1870, 5,124, of whom 102 were colored. The surface is uneven and the soil generally good. Iron and coal are abundant in the highlands. The chief productions in 1870 were 135,273 bushels of Indian corn, 7,957 of Irish and 3,523 of sweet potatoes, 6,296 Ibs. of wool, and 29,182 of butter. There were 589 horses, 1,376 milch cows, 2,539 other cattle, 4,505 sheep, and 3,381 swine. Capital, Arracoma. IL A S. W. coun- ty of Kentucky, bordering on Tennessee, and drained by branches of Green and Cumber- land rivers; area, 478 sq. m. ; pop in 1870, 20,429, of whom 5,723 were colored. The surface, resting on cavernous limestone, is finely diversified and well timbered, and the soil fertile. It contains a number of ancient artificial mounds. The Louisville and Nash- ville railroad passes through it. The chief productions in 1870 were 255,049 bushels of wheat, 931,666 of Indian corn, 140,927 of oats, 18,036 of Irish and 23,937 of sweet pota- toes, 2,707,571 Ibs. of tobacco, 30,833 of wool, and 172,001 of butter. There were 4,807 horses, 2,618 mules and asses, 3,357 milch cows, 3,992 other cattle, 11,865 sheep, and 29,583 swine; 4 manufactories of agricultural implements, 11 of carriages, 2 of tin, copper, and sheet-iron ware, 3 of woollen goods, 3 tanneries, 3 currying establishments 7 flour mills, 4 saw mills, and 3 wool-carding and cloth-dressing establishments. Capital, Rus- sellville. III. A W. central county of Ohio, drained by the Miami river and its branches ; area, 425 sq. m. ; pop. in 1870, 23,028. The surface is moderately rolling or level, and the soil fertile. The Cleveland, Columbus, Cin- cinnati, and Indianapolis, and the Cincinnati,
