BLOCKADE. 185 BLOCK-SIGNAL SYSTEM. favorable as ever can be expected. The South possessed a long land frontier, but except along the Mexican border it was dominated by the United States forces. The navy held several bases in the enemy's territory, and could have had others had it been deemed necessary. As the South had almost no seagoing naval force, many of the blockading ships were lightly armed mer- chantmen commissioned as auxiliaries. Block- ading fleets will always be largely composed of such craft if the extent of blockaded coast is great, because no nation has a sufticient number of regularly built war-ships available for such duty, and for stopping merchant vessels they are quite as good as more powerfully armed and better protected ships. If the enemy still pos- sesses seagoing fighting ships, they must be kept in port by an adequate force of tighting ships, or they may escape and raise the blockade of ports where the enveloping fleet is weak. One of the closest blockades ever maintained was that of Santiago by the fleet under Admiral Sampson during the Spanish War. Seven of the heaviest ships in the navy lay in a semicircle about the entrance to the harbor, about two thousand yards apart, and from four to six thousand from the entrance. In addition to these were several cruisers, auxiliary yachts, and torpedo- boats. At night, auxiliary cruisers and steam- launches patrolled the entrance, which was light- ed up by search-lights of one of the battle-ships. Not even a skiff could have left the harbor un- observed. The establishment of a blockade of the enemy's coast protects a country's commerce because it prevents, or tends to prevent, the fitting out of cruisers to prey upon it. But the war against commerce— what the French call the guerre dc course — is becoming of less and less importance. The capture of merchant vessels has never afi'ected the result of war, and the operations of 'commerce-destroyers' are likely to be attended with difficulties." It is no longer possible for them to keep the sea for long periods, as their radius of action is limited by their coal-supply. Furthermore, merchant vessels of belligerents are likely to be transferred to neutral flags if the insurance rates rise unduly through greatly in- creased danger of capture. And. lastly, the ten- dency of modern warfare is toward increased exemption of private property from capture. A military blockade is designed to shut off an enemy from" his source or base of supplies, make him inellective, and eventually force him to sur- render through lack of food, water, ammuni- tion, or other supplies. It is not a regular siege, in the sense that organized efforts are made to take the ba.se by assault; neither is it necessarily accompanied by a regular l)ombardment, though it may be subject to such intermittently. The military blockade, from the point of interna- tional law, does fiot occupy so important a place as the navul operation. BLOCK BOOKS. See Printing. BLOCK COAL. A name given to certain non-coking liiluminous coals of Ohio and In- diana, on account of the cube-like forms into which they break. BLOCKHOUSE. A temporary military for- tiflcatiiiM, u--ually made of logs banked with earth and surrounded by a stockade. Its con- struction will depend largely on the service it is intended for, the country in which it is used. the troops occupying it, and the material avail- able. Blockhouses were extensively used in the American Civil War of 18G1-G5; for instance, to protect the long line of communications of Sher- man's army in the Atlanta campaign. The Spaniards, during the closing years of their occu- pation of Cuba, adopted them extensively, nota- bly along the line of the 'Trocha.' The vastness of the theatre of operations in the British-Boer War of 18!)i)-l!l02, and the extreme mobility of the Boers, compelled the British to secure all cleared country by an extensive system of block- houses, built at intervals of from (iOO to 1000 yards, and connected when possible by wire en- tanglements. Such defenses can be made more or less strong and defensible, depending on time and conditions. See Fortification. BLOCK ISLAND. An island in the Atlan- tic, 10 miles south of the Rhode Island shore, and northeast of Long Island (Map: Rhode Is- land, Bo). It is about S miles long and from 2 to 4 miles wide, forming the town of New Shoreham, Xew2)ort County, R. I., well known as a popular summer resort. There are lighthouses on the northern and southeastern extremities. The island was named by Adriaen Block, who vis- ited it in 1014; was first settled in 1602, and was captured by French privateers in 1089. In 1720 a ship bearing emigrants from the Palatinate was wrecked here; and this, together with the occa- sional appearance of an irinis fat u us ofl'-shore, gave rise to the legend which forms the subject of Miittier's "The Palatine" and of Dana's "The Buccaneers." Population, in 1800. 1320; in 1000, 1.396. Consult Livermore. A Ilistori/ of Block Island from IfW, to 1S76 (Hartford. isTT). BLOCK PRINTING. See Printing. BLOCKSBERG, bloks'berK (corrupted, in German popular speech, from Brocksherg : the Brocken Mountain). A name given to various mountains and hills in Germany, but preemi- nently to the Brocken, 3745 feet, the highest point of the Harz Mountains, and, indeed, of the north of Germany (Jlap: Germany, D 3). In old legend it is the favorite haunt of the witches, where theyeelebrate the night of the first of May, Walpnriji'snacht (see Walpurga), with wild or- gies. Almost all mountains thus haunted have been famous as places of sacrifice in the ages of paganism. See Brocken. BLOCK-SIGNAL SYSTEM. A method in use on railways to insure increased safety by keeping trains a certain distance ajiart, by divid- ing the line into blocks or sections, the entrances to which are guarded by ap])ro])riate signals for the government of the train. The blocks may be of any reasonable length, depending upon the physical characteristics of the line and the fre- quency with which the trains are run. On lines of heavy traffic the blocks are often only several hundred yards long, while on lines with a light traffic they may be several Tuiles in length. The block systems used in modern railway practice are: (I) The manual; (2) the controlled man- ual: (3) the auto-manual; (4) the automatic, <ind (.5) the train staff or machine. In manual blocking the signals at the entrance to each block are ojjerated and controlled by the signal- man at that station. In controlled manual-l)look systems the signals at the entrance of each block are controlled either electrically or mechanically by the signalmsn in the next station ahead, but
