Page:Collier's New Encyclopedia v. 08.djvu/217

LEFT SArED 173 SAFETY LAMP on one or on all sides. These bolts are moved by the door handle, and the lock key fixes them in their positions. The first great improvements in locks, as applied to safes, ai*e due to Chubb of London; but numerous patents, mostly of American origin, have been introduced. Of these the keyless permutation locks deserve particular mention, as they ob- viate the danger which arises from lost or false keys. Such locks allow of open- ing only after an indicator has been moved in accordance with a certain com- bination of numbers arranged before clos- ing the safe. Some safe locks are so constructed that to be freed they require different keys on different days, some can only be opened at a certain hour, this being fixed on before the door is closed; while others again require two or more keys in charge of different persons; in fact, the arrangements contrived to render the plundering of safes next to impossible are too numerous even to men- tion. The connection of safes with elec- tric alarms in a variety of ways forms another safeguard. SAFED, one of the four holy cities of the modern Jews in Palestine; in horse- shoe shape round a hill 2,700 feet above the Mediterranean; 6 miles N. W. of the Sea of Galilee. Here dwell about 15,000 Jews, Moslems, and Christians. The town was overthrown by earthquakes in 1759 and 1837. A castle of the Christians, built during the Crusades, was destroyed by the Sultan of Damascus in 1220, and, having been rebuilt by the Templars, was various safety devices, and secondly to educate the workers and the public to a realization of the need for greater care and thoughtfulness in a world in which the use of mechanical devices is continu- ally on the increase. Contrary to gen- eral belief the education of the worker is found to be far more important than the use of mechanical safety devices. In a report made by the Industrial Commis- sion of Wisconsin the statement is made: "We must conclude that the great ma- jority of accidents are not preventible by guards. ... If every danger-point on every machine were perfectly guarded, making accidents upon them impossible, then we would have eliminated just about one-fourth of all accidents." In other words, carelessness is the chief cause of accidents. Mechanical safety devices are constant- ly being introduced and are, already, countless in number. They vary from simple metal guards placed around mov- ing machinery to automatic devices which prevent, for instance, the moving of an elevator until its doors have been closed; and from simple gates across a level crossing to elaborate automatic signaling devices. Safety engineering also concerns itself with the prevention and extinguish- ing of fires, the provision of fire escapes, installation of safety-valves on boilers, adequate timbering and roofing of mines and tunnels, and with many other mat- ters far too numerous to mention. SAFETY LAMP. It has been long known that when methane, marsh gas, or again taken and destroyedby Beybars of light carbu reted hydrogen, which is fre Egypt in 1266. The Jewish colony has been settled here since the 16th century, and embraces many immigrants from Poland. SAFED KOH (White Mountains), a mountain range in Afghanistan. The W. portion of the chain separates the Herat river valley from the Murghab, while the E. Safed Koh forms the S. boundary of the Kabul basin. These mountains are quite alpine in their character, and some of the peaks exceed 15,000 feet in height. Among the spurs of the E. sec- tion are the passes leading from Kabul to Jalalabad, and from Jalalabad to Peshawur famous in the annals of British military expeditions into Afghanistan. SAFETY ENGINEERING, the name given to the study of methods and ap- pliances for the prevention of accidents in industry. Of recent years the matter has received much attention and has pro- cooling, and its transmission rendered im'- duced a nation-wide "Safety first" cam- possible. In this experiment high con- paign. Its purpose is to reduce injury ducting power and diminished diameter and loss of life caused by preventible compensate for diminution in length; and accidents and it seeks first to introduce to such an extent may this shortening of L— Cyc Vol 8 quently disengaged in large quantities from coal seams, is mixed with 10 times its volume of atmospheric air, it becomes highly explosive. Moreover, this gas — the fire damp of miners — in exploding ren- ders 10 times its bulk of atmospheric air unfit for respiration, and the choke damp thus produced is often as fatal to miners as the primary explosion. With the view of discovering some means of preventing these dangerous results, Davy instituted those important observations on flame which led him to the invention of the safety lamp. He found that when two vessels filled with a gaseous explosive mix- ture are connected by a narrow tube, and the contents of one fired, the flame is not communicated to the other, provided the diameter of the tube, its length, and the conducting power for heat of its ma- terial bear certain proportions to each other; the flame being extinguished by