The daily morning journal and courier., 1904-12-10

than are buildings, even if the trees are, as a rule, higher.
 But there must probably be some unknown reason, not only for the fre- quency with which trees are struck, but for the recurrence of such shocks in the case of particular trees, or trees in the same locality. The common est form of injury is that the current passes down the bark. of the tree, stripping off a band. wider or nar- rower, from top to bottom. Sometimes on an oak two or three of these lightn- ing marks are seen, evidently caused at different times.
 There must be something in the form which endangers 1t. An instance is quoted in MT Andersons interesting book of the Church of St Mary, in Genoa, which was frequently struck by Tightening, sometimes as often as twice year. It was noticed that the electric force always followed the same track. It was dicovered later that the walls were clamped with iron, and that the lightning had followed the patch in which the metal offered the greatest continuity. destroying the zone ] between.
 If the ground below the tree or build ing is hard and dry, the contact with l the earth, in which the lightning ex- bands it's force and disperses, is diffi- cult, and the destruction of the object struck is likely to result. This may ex- 1 plain the frequency with which a { blasted" tree is seen extending it's dead arms on the summit, of some rocky cliff or peak The ground below is dry. and does not easily lead away the cur rent into the earth.
 At the same time, thunder clouds undoubtly tend to discharge, or per- haps it would be safer to say that the transmission from. the clouds to the earth more frequently takes place, near pieces of water and along the course of rivers than elsewhere. In park in one of the eastern coun- ties there is a large lake. The park con- tains more trees struck by lightning | than the whole of the rest of the estate Some miles away is a road, called lo- cally the lightning road" from the AA N4aSAASJ WILL WAAlNh GllC11S4AbS llctNG OC- cured there, either to trees, horses, cat- tie or passengers. In this park there re- gently occurred an instance of the ex- plosive effect in certain circumstances not perfectly known.
 A very tall spruce, probably 100 feet high, was exploded from top to bot tom into pieces the size of the wood used in making chairs. Every shred of , bark was stripped from them, and the wood looked as if 1t had been shredded up for firing. A similar instance oc- cured some years ago, when an oak in | the grove below the foot of the White Lodge, in Richmond Park, exploded under lightning shock. The bark flew off and simply disappeared in small patches, and the rest of the tree was shattered into white fragments In these cases 1t is probable that the current sets up such tremendous heat that all the sap in the tree is converted into superheated steam, which explod- es. The greater the heat, the more of the cells in which moisture lies are ex- ploded, and the greater the destruction of the tissues of the tree. As there is most moisture between the bark and i the trunk, the first and greatest ex- plosion takes place there, instanly driving the bark away into space. Ere quently the explosion only takes place at that point.
 As Sir Hiram Maxim pointed out after the explosion of Mont Pelee. a very similar method is now used by the American manufacturers of wood pulp. The logs of fire are placed in strong chamber, and there subjected to the action of superheated steam until the water in every cell is converted into ex- plosive gas. The chamber is then open and the log explodes converting itself into wood powder. London Spectator.