On board a cruiser that was recently undergoing repairs at Portsmouth, It was necessary to pierce a hole In the armor of a turret. The usual mechanical processes employed In such cases were so slow that a torpedo officer asked for permission to cut the hole by means of an electric arc. What this process consists of Is well known; one pole of a source of electricity Is joined to the mafis of steel to be cut; the other pole Is connected ? i'.h a large carbon having I in Insulated handle which the operator holds. The carbon Is placed in contact with the metal and an electric arc is formed, melting the metal at the points where the carbon Is successively presented. This undertaking, although not uncommon, caused a great deal of curiosity among the crew and drew a large number of spectators. Everything went well, and the steel of the armor, under the action of the current, melted like ice. But the next day all the men who were present at the operation, were either half blind or terribly burned. The officer who had directed the current, had the skin of his face completely puffed up, and of a leathery color; from It ran a serous liquid like that from a blister occasioned by a burn. Several sailors who were at quite a long distance from the turret had their sight so badly affected that they had to be treated In the hospital, lest they should lose It entirely. This was a characteristic case of electric sunstroke. It Is known that In the most common and least severe form, sunstroke consists In a redness accompanied by an irritating burning sensation that manifests Itself on the parts of the body that have been exposed to the sun. Sometimes, If a person has remained for a long time under a very hot sun, the burning becomes a pain. The red. tumefied skin looks like a case of erysipelas; later, little blisters, full of a clear liquid, may appear on the Injured portions. It was for a long time thought that these blisters due to the sun were burns; but It Is not so; they are not present In the burns that workmen have received when exposed to very Intense heats. They are produced by the light of the sun alone. If this light Is reflected by snow. It becomes particularly dangerous, and more than one Alpine climber has learned this to his disadvantage. On the mountains, on glaciers, or on fields of snow, the tourist may receive severe sunstrokes even with a cloudy sky and a cold atmosphere. These are true "sunstrokes In the shade" produced by the chemical rays of light. The electric arc, rich In chemical rays, particularly so when produced between certain metals, can give rise, as we have seen above, to the same symptoms that the sun Is able to produce. Therefore, It is extremely necessary to protect one's self when one Is exposed to a powerful arc or to the light of a mercury vapor lamp Inclosed In quartz glass, which Is permeable to ultra-violet rays. Ordinary glass employed In the manufacture of Cooper Hewitt lights stops the dangerous chemical rays sufficiently to render their effect unnotlceable. Cosmos. News has been brought by the United States revenue cutter "McCulloch" that the islands that recently appeared in the Bogostoff group, described In the SCIENTIFIC AMEKICAIS of October 26, 1907, and which were named McCulloch Peak and Perry Peak, have been destroyed through volcanic subsidence.