1878] WRITINGS OF JOSEPH HENRY. 533 



stance in which the whole body of the tree was separated 

 from the trunk, and falling into soft earth, was left standing 

 in a vertical position. 



The other phenomenon of the burned gilding in the inner 

 room appears to me to be due to the action of what is called 

 the return stroke. The house and all conducting material 

 within it, before the moment of the discharge, supposing the 

 cloud to be positive, were electrified negatively. When the 

 discharge took place the tension was suddenly relieved and 

 the natural equilibrium restored with such intensity that the 

 effect described was produced. 



The other storm occurred at Carysfort Reef light-house, 

 Key West, Fla., about seven miles from the nearest land, 

 on the 12th of April, 1877. This light-house is built in the 

 water on a submerged reef, and consists of a framing of stout 

 iron pillars or piles, each about 100 feet in length, arranged 

 in the form of an octagon, with one pillar in the centre, 

 interlaced at various points regularly with smaller iron rods. 

 It is 122 feet in height to the top of the lantern. At about 

 forty feet above the water is the keeper's dwelling, some forty 

 feet in diameter, the roof and sides of which are of iron-plate, 

 while the floor is of wood. From the roof of this dwelling, 

 extending to the lantern directly above, is an iron cylinder 

 thirteen feet in diameter, containing the spiral stairway. 



The following account of the storm and its effects, is given 

 in a letter to Capt. W. H. Heuer, light-house engineer, from 

 C. D. Hawkins, lampist of the seventh light-house district: 



" On the afternoon of the 12th of the present month (April, 

 1877) I noticed indications of a squall, and on consulting 

 the barometer found it was falling. At sunset the wind was 

 blowing rather fresh from the southward, — the sky being 

 dark and wearing a thickened aspect. About 9 p. m. a 

 very severe squall struck the light-house, the wind having 

 increased to a perfect gale, which was accompanied by thun- 

 der and lightning. The thunder was of the most terrific 

 character, resembling in sound an artillery duel. There 

 was not exceeding one-fourth to one-half a second between 

 the flashes of lightning. About 10:30 p. m. the light- 

 house was struck. The report caused thereby resembled 



