Mr. W. R. Raymond, in 1869, concluded from his own observations about the lava cave in Washington: that the cold air of winter freezes up the percolating waters from the surface, layer upon layer, solid from the bottom, and the accumulated ice thaws slowly in summer, being retarded by the covering which keeps out the direct rays of the sun, and by the fact that the melting ice at one end of the cave, through which the summer draught enters, itself refrigerates the air and maintains a freezing temperature at the other end. Dr. C. A. White, in 1870, says of the cavern at Decorah: "The formation of the ice is probably due to the rapid evaporation of the moisture of the earth and rocks, caused by the heat of the summer sun upon the outer wall of the fissure and valley side. This outer wall is from ten to twenty feet in thickness where the ice was seen to be most abundant. The water for its production seems to be supplied by slow exudation from the inner wall of the cave." Dr. Krenner, in 1874, wrote of Dóbsina as "a natural ice cellar of giant dimensions, whose ice masses formed in winter, the summer does not succeed in melting." Professor W. Boyd Dawkins wrote in 1874: "The apparent anomaly that one only out of a group of caves exposed to the same temperature should be a glacière, may be explained by the fact that these conditions [those formulated by the Rev. G. F. Browne] are found in combination but rarely, and if one were absent there would be no accumulation of perpetual ice. It is very probable that the store of cold laid up in these caves, as in an ice house, has been ultimately derived from the great refrigeration of climate in Europe in the Glacial Period." Mr. Theodore Kirchhoff examined the lava caves in the State of Washington and in 1876 wrote that he considered that the ice in the smaller ones were simply remains of the winter's cold. He thought that the ice in the large cave where there is a draught could not be accounted for in the same way, so he concluded that the ice must be due to the draught. Mr. N. M. Lowe, in 1879, proposed the Compressed Air or Capillary theory[74] about the Cave at Decorah. [74] See Part II., page 142. Mr. John Ritchie, Jr., in 1879, gave an exceedingly clear exposition of the theory in the same journal.