Page:Popular Science Monthly Volume 70.djvu/563

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of about one foot, and this may readily be conceived of as possible in cases where there was an unusual discharge of gas.

The explanation originally offered appears to fulfill all the observed conditions, and upon further study there seems to be no good reason for regarding it as other than valid. The flames are to be considered as resulting directly from the spontaneous combustion of light carburetted and phosphuretted hydrogen at the moment of their contact with the air, and these flaming gases in turn ignited the associated sulphuretted hydrogen, which gas then gave rise to secondary features such as the bluish, luminous flame and the sulphurous acid fumes. Examination showed that there was no adequate basis for any of the various attempts to explain the phenomenon as the result of volcanic action, the disruptive effects of a blast of fifty tons of dynamite two miles away, or the decomposition of fish, the phosphorescence of which was not clearly differentiated from the main features of the conflagration.

While it is a comparatively simple matter to reach the conclusions thus far given, it is altogether a more serious problem to ascertain the origin of the gas, the greatest difficulty being to determine how gas could be produced in sufficient quantity to give rise to a conflagration of the extent and duration observed. It is perhaps justifiable to conclude that the gas must have been accumulating at a slow rate for a long time, otherwise there would not have been such a large volume; and it is also reasonable to suppose that, unless liberated as fast as formed, smaller conflagrations should have been noted on previous occasions. But the local records, so far as the memory of 'the oldest inhabitant' extends, can show no similar occurrence in the past. Such storage of gas would be quite possible in a deposit of coarse gravel, pebbles and coarse sand, overlaid by a layer of fine, wet and compact sand acting as a retaining layer. It is possible, also, that the accumulation of gas may have been brought about under slight pressure, so that the earthquake of the day before may have furnished just that shaking which was necessary to disturb the conditions of equilibrium and liberate the gas at a critical moment. The occurrence of a smaller conflagration one month later may or may not harmonize with this idea, but it does seem to emphasize the suggestion of the storage of large volumes of gas which were not wholly set free on the first occasion. In endeavoring to account for the source of the gases, three explanations have been found to be possible:

1. The area protected by the barrier beach is, as already noted, somewhat depressed. It extends from the beach to a stone wall which may be seen just beyond the two elm trees; and from the square house to an almost equal distance beyond the corner of the hotel piazza on the right. It was originally occupied by Sir William Pepperrell as a deer park, but later it was utilized as a tan-yard.

Some years since two drains were laid through this area in such a way as to make sections of its entire extent. The ditches were car-