Page:Popular Science Monthly Volume 86.djvu/304

300 eruption to casual observers at a distance. With the intense sunshine of a July day at that elevation and with the dry air marked differences in temperature occurred between sunlight and shadow and between wet and dry areas. Under these circumstances strong whirlwinds developed at intervals which sent the dust high into the air in columns strongly resembling steam jets. In fact, the writer when within two miles of the peak on July 25 for a time mistook them for new steam vents, all the more readily since they were situated along the line of reported extensions of the crater. Actual inspection of the area showed the real character of the columns and also that no new vents had been formed in that locality. Probably several of the incorrect reports of eruptions and of new craters came from the same failure to distinguish wind-formed dust clouds from steam explosions.

During the month of August there were but eight eruptions, fewer than either of the preceding months, and seven of the eight, all quite severe occurred August 19-23, inclusive, two of them throwing ash columns to a height of over 10,000 feet. The record for September shows seventeen eruptions, the largest number for any of the six months covered by the tabular list. During the month there was a continuous enlargement of the vent within the basin of the old crater and there were also new vents opened (see Fig. 4) on the outer slopes of the main cone. These vents are clearly identified from photographs taken by Mr. Jack Robertson of Oakland as being in line with the main axis of the first opening. Mr. Robertson had an interesting experience. He was at Drakesbad on the evening of September 19 when he heard a “tremendous explosion” during the night. The next morning he climbed the mountain and had the good fortune to watch at close range the eruption beginning at 11:30 (eruption no. 46) without receiving any serious injury. The crater was belching smoke at short intervals every few minutes and while he was quite near, steam and ashes poured out from its entire length. The ashes were so hot that they burned his feet as he walked over them. He reports having heard the roar and rumble of the explosions, but was not conscious of any apparent quaking of the ground.

The most marked changes in the new crater since the middle of June occurred during the month of September. The inner vent is reported to have grown to 900 feet in length and photographs taken early in October show that the area of the opening had become fully five times its area at the end of June. The severity of the September eruptions is also attested by the fact the lookout house (Fig. 5 and 6) was completely demolished on the twenty-ninth, no part of the walls being left standing. During the same eruption the forest lookout on Turner Mountain distinctly saw luminous bodies thrown out which appeared to him to be red-hot stones. This report is con-