“From one of the last columns about a third broke off, and, bending between me and the sun, left his image quite black upon the retina.
“Prepared for the close, we had reached the basin in time to see the last portion of its contents running into the well, leaving the basin burning hot, and not a drop of water in it. The well was standing about 12 feet down, the water slowly rising, and taking about 15 minutes again to fill the basin.
“During these eruptions the rush of boiling water never ceased; but uniting to the east of the mound, it flowed down to the river in a continuous stream, in some places 20 yards in breadth.
“Taking the average height of the columns of water at 45 feet, and eight shoots in a minute during a period of eruption of 7½ minutes, the discharge is 1,410,600 gallons; or take one column 80 feet by 10 feet 4 inches diameter, gives 41,797 gallons at one discharge; a shot weighing 186 tons 11 cwts. 3 qrs. 17 lbs. from this great gun, to which the Woolwich Infant is but a babe.
“To the eye, so far as could be seen, the pipe was quite cylindrical; and, plumbed all round, no irregularity was discovered, except at the bottom, which was very irregular, giving to my line a depth of 80 feet on one side, 82 on the other. My tent companion and friend, the late Robert Allan, in a paper read at the meeting of the British Association at Glasgow in 1855, and published in its Transactions, gave the depth 83 feet 2 inches. The diameter of the basin from two points—72 feet 6 inches, 68 feet 1 inch: my four measurements taken twice on the surface of the water gives the average of 66 feet.
“Assembled round the basin, which had now filled, the water smooth and bright, with a thin screen of vapour carried to the south, a curious discovery was made. Standing with his back to the sun, and looking into the basin, the spectator saw his face and head clear as in a mirror, surrounded by a halo of bright prismatic colours. The coloured rays extended round the head to the distance of 2 or 3 feet, forming two-thirds to three-fourths of a circle, the lower portion wanting. The observer could only see his own likeness, not that of his neighbour.
“The temperature of Geyser at rest varied from 180° to 188°, but no perceptible difference was noticed before or after the explosions.
“The heat of the water may be ascertained very nearly by observing the amount of steam given off.
“During eruptions the water was expelled at a temperature far above the boiling point, as the dense masses of steam clearly showed.
“There was no steam from Geyser, which was not given out from the water itself, during the explosions.