Page:Popular Science Monthly Volume 59.djvu/545

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FOG STUDIES ON MOUNT TAMALPAIS.

FOG STUDIES ON MOUNT TAMALPAIS.
By ALEXANDER McADIE.

LATE on a February afternoon the passengers on a large Pacific Mail steamship sighted the Farallones and doubtless thought as the pilot came aboard that the long run across the broad ocean not always true to its name was safely over and danger past. The 'Rio de Janeiro' came to anchor a little before six o'clock on Thursday night, February 21, 1901, and the weather being foggy, the captain wisely remained at anchor until about 4 a. m. when the fog lifted. The lights of the Cliff House two or three miles away could be seen and the vessel started on a northeast course with Lime Point dead ahead. There is some difference of testimony as to whether the Captain or Pilot gave the order to go ahead. The fog closed down again and the Pilot steered by the whistle hoping to get the echo from Point Diablo. No echo was heard. The vessel was not moving at full speed, the First Officer was standing on the starboard side listening for the Fort Point bell and the Captain and Pilot were on the bridge. No soundings however were taken. At about 5:30 a. m. the vessel struck the Fort Point Reef, backed off and within twenty minutes had gone from sight with 130 of the 210 persons aboard.

The two diagrams herewith show the general approach to the Bay of San Francisco and in more detail the probable path steered by the 'Rio' with zones of inaudibility of the fog signals.

When all is said and done it appears that the fog was the prime cause of this appalling accident. Now, while an accident of such magnitude gives startling emphasis to the need of studying fog, a summation of the minor accidents for a single year due to fog in any large seaport would be equally impressive. One cannot cross the sea, run down the coast or even go over a bay upon a ferry-boat without experiencing at times this troublesome condition. Nor is it only when on the water that we are at the mercy of the fog. Study the statistics of railway accidents and you will be surprised how often, in the column giving the cause of collision or other accident, the word fog appears. Can we help ourselves? Yes; and the first step is to study patiently and systematically the various types of fog formation. Already the ability to communicate by means of wireless telegraphy between vessels at sea and the land removes the greatest element of danger to vessels caught in fog. The 'Rio de Janeiro' was lost at the entrance to