In one zone, however, the attack of the storm upon the wires was more serious. Between the snow of the higher mountains and the rain of the foothills lay necessarily a region of transition in which the precipitation was neither rain nor snow but something about half way between and much more clinging and tenacious than either. This half-frozen rain and half-melted snow often built up a solid sheathing, not to be shaken off of its own weight, and steadily growing heavier as the storm lasted. A catastrophic snapping of wires was prevented only by the saving circumstance that the zone was seldom more than a few miles broad and frequently shifted location as colder or warmer air blew in from the Pacific. With each shift of position the wires of any particular region had a respite and might manage to relieve themselves of their loads.

So, although no storm passed without damage, the actual damage could usually be attributed to some pyramiding of accidents which managed to overcome the margin of safety which man’s ingenuity had established.

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During the early hours of Monday morning such a critical condition existed at a point where the transmission line from French Bar Power-House ran along the side of a foothill ridge at an elevation of about three thousand feet. The line was of a kind which may be seen almost anywhere in the United States. The sturdy spruce poles were sixty feet high; each bore two well braced cross-arms, and eight wires. The three topmost wires were the heaviest and served as the three-phase high-voltage transmission line. These wires were carried upon large insulators, one at the very top of the pole, and the others at the ends of the upper cross-arm. Upon one side of the lower cross-arm, smaller insulators supported the three service wires, operating at a lower voltage and supplying current to the near-by district; the other side of this cross-arm carried the two wires of the company’s telephone.

The conditions of the storm were such that a strong south wind, funneling through a gap, was blowing up-hill and across the wires. Several miles farther south snow was falling from the clouds. As it fell, the snow half melted; then, as it was about to reach the ground, the strongly blowing wind swept it along and carried a large part of it actually up-hill. Since rising air grows cooler, the half-melted snow was quickly chilled below freezing, and in that condition was blown across the wires. Every particle which lodged upon them froze into solid ice at the moment of coming to rest. The lower wires were somewhat protected by the pine trees growing along the edge of the right-of-way, but the upper wires took the full attack of the storm.