Page:Popular Science Monthly Volume 16.djvu/718

688 remarkable for their regularity and uniformity. This was the second stage, and the heavily laden wires looked like nothing so much as gigantic combs.

It is not often that the third stage of development is reached; but it does sometimes happen that, when icicles and cylinder have attained their full size, the rain ceases, the sky clears, and the sun begins to shine. Its rays are much too feeble to melt the ice; but they pass through it to the more sensitive black wire within, whose temperature is so much raised that it melts the particles of ice in immediate contact with itself; its cohesion with the heavy roll of ice above is destroyed, and the latter, unable any longer to maintain its balance, twists round so as to describe a semicircle and exactly reverse its position. The icicles now stand up in the air above the wire, while the roll hangs below it; and, if there should be more rain, a second row of icicles will be formed opposite the first, producing a striking resemblance to the backbone of a fish, which is rendered still more perfect if there happens to be any wind blowing in the direction of the telegraph line, as in that case both rows of icicles will be slightly inclined toward the wire in the same direction. This last stage of. development may also be attained without rain, should the sun have sufficient power to melt some of the ice; the water from which will then trickle down to the under-side of the roll of ice, and there form icicles in a similar manner. As the sun gains in power, the wire increases in temperature, and melts away more of the ice from within; the icicles, borne down by their own weight, drop lower and lower, until the wire reaches the extreme points of the upper row, when of course the whole congealed mass soon drops off.

Herr Bajohr noticed that the effect produced by this phenomenon on the two lines of telegraph differed considerably, that of the Russian government suffering far more than the other. The posts of the Indo-European line are of iron, and the conducting-wires are thick and strong; and, though the wire was considerably stretched, it had on the whole borne well the immense strain put upon it. Here and there, where the line made a bend, the post at the angle, firmly fixed though it was, had sometimes given way, and, wherever this was the case, several of the neighboring posts had also succumbed. But the government line, with its oaken posts and four thin wires, running parallel with the Indo-European line, presented a much more dismal appearance. The oaken posts, somewhat crooked to begin with, had not all proved strong enough to sustain the weight of the four heavily laden wires, and in some places had broken down altogether; while, where they remained erect, the wires were either broken, or completely weighed to the ground by the burden laid upon them. All the posts, both iron and oaken, were covered on the windward side with a crust of ice several inches thick, reaching from the ground to the insulators, where it joined the ice on the wires; and in this way insulation was