Page:The fairy tales of science.djvu/293

 This strange property of ice fully accounts for its obedience to the law of glacier motion discovered by Professor Forbes. “All the phenomena of motion,” says Tyndall, “on which the idea of viscosity has been based are brought by such experiments as the above into harmony with the demonstrable property of ice. In virtue of this property the glacier accommodates itself to its bed, while preserving its general continuity; crevasses are closed up; and the broken ice of a cascade, such as that of the Talèfre or the Rhone, is re-compacted into a solid continuous mass.

“But if the glacier accomplishes its movements in virtue of the incessant fracture and regelation of its parts, such a process will be accompanied by a crackling noise, corresponding in intensity to the nature of the motion, and which would be absent if the motion were that of a viscous body. It is well known that such noises are heard, from the rudest crashing and quaking down to the lowest decrepitation, and they thus receive a satisfactory explanation.” The reader will now be able to comprehend the wonderful phenomena presented by our moving lands; a glacier does not slide along its bed like a launching ship along her ways, nor does it flow, in virtue of any viscous quality, like thick mud or melted pitch; but its motion is the result of the minute, almost molecular, fracture and regelation of the ice particles, which move as if they were sand, continually thawing and re-freezing.