"What is that?" she asked as the tremors grew stronger.
This instrument, which has a magnification of 2200, detects the slightest tremors, and is consequently most useful in recording earthquakes of distant origin; its high sensitiveness and complications, however, militate against its common use.
Tremors of the muscles more or less violent accompany the cold sensations, beginning with the muscles of the lower jaw (chattering of the teeth), and extending to the extremities and trunk.
Earthquakes and earth-tremors grade into one another, and in almost every earthquake there is some tilting of the surface.
Lead poisons the muscular and nervous systems, and gives rise to paralysis, wasting, colic and other symptoms, while in the case of mercury, tremors, salivation, anaemia and very marked cachexia are induced.
Some of these, which may be called " earth-tremors," resemble earthquakes in the rapidity with which they occur, but differ from earthquakes in being imperceptible (owing to the smallness of the motion) until instrumental means are used to detect them.
They occur in all seasons, scores of slight tremors being recorded every year by the Weather Bureau; but they are of no importance, and even of these the number affecting any particular locality is small.
When this gland becomes enlarged, and its secretion consequently increases, the vessels dilate, the heart beats more rapidly, the skin becomes too hot, the nervous system becomes irritable, and tremors occur in the limbs.
Savart showed, by a suitable isolation of the reservoir from tremors, whether due to external sources or to the impact of the jet itself in the vessel placed to receive it.