A million of facts connected with the studies, pursuits, and interests of mankind; serving as a common-place book of useful reference on all subjects of research and curiosity

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1836 Excerpt: ...on the barometer over an extensive region of country at nearly the same time. The extent of the vibrations of the column of mercury between the tropicks was.067. The highest range in the polar regions observed by Capt. Parry, was 30.86. During a violent storm or hurricane the narometer has sometimes fallen below 28 inches. The fall of the barometer has no necessary and immediate connexion with rain, although storms of wind which effect the barometer are often attended by rain. It appears from the observations of the Marquis Poleni, that in 1175 instances of falls of rain, the barometer sunk only 758 times, being 645 to 1000. The most copious rains sometimes fall during an unusual elevation of the barometer., The prognostications of rain and fair weather which are usually affixed to the scale of the barometer, are entitled to no attention, and often serve to discredit this valuable instrument. Changes of weather are indicated, not by the actual height of the mercury, but by its change of height. Violent storms of wind are always preceded by a fall of the barometer, and one of the most general rules is, that when the mercury is very low, high winds may be expected. Capillary attraction is an effect or motion of parts of fluids when the general pressure on the mass is.intercepted by any intervening solid. Thus in a barometer or pump-bore the pressure is taken off in the tube or bore, while it continues on the outer surface: if a solid be placed in the water the Water rises round the solid, because the solid intercepts the pressure on its own side. If two solid plates are brought together, the water rises much higher, being pressed upon only through the sides. If the plates are closed at the side, as in the manner of a tube, the water rises in the tube in propo...