Gulf Stream.

477

Chap. 1.]

The trombe is of eonsiderable antiquity. It was known to Heron , andis referred to in Pliny’s Natural History . Kircher has given several figuresof it. See tom. i, 203, of his Mundus Subterraneus, and tom. ii, pp. 310,347, of his Musurgia Universalis ; in which last work he shows its appli-cation to supply wind to Organs, and by discharging the water from thebottom of the vessel upon a wheel he imparted motion to the keys of thoseinstruments. See also Phil. Trans. Abridg. vol. i, 498.

Liquids raised by currents of air may be illustrated by operations incommon life. Whenever water in a well settles to a level with the orificeof the pump pipe, air rushes in (on the ascent of the sucker) and sweepsup with it portions of the liquid in the form of dense rain. On the sameprinciple people are enabled to taste sealding liquids. The next time thereader sips hot soup, or tea, or coffee, he will find himself involuntarilykeeping the edge or rim of the spoon or vessel a short distance from hismouth, and protruding his lips tili the upper one projects a little over theedge : then drawing in his breath, the entering air ripples the surface ofthe liquid, and by its velocity bears broken portions along, precisely likethe pump just mentioned. The liquid particles being thus mixed withcomparatively large volumes of cool air, are so reduced in their tempera-ture as to be received without injury and without inconvenience.®

Water-spouts appear to be charged in much the same way, whatevermay be the active agent in the formation of these singulär phenomena ; forthe sea immediately under their orifice has often been observed to bubbleor boil violently, and rise into the spout in disjointed masses.

A stream of water directed into or through a body of the same liquid,also communicates motion to those particles of the latter that are in contactwith or adjacent to the current. Examples of this are furnished in severalof nature’s hydraulic operations. That constant oceanic current producedby the trade winds is one. It sweeps round the globe, but is deflectedand divided by the varying configuration of the lands that lie in its way.Under the torrid Zone, it passses through the Pacific and Indian oceans,whirls round the Southern point of Africa, inclines to that continent inagain approaching the equator, then Stretching across the Atlantic is di-vided by the South American coast—one part turning northward to theGulf of Mexico —thence this last division issues as the Gulf Stream , andbeing turned in an easterly direction by the coast of the United States , itbears away past the banks of Newfoundland , and extends its influence toIreland , Iceland , Norway and the North Sea . This mighty current notonly draws with it the liquid channel through which it flows, but the oceanfor leagues on each side is carried along with it, or follows in its train;

a Some of the operations of the mouth are deserving of particular notice. They willbe found to elucidate several philosophical principles, and attention to them would eer-tainly have enabled inventors to have anticipated rnany useful discoveries. We havein a preceding book observed that the mouth is often employed as a forcing pump inejecting liquids, and as a sucking one when drawing them through siphons, or throughsimple tubes. We have just seen how it raises hot liquids by drawing a stream of airover thein, and machines on the same principle have been made to raise water. It isoften used as a bellows to kindle fires, and every body employs it to cool hot victualsby blowing. It even acts as a stove to warm our frozen fingers, by giving out heatedair. Many make a condensing air-pump of it, to fill bladders, air-beds and air-pillows;some make an exhausting one of it, and in all it acts continually as both in respiration.How often does it perform the part of a fife, an organ, or a whistle, to produce music ?—of an air-gun to shoot bullets and arrows from the sarbacan 1 —and, not to weary thereader, when employed in smoking a pipe of tobacco, we see in Operation the identiealprinciple of increasing the draft of locomotive chimneys by exhaustion—i. e. a suckingapparatus is applied to that extremity of the fluethat is the farthest from the fire—a devicepatented in Eurepe a few yearsago.