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be admired, is the conftant, round which it travels; and by which, without fuffering either adulteration or wafle, it is continually offering itself to the wants of the habitable globe. From the fea are exhaled those vapours which form the clouds. These clouds defcend in fhowers, which, penetrating into the crevices of the hills, fupply fprings.. Which fprings flow in little ftreams into the valleys; and, there uniting, become rivers. Which rivers, in return, feed the ocean. So there is an inceffant circulation of the fame fluid; and not one drop probably more or less now, than there was at the creation. A particle of water takes its departure from the furface of the fea, in order to fulfil certain important offices to the earth; and having executed the fervice which was affigned to it, returns to the bofom which it left.

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Some have thought that we have too 'much water upon the globe; the fea occupying above, three quarters of its whole furface. But the expanfe of ocean, immenfe as it is, may be no more than fufficient to fertilife the earth. Or, independently of this reason, I know not why the fea may not have as good a right to its place as the land. It may proportionably fupport as many inhabi

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tants; minifter to as large an aggregate of enjoyment. The land only affords a habitable furface; the fea is habitable to a great depth.

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III. Of FIRE, we have said that it diffolves. The only idea probably which this term raised in the reader's mind was, that of fire melting metals, refins, and fome other substances, fluxing ores, running glafs, and affifting us in many of our operations, chymical or culinary. Now these are only uses of an occafional kind, and give us a very imperfect notion of what fire does for us. The grand importance of this diffolving power, the great office indeed of fire in the economy of nature, is keeping things in a state of solution, that is to say, in a ftate of fluidity. Were it not for the prefence of heat, or of a certain degree of it, all fluids would be frozen. The ocean itself would be a quarry of ice: univerfal nature ftiff and dead.

We fee therefore, that the elements bear, not only a strict relation to the constitution of organized bodies, but a relation to each other. Water could not perform its office to the earth. without air; nor exist, as water, without fire.

IV. Of LIGHT, (whether we regard it as of the fame fubftance with fire, or as a different fubitance,)

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fubftance,) it is altogether fuperfluous to expatiate upon the ufe. No man difputes it, The obfervations, therefore, which I shall offer, respect that little which we feem to know of its conftitution.

Light paffes from the fun to the earth in eleven minutes; a diftance, which it would take a cannon ball twenty-five years, in going over. Nothing more need be faid to fhew the velocity of light. Urged by fuch a velocity, with what force muft its particles drive against, I will not fay the eye, the tendereft of animal fubftances, but every substance, animate or inanimate, which ftands in its way? It might feem to be a force fufficient to fhatter to atoms the hardest bodies.

How then is this effect, the confequence of fuch prodigious velocity, guarded againft? By a proportionable minuteness of the particles of which light is compofed. It is impoffible for the human mind to imagine to itself any thing fo small as a particle of light. But this extreme exility, though difficult to conceive it is cafy to prove.. A drop of tallow, expended in the wick of a farthing candle, fhall fhed forth rays fufficient to fill a hemifphere. of a mile diameter; and to fill it fo full of these

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rays, that an aperture not larger than the pupil of an eye, wherever it be placed within the hemifphere, fhall be fure to receive fome of them. What floods of light are continually poured from the fun we cannot estimate; but the immensity of the sphere which is filled with its particles, even if it reached no further than the orbit of the earth, we can in some fort compute: and we have reason to believe, that, throughout this whole region, the particles of light lie, in latitude at least, near to one another. The fpiffitude of the fun's rays at the earth is fuch, that the number which falls upon a burning glass of an inch diameter, is fufficient, when concentrated, to set wood on fire.

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The tenuity and the velocity of particles of light, as ascertained by separate obfervations, may be faid to be proportioned to each other: both furpaffing our utmost stretch of compre henfion; but proportioned. And it is this proportion alone, which converts a tremendous element into a welcome vifitor.

-zIt has been obferved to me by a learned friend, as having often ftruck his mind, that, if light had been made by a common artist, it would have been of bane unitorm caloune wherea

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whereas, by its prefent compofition, we have that variety of colours, which is of such infinite ufe to us for the diftinguishing of objects; which adds fo much to the beauty of the earth, and augments the stock of our innocent pleafures.

With which may be joined another reflection, viz. that, confidering light as compounded of rays of feven different colours, (of which there can be no doubt, because it can be refolved into thefe rays by fimply paffing it through a prifm,) the conftituent parts must be well mixed and blended together, to produce a fluid, fo clear and colourlefs, as a beam of light is, when received from the fun.

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