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The Approach of Winter is also thus admirably represented by Mr. Thomson, on the Seasons.
Now when the chearless Empire of the Sky
And fierce Aquarius stains th' inverted Year;
Refounding long in lift'ning Fancy's Ear.
: Well, Cleonicus, the Pleasure which these Conversations on the Seasons afford me are inexpreffible, Their Nature explained by the Orrery, and their Properties and Qualities as finely described by the Poets, give me perfect Ideas thereof; such as I should never have otherwise been able to have attained.-But see, the Year is compleated, and the Evening is spent.--The Machine may therefore rest for this Time. - And, pray, Cleonicus, what do you propose for the next Spe. culation ?
Cleon. I purpose to thew you next, the Theory of Day and Night, the Alternation, and various Length of each, in every Season of the Year; and that in the fame Manner by the Orrery, as I have explained to you the Seasons.
The Theory of Day and NIGHT, explained by the
best Machine for explaining the Nature and Difference of Night and Day.
Cleon. Undoubtedly, 'tis the best Instrument for that Purpose ever yet invented. For here you see the very Thing itself in Miniature. Here the Taper is the Sun, illuminating one Half of this small, terraqueous Globé, which represents the Earth ; having all the Parts of Land and Water duly represented on it, with all the Meridians and Parallels of Latitude. As it moves in its annual Course, you observe it turns about its own Axis; and is furnished with an Hour-Circle and Index for measuring the Time. All which Things are now to be regarded in the Representation of Day and Night by the Machine. Eupbrof. These Things I shall readily attend to.
Therefore, put the Machine in Order, for the Experiment, and I'll put to the Window-fhutters to darken the Room.
Cleon. Stay a little, 'till I have placed the Earth in its proper Position for shewing the shortest Night and longest Day of the Year ; and that is, in the Beginning of Capricorn, when the sun will appear to enter Cancer.
-In the next Place, we will put a very small Patch on the Place of London, which, by its Rotation, will thew the Parallel of London (X Y Z), described in each Revolution of the Earth about its Axis.- Lastly, to
bring the Patch to that part of the Meridian (X) which is opposite to the Sun; and set the Hour-Index at 12 precisely, -These Things being done, you may darken the Room as soon as you please, and then I'll put the Instrument in Motion,
Euphrof. 'Tis done.
Cleon. Observe the Earth equally divided into a light and dark Hemisphere, which represent Day and Night; as the Meridian passes over the Middle Part of each; so it thews the Noon, or Mid-day to all Parts under it at the one, and Mid-night to all Parts under it in the other ; among which
you see London (at X).-I'll now set the Machine a-going :
-Obferve the Earth revolving about its Axis from left to East.
Euphrof. I do, with Pleasure, behold it; and I observe, that the Position of the Earth's Axis is such, as will bring London soon out of the dark Hemisphere into the enlightened one.
Cleon. It will so; and I need not tell you, that that will be the Time from Mid-night to Sun-rising, or the Length of Half the Night, at that Tiine. Observe nicely the Time when the Patch begins to enter the Light.
Euphros: I will.-- It will not be long I fee- It is now just come to the Point (O) or Circle of Illumination, and the Index is at 3' 47'.
Cleon. That is the Time of Sun-rising on the 21st of June, and is the Morning of the Day: A Time very delightful in Summer, and is a favourite Theme with the
* As some of our Readers may not have seen an Orrery, and others may not particularly remember the Phänomena of Day and Night which they saw represented in it, I have judged it necessary to add a Diagram thereof (in Plate XXIV.) to assist the Understanding and Memory, in which, by a bare Inspection, all the variety of the Alternations of Day and Night in the Summer, Equinoxial and Winter Seasons, is, it is presumed, very easy to be understood; and in a good Measure, such a Print may supply the Want of an Orrery, or other Instrument for this purpose.
N. B. In the Orreries which I make, the Earth is a Globe of
3 Inches Diameter, with all the Circles, Continents, and Oceans very diftinct.
Poets, who have all given us beautiful Descriptions
Now rose the ruddy Morn from Tithon's Bed,
But added Colours to the World reveal d.
Aurora, on Etoian Breezes borne,
And Cynthia with her lov’d Endyinion seeps. And Homer thus finely personates the Morn in the following Distich :
Now rosy Morn ascends the Court of Jove,
Lifts up her Light, and opens Day above. Allo Mr. Thomson's Description of Sun-rising is too fine not to be taken Notice of.
Fierce flaming up the Heavens, the piercing Sun
Seasons, 74 Euphrof. These are very beautiful and natural Delcriptions, which, while you trave been repeating, the Patch has. got good Part of the Way towards the Meridian of Noon.
Cleon. I see it is and thus the Sun rises gradually higher and higher to the Inhabitants of London, till the Patch comes under the Meridian (at Z) where the Sun is at its greatest Meridian Height in the Tropic of Cancer (at r.) This makes the Non of the Day thus admirably described by the last mentioned Poet.
'Tis raging Noon; and, vertical, the Sun
for Relief; thence hot ascending Steams
Of Vegetation parch’d, the cleaving Fields
Seasons, Page 81. Euphros. It is now just Noon in the Orrery, but fat different from that you have now been describing:—Here every Thing is quiet and serene; no scorching Sun, no Sweating, fainting Swains.--How inoffensively, as well as pleasant, is the most irkfome Part of the Day here represented by Art !
Cleon. Very true, Sifter; we here observe the Hours of a Summer's Day pass without the Fatigue and Pain of enduring it. But Night comes stealing upon us ; the Patch approaches the Confines of Darkness, and the Sun as gradually declines. You will observe, it takes the same Time in paffing over this Half of the enlightened Hemisphere as it did the other, viz. 81 Hours nearly; which, therefore, makes the longest Day 161 Hours at London.
Euphrof. I fee what you say is Fact.-The Sun is now just entering the Shades ; and the Index points at viii, 13. How consistent is Art with Nature !
Cleon. Nature is the Contrivance of an infinitely wise Artist; if we poor Mechanics can fabricate an artificial World so exactly, it is nothing wonderful to see such Beauty, Order, and Harmony in the Mundane System.
The Close of the Day is thus beautifully described by Homer :
As when the Morn, refulgent Lamp of Night,