"Thus when the PLAGUE, upborne on Belgian air,
Look'd through the mist and shook his clotted hair,
O'er shrinking nations steer'd malignant clouds,
90 And rain'd destruction on the gasping crouds.
The beauteous AEGLE felt the venom'd dart,
Slow roll'd her eye, and feebly throbb'd her heart;
Each fervid sigh seem'd shorter than the last,
And starting Friendship shunn'd her, as she pass'd.
95 —With weak unsteady step the fainting Maid
Seeks the cold garden's solitary shade,
Sinks on the pillowy moss her drooping head,
And prints with lifeless limbs her leafy bed.
—On wings of Love her plighted Swain pursues,
100 Shades her from winds, and shelters her from dews,
Extends on tapering poles the canvas roof,
Spreads o'er the straw-wove matt the flaxen woof,
Sweet buds and blossoms on her bolster strows,
And binds his kerchief round her aching brows;
105 Sooths with soft kiss, with tender accents charms,
And clasps the bright Infection in his arms.—
With pale and languid smiles the grateful Fair
Applauds his virtues, and rewards his care;
Mourns with wet cheek her fair companions fled
110 On timorous step, or number'd with the dead;
Calls to its bosom all its scatter'd rays,
And pours on THYRSIS the collected blaze;
Braves the chill night, caressing and caress'd,
And folds her Hero-lover to her breast.—
115 Less bold, LEANDER at the dusky hour
Eyed, as he swam, the far love-lighted tower;
Breasted with struggling arms the tossing wave,
And sunk benighted in the watery grave.
Less bold, TOBIAS claim'd the nuptial bed,
120 Where seven fond Lovers by a Fiend had bled;
And drove, instructed by his Angel-Guide,
The enamour'd Demon from the fatal bride.—
—SYLPHS! while your winnowing pinions fan'd the air,
And shed gay visions o'er the sleeping pair;
125 LOVE round their couch effused his rosy breath,
And with his keener arrows conquer'd DEATH.
[The beauteous Aegle. l. 91. When the plague raged in Holland in 1636, a young girl was seized with it, had three carbuncles, and was removed to a garden, where her lover, who was betrothed to her, attended her as a nurse, and slept with her as his wife. He remained uninfected, and she recovered, and was married to him. The story is related by Vinc. Fabricius in the Misc. Cur. Ann. II. Obs. 188.]
IV. 1. "You charm'd, indulgent SYLPHS! their learned toil,
And crown'd with fame your TORRICELL, and BOYLE;
Taught with sweet smiles, responsive to their prayer,
130 The spring and pressure of the viewless air.
—How up exhausted tubes bright currents flow
Of liquid silver from the lake below,
Weigh the long column of the incumbent skies,
And with the changeful moment fall and rise.
135 —How, as in brazen pumps the pistons move,
The membrane-valve sustains the weight above;
Stroke follows stroke, the gelid vapour falls,
And misty dew-drops dim the crystal walls;
Rare and more rare expands the fluid thin,
140 And Silence dwells with Vacancy within.—
So in the mighty Void with grim delight
Primeval Silence reign'd with ancient Night.
[Torricell and Boyle. l. 128. The pressure of the atmosphere was discovered by Torricelli, a disciple of Galileo, who had previously found that the air had weight. Dr. Hook and M. Du Hamel ascribe the invention of the air-pump to Mr. Boyle, who however confesses he had some hints concerning its construction from De Guerick. The vacancy at the summit of the barometer is termed the Torricellian vacuum, and the exhausted receiver of an air pump the Boylean vacuum, in honour of these two philosophers.
The mist and descending dew which appear at first exhausting the receiver of an air-pump, are explained in the Phil. Trans. Vol. LXXVIII. from the cold produced by the expansion of air. For a thermometer placed in the receiver sinks some degrees, and in a very little time, as soon as a sufficient quantity of heat can be acquired from the surrounding bodies, the dew becomes again taken up. See additional notes, No. VII. Mr. Saussure observed on placing his hygrometer in a receiver of an air- pump, that though on beginning to exhaust it the air became misty, and parted with its moisture, yet the hair of his hygrometer contracted, and the instrument pointed to greater dryness. This unexpected occurrence is explained by M. Monge (Annales de Chymie, Tom. V.) to depend on the want of the usual pressure of the atmosphere to force the aqueous particles into the pores of the hair; and M. Saussure supposes, that his vesicular vapour requires more time to be redissolved, than is necessary to dry the hair of his thermometer. Essais sur l'Hygrom. p. 226. but I suspect there is a less hypothetical way of understanding it; when a colder body is brought into warm and moist air, (as a bottle of spring-water for instance,) a steam is quickly collected on its surface; the contrary occurs when a warmer body is brought into cold and damp air, it continues free from dew so long as it continues warm; for it warms the atmosphere around it, and renders it capable of receiving instead of parting with moisture. The moment the air becomes rarefied in the receiver of the air-pump it becomes colder, as appears by the thermometer, and deposits its vapour; but the hair of Mr. Saussure's hygrometer is now warmer than the air in which it is immersed, and in consequence becomes dryer than before, by warming the air which immediately surrounds it, a part of its moisture evaporating along with its heat.]
2. "SYLPHS! your soft voices, whispering from the skies,
Bade from low earth the bold MONGULFIER rise;
145 Outstretch'd his buoyant ball with airy spring,
And bore the Sage on levity of wing;—
Where were ye, SYLPHS! when on the ethereal main
Young ROSIERE launch'd, and call'd your aid in vain?
Fair mounts the light balloon, by Zephyr driven,
150 Parts the thin clouds, and sails along the heaven;
Higher and yet higher the expanding bubble flies,
Lights with quick flash, and bursts amid the skies.—
Headlong He rushes through the affrighted air
With limbs distorted, and dishevel'd hair,
155 Whirls round and round, the flying croud alarms,
And DEATH receives him in his sable arms!—
So erst with melting wax and loosen'd strings
Sunk hapless ICARUS on unfaithful wings;
His scatter'd plumage danced upon the wave,
160 And sorrowing Mermaids deck'd his watery grave;
O'er his pale corse their pearly sea-flowers shed,
And strew'd with crimson moss his marble bed;
Struck in their coral towers the pausing bell,
And wide in ocean toll'd his echoing knell.
[Young Rosiere launch'd. l. 148. M. Pilatre du Rosiere with a M. Romain rose in a balloon from Boulogne in June 1785, and after having been about a mile high for about half an hour the balloon took fire, and the two adventurers were dashed to pieces on their fall to the ground. Mr. Rosiere was a philosopher of great talents and activity, joined with such urbanity and elegance of manners, as conciliated the affections of his acquaintance and rendered his misfortune universally lamented. Annual Register for 1784 and 1785, p. 329.]
[And wide in ocean. l. 164. Denser bodies propagate vibration or sound better than rarer ones; if two stones be struck together under the water, they may be heard a mile or two by any one whose head is immersed at that distance, according to an experiment of Dr. Franklin. If the ear be applied to one end of a long beam of timber, the stroke of a pin at the other end becomes sensible; if a poker be suspended in the middle of a garter, each end of which is pressed against the ear, the least percussions on the poker give great sounds. And I am informed by laying the ear on the ground the tread of a horse may be discerned at a great distance in the night. The organs of hearing belonging to fish are for this reason much less complicated than of quadrupeds, as the fluid they are immersed in so much better conveys its vibrations. And it is probable that some shell-fish which have twisted shells like the cochlea and semicircular canals of the ears of men and quadrupeds may have no appropriated organ for perceiving the vibrations of the element they live in, but may by their spiral form be in a manner all ear.]
165 V. "SYLPHS! YOU, retiring to sequester'd bowers,
Where oft your PRIESTLEY woos your airy powers,
On noiseless step or quivering pinion glide,
As sits the Sage with Science by his side;
To his charm'd eye in gay undress appear,
170 Or pour your secrets on his raptured ear.
How nitrous Gas from iron ingots driven
Drinks with red lips the purest breath of heaven;
How, while Conferva from its tender hair
Gives in bright bubbles empyrean air;
175 The crystal floods phlogistic ores calcine,
And the pure ETHER marries with the MINE.
[Where oft your Priestley. l. 166. The fame of Dr. Priestley is known in every part of the earth where science has penetrated. His various discoveries respecting the analysis of the atmosphere, and the production of variety of new airs or gasses, can only be clearly understood by reading his Experiments on Airs, (3 vols. octavo, Johnson, London.) the following are amongst his many discoveries. 1. The discovery of nitrous and dephlogisticated airs. 2. The exhibition of the acids and alkalies in the form of air. 3. Ascertaining the purity of respirable air by nitrous air. 4. The restoration of vitiated air by vegetation. 5. The influence of light to enable vegetables to yield pure air. 6. The conversion by means of light of animal and vegetable substances, that would otherwise become putrid and offensive, into nourishment of vegetables. 7. The use of respiration by the blood parting with phlogiston, and imbibing dephlogisticated air.