Archelogia philosophica nova, or, New principles of philosophy containing philosophy in general, metaphysicks or ontology, dynamilogy or a discourse of power, religio philosophi or natural theology, physicks or natural philosophy / by Gideon Harvey ...

CHAP. III. Comprizing Problems touching the Air.

• 1. Whether Air be weighty.
• 2. Whether a Bladder blown up with wind be heavier than when empty.
• ...

• 3. Why water contained in a beer glass, being turned round with ones hand, doth turn contrary against the motion of the Glass.
• 4. Why a breath being blown with a close mouth doth feel cool, and effla∣ted with a diducted mouth feel warm.
• 5. Why an armed point of an Arrow groweth hot in being shot through the air.
• 6. Why Beer or Wine will not run out of the Cask without opening a hole atop.
• 7. What difference there is between an Oricane and a Travada.
• 8. Whether it be true that Winds may be hired from Witches or Wizards in Iseland.
• 9. Why is it quieter in the night than in the day?

I. VVHether Air be weighty?

Answ. Air considered as enjoying its Center, is light and doth not participate of any weight, since it would only move from the Center to the Circumference, and ever force ex∣traneous bodies upwards; Ergo Air absolutely conceived is only light. 2. Air in its present state is also weighty (but accidentally only, and not essentially,) because of its sinking downwards towards the Center.

II. Whether a Bladder blown up with wind be heavier than when empty?

Answ. There hath been trial made of this (to wit, of the weight of a bladder blown up by Bellows atop of a high hill) in a pair of Scales, and it was found that an empty bladder weighed heavier than one filled with wind; the same is also deprehended by casting them both into the water, where we shall find the empty bladder first to be equal with the Surface of the water, and afterwards to sink down a little, whereas the windy one swimmeth atop. The cause is, by reason a bladder extended by the air within is supported by it, and being rendred more porous and subtil through its obdu∣ction the air doth easily pass without any resistance, and therefore doth not depress it so much as an empty bladder, which through its corrugation and lesser diduction is more dense, and therefore re∣ceiving the depressing force of the air much stronger, besides being more acute, is apter for to cut through the inferiour air; whereas a bladder blown up is obtuse and doth as it were swim in the air: But if a bladder be blown up with ones breath, then doubtless it will prove heavier than an empty one, because of the vaporous or heavy waterish air contained within.

III. Why doth the water, contained in a beer glass being turned round with your hand, turn contrary against the motion of the glass; the same is observed in rouling a barrel full of water, where the liquor turns contrary against the barrel?

Ans. The water is here detained flat, or held fast by the air sinking down, whence it is, that the water seems to move against the motion of the Vessel, being glib, or slippery and smooth, and therefore not detaining the vessel in its motion.

IV. Why doth a breath being blown with a close mouth feel cool, and efflated with a diducted mouth feel warm?

Answ. Because the breath or incrassated air of a close mouth is more united and longer continuated, whereby it doth vigorously puffe the ambient air, whose compression felt, causes cold, as I have explained it in Book 1. Part 2. Now through the union of the in∣crassated air that is efflated, the hot minims of the breath are deeply and equally impressed into the substance of the vaporous air, whence their vertue is also suppressed; but in breathing of the said air out of an open mouth the fiery minims do come forth in troops unequally and but superficially mixt in or supported by the said incrassated air, whence they abide energick; besides the air being but little puffed makes little or no compression: Hence you may also collect a reason, why the air doth refrigrate being agitated with a Fan.

V. Why doth an armed point of an Arrow grow hot in being shot through the air?

Answ. Because its body and pores are somewhat opened by the air grinding against it, whereby its fiery parts procure an occasion of being unired and condensed. This doth also resolve us, why a Knife being smartly whetted emits sparks of fire; or why a Flint being struck hard against a piece of Steel doth likewise sparkle fire from it, viz. because its solid parts are opened and disjoyned through the concussion, whereby the fiery minims happen to be uni∣ted and condensed. Likewise many cold bodies by being chawed or contrited do afterwards grow hot.

VI. Why will not Beer or Wine run out of the Cask without opening a hole atop?

Answ. Because of the continuous adhesion, or cohesion of the continuous parts of the liquor to the continuous parts of the Cask; but as soon as it is averruncated, divided, and impelled downwards

by the air entring at the upper hole, it runs freely out of the Tap. That it is the air entring atop which presseth out the liquor is appa∣rent by the cavity atop, which the fore-impulse of the air entring causeth.

VII. What difference is there between an Oricane and a Tra∣vada.

Answ. An Oricane is usually much more violent, and therefore also much less lasting, bursting down circularly from all parts like to a Whirlwind. A Travada is more lasting and less violent, and erupts directly down, from one tract, and in no wise circularly, which as it oft rages upon the Seas off the shores of Coramandel, Manicongo, Guiny, &c. so the former is more frequent in the West-Indian Climates.

VIII. Whether it be true, that Winds may be hired from Witches or Wizzards in Iseland?

Answ. It is certain, that the Winds blow very variously and ma∣nifold about that Island, insomuch that it is not rare to see Ships sailing several courses at once, all of them being equally favoured by a good wind. The cause of this being vulgarly not known, hath occasioned people to brand the old men and women there with Witchcraft, whom the roughness of the air may cause to look rug∣ged like the devils correspondents, selling the winds by retail. The causes of this variety are great winds, erupting oft out of several holes of the earth about the Island, especially about the Mount Hecla, which many believe to be the mouth of hell, because of those prodigious thunders and murmurings of winds that are perceived thereabout.

IX. Why is it quieter in the night than in the day?

Answ. Because in the day the air being fluid and continuous is agitated into waves by the Suns fiery beams, whose bodies clashing together cause a small noise in the day, which the night season is freed of.