Exclufion leads to In

duction.

(11.) By the Dilatation of the Air in Weather-Glaffes, and the like; where the Air is evidently moved locally, and expanfively, without becoming manifeftly botter; again, reject local or expanfive Motion in the whole.

(12.) By the Facility wherewith all Bodies are warmed, without Deftruction, or remarkable Alteration; reject Destruction, and great Communication of any new Nature.

(13.) By the Similitude and Conformity of certain Operations, performed both by Cold and Heat; reject as well expansive as contractive Motion, in the whole.

(14.) By Fire following Heat upon the Attrition of Bodies; reject principal Nature, that is, a pofitive Nature, not caused by a pre

cedent one.

N. B. There are alfo other Natures to be excluded: for our Tables are not defigned as perfect, but only as Examples.

N. B. Neither all, nor any one of the preceding Natures, are of the Form of Heat: fo that Men in their Practices upon Heat, are freed from the Neceffity of introducing any, or all of them.

Obferve how this Investigation of Forms, correfponds to a juft Practical Rule, (for producing unlimited Effects,) laid down above, under Aph. 4. (5. and 6.) If due Attention has been ufed, the Reader will now begin to fee the the Scene open; and find Caufe to expect more confiderable Things from the human Power and Knowledge, than have hitherto been produced by any Philofophers unacquainted with the true Method of Enquiring into Nature, by the Means of this New Engine of the Mind.

:

APHORISM XIX.

35. The Business of Exclufion lays the Foundations for a genuine In duction; which, however, is not perfected till it terminates in the Affirmative but our Exclufion is by no means perfect; nor can it poffibly be fo at first. For Exclufion, as we plainly fee, is the Rejection of fimple Natures; and if we have hitherto no juft and true Notion of fimple Natures,. how can the Bufinefs of Exclufion be rectified? But fome of the abovemention'd Notions, as thofe of Elementary Nature, Celestial Nature, and Tenuity, are vague and ill defined. Wherefore, not forgetting how great a Task we have undertaken; viz. no lefs than that of rendering the human Understanding equal to Things and Nature; we are by no means to stop here; but muft proceed to invent and afford greater Helps to the Mind. For, doubtlefs, in the Interpretation of Nature, the Mind is

to

See Table IV. §. 1, 2, 7.

to be fo prepared and formed, that it may both reft upon proper Degrees of Certainty; and yet conceive, especially in the Beginning, that the Things which are prefent, have a great Dependance upon those behind .

APHORISM XX.

tage of En

36. And yet, because Truth will fooner emerge from Error, than Permiffion to from Confufion; we judge it useful to allow the Understanding, after having the Undermade and considered the three Tables of preparatory View; in the Manner anding; or the first Vinwe have laid them down; to apply itself, and attempt the Bufinefs of Interpreting Nature in the Affirmative; on the Strength of the Inftances quiry. contained in thefe Tables; and fuch as may be otherwife procured. And this kind of Attempt, we call a Permission to the Understanding, the Rudiments of Interpretation, or the first Vintage of Enquiry f.

• See above, Part I. Aph. 130. ad finem.

f The first Vintage, in Wine-Countries, produces the pooreft Wines; which they ufually diftil, for Brandy; as being not fit to keep, in the Form of Wines.

TABLE V.

The First VINTAGE, or Dawn of Doctrine, from the
FORM OF HEAT.

(1.) IT appears from the preceding Doctrine, that the Form of a Thing refides in all the particular Inftances, wherein the Thing refides; otherwife it would not be a Form: and therefore no contradictory Inftance hereof can be given.

eminently in

(2.) Yet the Form is found much more confpicuous in fome In- The Form ftances, than in others; efpecially in thofe where the Nature of the found more Form is lefs confined, obftructed and Jubdued by other Natures: fome Inand this Kind of Inftances we call fhining or glaring Inftances b. ftances, than And thus we now proceed to reap the First Fruits of our Enquiry after the Form of Heat, in the Way of Example.

in

(3.) In all the Inftances, confidered as well feparately as col- Motion the lectively, the NATURE WHOSE LIMITATION IS HEAT, Form of APPEARS то BE MOTION C. This we find chiefly in Flame,

* See above, Part II. Aph. 4. See below, Sect. II. Aph. 24. See above, Aph. 4.

Nnn 2

which

Heat.

Or its Genus.

to Man.

d

which is in perpetual Motion; and in hot, or boiling Liquors, which are alfo in a continual Agitation. It likewife appears, by the Sharpnefs or Increase of the Heat, caus'd by Motion; as in Bellows and Blafts and again, in other Kinds of Motion; for which fee the twenty-eighth and thirty-firft Inftances of the Third TABLE. 'Tis found alfo in the Extinguishing of Fire, and Heat, by all ftrong Compreffion, which checks and puts a flop to Motion. See the thirtieth and thirty-fecond Inftances of the Third TABLE. Again, it is fhewn by this, that all Bodies are deftroy'd, or at leaft remarkably alter'd, by all kinds of Fire, or strong or vehement Heat. And from hence it plainly appears, that Heat causes a Tumult, Disturbance, and brisk or eager Motion in the internal Parts of Bodies; which gradually tends to a Diffolution of the Body.

be

(4.) What we have thus faid of Motion, is to be under food of it, as of a Genuse, with regard to Heat: and not as if Heat generated Motion; or as if Motion generated Heat; tho' this may true in fome Cafes: but the Meaning is, that Heat itself, or the very Exiftence of Heat, is Motion, and nothing else ; tho' Motion limited by the Differences we fall presently fubjoin; after giving a few Cautions for the avoiding of Ambiguity.

f

Heat relative (5) Heat to the Senfe is a relative Thing, that regards Mankind, not the Univerfe; and is justly affigned only as the Effect of Heat upon the animal Spirit or Mind; being in itfelf an indeterminate Thing: for the fame Body, according as the Senfe is predifpofed, may give the Preception as well of Heat as of Cold; as appears by the forty-firft Inftance of the Third TABLE.

Heating not of the Form

of Heat.

(6.) But the Communication, or tranfitive Nature of Heat, whereby one Body conceives Heat upon being applied to another that is hot, must not be confounded with the Form of Heat: for Heat is one Thing, and Heating another. Heat is produced by the Motion of Attrition, without any Heat preceding that Motion; whence Heating is excluded from the Form of Heat. And when Heat is produced by the Approach of a hot Body; this does not proceed from the Form of Heat; but depends entirely upon a higher and more common Na

ture;

See Tab. III. Inftance 27.

• Or univerfal Kind.

See above, Part II. Aph. 4..

ture ; viz. upon the Nature of Communication, Affimilation, or Self-multiplication; which demands a feparate Enquiry.

(7.) The Notion of Fire is vulgar; and compofed of Heat and Splendor, as exifting in fome one Thing: for Example, in common Flame, and Bodies ignited, or made red-hot. And having thus removed all Ambiguities; we at length come to the true Differences, which limitate Motion, fo as to conftitute it the Form of Heat b.

I.

the Form of

(8.) The firft Difference is this; that Heat is an expanfive Mo- The firft tion, whereby a Body endeavours to dilate itself, and ftretch into Difference a greater Sphere, or Dimension, than it before poffeffed. And of Motion in this Difference appears principally in Flame, where the Smoak, or Heat. unctuous Vapour, manifeftly dilates and opens itself into Flame. It appears likewife in all boiling Liquors; which manifeftly fwell, rife up, bubble, and carry on their Procefs of Expanfion, till they change into a much more rarified Body, than the Liquors themselves; as for Example, into Vapour, Flame or Air.

(9.) It appears likewife in Wood, and all combustible Bodies, which fometimes fweat; but always evaporate.

(10.) It appears again, in the melting of Metals, which being of a very compact Substance, do not easily fwell and dilate; yet their Spirit, after being itself dilated, and endeavouring at a still greater Extenfion, forces and agitates the more grofs Parts into a fluid State: and if the Heat be greatly increased, it refolves, volatizes, and drives off much of their Subftance.

(11.) It appears alfo in Iron and Stone; which at least are foften'd, if not liquified and fufed by Fire. So likewife Rods of Wood become flexible, by being fomewhat heated in hot Afbes.

(12.) But

This is a fubtile and curious Diftinction. The Meaning appears to be, that, when Heat is once produced by the Exiftence of its Form, that is, by a particular Motion; it propagates itself, not by means of its Form, but by the Principle of Affimilation, or SelfMultiplication. See Sir Ifaac Newton upon the Heat of the Comets. Princip. Lib. III.. P. 467, &c.

See Part II. Aph. 4.

i Obferve, that this does not contradict, but coincide with the tenth and eleventh In-ftances of the Fourth Table; tho' the correfpondence may not, perhaps, appear at fift Sight. For farther Confirmation, fee below, §. (15.) (19.) (26.)

See the Sylva Sylvarum, p. 48, 49, 50.

The fecond

(12.) But this Motion is beft perceived in Air; which continually and manifeftly diliates itself, with a Small Heat; according to the thirty-eighth Inftance of the Third ŤABLE'.

(13.) Again, it appears from the contrary Nature of Cold: for Cold contracts all Bodies, and makes them shrink; infomuch that Nails have dropt out of Walls, and brafs Veffels bave crack'd, through Cold. So likewife Glass heated, and fuddenly brought into the Cold, cracks and flies to pieces. Air contracts itself even upon lightly cooling; as appears by the thirty-eighth Inftance of the Third TABLE". But the full Confideration of thefe Particulars belongs to the Enquiry of

Cold.

(14) And it is no Wonder that Cold and Heat should perform many Actions in common; according to the thirty-fecond Inftance of the fecond Table; because two of the Differences, which we shall prefently mention, belong to both Natures: tho' in the prefent Difference, their Actions are diametrically oppofite; for Heat gives an expanfive, and Cold a contractive Motion.

II.

(15.) The fecond Difference is a Modification of the former; and Difference. depends upon this, that Heat is an expanfive Motion, or a Motion towards the Circumference; but with this Law, that at the same Time it rifes upwards. And we cannot doubt but there are many mixt Motions; as that of an Arrow, for Example, which revolves in going forwards, and advances by revolving. And, in like manner, the Motion of Heat is, at the fame Time, both expanfive and upwards.

(16.) This Difference is perceived by beating one End of an Iron Rod, held perpendicularly in the Fire; in which Pofture it will burn

the

Neither does this contradict the eleventh Inftance of the fourth Table. The affigning of these Differences is a particular Work of the Understanding, employ'd folely in adjutting and reconciling the Inftances of the preceding Tables, without Distraction or Avocation.

m It fhould here be remember'd, that Water expands in Freezing: for Ice is fpecifi cally heavier than the Water that affords it. How this happens, the Author explains in the History of Condensation and Rarifaction, p. 551. But, perhaps, if the Water be very well purged of its Air, before it is froze, the Ice will not be lighter than Water. See Boerhaave's Chemistry, under the Chapters of Fire and Water. See also Mr. Hawksbee's Phyfico-Mechanical Experiments, p. 257.

See below, $. (25.) (26.) (29.)