7. They must be probable in their own Nature.

8. They must be free from all Sufpicion of Prejudice, Affection, or Prepoffeffion, in their Author.

A. I believe, Sir, few will deny you the Ufe of Hypothefes thus circumftanced and qualified: But pray, what Kind of Demonftrations are thofe by Experiments, which you intimate they rely fo much upon?

B. The very best of all Nature can produce; they far exceed the keenest Glance of the Eye of Reafon, and nothing but divine Revelation can inform us more truly of the intimate Natures of Things.

A. Very wonderful indeed! Happy the Age in which this Art receiv'd Improvements from fuch extraordinary Inventions. Pray who were the firft Authors of improving Philofophy by Experiments?

B. Their Names are recorded in the Book of Fame; have you not feen therein the glaring Characters of Bacon, Boyle, Sir Ifaac Newton, Woodward, Dr. Halley, Ray, Derham, and feveral other exalted Virtuofo's? Some of which are now living; and others, fubfift in marble Monuments to gratify the Curiofity of, and be admired by all Pofterity.

A. Yes, I have heard of thofe great Names you mention'd, but not being very conver

fant

Of Hypothefes, Experiments, &c. 25 fant in the learned World, know but little about them; yet, take an exceflive Pleafure in hearing Relations of them, and the wonderful Things they have discover'd.

B. I am glad to find in you fuch a Difpofition, and queftion not but you will be highly gratified with the Series and Sequel of our Difcourfe.

A. I believe I fhall; but to the Point, in what Manner, I pray you, are thofe Experiments perform'd? for, as you have feen the Manner thereof, you can well inform

me.

B. They who have reduced experimental Philofophy to Method, and make it their Bufinefs to teach it others, prepare a large Apparatus of Inftruments of all Kinds, to the Value of five or fix hundred Pounds; and at ftated Times, in a very large Room, there is an Operator appointed to perform a Courfe of Experiments therewith, in all the various Parts of natural Philofophy, in the open View of all who are present to fee and learn the Manner thereof.

A. Cannot you give me fome particular Account of thofe Inftruments, and the Manner of ufing them?

B. It is the Subject of a large Volume to defcribe them with their Ufes in particular: However of fuch as are most common, to be had in the eafieft Manner, and which you your felf may understand, and ufe it

you

you please, you may take the following Ac

Count:

The Telescope, is an optic Inftrument, wherewith to view diftant Objects, which it greatly enlargeth, and makes them feem near us; by which Means the Aftronomers and Philofophers have made wonderous Discoveries in the Sun, Moon, and Planets.

The Microscope, is contriv'd to augment and render visible very minute and small Objects, which otherwise escape the Sight.

The Heliofcope, is a Sort of Telescope, fitted fo, as to look on the Body of the Sun without Offence to the Eyes.

The Barometer, or Baroscope, is contriv'd to estimate the fmall Variations of the Weight or Preffure of the Air.

The Anemofcope, is a Machine, invented to forefhew the Change of the Air, or Wind.

The Acolipile, is contriv'd to fhew the Nature and Force of pent up Air, rarified and breaking forth, refembling a Tempeft, &c.

The Aerometer, is an Inftrument to meafure the specific Gravity of Liquids.

The Hygrometer, is an Inftrument to measure the Moisture and Drynefs of the Air.

The Hygrofcope, fheweth the Increase and Decrease of the Drynefs of the Air.

The

Various Inftruments defcrib'd.

27

The Thermometer, measureth the Heat and Cold of the Air.

The Thermoscope, only fheweth the Increase and Decrease thereof.

The Hydrostatic Ballance, is an exceeding exact fine Pair of Scales for making Experiments, relating to the Gravity of Fluids.

Dioptrick Inftruments of various Sorts to explain the Nature of refracted Rays of Light, through various Mediums.

Catoptrick Inftruments are alfo manifold, which fhew the Nature of reflected Rays of Light.

The Pneumatick Engine, called the AirPump, is the most universal of all others; it's the very Basis of the Philosophy of the Air, and hath opened a greater Door to the Secrets of Nature, than any Thing that was ever invented befides; and it were endless to speak of this in particular, and all the other Inftruments in general, that are invented to explain and confirm the other Parts of Phyfiology.

4. Surely wonderful Curious and Delightful muft it then be to fee all those extraordinary Things performed by fuch nice Inftruments! Alas! what inert, ignorant, and narrow Souls have we poor Mechanics and Plebeians; what wretched, unworthy, and uncouth Notions have we conceiv'd of the World, and Things therein! We think

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our felves learned, if we know how to find out a Word in Bailey's Dictionary, little dreaming fo much Pains, Expence, and Time, neceffary to acquire but a partial Knowledge, and to be esteemed bur moderately learned!

B. Well, but don't be difcouraged; the Knowledge of thefe Things will be much eafier and cheaper to us, than they were to our Forefathers; what coft them Pounds, we may have for fo many Pence; what coft them Years of Study, Fatigue, and Difquietude, we may acquire with Eafe and Pleasure in a few Days or Months; what they rejoyced to come at by Piece-meals, and in an imperfect Manner, we have presented, as in one intire methodical View. Where

fore if we are Ignorant, 'tis because we are idle and indolent indeed: If we live fatisfied only with the vulgar erroneous Notions of fallacious Senfe, and endeavour not to rectify them by the Precepts of refined and learned Reason, and the Methods put into our Power; in vain then, hath God given us Ability to be wifer than the Fowls of Heaven, and to have more Understanding than the Beafts which perish.

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