Let the required nature, therefore, be the action and motion of the spirit enclosed in tangible bodies. For every tangible body, with which we are acquainted, contains an invisible and in-nor emitted, but only strives and exercises itself tangible spirit, over which it is drawn, and which it seems to clothe. This spirit being emitted from a tangible substance, leaves the body contracted and dry, when retained it softens and melts it, when neither wholly emitted nor retained, it models it, endows it with limbs, assimilates, manifests, organizes it, and the like. All these points are reduced to the sphere of the senses by manifest effects.

Let the required nature then be the expansion, or coherence of matter in different bodies, or the quantity of matter relative to the dimensions of each. For, there is nothing in nature more true. than the twofold proposition, "That nothing quently recurs is very obscure, especially as applied to inani- proceeds from nothing," and "that nothing is mate objects. His theory as to the generation of animals, is reduced to nothing," but, that the quantum, oz

sum total of matter, is constant, and is neither bodies which are compact and not hollow. Then increased nor diminished. Nor is it less true, "that out of this given quantity of matter, there is a greater or less quantity contained within the same space or dimensions, according to the difference of bodies;" as, for instance, water contains more than air. So that, if any one were to assert, that a given content of water can be changed into an equal content of air, it is the same as if he were to assert that something can be reduced into nothing. On the contrary, if any one were to assert, that a given content of air can be changed into an equal content of water, it is the same as if he were to assert that something can proceed from nothing. From this abundance, or scarcity of matter, are properly derived the notions of density and rarity, which are taken in various and promiscuous senses.

we noted exactly the weight of the liquid and vial. We next took a bladder, containing about two pints, and squeezed all the air out of it, as completely as possible, and until the sides of the bladder met. We first, however, rubbed the bladder gently with oil, so as to make it air-tight, by closing its pores with the oil. We tied the bladder tightly round the mouth of the vial, which we had inserted in it, and with a piece of waxed thread to make it fit better and more tightly, and then placed the vial on some hot coals in a brazier. The vapour or steam of the spirit, dilated and become aeriform by the heat, gradually swelled out the bladder and stretched it in every direction like a sail. As soon as that was accomplished, we removed the vial from the fire and placed it on a carpet, that it might not be cracked by the cold: we also pricked the bladder immediately, that the steam might not return to a liquid state by the cessation of heat, and confound the proportions. We then removed the bladder, and again took the weight of the spirit which remain

This third assertion may be considered as being also sufficiently certain; namely, that the greater or less quantity in this or that body, may, by comparison, be reduced to calculation, and exact, or nearly exact proportion. Thus, if one should say that there is such an accumulation of mattered; and so calculated the quantity which had been in a given quantity of gold, that it would require twenty-one times the quantity in dimension of spirits of wine, to make up the same quantity of matter, it would not be far from the truth.

converted into vapour, or an aeriform shape, and then examined how much space had been occupied by the body in its form of spirits of wine in the vial, and how much on the other hand had been occupied by it in its aeriform shape in the bladder, and subtracted the results; from which it was clear, that the body, thus converted and

The accumulation of matter, however, and its relative quantity are rendered sensible by weight. For weight is proportionate to the quantity of matter, as regards the parts of a tangible sub-changed, acquired an expansion of one hundred stance, but spirit, and its quantity of matter, are not to be computed by weight, which spirit rather diminishes than augments.

We have made a tolerably accurate table of weight, in which we have selected the weights and size of all the metals, the principal minerals, stones, liquids, oils, and many other natural and artificial bodies: a very useful proceeding both as regards theory and practice, and which is capable of revealing many unexpected results. Nor is this of little consequence, that it serves to demonstrate that the whole range of the variety of tangible bodies, with which we are acquainted, (we mean tolerably close, and not spongy, hollow bodies, which are for a considerable part filled with air,) does not exceed the ratio of one to twenty-one. So limited is nature, or at least that part of it to which we are most habituated.

We have also thought it deserving our industry, to try if we could arrive at the ratio of intangible or pneumatic bodies to tangible bodies; which we attempted by the following contrivance. We took a vial capable of containing about an ounce, using a small vessel in order to effect the subsequent evaporation with less heat. We filled this vial, almost to the neck, with spirits of wine, selecting it as the tangible body which, by our table, was the rarest, and contained a less quantity of matter in a given space, than all other tangible

times beyond its former bulk.

Again, let the required nature be heat or cold, of such a degree as not to be sensible from its weakness. They are rendered sensible by the thermometer as we described it above;* for the cold and heat are not actually perceived by the touch, but heat expands and cold contracts the air. Nor, again, is that expansion or contraction of the air in itself visible, but the air when expanded depresses the water, and when contracted raises it, which is the first reduction to sight.

Again, let the required nature be the mixture of bodies; namely, how much aqueous, oleaginous, or spirituous, ashy or salt parts they contain; or, as a particular example, how much butter, cheese, and whey there is in milk, and the like? These things are rendered sensible by artificial and skilful separations in tangible substances, and the nature of the spirit in them, though not immediately perceptible, is nevertheless discovered by the various motions and efforts of bodies. And, indeed, in this branch men have laboured hard in distillations and artificial separations, but with little more success than in their other experiments now in use; their methods being mere guesses and blind attempts, and more industrious than intelligent; and what is worst of all, without

* See Table of Degrees, No. 38.

any imitation or rivalry of nature, but rather by violent heats and too energetic agents, to the destruction of any delicate conformation, in which principally consist the hidden virtues and sympathies. Nor do men in these separations ever attend to or observe what we have before pointed out; namely, that in attacking bodies by fire, or other methods, many qualities are superinduced by the fire itself, and the other bodies used to effect the separation, which were not originally in the compound. Hence arise most extraordinary fallacies. For the mass of vapour, which is e:nitted from water by fire, for instance, did not exist as vapour or air in the water, but is chiefly created by the expansion of the water by the heat of the fire.

scents) to that of the dog, and with regard to light existing imperceptibly in the air, when not illumined from any extraneous source, to the sense of the cat, the owl, and other animals which see by night. For Tclesius has well observed that there appears to be an original portion of light even in the air itself, although but slight and meagre, and of no use for the most part to the eyes of men, and those of the generality of animals; because those animals to whose senses this light is proportioned, can see by night, which does not, in all probability, proceed from their seeing either without light, or by any internal light.

Here, too, we would observe, that we at present discuss only the wants of the senses, and their remedies; for their deceptions must be re

So, in general, all delicate experiments on natural or artificial bodies, by which the genuine | ferred to the inquiries appropriated to the senses, are distinguished from the adulterated, and the better from the more common, should be referred to this division; for they bring that which is not the object of the senses within their sphere. They are, therefore, to be everywhere diligently sought after.

With regard to the fifth cause of objects escaping our senses, it is clear that the action of the sense takes place by motion, and this motion is time. If. therefore, the motion of any body be either so slow, or so swift, as not to be proportioned to the necessary momentum which operates on the senses, the object is not perceived at all; as in the motion of the hour hand, and that again of a musket ball. The motion which is imperceptible by the senses from its slowness, is readily and usually rendered sensible by the accumulation of motion; that which is imperceptible from its velocity, has not, as yet, been well measured; it is necessary, however, that this should be done, in some cases, with a view to a proper investigation of nature.

and sensible objects; except that important deception, which makes them define objects in their relation to man, and not in their relation to the universe, and which is only corrected by universal reasoning and philosophy.

41. In the eighteenth rank of prerogative instances, we will class the instances of the road, which we are also wont to call itinerant and jointed instances. They are such as indicate the gradually continued motions of nature. This species of instances escapes rather our observation, than our senses; for men are wonderfully indolent upon this subject, consulting nature in a desultory manner, and at periodic intervals, when bodies have been regularly finished and completed, and not during her work. But if any one were desirous of examining and contemplating the talents and industry of an artificer, he would not merely wish to see the rude materials of his art, and then his work when finished, but rather to be present whilst he is at labour, and proceeding with his work. Something of the same kind should be done with regard to nature. For in stance, if any one investigate the vegetation of plants, he should observe from the first sowing of any seed (which can easily be done, by pulling up every day seeds which have been two, three, or four days in the ground, and examining them diligently) how and when the seed begins to swell and break, and be filled, as it were, with spirit; then how it begins to burst the bark and The seventh case, where the senses are so push out fibres, raising itself a little at the same overcharged with the object, as to leave no fur- time, unless the ground be very stiff; then how ther room, scarcely occurs, except in the smell it pushes out these fibres, some downwards for or taste, and is not of much consequence as re-roots, others upwards for the stem; sometimes, gards our present subject. Let what we have also, creeping laterally, if it find the earth open said, therefore, suffice with regard to the reduction to the sensible sphere of objects not naturally within its compass.

The sixth case, where the sense is impeded by the power of the object, admits of a reduction to the sensible sphere, either by removing the object to a greater distance, or by deadening its effects by the interposition of a medium, which may weaken, and not destroy the object; or by the admission of its reflection, where the direct impression is too strong, as that of the sun in a basin of water.

Sometimes, however, this reduction is not extended to the senses of man, but to those of some other animal, whose senses, in some points, exceed those of man: as (with regard to some

and more yielding on one side, and the like. The same should be done in observing the hatch ing of eggs, where we may easily see the pro cess of animation and organization, and what parts are formed of the yolk, and what of the white of the egg, and the like. The same may be said of the inquiry into the formation of ani

to attention, observation, and proper inquiry: as, | two defects in practice, and as many divisions of for instance, that a little drop of ink should be important instances. Practice is either deceptive drawn out into so many letters; that silver merely or too laborious. It is generally deceptive, (espegilt on its surface should be stretched to such a cially after a diligent examination of natures,) on length of gilt wire; that a little worm, such as account of the power and actions of bodies being you may find on the skin, should possess both a ill defined and determined. Now, the powers and spirit and a varied conformation of its parts; that actions of the bodies are defined and determined a little saffron should imbue a whole tub of water either by space or by time, or by the quantity at with its colour; that a little musk or aroma should a given period, or by the predominance of energy; imbue a much greater extent of air with its per- and if these four circumstances be not well and fume; that a cloud of smoke should be raised by diligently considered, the sciences may indeed be a little incense; that such accurate differences beautiful in theory, but are of no effect in practice. of sounds as articulate words should be conveyed We call the four instances referred to this class, in all directions through the air, and even pene- mathematical instances and instances of measure. trate the pores of wood and water, (though they Practice is laborious either from the multitude become much weakened;) that they should be of instruments, or the bulk of matter and submoreover reflected, and that with such distinct- stances requisite for any given work. Those inness and velocity; that light and colour should stances, therefore, are valuable, which either for such an extent, and so rapidly pass through direct practice to that which is of most consesolid bodies, such as glass and water, with so quence to mankind, or lessen the number of ingreat and so exquisite a variety of images, and struments, or of matter to be worked upon. We should be refracted and reflected; that the mag-assign to the three instances relating to this class net should attract through every description of the common name of propitious or benevolent body, even the most compact; but (what is still instances. We will now separately discuss these more wonderful) that in all these cases the seven instances, and conclude with them that action of one should not impede that of another part of our work which relates to the prerogative in a common medium, such as air; and that or illustrious instances. there should be borne through the air, at the same time, so many images of visible objects, so many impulses of articulation, so many different perfumes, as of the violet, rose, &c., besides cold and heat, and magnetic attractions; all of them, I say, at once, without any impediment from each other, as if each had its paths and peculiar passage set apart for it, without infringing against or meeting each other.

To these lancing instances, however, we are wont, not without some advantage, to add those which we call the limits of such instances. Thus, in the cases we have pointed out, one action does not disturb or impede another of a different nature, yet those of a similar nature subdue and extinguish each other; as the light of the sun does that of the candle, the sound of a cannon that of the voice, a strong perfume a more delicate one, a powerful heat a more gentle one, a plate of iron between the magnet and other iron the effect of a magnet. But the proper place for mentioning these will be also amongst the supports of induction.

44. We have now spoken of the instances which assist the senses, and which are principally of service as regards information; for information begins from the senses. But our whole labour terminates in practice, and as the former is the beginning, so is the latter the end of our subject. The following instances, therefore, will be those which are chiefly useful in practice. They are comprehended in two classes, and are seven in number. We call them all by the general name of practical instances. Now, there are

45. In the twenty-first rank of prerogative instances, we will place the instances of the rod or rule, which we are also wont to call the instances of completion, or non-ultra. For the powers and motions of bodies do not act and take effect through indefinite and accidental, but through limited and certain spaces; and it is of great importance to practice that these should be understood and noted in every nature which is investigated; not only to prevent deception, but to render practice more extensive and efficient. For it is sometimes possible to extend these powers, and bring the distance, as it were, nearer, as in the example of telescopes.

Many powers act and take effect only by actual touch, as in the percussion of bodies; where the one does not remove the other, unless the impelling touch the impelled body. External applications in medicine, as ointment, and plasters, do not exercise their efficacy, except when in contact with the body. Lastly, the objects of touch and taste only strike those senses when in contact with their organs.

Other powers act at a distance, though it be very small, of which but few have, as yet, been noted, although there be more than men zuspect; this happens (to take every day-instances) when amber or jet attract straws, bubbles dissolve bubbles, some purgative medicines draw humours from above, and the like. The magnetic power by which iron and the magnet, or two magnets, are attracted together, acts within a definite and narrow sphere; but if there be any magnetic power emanating from the earth, a little