tral or indifferent medium, such as the air is. Thus numberless images of visible objects are carried through the air; numberless percussions of articulate voices; numberless specific odours, as those of violets, roses, &c. even cold, heat, and magnetical virtues, all pass through the air at once, without obstructing one another, as if each of them had its own separate way or passage, so as to prevent impinging against, meeting with, or obstructing one another.

218

12

To these lancing instances may be advantageously subjoined those we term the limiting ginstances, with regard to this lancing; as for example, in the cases just mentioned, that (1.) one action does not disturb or hinder another of a different kind, though two of the same kind damp or extinguish each other; that (2.) the light of the sun extinguishes or over powers the light of the glow-worm; that (3.) the report of a cannon drowns the voice; that (4.) a stronger odour overpowers one that is more delicate; that (5.) a stronger heat prevails over one that is more gentle; and, (6.) that an iron plate put between' the loadstone and a needle hinders the magnetic virtue. But the proper place of treating these instances also, is under the helps of induction*,

་་

And so much for the instances of help to the senses, which are of capital use in the business of information, for information begins with the sense *. But the whole affair terminates in practice and works, which are the end; as infor mation is the beginning t. And, therefore, the instances of principal use in practice are next to follow.

44. The instances of principal use in practice are of two kinds, and seven in number; all which we call by the general name of practical instances. Now practice has two inconveniences or defects; and so many general kinds of prerogative instances. For practice either fails or overburdens. Practice fails principally from a wrong determination and measure of the powers and actions of bodies; especially after a diligent enquiry into the subject. But the powers and actions of bodies are circumscribed and measured, either (1.) by space of place §; (2.) by moments of time; (3.) by the correspondence or proportion, of quantity ¶; or, (4.) by the predominancy of virtue ** : and unless these four things

*See above, Aph. 38.

+ See Part II. Aph, 1.

Viz. Two, corresponding to the two kinds of defects of practice; four defects of the first kind are enumerated in this paragraph, and three of the second in the next.

See below, Aph. 45. ¶ See below, Aph. 47.

See below, Aph. 46. ** See below, Aph. 48.qh

are well and diligently weighed, the sciences indeed may, perhaps, be beautiful in show and ap pearance, but they will remain unfruitful or bar ren of works. And the four instances, with res gard to these four particulars, we call, in gene ral, mathematical instances, or instances of men suration*.

Practice proves burdensome either.(1.) from the admixture of useless things†; (2.) from a multiplicity of instruments; or, (3.) from the bulk of the matter, and bodies required, in certain works§. Those instances, therefore, ought to be highly esteemed, which either (1.) direct and determine practice to such things as chiefly regard the benefit and advantage of mankind; or, (2.) retrench the number of instruments required; or, (3.) save and lessen the materials to be employed.

And the three instances corresponding to these three particulars or requisites, we call by the sin gle name of propitious or benevolent instances | We shall speak of these seven instances separately; and with them conclude this section of the doctrine of prerogative instances.

45. In the twenty-first place, therefore, among

prerogative instances, come instances of the staff, or measuring-rod, which we also call permeating or teminating instances; for the forces and mo tions of things operate and exert themselves in certain spaces, that are not indefinite or fortui, tous, but determinate and finite; and the due observance and marking of these spaces in every nature sought, is of great importance to practice, not only in preventing us from being deceived by it, but also in enlarging and rendering it more extensive and powerful; for it is some. times possible to extend virtues and powers, and, as it were, bring distances nearer, as we see in telescopes.

There are also many virtues that operate and extend their force only by manifest contact; as in the percussion of bodies, where one body does not move another,, unless the impelling body touches the body impelled. So, likewise, external remedies, as unguents and plaisters, exert not their virtues without touching the body. And, lastly, the objects of the taste and touch do not strike or effect, if not contiguous to the respective organs.

There are also other virtues, which operate at a small distance, very few whereof have been hitherto observed, whilst there are more of them than men suspect. Thus, to give obvious ex

amples, amber and jet attract straws, and other light bodies. Bubbles of water, approaching each other, run together. Some purgative medicines draw the humbur downwards, and the like. But that magnetic virtue whereby iron and the loadstone, or loadstones themselves, meet each other, operates only in a certain little sphere of activity, but if there be any magnetic virtue flowing from the inner parts of the earth, to the needle, in respect of its verticity, the operation is performed at a great distance.

Again, if there be any magnetic virtue, which operates by consent, between the globe of the earth, and ponderous bodies; or between the globe of the moon and the waters of the sea, which seems highly probable from the spring tides; or between the sphere of the fixed stars and the planets, so as to attract the planets to their apogees, all these must, operate at very great distances.

There are also found certain communications of flame, to considerable distances, in certain materials, as they relate, in particular, of the Naphtha of Babylon. Heat likewise insinuates itself to great distances, and so does cold, insomuch that the huge masses of ice broke off, and floating in the north sea, and thence coming into the Atlantic Ocean, strike a coldness many