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Modern science affords numerous examples of this class of instances of power. The Davy, or safety-lamp, consisting only of a small oil light covered by a cylinder of wiregauze, has disarmed an explosive atmosphere, perilous to human life, of all its power:-the Steam Engine, whose prodigious effects are so well known and appreciated in this country, is civilizing the world; and the Calculating Engine, contrived by Mr. Babbage, has been taught arithmetic by its celebrated inventor; †-these, and others which might be mentioned, are indeed wonderful masterpieces of art.

In surveying such splendid instances as these of skill and intellect, we are not to

* M'Culloch's Commercial Dictionary, art. Paper, p. 876, (second edition.)

It is quite impossible to describe, in a few words, the astonishing powers of this Engine. For a particular account of it, see Babbage's Economy of Machinery and Manufactures, §§ 190, 191; and the Edinburgh Review for July, 1834, art. 1.

damp the ardour of our pursuits in science by entertaining the opinion that man can advance no further, that he has already reached the highest pinnacle of human power; we ought rather, from the experience of the past, to replenish our lamp of hope, and to keep it burning. I know not,' said sir Isaac Newton, a little while before he died,' I know not what I may seem to the world; but, as to myself, I seem to have been only like a boy playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.'*

6. Instantie Crucis, or crucial instances, are so called because when there are two rival hypotheses, and we are in doubt which is the true one, they serve the purpose of a cross or finger-post placed in the focus of divergent roads, to point out which way the

* Spence's Anecdotes, p. 158. Malone's edit.

traveller should take. In illustration of this class, which is of the highest importance in physical inquiries, Bacon adduces various instances: one has justly been noticed by sir John Herschel as very remarkable, being, in fact, the proposal of a direct experiment to determine whether the tendency of heavy bodies downwards is a result of some peculiar mechanism in themselves, or of the attraction of the earth by the corporeal mass thereof, as by a collection of bodies of the same nature.'

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If it be so,' says Bacon, 'it will follow that the nearer all bodies approach to the earth, the stronger and with the greater force and velocity they will tend to it; but the farther they are, the weaker and slower.' His experiment consists in taking two clocks, one moved by leaden weights, and the other by a spring; and, having set them together,

*By clocks,' says sir John Herschel, he could not have meant pendulum-clocks, which were not then known, (the first made in England was in 1622,) but

carrying the first to the top of a high church, and leaving the spring clock below; so that we may then observe whether the former move slower. He suggests, also, that this clock should then be carried down to the bottom of some deep mine, in order to ascertain if its rate of going be accelerated. 'In short,' says sir John Herschel, 'the principle of this experiment was the comparison of the effect of a spring with that of a weight, in producing certain motions in certain times, on heights and in mines. Now this,' he adds, 'is the very same thing that has really been done in the recent experiments of professors Airy and Whewell in Dolcoath mine: a pendulum (a weight moved by gravity,) has been compared with a chronome

Ay clocks, so that the comparison, though too coarse, was not contrary to sound mechanical principles.'Discourse on Nat. Phil. § 196. It is very doubtful whether pendulum clocks were made in England so early as 1622.-See the art. 'Clock and Watch Work,' in the Ency. Brit. vol. 6, p. 767.

ter balance, moved and regulated by a spring.'*

In chemical inquiries, crucial instances are frequently resorted to-most tests are of this description.

With these six classes of instances, selected from the twenty-seven enumerated and explained by Bacon, we must close our account of the Novum Organum; referring those of our readers who are desirous of pursuing the subject, (and of such we hope there will be many,) to the work itself, and to the profound and beautiful Dissertation on the Progress of Mathematical and Physical Science by Professor Playfair.†

To have given a complete analysis of the Novum Organum with appropriate illustrations, (however agreeable to the writer,) would have been inconsistent with his de

*Herschel on Nat. Phil. § 196.

See also 'An Account of lord Bacon's Novum Organon Scientiarum,' published in the Library of Useful Knowledge :-a very cheap and valuable treatise.

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