[144] Dr. WHEWELL, ON THE TRANSFORMATION OF HYPOTHESES 



give them up. In his Prize Essay for 1734, (on the Inclinations of the Planetary Orbits*,) he 

 says (Art. viu.), " The gravitation of the Planets towards the center of the Sun and the 

 weight of bodies towards the center of the earth has not, for its cause, either the attraction of 

 M. Newton, or the centrifugal force of the matter of the vortex according to M. Descartes;" 

 and he then goes on to assert that these forces are produced by a perpetual torrent of matter 

 tending to the center on all sides, and carrying all bodies with it. Such a hypothesis is very 

 difficult to refute. It has been taken up in more modern times by Le Sage-f, with some modi- 

 fications ; and may be made to account for the principal facts of the universal gravitation of 

 matter. The great difficulty in the way of such a hypothesis is, the overwhelming thought of 

 the whole universe filled with torrents of an invisible but material and tangible substance, 

 rushing in every direction in infinitely prolonged straight lines and with immense velocity. 

 Whence can such matter come, and whither can it go ? Where can be its perpetual and 

 infinitely distant fountain, and where the ocean into which it pours itself when its infinite course 

 is ended ? A revolving whirlpool is easily conceived and easily supplied ; but the central torrent 

 of Bernoulli, the infinite streams of particles of Le Sage, are an explanation far more incon- 

 ceivable than the thing explained. 



But however the hypothesis of vortices, or some hypothesis substituted for it, was 

 adjusted to explain the facts of attraction to a center, this was really nearly all that was 

 meant by a vortex or a " tourbillon," when the system was applied. Thus in the case 

 of the last act of homage to the Cartesian theory which the French Academy rendered 

 in the distribution of its prizes, the designation of a Cartesian Essay in 1741 (along with 

 three Newtonian ones) as worthy of a prize for an explanation of the Tides ; the differ- 

 ence of high and low water was not explained, as Descartes has explained it, by the pressure, 

 on the ocean, of the terrestrial vortex, forced into a strait where it passes under the Moon ; 

 but the waters were supposed to rise towards the Moon, the terrestrial vortex being disturbed 

 and broken by the Moon, and therefore less effective in forcing them down. And in giving an 

 account of a Tourmaline from Ceylon, (Acad. Sc. 1717) when it has been ascertained that 

 it attracts and repels substances, the writer adds, as a matter of course, " It would seem 

 that it has a vortex." As another example, the elasticity of a body was ascribed to vortices 

 between its particles : and in general, as I have said, a vortex implied what we now imply by 

 speaking of a central force. 



4. In the same manner vortices were ascribed to the Magnet, in order to account for its 

 attractions and repulsions. But we may note a circumstance which gave a special turn to 

 the hypothesis of vortices as applied to this subject, and which may serve as a further 

 illustration of the manner in which a transition may be made from one to the other of two 

 rival hypotheses. 



If iron filings be brought near a magnet, in such a manner as to be at liberty to 

 assume the position which its polar action assigns to them ; (for instance, by strewing them 

 upon a sheet of paper while the two poles of the magnet are close below the paper;) 



* Nouvelle Physique Celeste, Op. T. m. p. 163. i the sun's rotation caused, or at least rendered evident. Ber- 



The deviation of the orbits of the planets from the plane of 

 the sun's equator was of course a difficulty in the system which 



noulli's explanation consists in supposing the planets to have a 

 sort of leeway (derive des vaisseaujc) in the stream of the vortex. 



supposed that they were carried round by the vortices which ■(• s ee Phil. Ind. Sc. B. m. c. ix. Art. 7. 



