Experimental investigation of the spirit manifestations, [electronic ...

372 OF MATTER, MIND, AND SPIRIT.lucnt of the letter, weight, in its usual practical sense, is only one case ofthe general force which causes all ponderable masses of matter to gravitatetoward each other, and which is of course liable to resist any conflictingmotion, whatever may be the direction.AVhen, in the form of solar attraction,it overcomes that inertia of the planets which would otherwise causethem to leave their orbits, does gravitation ^^ resist motion upward ?^^1813. In the next paragraph you allege, that "iJicre is a difference inthese two kinds of resistance to motion. Inertia is instantaneousy weightis continuous^ resistance."1814. It is to this allegation I object, that as you have defined inertiato be ^^ resistance to motion, or to change of motion,'' it follows that itcan be instantaneous only where the impulse which it resists is instantaneous.It cannot be less continuous than the force by which it isovercome.1815. Gravity has been considered as acting upon falling bodies by aninfinity of impulses, each producing an adequate acceleration ;but to everysuch accelerating impulse, producing of course a ^^ change of motion,^'will there not be a commensurate resistance from inertia ? and the impulsesand resistances being both infinite, will not one be as continuous asthe other ?1816. I have already adverted to inertia as the continuous antagonistof solar attraction in the case of revolving planets.1817. Agreeably to Mossotti, the creation consists of two kinds ofmatter, of which the homogeneous particles are mutually repellent, theheterogeneous mutually attractive.Consistently with this h3'pothesis, j^erse, any matter must be imponderable ; being endowed with a property thevery opposite of attraction of gravitation. This last-mentioned propertyexists between masses consisting of both kinds of particles, so far as theattraction between the heterogeneous atoms predominates over therepulsionbetween those which are homogeneous. It would follow from thesepremises, that all matter is ponderable or otherwise, accordingly as it maybe situated.1818. Can the ether by which, according to the undulatory theory, lightis transmitted, consist of ponderable matter ? Were it so, would it not beattracted about the planets with forces proportioned to their weight, respectively? and becoming of unequal density, would not the diversity inits density, thus arising, affect itsundulations, as the transmission of soundis influenced by any variations in the density of the aeriform fluid bywhich it is propagated ?"With esteem, I am yours truly,Egbert Hare(See appendix for Whewell's Essay.)