compared ulth the Principle of Galvmiism. 157 



that by its compressed elasticity, and its vibrations, it ap- 

 pears to attcnid and cooperate in all the known operations 

 of nature; in gravity ; in attraction of aggregation, and in 

 all the chemical interchanges therein ; in repulsion ; in the 

 various movemeuls of light, as its direction goes in right 

 lines; in its inflections, its refractions, and rei^ections ; in 

 its fits of easy transmission and reflexion ; in heat and lis;ht; 

 in magnetism*; in electricity, and in that species of elec- 

 tric attractionf, " quae tarn angustis finibus contineatur ut 

 us(jue ad hue omnem observationem fugerit : ct fortasse 

 attractio electrica ad istius modi exigua mtervalla extendi 

 potest, etiamsi non excitetnrj'nctione." This appears spe- 

 cifically to distinguish that electric operation which has 

 course given to it, by the simple contact of metallic and 

 other substances, without bemg excited by friction, as 

 vitreous and resinous electricity is. This ether, by its 

 compressed elasticity, or by its vibrations, appears to attend 

 or cooperate in the sense of sight and hearmg, and in ani- 

 mal motion %. 



It evidently appears that Sir Isaac Newton had investi- 

 gated the nature of this ether, so far as to substantiate long 

 ago its existence, and its operations as a cooperating-ybrrao^ 

 cause, so as to recommend it to investigation how far it 

 may be found to be an ejjicient cause, general to all the 

 .phaenomena therein referred to by him. Although he stated 

 this his information, mcr-ely as matters of incniiry, to be 

 pursued by others, yet these phsenomcna, and the opera- 

 tions whence they arise, have been but lately submitted to 

 experiment ; and that with a view and in a line referring 

 to supposed newly discovered principles in nature, and to 

 unknown causes therein. 



Here I would wish to recommend the opinion and the 

 words of Professor Cotes to such of the late philosophers 

 who have these views § — " ad verani philosophiam pertinet 



* There is a peculiar phaenomenon, different from all others, by whicli 

 this principle acts or is acted upon. Jt appears to be connected with 

 some agent extern. il to it, by which it ictjuiies and maintains a direction 

 to the north pole of our globe ; but yet, whatever be this cooperating 

 agent, whose current gives this specific tendency to the magnet or niatr- 

 netic needle, this tendency, so f^r as relates to the magnetic body itsetf, 

 can be reversed in the body iiself, as the current of the power which 

 actuates the voltaic pile can, by an alteration in the position of its parts, 

 be reversed. It is known that the magneiic needle, on being stricken 

 witii lightning, has been reversed j and the anificial magnet can have its 

 poles reversed by the same nteani by which it was tirst made a magnet. 



+ Ncwtoni Opt. qua;re 31. at the time in which Newton speaks. 



H (in,.-re 2 3 et n.4.. 



§ IVa-fjitio ad Newtoni Piincipia. 



rcruni 



