THE ASTRONOMICAL VIEW OF NATURE. 357 



pheric refraction as well as those of cohesion and adhesion 



of bodies i.e., the attraction of particles of the same or of 



different matter under what is commonly called contact or 



at distances which we call in science molecular were thus 



submitted to calculation, and the results brought largely 



into harmony with experience.^ The problem presented 



itself and occupied natural philosophers all through the 



last century, whether a more general law of action at a 



distance could be found which comprised the phenomena 



of molecular as well as of molar attraction. 



The most celebrated attempt in this direction is that 33. 



of the Jesuit Koger Boscovich, who in 1758 published an extension olr 

 IT , , . , . , . o the Newton- 



elaborate treatise on this subject. lan formula. 



m'ont enfin conduit a faire voir 

 qu'ils sont tous representes par les 

 memes lois qui satisfont aux phe- 

 nomeaes de la refraction, c'est-k-dire 

 par les lois dans lesquelles I'attrac- 

 tion n'est sensible qu'k des distances 

 insensibles ; et il en resulte une the- 

 orie complete de Taction capillaire." 

 ^ The terms insensible and im- 

 perceptible, which are commonly 

 used in these discussions, must be 

 taken with caution. It is now 

 known that, though not directly 

 perceptible or sensible, the distance 

 through which molecular action 

 takes place is measurable. Plateau 

 in Belgium (1843 and following 

 years) and Quincke in Germany 

 (1868) made experiments on inde- 

 pendent lines, and came to very 

 similar results. The distance of 

 molecular action appears to be about 

 the twenty thousandth part of a 

 millimetre. See Clerk Maxwell's 

 article on Capillary Action in the 

 9th edition of the ' Ency. Brit.,' 

 reprinted in ' Scientific Papers,' 

 vol. ii. ; also Violle's ' Cours de 

 Physique,' German edition, vol. i. p. 

 591, &c., and p. 639. 



'^ Roger Joseph Boscovich, of the 

 Society of Jesus (1711-87), took up 

 the ideas thrown out by Newton in 

 the last query to the ' Opticks,' and 

 published in 1758 at Vienna an 

 elaborate treatise with the title 

 ' Theoria Philosophise Naturalis re- 

 dacta ad unicam legem virium in 

 Natura existentium.' A second 

 edition was published at Venice in 

 176-3. His speculations begin with 

 the year 1745, when he hit upon 

 his general view that all forces in 

 nature can be reduced to the action 

 of indivisible and inextended atoms, 

 endowed with inertia and with a 

 mutual force which at vanishing 

 distances is repulsive, which at in- 

 sensible distances alternates accord- 

 ing to some mathematical formula 

 between repulsion and attraction, 

 and, finally, at sensible distances 

 becomes identical with Newton's 

 force of gravitation. The general 

 form of the curve which exhibits 

 this action at a distance is given, 

 and the algebraical formula dis- 

 cussed, in the Supplement. But 

 it was, of course, impossible to 

 define the law any further. The 



