The Four Forces in Nature. 
639 
1880.] 
and exciting times of the American War of Independence 
and of the first French Revolution, only once does a political 
reflection escape him. In the ninth of his recently discovered 
letters to Robert Marsham, he writes — “You cannot abhor 
the dangerous doCtrines of levellers and republicans more 
than I do. I was born and bred a gentleman, and hope I 
shall be allowed to die such.” Perhaps he was aware that 
political agitation is more hostile to scientific research than 
is even war. Waterton, on the other hand, is for ever ob- 
truding his Catholicism and his somewhat anti-national 
politics upon our notice. We cannot help regretting that if 
he must write on such subjects he did not embody his 
opinions in distinct treatises, addressed to different classes 
of readers. Upon the whole we must pronounce White the 
superior, inasmuch as he made the better use of more 
limited opportunities. 
Both these naturalists, it must be noted, protested— each 
in his distinCt fashion — against the reckless waste of animal 
and especially of bird life, which still goes on. White com- 
plains bitterly of the persecutions to which our rarer birds 
are subject. We feel certain that the golden oriole, the 
hoopoe, and even the bee-eater, once ranked among our 
regular summer visitants. Perhaps their disappearance is due 
as much to the butchery which they suffer in Southern Europe 
as to their inhospitable reception on reaching our shores. 
The present edition of “ Selborne ” presents certain re- 
commendations. The ten newly-discovered letters to R. 
Marsham form a valuable feature, and the editor unlike 
some of his predecessors — does not use the author’s text as a 
peg on which to hang irrelevant notes for his own glorification. 
V. THE FOUR FORCES IN NATURE. 
By George Whewell, F.I.C., F.C.S. 
S HE forces in Nature may be divided into four kinds, 
and we assume that all atoms are endowed with these 
four forces, either in an aCtive or latent condition. 
We have ventured to call these four forces “ Viva.” The 
word Viva is used as a limited expression for the term “life,” 
and means, in the physical world, the motion which pro- 
duces expansion and contraction, which causes molecules to 
assume the form of solid, liquid, gas, or ultra gaseous. 
VOL. II. (THIRD SERIES.) 2X 
