400 Notices of Scientific Worlcs. [July, 



nature we see ttat life is maintained by tlie effort ever made to 

 maintain the equilibrium of forces. A positive and a negative — a 

 plus, minus — is found everywhere in the material universe, and, as 

 the jar of Leyden owes its power to the effort it makes, — almost as 

 if a sentient thing, — to equalize the conditions of its inner and its 

 outer coating in relation to electrical power, so is there an analogous 

 condition of this kind at work everywhere. This is perhaps more 

 strongly shown in the phenomena of heat than of any other power, 

 and nowhere is it more strikingly exhibited than in those regions 

 where the deprivation of the sun for a long period reduces external 

 nature to the extremity of cold. Those who can read this popular 

 book with such a touch of philosophy in their miuds as we have 

 imperfectly indicated, will derive a double charm from the volume. 

 Those who go to it merely for the interest which ever belongs to a 

 well-written book on strange lands, will not be disappointed. 

 They will find Man in what would appear to be the most wretched 

 condition in which it is possible for him to exist, living with a 

 certain amount of enjoyment ; his very animal necessities are 

 made so many ministers of contentment. Any one who will read 

 with care the relation given by Dr. Hartwig, must rise from his 

 task with liis conviction strengthened that a superintending Provi- 

 dence alone could produce the remarkable results which astonish 

 the traveller in the polar regions. To borrow some of the author's 

 words, the influence on the development of vegetable and animal 

 existence, of the long polar winter nights, and its fleeting summer, 

 is amongst the most striking of natural phenomena. To picture 

 Man waging the battle of Life against the dreadful climate of the 

 high latitudes of our globe — as the inhabitant of their gloomy 

 solitudes, or as the bold investigator of their mysteries — is to bring 

 into strildng contrast the highest and the lowest operations of mind, 

 and to show how nearly equal are the animal conditions of him who 

 is bora amidst the eternal snows, and of him who would pierce the 

 barriers of ice and knows what wonders lie enchained within them. 

 Dr. Hartwig has written, for a foreigner, a book in capital EngUsh. 

 He has, as ho says, a " great variety of interesting subjects, embraced 

 within a comparatively narrow compass," and he lias conveyed 

 much solid instruction under an entertaining form. To every one 

 the ' Polar World ' must prove a book of interest, and to many, 

 especially to the young, it cannot fail to be a volume full of 

 instruction. 



