110 HISTORY OF THE PHYSICAL 



us the means of following the processes of development in 

 organisation (the formative activity, the origin of being 

 or production, as Aristotle finely says) ; the compass, with 

 the different mechanical contrivances for investigating the 

 earth's magnetism ; the pendulum, employed as a measure 

 of time ; the barometer ; the thermometer ; hygrometric and 

 electrometric apparatus ; and the polariscope, in its applica- 

 tion to the phsenomena of colored polarisation of light, 

 either of the heavenly bodies or of the illumined atmo- 

 sphere. 



The history of the physical contemplation of the universe, 

 based, as we have seen, on the thoughtful consideration of 

 natural phsenomena, on the occurrence of influential events, 

 and on discoveries which have enlarged our sphere of per- 

 ception, is, however, to be here presented only in its lead- 

 ing features, and in a fragmentary and general manner. I 

 flatter myself with the hope, that brevity in the treatment 

 may enable the reader more easily to apprehend the spirit in 

 which an image, so difficult to be defined, should, at some 

 future day, be traced. Here, as in the " picture of nature" 

 contained in the first volume of Cosmos, I aim not at com- 

 pleteness in the enumeration of separate parts, but at a clear 

 development of leading ideas, seeking, in the present case, 

 to indicate some of the paths which may be traversed by the 

 physical inquirer in historical investigations. I assume on 

 the part of the reader such a knowledge of the different 

 events, and of their connection and causal relations, as may 

 render it sufficient to name them, and to shew the influence 

 which they have exerted on the gradually increasing know- 

 ledge and recognition of nature as a whole. Completeness, 

 I think it necessary to repeat, is neither attainable, nor is it 



