200 THE POPULAR SCIENCE MONTHLY. 



spiration of mechanics and the pride of mathematics, how trifling is 

 the region which has been subjugated to the rigid rules of the exact 

 sciences when compared with the immense territories which remain 

 under the jurisdiction of natural history, and must be studied, if at 

 all, by the methods of the naturalist, though with an inverted micro- 

 scope ! 



If, now, we circumscribe our outlook by the line which marks where 

 physical science ends and natural history begins, it will be possible to 

 examine only a tew of the salient points in the prospect before us ; 

 and what these are will depend upon the point of view which we 

 select. Whewell presents the history of any science at each of its 

 successive epochs as circulating around one powerful mind, which 

 figures as the hero of the drama, and whatever immediately precedes 

 or follows is only the prelude or the closing strain to the great move- 

 ment. In the philosophy of Comte, every science passes through a 

 theological and metaphysical crisis before it reaches the healthy con- 

 dition of positive knowledge, and its whole history is written out by 

 him in these three acts. With Buckle, the progress of science, with- 

 out which there could be no history, is coincident with the advance 

 in civilization ; but the action begins with science, and the reaction 

 only comes from external causes. All that science and civilization 

 demand is perfect freedom of thought. The worst enemy of both is 

 the protective spirit in church and state, the former telling men what 

 they must believe, the latter what they must do. 



Each of these views of scientific development may be true, but not 

 to the exclusion of all others. Metaphysical blindness or theologi- 

 cal prejudice may block the way of science or defame its fair name. 

 It has been stated that six members of the ultra-clerical party at Ver- 

 sailles voted against the appropriation for securing observations of 

 the approaching transit of Venus, because they did not believe in the 

 Copernican system, and this, too, while the echoes of the celebration 

 of the four-hundredth birthday of Copernicus are still resounding over 

 the earth ! So, also, circumstances, and even accidents, may shape the 

 course of discovery ; the happiest of all accidents, however, being the 

 appearance on the stage of the discoverer himself. 



The point of view which I have chosen for reviewing the close and 

 advancing columns of the physical sciences is this : Are there any im- 

 provements in the weapons of attack, or have any additions been made 

 to them ? These are of two kinds : 1. Instruments for experiment, and 

 2. The logic of mathematics. These are the lighter and the heavier 

 artillery in this peaceful service. 



If we cast a hurried glance over that long period of experimental 

 research which began with Galileo and ended with Davy, we recog- 

 nize, as the chief instrumentalities by which physical science has been 

 promoted, the telescope, the microscope, the pendulum, the balance, 

 and the voltaic battery. It is not necessary for me to enlarge upon 



