98 G. F. Becker — Kant as a Natural Philosopher. 



to complete his studies for the degree of Doctor of Philosophy. 

 The paper on the volcanoes of the moon gave him an oppor- 

 tunity of reasserting his belief in his nebular hypothesis after 

 many years of reflection, and of making a very great addition 

 to the cosmogonic apparatus. The discussion of the meta- 

 physical bases of natural science contains interesting reflections 

 and definitions. It is difficult to say how much of it was abso- 

 lutely new, since all natural philosophers have dealt with the 

 same ideas. His definitions of fluids and solids* sound 

 extremely modern. " A material in which a motive force, how- 

 ever small, produces shear is a fluid, no matter how powerful 

 the cohesion of its parts." A solid is a body " which resists 

 shear with a certain degree of force." " The resistance to 

 shearing is die Reibung," by which he means what is now 

 denoted by rigidity; liquids, he says, have none of it. In his 

 theory of the winds Kant was anticipated by Geo. Hadley,t 

 but he supposed himself to be the first to perceive the effect of 

 the rotation of the earth on northerly or southerly winds. He 

 deduced from this effect the cause of the easterly trades, the 

 westerly winds of latitude 28° to 40° and the monsoons. 

 Kant's paper on this subject was very probably intended as a 

 reply to D'Alembert, whose theory of the winds procured him 

 the prize of the Berlin Academy in 1746. D'Alembert 

 endeavored to account for atmospheric currents as an imme- 

 diate result of the attraction of the sun and moon. The 

 physical geography was edited from lecture notes by a pupil 

 when Kant was an old and broken man. There is good reason 

 to suppose that it would have been more valuable if Kant had 

 written it out himself at an earlier date. 



Kant was indeed no dreamer, but one of the best informed 

 men of his time. It was the great object of his life to dis- 

 courage visionary speculations, " Schwarmerei," and to reduce 

 all subjects to the confines of reason. His theory of the 

 heavens, however it may appear to modern readers, was con- 

 ceived from this point of view. Even Newton had felt him- 

 self called upon to attribute various details of the solar system 

 to the direct intervention of the Creator, and it was the habit 

 of that day, as of other days, to confound the mysterious with 

 the miraculous. Kant endeavored to offer a rational explana- 

 tion of many mysteries and in large measure he was successful. 

 He saw, as well as one can see now, that astronomy has two 

 divisions. In spherical and gravitational astronomy mathe- 

 matics reigns supreme, and certainty is attainable. In phys- 

 ical and historical astronomy, on the other hand, a high degree 

 of probability is the nearest possible approach to absolute 

 truth. Kant says of his theory of the heavens : " In general, 



* Kant's Werke, vol. iv, p. 420. f Phil. Trans., vol. xxxix, 1735, p. 58. 



