326 THE POPULAR SCIENCE MONTHLY. 



ated phenomena appeared first, then chemical, then vital, and, lastly, 

 rational (if these can be at all considered in the same categor}'). It is 

 also the order of dependence, and therefore, also, of historic development 

 of the sciences based upon them. Mechanics is absolutely dependent 

 on mathematics, and must, therefore, have awaited its development. 

 Similarly, physics is dependent on both mathematics and mechanics, 

 but especially the latter, and therefore must await its development. 

 Similarly, chemistry must wait on all the preceding, but especially on 

 physics ; and biology must patiently await the development of all the 

 preceding, but especially of chemistry. 



But observe the following qualification : This is the necessary order 

 in which these departments taJce on true scientific form^ but not neces- 

 sarily the order in which they are first commenced to be cultivated. 

 Astronomy commenced to be cultivated by the Chaldeans long before 

 mathematics or mechanics was sufficiently advanced to be applied to 

 it. Biology commenced to be cultivated by Aristotle, or perhaps even 

 by Solomon, long before chemistry and physics were sufficiently ad- 

 vanced to be of any use in biological investigations, add indeed before 

 these sciences were born. In all sciences, but especially in the higher 

 and more complex departments, there are three distinct stages of ad- 

 vance : The first consists in the observation, collection, and arrange- 

 ment of facts — descriptive science. The second is the reduction of 

 these to formal laws — -formal science. Thus far the science is indepen- 

 dent of other sciences. The third is the reference of these laws to the 

 more general laws of a more fundamental science — in the hierarchy as 

 their cause — causal science. It is this last change only which neces- 

 sarily follows the order indicated above. Its effect is always to give 

 great impulse to scientific advance ; for then only does it take on the 

 highest scientific form, then only does it become one of the hierarchy 

 of sciences, and receives the aid of all. Thus to illustrate : Tycho-Brahe 

 laboriously gathered and collated a vast number of facts concerning 

 planetary motions — descriptive astronomy. Kepler reduced these to 

 the three great and beautiful laws known by his name — formal astron- 

 omy. But it was reserved for Xewton, by means of the theory of 

 gravitation, to explain the Keplerian laws by refemng them to the 

 more general and more fundamental laws of mechanics as their cause, 

 and thus he became the founder of physical or causal astronomy. In 

 other words, astronomy was first a separate science based on its own 

 facts. Newton connected it with mechanics, and thus made it one of 

 the hierarchy. From that time astronomy advanced with increased 

 rapidity and certainty. Astronomy first rose as a beavitiful shaft, un- 

 connected and unsupported, except on its own pediment. In the mears 

 time, however, another more solid and more central shaft had grown 

 up under the busy hands of many builders, viz., mechanics. Newton 

 connected the astronomical shaft with the central column of mechan- 

 ics, and thus formed a more soKd basis for a yet higher shaft. 



