46 THE POPULAR SCIENCE MONTHLY. 



themselves, to science, and to the countries which have welcomed 

 them, in proportion as rulers have had the good sense to leave them 

 time to work. 



Democracies encourage savants most by leaving them the widest 

 liberty of opinion. They have furthermore the advantage of causing 

 the separation from political life and public functions of those men 

 who have taste for research, cabinet-work, independence of thought, 

 and for the truth as set above popularity and material considerations, 

 or for precisely those things which most further the advance of science. 

 In general, whatever may be the form or the tendency of the govern- 

 ment, men who cultivate science for itself should rather consider them- 

 selves fortunate if they are out of favor with the administration. 



-***- 



THE PEOBLEM OF CRYSTALLIZATION. 



By ALFEED EINHOEN, Ph.D., M. E. 



CRYSTALS are symmetrical forms bounded by plane surfaces. A 

 surface is said to be plane or level when its nature is such as is 

 exemplified in a sheet of water extending over dimensions very small 

 when compared to the radius of the earth. Crystals occur abundantly ; 

 they are generally diminutive and frequently microscopic in size, and 

 therefore readily escape ordinary observation. Quite different in this 

 respect are many forms caused by the rougher forces active in Nature, 

 and analogous to crystals in the regularity of the shapes they assume. 

 They are not unfrequently noted for their unique and startling appear- 

 ance, as is instanced in the five-sided columns of basalt, known in 

 some volcanic regions, and distinguished for their weird forms and the 

 awe and superstition they give rise to among the inhabitants. Also 

 many erosion figures resulting from the disintegrating action of water 

 and air upon rocks. Many examples of this category may be seen in 

 the scenic displays of unexcelled grandeur afforded by our far West. 

 Not to these, but to a more commonplace phenomenon, I will now 

 direct the attention of the reader, inasmuch as it is, mechanically speak- 

 ing, related to and will serve to elucidate the subject under consid- 

 eration. I have reference to a heap of particles of more or less uniform 

 size, arranging themselves under the influence of the pull or gravity 

 of the earth, with the provision that their magnitude should be very 

 small relative to that of the whole heap. Thus, a grain or gravel heap 

 is an excellent example of the phenomenon I refer to, and it is a very 

 remarkable circumstance that different heaps have the same slope, pro- 

 vided the character of the material and the support upon which they 

 rest remain the same. The slope (the inclination of the sides of the 

 heap with the horizon) is dependent upon the magnitude and shape of 

 the particles, and also upon the nature of the support ; the whole sys- 



