PRINCE RUPERT'S DROPS. 



315 



according to the theory of evolution, it is related by an unbroken line 

 of descent granting that we ai-e, if possible, still less able to picture 

 in imagination the process of cliange from any one form to another 

 what then ? Not surely that the theory of evolution is false ! For 

 the same argument will prove that no man present can possibly be 

 tlie son of his father. Our ignorance is very great, but it is not a 

 very great argument. 



The other objection, that the creatures could never have lived to 

 acquire their more important instincts, rests on a careless misunder- 

 standing of the theory of evolution. It assumes in the drollest possi- 

 ble way that evolutionists must believe that in the course of the evo- 

 lution of the existing races there must have from time to time ap- 

 peared whole generations of creatures that could not start on life from 

 the want of instincts that they had not got. There can be no need to 

 say more than that these unfortunate creatures are assumed to have 

 been singularly unlike their parents. The answer is, that it is not the 

 doctrine of evolution that the bodies are evolved first by one set of 

 causes and the minds are put in afterward by another. This notion is 

 but the still lingering shadow of the individual-experience psychology. 

 As evolutionists, whether we take the more common view and regard 

 the actions of animals as prompted by their feelings and guided by 

 their thoughts, or believe, as I do, that animals and men are conscious 

 automata, in either case we are under no necessity of assuming, in ex- 

 planation of the origin of the most mysterious instincts, any thing 

 beyond the operation of those laws that we see operating around us, 

 but concerning which we have yet to learn more, perhaps, than we 

 have learned. Nature. 



PRINCE RUPERT'S DROPS. 



Br WILLIAM LEIGHTON, Jr., S. B. 



WHEN" from fluidity glass is cooled to a solid structure in the 

 ordinary temperature of the atmosphere, it is found to be very 

 brittle or liable to fracture. 



If the glass is so shaped as to be of unequal thickness in its difier- 

 ent parts, it can seldom be cooled without fracture, and, if unbroken 

 when cool, is liable to fracture with any subsequent change of temper- 

 ature or by a sudden jar. Often this fracture takes place, in articles 

 of considerable thickness, with an explosive force, perhaps breaking 

 the glass into a thousand pieces. AVhen glass breaks in this manner, 

 it is said to " fly." 



In order to prevent such liability to " fly," glass-ware is annealed. 



The process of annealing glass consists in reducing its temperature 

 more slowly than would occur in the air at ordinary temperatures. 



