94 THE POPULAR SCIENCE MONTHLY. 



radesliip is lost through this want of understanding. It is this gulf 

 that I desire to bridge over, to the best of ray power. That the scien- 

 tific thinker may consider his business in relation to the great life of 

 mankind ; that the noble army of practical workers may recognize 

 their fellowship with the outer world, and the spirit which must guide 

 both ; that this so-called outer world may see in the work of science 

 only the putting in evidence of all that is excellent in its own work ; 

 may feel that the kingdom of science is within it : these are the objects 

 of the present discourse. And they compel me to choose such por- 

 tions of my vast subject as shall be intelligible to all, while they ought 

 at least to command an interest universal, personal, and profound. 



In the first place, then, what is meant by scientific thought ? You 

 may have heard some of it expressed in the various sections this morn- 

 ing. You have probably also heard expressed in the same places a 

 great deal of unscientific thought ; notwithstanding that it was about 

 mechanical esergy, or about hydrocarbons, or about eocene depos- 

 its, or about malacopterygii. For scientific thought does not mean 

 thought about scientific subjects with long names. There are no sci- 

 entific subjects. The subject of science is the human universe ; that 

 is to say, every thing that is, or has been, or may be, related to man. 

 Let us, then, taking several topics in succession, endeavor to make 

 out in what cases thought about them is scientific, and in what cases 

 not. 



Ancient astronomers observed that the relative motions of the sun 

 and moon recurred all over again in the same order about every nine- 

 teen years. They were thus enabled to predict the time at which 

 eclipses would take place. A calculator at one of our observatories 

 can do a great deal more this. Like them, he makes use of past expe- 

 rience to predict the future ; but he knows of a great number of other 

 cycles besides that one of the nineteen years, and takes account of all 

 of them ; and he can tell about the solar eclipse of six years hence ex- 

 actly where it will be visible, and how much of the sun's surface will 

 be covered at each place, and, to a second, at what time of day it will 

 begin and finish there. This prediction involves technical skill of the 

 highest order ; but it does not involve scientific thought, as any as- 

 tronomer will tell you. 



By such calculations the places of the planet Uranus at different 

 times of the year have been predicted and set down. The predictions 

 were not fulfilled. Then arose Adams, and from these errors in the 

 prediction he calculated the place of an entirely new planet, that had 

 never yet been suspected ; and you all know how the new planet was 

 actually found in that place. Now, this prediction does involve scien- 

 tific thought, as any one who has studied it will tell you. 



Here, then, are two cases of thought about the same subject, both 

 predicting events by the application of previous experience, yet we 

 sav one is technical and the other scientific. 



