FUNDAMENTAL CONCEPTIONS 371 



In this undertaking we have a most striking illustration of an altruis- 

 tic spirit toward posterity which must be regarded as the finest attri- 

 bute of a civilization having at heart the collective interests of the race. 



In the struggle to secure the extraordinary degree of real accuracy 

 required in the effective treatment of important problems in modern 

 astronomy, the scrutiny to which the fallibility of the senses is sub- 

 jected is a notable feature. Scarcely a measurement can now be made 

 concerning which a doubt is not interposed as to the possible effect of 

 personal idiosyncracies of the observer, or as to some unrecognized 

 effect due to the instrument employed. Accordingly there has grown 

 up during the last few years the habit of special research with a view 

 either to the determination of the effect of these peculiarities, or to 

 devising the means whereby they may be eliminated. 



In modern astronomy even the direct testimony of vision is sub- 

 jected to a similar doubt. Thus we have the testimony of various 

 observers that they have seen on the surface of Mars certain very 

 faint markings which they call canals. At the same time other inves- 

 tigators declare that these markings may be merely illusions due to 

 optical and mental strain; and they produce ingenious experiments 

 to prove their contention. These facts, and many others that might 

 be cited, illustrate the critical tendencies of modern astronomy which 

 are now somewhat more accentuated than they were in former 

 times. 



The present course of astronomy strongly tends toward future 

 development of the power to apprehend and reason about quantities 

 that are too small for direct perception. If this be so, the essentially 

 intellectual character of the processes employed will become still 

 more evident than it has been in the past of astronomical investiga- 

 tion. This modern development that is working in all branches of 

 exact science appears to be of more than temporary significance in 

 the history of the race. Its effect is to enlarge the domain of human 

 experience by discoveries in territory before unknown. This is equi- 

 valent to enlarging the world in which we live and adding to its 

 variety. The same significance should attach to this work that would 

 be ascribed to the discovery of a new continent. In effect these 

 quasi-supersensual discoveries introduce us into regions of know- 

 ledge which are absolutely new to human experience; and when the 

 number of those who are able to enjoy an intellectual tour in these 

 regions shall become a relatively numerous element of population, 

 this species of additions to knowledge will become still more highly 

 appreciated. 



In recent times we have become distinctly conscious that astronomy 

 has enlarged its field of investigation to cover a class of researches 

 not immediately reducible to the study of apparent motion. The 

 development of the spectroscope has brought this about. Some 



