EXPLORING THE GLORIES OF THE FIRMAMENT 



165 



TRANSPORTING THE PRICELESS HUNDRED-INCH MIRROR FROM PASADENA TO 

 MOUNT WILSON (SEE PAGE 1 64) 



The motor truck carrying" this treasure of the astronomical world up the great mountain was 



geared down to four miles an hour. 



away from us, is coming or going, and 

 how fast. 



Did you ever notice, in traveling, when 

 meeting a train on a double-tracked rail- 

 road, how much higher the pitch of the 

 bell is as it comes toward you than when 

 going from you? More sound-waves 

 reach your ears as the train comes toward 

 you than as it goes from you. The same 

 is true with the light-waves in the spectro- 

 scope. If the star is coming toward us, 

 the lines shift toward the violet or higher 

 pitch ; if receding, toward the red. And 

 these shifts are always proportional to the 

 speed of the star ; so that not only the 

 coming and the going are recorded, but 

 the velocity as well. 



THE PATIENCE OF ASTRONOMERS 



The patience with which astronomers 

 make their studies in their unrelenting 

 pursuit after truth is unsurpassed in any 

 field of human inquiry. At the Naval 

 Observatory in AYashington computations 

 based on a single series of observations 



have been in progress for a period of 

 nineteen years, but are not yet completed. 

 The results of the various expeditions 

 that observed one of the transits of 

 Venus were for half a century under cal- 

 culation and comparison. 



A single investigation of the inequali- 

 ties of the changes of the moon required 

 9,000 hours of hard calculations by a 

 trained mathematician. There were 

 13,000 multiplications of series, contain- 

 ing some 400,000 separate products. The 

 whole computation required the writing 

 of nearly five million digits and plus and 

 minus signs. And even then the author 

 felt that much remained to be done be- 

 fore he could construct the tables he had 

 undertaken to make. 



OUR STUPENDOUS I XSIGXI E ICAXCE 



Before starting out to explore the 

 heavens and to make a biographical sur- 

 vey of its more prominent folk, one here 

 might well revert to that old, old ques- 

 tion : "What is the good of it all " Are 



