Masterpieces of Science 



moon's present state with those that are to be 

 obtained hereafter will surely settle the interest- 

 ing questions relating to changes in progress upon 

 the surface of our satellite. Doubtless, also, the 

 improved instruments for the measurement of 

 heat and other radiations will make our under- 

 standing of its physical conditions vastly more 

 sure and definite. 



While we are now certain that the average 

 temperature of the moon is very low, we know 

 nothing definite as to its range, nor how hot the 

 surface rocks may become during the moon's 

 long day of unclouded sunshine, lasting more 

 than three hundred hours. 



As to the moon's averted face the side never 

 yet seen from the earth there is no prospect 

 that the future will do anything for us. There is 

 no reason to suppose that it differs in any impor- 

 tant respect from the face we see and study; 

 probably, however, men will never know; and 

 yet more than once in the history of science some- 

 what similar negative predictions have been dis- 

 credited. 



Solar astronomy promises rapid advance. 

 Even with our present means of investigation, 

 facts and data are fast accumulating which, by 

 the mere lapse of time, will furnish an answer to 

 many of the most important questions now open, 

 such as those which relate to the imagined in- 

 fluence of the planets in causing disturbances of 

 the sun's surface and the effect, if any, of such 

 disturbances upon our own terrestrial affairs. 

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