12 W. J. MCGEE 



great lakes to the gulf, but, through international comity, from. 

 Canadian territory on the north to Mexican territory on the 

 south. The observations yield predictions benefiting agri- 

 culture and shipping to the extent of millions annually. They 

 yield also principles which are enlightening the world, miti- 

 gating faith in Moloch and strengthening confidence in human 

 might, and so preparing the way for still more brilliant con- 

 quest by generations yet to come. 



Meteorology does not give control of the powers of the air 

 and the vapors within it (pseudo-science to the contrary not- 

 withstanding), but only enables men so to adjust themselves 

 to these agents as to gain benefit and to avoid injury; yet 

 conquest over the immeasurable potentialities of the atmos- 

 phere is extending in other ways. Half a century ago gases 

 were the most elusive of substances, seldom allied in thought 

 to liquids save in loose speculation, hardly brought from the 

 domain of mysticism into the realm of reality. Now the con- 

 tinuity of the gaseous condition with liquidity and solidity has 

 been established for the more important terrestrial substances. 

 A dozen years ago Cailletet in France and Pictet in Switzerland 

 liquefied various gases by high pressure and low temperature. 

 Dewar, of England, followed in a striking series of operations, 

 liquefying gas after gas, until within a few weeks hydrogen — 

 most refractory of the elements and the unit of matter — has 

 been brought into liquid form, and the American Tripler has 

 devised means of liquefying air in large quantities at limited 

 cost. To-day scientists find themselves on the threshold of 

 a new prospect opened by these conquests. The possibilities 

 of future applications cannot be presaged clearly, but there 

 are indications that they will equal those made through the 

 control of electricity. Liquid hydrogen is only one fourteenth 

 the weight of water; it boils at —238° C. (—396° F.), or only 

 35° C. above absolute zero, while liquid air is a little lighter 

 than water, and boils (or vaporizes) at — 191° C. ( — 312° F.). 

 In the abstract the figures carry little meaning, but made con- 

 crete they signify that just as the astronomer finds himself 

 approaching the limits of the material universe through the 

 telescope and the spectroscope, and just as the morphologist is 

 approaching actual vision of molecular constitution through 



