﻿EQUIPMENT AND WORK OF AN AERO-PHYSICAL OBSERVATORY. 7 



How important to know the atmospheric conditions as influencing ex- 

 hilaration and fatigue. The so-called " sensible " temperature, for exam- 

 ple, enables one to live in the temperatures of the Southwest in summer 

 and renders temperatures lower by twenty degrees elsewhere unbearable. 



In such a laboratory, then, trained intellects studying the properties of 

 atmospheric air, would, we firmly believe, influence research in every de- 

 partment of applied science. In agriculture the value is apparent ; in 

 ■economics, history, hygiene, botany, geology, and biology, questions now 

 unanswered would be disposed of. In that much-dreamed-of consumma- 

 tion, the conquest of the air, when transportation shall be by air-ships and 

 communication by air-runners or disturbances of the electrified air, the 

 contributions to knowledge from such a laboratory would be incessant and 

 without price. Aye, in directions now unthought of, the aero-physicist 

 would push onward in the great region now unexplored. When the 

 Berlin Academy, in 1879, offered a prize for the experimental determi- 

 nation of a relation between electromagnetic forces and the dielectric 

 polarization of insulators, perhaps no one — certainly neither Helmholtz 

 nor his assistant, whose attention he directed to the matter — foresaw 

 more than certain experimental determinations. Hertz took his prob- 

 lem as he received it. We have his own words that he started out to 

 prove that changes of dielectric polarization in non-conductors produced 

 the same electromagnetic forces as do currents which are equivalent to 

 them, and that electromagnetic as well as electrostatic forces are able to 

 produce dielectric polarizations ; and yet, further, that in all these re- 

 spects air and empty space behave like all other dielectrics. " I saw no 

 way," he says (see '' Electric Waves "), " of testing the first and second for 

 air, but both would be proved simultaneously if one could succeed in 

 demonstrating for air a finite rate of propagation and waves." Let us 

 ■exult in Hertz as the first aero-physicist and join Lord Kelvin in his 

 triumphant declaration, when referring to waves of electric' force, that 

 *'the processes in air represent on a million fold larger scale the same 

 processes which go on in the neighborhood of a Fresnel mirror or between 

 the glass plates used for exhibiting Newton's rings." 



The direction in which the demand for immediate application of our 

 knowledge of aero-physics is greatest is in connection with the tides and 

 fluxes of the aerial ocean in which we live, the storms and currents of 

 the atmosphere. There is a popular impression that forecasting weather 

 conditions is in a high degree a matter of scientific procedure. Much 

 that is scientific in character has been done, it is true ; but, Avithout dis- 

 paraging such work, it remains none the less true (and we but echo the 

 sentiments of those professionally engaged in forecasting) that the present 

 condition of our knowledge is quite unsatisfactory. Newton's boy play- 



