﻿EQUIPMENT AND WORK OF AN AERO-PHYSICAL OBSERVATORY. 29 



We have referred above to the possibility of studying electrical dis- 

 charges in the atmosphere from an entirely new standpoint. The method 

 would consist in the use of a resonator or resonators, with proper vibra- 

 tion periods, capable of responding to the ether oscillations. The rapidity 

 of vibration in any electrical systein being directly proportional to the 

 linear dimensions, we may assume for a flash of lightning one thousand 

 meters long the existence of vibrations at a rate of, say, three hundred 

 thousand per second. 



Dr. Lodge (see " Phil. Mag.," August, 1888), has worked out at some 

 length the values for an ordinary flash of lightning. 



Now V, the velocity of propagation, is equal to ^ /—r7\ ^^^ ^^^® wave- 

 length A = VT= 2 7:^ — • -7^ where — is the electromagnetic measure 

 of induction and ^ is the electrostatic measure of capacity. 



. 27rF [LS 1 



We may expect the longest sparks when the periods of the cloud- 

 earth system and the proposed resonator are the same. The length of 

 each conductor, then, should be half a wave-length or some multiple of 

 half a wave-length. 



Such resonators may occur naturally, and perhaps herein is an explana- 

 tion of sympathetic distant Hashes which are sometimes seen, the second 

 flash being the response of a natural resonator. 



Conclusion. 



An aero-physical laboratory would afford opportunity for important 

 research and investigation. A most promising field, we have attempted 

 to show, lies in the increase of knowledge of conditions controlling the 

 weather. We urge investigations in all lines bearing upon forecasting or 

 foretelling weather. As examples of proper and profitable lines of study 

 in this direction, let us mention : v. Helmholtz on " Studies of viscosity 

 effects in the general circulation of the atmosphere;" "Studies of the 

 mutual influence of whirls." Practical application of knowledge of- this 

 character being the great desideratum of modern meteorolog,y. For 

 example, Helmholtz gives as a practical deduction in one of his papers 

 the statement that extremely violent winds are prevented in the general 



