-1859] WRITINGS OF JOSEPH HENRY. 367 



two,) a glow of light will appear, attended with a hissing 

 noise on the end of the conductor connected with the 

 earth. Now, if we suppose that in the atmosphere between 

 the cloud and the earth there exists a stratum or current of 

 very dry air, while the remaining portions are in a very 

 moist condition, and that the silent discharge from the 

 cloud is taking place (for example) nearly perpendicularly to 

 the earth, and passing through the dry stratum, then the 

 partial interruption of conduction as the current of electric- 

 ity passes through the dry stratum will give rise to the ex- 

 hibition of light. Again if we suppose the cloud to be in 

 motion, this appearance will travel with it, and the patch or 

 glow of light will thus exhibit in mid-air a comparatively 

 slow progressive motion, and disappear as if with an ex- 

 plosion, when a disruptive discharge takes place. This hy- 

 pothesis can only be considered as an antecedent possibility, 

 and is not presented as a full or satisfactory explanation ; the 

 phenomenon itself must be more frequently observed, and 

 the associated condition of its appearance more minutely 

 noted, before a definite hypothesis can be formed as to its 

 cause. 



Records of observations therefore with regard to this 

 meteor are exceedingly desirable ; they should however be 

 made with scrupulous accuracy, and by persons accustomed 

 to scientific investigations. We have found in examining tes- 

 timony great difficulty in obtaining an accurate account of all 

 the circumstances attending a peculiar occurrence of nature, 

 from those who were present at the time and witnessed the 

 phenomenon. It is astonishing how much the products of 

 the imagination are mingled with the actual impressions 

 made upon the senses, and how difficult it is to separate 

 from the testimony of a witness what he actually saw and 

 what he unconsciously infers from the previous crude con- 

 ceptions of his mind, awakened at the instant by a powerful 

 association of ideas. In the transit of the meteor which 

 passed over a considerable portion of the United States, in 

 November last, [1859,] a large number of persons declared 

 that it fell in an adjoining field or in the water near by, 



