162 Mr. W. R Birt on the Production of Lightning hy Rain. 



which within two seconds, by estimation, was succeeded by a 

 vivid flash of lightning : the thunder occurred at a further 

 interval of some few seconds. From this it would appear, 

 provided the heavy rain fell over the entire space between the 

 place of observation and that of the electric discharge, that it 

 was not a consequence of that discharge, the gush occurring at 

 a sensible interval previous thereto. The setting in of the 

 storm of the 26th, about l'^ 45"^ p.m., again called the atten- 

 tion of the writer to this point ; and several flashes occurred 

 between 1^ 45°^ p.m. and 2^ 3"^ p.m. without being preceded 

 by a gush, although heavy rain more or less accompanied the 

 discharges, in one or two instances almost simultaneously or 

 immediately afterwards. At length, about 2^ 4'°^ p.m., a most 

 violent and very remarkable gush of rain occurred, which was 

 followed within one minute by a most vivid flash of lightning, 

 the thunder succeeding almost instantaneously. The windows 

 of the house in which the writer was observing the storm were 

 sensibly shaken, and portions of the mortar between the arches 

 over the windows and the frames thrust out, of course by con- 

 cussion. Within a minute or two after this discharge a par- 

 tial cessation of the heavy rain took place, but sudden gushes 

 occurred at short intervals within the next six or seven mi- 

 nutes ; they were, however, unaccompanied by lightning. At 

 the end of this period the atmosphere presented a very re- 

 markable appearance ; a perfect stillness characterized the air, 

 which possessed great transparency, so that the surrounding 

 objects were seen with very minute distinctness of detail. The 

 stillness and transparency during the time they continued, 

 riveted the observer to their contemplation. It appeared that 

 during this time the storm was hushed, and a calm of a rather 

 extraordinary character succeeded it, during which a rather 

 large break in the clouds was seen towards the south-east, and 

 the entire phaenomena at this time induced the idea that the 

 weather was clearing up. Within ten minutes, however, the 

 storm again burst forth; the lightnings played, the thunder 

 roared, and heavy rain, mingled with hail so thickly that com- 

 paratively near objects could scarcely be distinguished, fell in 

 torrents, and the writer observed during the remainder of the 

 storm four or five sudden gushes that were quickly succeeded 

 by lightning. On all these occasions he is quite certain that 

 the sudden gush of rain preceded the electric discharge. Of 

 all the discharges, which were very frequent, that at or near 

 gh 5m pjyi, appeared to the writer to be nearest his own locality; 

 the lightning appeared to him to be quite as, if not more, vivid 

 than that at any other discharge; and the interval between it 

 and the thunder was certainly the shortest, the thunder being 



