154 PHILOSOPHY OF STORMS. 



books cirrus ; but which is very generally known by the 

 name of haze. 



This cloud, at Philadelphia, nearly always comes from 

 some western or south western point ; and it is believed, 

 both from theory and numerous observations, that, when a 

 rain is going on at the north west, it becomes more western, 

 or even north of west. The cause of this is manifestly the 

 outspreading of the cloud, which protrudes the air outwards 

 in an annulus all round the region of the cloud, at the height 

 of the cloud itself. This protrusion of the cloud is some- 

 times manifest from the shape of the thunder storm cloud, 

 especially the hail cloud, spreading out at the top like a 

 mushroom, or hour-glass ; and, in such cases, the precipita- 

 tions of hail and rain are seen falling from the outspread 

 annulus into the clear air below. The height of this annu- 

 lus is great, but not exactly known. 



These points, therefore, require further observation and 

 confirmation. 



When any sudden change in the wind takes place, let 

 the time and direction be carefully noted. And when a 

 tornado occurs, run to the barometer and mark the lowest 

 point to which it sinks, and the time it takes to rise a 

 given quantity after the passage of the tornado. Also, if 

 any remarkable tornadoes happen, or have happened, in 

 your neighborhood, visit the ground where they have 

 passed, and see in what manner the trees have been thrown 

 down. In the Brunswick tornado, in 1835, June 19, all 

 the trees were thrown with their tops inwards, and gen- 

 erally forwards ; if some were occasionally thrown back- 

 wards, they were invariably found to be underneath those 

 which were thrown forwards, when any were lying across, 

 and those trees underneath, it is believed, were the most 

 easily thrown down. Let this point be examined as to 

 other tornadoes or spouts. In the Brunswick spout, a vein 

 of hail fell, not in the path of the spout, which was not 



