1888.] occurred at Dacca on April 7th, 1888. 203 



absolutely flat by the violence of the fall. In another case a large boat 

 was blown up the river-bank, and is now blocking a road within the 

 Gunge. In all as far as I could ascertain, 7 persons had been killed, 3 

 were missing apparently in the river — nine persons were seriously in- 

 jured ; of these eight were put in a boat and brought to Serampore, and 

 an unascertained number had sustained slight injuries. The material 

 damage I have as yet no means of estimating ; when accurate figures are 

 available on mortality, injuries and losses, I will forward them. Tempor- 

 ary accomodation must be provided for the Police. The outpost and 

 barracks are utterly laid waste, and quite beyond repair." 



PART II. 



An account of the Dacca Tornado of the 7th of April, 1888. 

 Bij Dr. a. Crombib, Civil Surgeon of Dacca. 



There can be no question that the storm which wrecked a portion 

 of Dacca (on the evening of the 7th of April, 1888, was a tornado or 

 whirlwind. The evidences of its nature are quite conclusive. They 

 consist in observations of the directions in which objects which it en- 

 countered have been thrown down or distorted. The objects which 

 give the most unmistakable evidence are walls running at right angles 

 to the track of the tempest, trees, especially plantain trees, the pinnacles 

 of mats and masjids, and kutcha huts ; and the experiences of persons 

 who were stationed at or near the vortex as it passed over them. 



A tornado is a whirling wind rotating at an enormous speed, and 

 advancing rapidly at the same time, along a more or less straight line. 

 For convenience of description, such a whirlwind may be said to have 

 four radii, an anterior in advance of the vortex, a posterior behind the 

 vortex, and two lateral radii at right angles to the centre line of the 

 track of the storm. All objects situated directly in the centre line of 

 the track will be driven in a direction at right angles to that line, in one 

 direction by the anterior radius, and in the opposite direction by the 

 posterior radius, while objects situated near the sides of the track will 

 be carried or driven forwards on one side, and backwards on the other, 

 in relation to the track of the tempest. One of these lateral radii, that 

 which carries objects in the same direction as that in which the tempest 

 is advancing, may be called the advancing lateral radius, while the 

 opposite which drives objects in the opposite direction may be called 

 the retrograding lateral radius. 



In the diagram shown as Fig. A., PL XXVII., AB is the line taken 

 by the vortex in its advance, C is the vortex, the circle FLEK represents 

 the whirling of the wind round the vortex C. The arrows indicate 



