44 J. HOPKTNSON — THE EAINFALL IK 1893. 



" The thunderstorm was a very remarkable one, being of a trae 

 cyclonic character, a tornado in fact. During the whole afternoon 

 electrical tension had been extreme, the instruments here, especially 

 the electrometer, being much disturbed. Distant thunder was 

 heard about 3.30 p.m., and a sharp fall of the barometer set in. 

 At about 6.5 the storm broke out to the S.W. It appeared to 

 have originated to the south of the village of Pinner, but did 

 not then develop the energy it aiterwards displayed, the first 

 case of damage being the partial unroofing of a barn near Pinner 

 Church. It then passed at the back of Woodridings, where 

 several large trees were torn up and garden-fences and roofs 

 broken, and crossed the L. and N.W. main line at Pinner Station, 

 lifting up the seats on the platform and carrying the corrugated- 

 iron I'oof of a shed nearly a mile, depositing it in a field, where 

 also were found the tops of two fir trees which must have been 

 blown a mile and a half. After crossing the Watford road near 

 Burnt Oak Farm, it passed up the valley below Graeme's Dyke 

 to Hartsbourne. (Its further track is given above.) 



" The width of the whirlwind was only about 50 yards, and 

 outside this track nothing was touched, but within its influence 

 the effects were remarkable. It appeared to have exerted the 

 greatest force in the hollows, nearly all the trees blown down 

 being in the lowest positions ; in many cases where the trunks 

 were too firmly rooted they were wrung in half about eight feet 

 from the ground, the fibres of the wood being twisted like the 

 strands of a rope. A line of trees standing parallel to the course 

 of the storm had all the branches on one side broken, on the other 

 untouched, while some of the trees uprooted were lying with their 

 tops to the direction from which the wind had come. 



' ' As seen from here the cyclone appeared as a very low cloud, 

 absolutely black, and apparently reaching the ground. It appeared 

 to completely envelop the trees, and travelled with great velocity, 

 while the enormous speed with which it rotated on its axis is 

 shown by the damage done. The noise when distant was like that 

 produced by a large flock of starlings in flight ; as it approached, 

 however, the roar resembled that of a train, but at this point, 

 some 800 yards distant fi-om the track of the storm, the air was 

 perfectly still. Tlie electrical phenomena accompanying it were 

 very intense, but I have not been able to trace any actual damage 

 by lightning, although the close proximity of the storm is proved 

 by the fact that three of the fuses in the electric-lighting engine- 

 room in the garden were melted, probably by induction, as there 

 was no sign of the building having been struck. From 6.40 the 

 barometer commenced to recover itself. I am strongly of opinion 

 that a so-called cyclone is simply an effect of electrical tension, 

 and that any thunderstorm of sufficient energy is likely to be 

 accompanied by a ' wind-spout' similar to the above." — K.J. Tarrant, 



