52 
The chief difference in the three other English tracings is 
the absence of the npivard jerk, at the close of the slight rise 
coinciding with the thunderstorm. This rise with a sudden 
rain or hail storm is a familiar occurrence, though the cause is 
obscure. It is possibly due to the sudden contraction of the air 
in cooling, which causes an inrush from outside the storm area. 
The sudden jerk would seem to be connected with the 
whirlwind ” itself. But does it represent cause or effect ? 
Mr. Brook thinks that his barogram at Meltham has a similar 
jerk, in addition to the slight'rise shown about 2-15 p.m. 
in fig. 3. 
Eig. 3, from Mr. 0. L. Brook, of Meltham, near Hudders¬ 
field, 38 miles S.W. of York, is on a much larger scale and 
shows clearly the delieate variations of pressure. Fig 4, from 
Messrs. E-eynolds and Branson, Leeds, is apparently an hour 
fast. Leeds is 23 miles S.W. by W. Fig. 5 is from Mr. H. 
Mellish, Hodsock Priory, near Worksop, 46 miles S. of York. 
Almost identical too, is the record kindly submitted to me, 
obtained by the Rev. W. C. Ley, at Ashby Parva, near 
Lutterworth, 95 miles S. of York. The rise accompanying the 
thunderstorm was here very slight however. It occurred at 
5 p m. If, as the facts mentioned previously seem to indicate, 
the storm advanced in a S.S.E direction, it had traversed the 
82 miles here from Huddersfield in 2^ hours, or with a speed 
of translation of about 33 miles an hour. The recovery after 
the secondary depression is at 5-40 and very sharp ; indeed a 
jump of O’03 inch. 
A glance at the 2 p.m. chart (fig. 1) shows that the thunder¬ 
storm, as is customary, was S E. of the main depression, and at 
York in the south-eastern “octant” of the secondary depression 
as well. It occurred at all five stations, from which our 
aneroidograms are sent, about an hour before this traversed the 
district. 
By 6 p m. the main depression was near Glasgow and had 
slightly filled up. Next morning it was at Christiana and 
pressure had rapidly recovered over England, where clear, cold 
weather prevailed, with moderate, north-westerly breezes. 
There now only remains the comparison with American 
