OF THE 22ND OF APRIL, 1884. 
25 
moved at the same time in the same manner,” and also one at 
Thaxted in Essex.* 
In commencing our investigations on the recent earthquake, 
we took measures to procure records from persons living in and 
around the area of destruction, and we received altogether between 
300 and 400 such records, besides making ourselves two tours 
of inspection throughout the area. 
The shock was felt over a very wide area, extending on its 
extreme eastern limit to Ostend; on the west to Street, in 
Somersetshire ; on the south to Freshwater, Isle of Wight; and on 
the north to Brigg, in Lincolnshire!; the total area affected by the 
shock amounting in all to at least 50,000 square miles, so that 
it was certainly an earthquake of very great intensity (see Plate I). 
The data necessary for calculating the intensity of the shock 
with any approach to accuracy can only be obtained by means of 
appropriate instruments, and as these were wholly wanting in the 
present instance, we could only estimate the intensity, as compared 
with that of other earthquakes, in a very crude way by comparing 
the relative areas shaken. Comparing the area shaken in this case 
with that affected by the great Lisbon earthquake, we found that 
the intensity of the Essex shock was somewhere about one-twentieth 
of the great Lisbon shock in 1755. 
One interesting feature of the disturbance was that it occurred 
during a period of general seismic activity throughout the world.! 
We have given in the report a list of the earthquakes which 
occurred during the three years preceding this shock, and during 
that time there were some of the most violent of modern seismic 
catastrophes. Eor instance, in 1881 there were the great earth¬ 
quakes in the Azores, in Ischia, and in the Island of Chios; in 
1883 there was another great earthquake in Ischia; and about the 
same time there was the great eruption in the Sunda Straits, which 
was certainly one of the most stupendous volcanic eruptions of 
modern times. 
With regard to the meteorological conditions which accompanied 
the Essex earthquake, there has always been a tendency among the 
populace to associate visitations of this kind with some extraordinary 
atmospheric phenomena, which they were ready to connect in some 
mysterious way with the earthquake; and to show how the love of 
the marvellous still lingers among some people, I may mention 
that one observer at Tillingham sent in a report' saying that 
immediately after the shock had passed u a sulphureous vapour was 
noticed to arise,” but I do not think it likely that anything of the 
* See Cussans, ‘ Hist. Herts,’ Edwinstree Hundred, p. 164. 
t See p. 32 as to its effects at Leeds, still further north. 
f In connection with this feature it may he of interest to mention two earth¬ 
quakes which have recently been felt in Hertfordshire. One which occurred on 
the 28th of February, 1878, in the south of England, was felt at St. Albans, as 
recorded in ‘Trans. Watford Nat. Hist. Soc.,’ Vol. II, p. 215 ; and the other, 
which occurred on the 20th of January this year (1886), in the west of England, 
caused a slight oscillatory movement at H ertford, and a notice of it will be com¬ 
municated to the Society by Dr., Shelly.—E d. 
