GENERAL MEETING. 39 
cussed at the last meeting were not touched upon. The data used 
came for the most part from correspondence with private parties, 
although some valuable information had been received from the 
Signal Service, Light-House Board, and Hydrographic Office—only 
a small portion, however, of what they would eventually furnish. 
The State Department had reported that the shock was felt very 
slightly in Bermuda, and would report later as to Cuba and the 
Bahamas. 
The isosetsmals were plotted on an enlarged photograph of the 
relief model of the eastern United States in the Coast Survey Office, 
which illustrated the general topographic features more graphically 
than an ordinary map. In the discussion special attention was paid 
to explaining their irregular shapes by reference to the surface con- 
figuration as well as the geologic structure of the country. The 
inclosed area, marked 4, in West Virginia and Kentucky, well 
illustrates the fact that a shock may be felt with greater severity 
beyond a mountain range than in its midst. The similar isolated 
areas of less intensity in Indiana and Illinois are also typical of 
variations due to local conformations ; were it possible to plot inten- 
sities in still greater detail there would doubtless be hundreds of 
such isolated districts all through the disturbed area. Other points 
dwelt upon were the unobstructed transmission of the vibrations 
along the parallel ridges of the range and up the valleys of the 
Connecticut and Hudson rivers; the obstruction offered by ridges, 
valleys, and strike of strata transverse to the direction of propaga- 
tion; and the rapid loss of energy in the sands and alluvial deposits 
of the northeast coast and lower Mississippi valley. The total 
land area included within the outer isoseismal is 774,000 square 
miles, and if we add only half as much more for ocean area it 
closely approximates to that given by Reclus for the great Lisbon 
earthquake. Special acknowledgement was made for valuable 
positive and negative reports received from members of the New 
England Meteorological Society through their secretary, Prof. W. 
M. Davis; they accurately fixed the limits of the disturbed area 
in New England. 
' The coseismals were plotted from the most reliable and consist- 
ent among a hundred or more good time observations, and special 
care was taken to make them conform to the actual facts, unin- 
fluenced by any preconceived theoretical ideas. Attention was 
called to certain peculiarities of these lines, such as their noticeable 
3 
