INTRODUCTION. 



" EVERY beginning is difficult ;" and to render the following 

 work, which is the beginning of our knowledge on the causes of 

 storms, the more easy to be comprehended, I have thought proper, 

 even at the expense of much repetition, to give in advance a gen- 

 eral outline of the whole theory, in one connected chain of cause 

 and .effect, following nature in her manner of operating, in pro- 

 ducing these meteors. 



The paper which was read to the British Association, in Sep- 

 tember, 1840, contains this outline ; and, as the whole work is 

 intended both to develop the cause of storms, and to exhibit the 

 manner in which, according to the strict rules of induction, the 

 development was gradually made, I present that paper here, as 

 an introduction to the whole. 



Mr. Espy's paper " On Storms," which excited much attention, 

 was appointed for half past twelve o'clock, and that hour having 

 now arrived, the President, Professor Forbes, called on Mr. Espy, 

 who commenced by stating that he had found by examining simul- 

 taneous observations in the middle of storms, and all round their 

 borders, that the wind blows inward on all sides of a storm to- 

 wards its central parts ; towards a point if the storm is round, and 

 towards a line, if the storm is oblong, extending through its longest 

 diameter. Mr. Espy stated that he had been able to investigate 

 b 



