BY 
FREDERICK GUTHRIE. 
» M M«' 
In the following investigation the word drop is used with a 
more definite meaning than that which is usually fastened to 
it. In common speech it includes every mass of liquid matter 
whose form is visibly influenced towards the spherical by the 
attraction of its parts, and whose sensible motion or tendency 
is towards the earth. This definition includes drops with 
which we ai’e not here concerned, and excludes others which 
we shall have to consider. We shall have to measure the size 
of drops ; and it can only be of avail to measure the size of such 
drops as are formed under fixed and determinable conditions. 
Many drops, according to the usual scope of the term, are 
formed under indefinite conditions. For instance, a rain-drop 
depends for its size upon such circumstances as the quantity of 
